Planet ChrisDolan

March 09, 2008

use Perl Journals

RFC: lethal - lexical exceptions for Perl (2008.03.09 8:50)

RFC: lethal - lexical exceptions for Perl
I've been scratching a long-time itch of mine, which is that while Perl allows me to use Fatal to get subroutines and built-ins to throw exceptions on failure, such a change was always done on a package-wide, rather than lexical (block) basis.

However with Perl 5.10 we have the ability to fix that, and I've put together a proof-of-concept module that enables exception-throwing subroutines on a lexical basis.

I'm looking for input into its naming, interface, and concept in general. Rather than filling up a blog post with it, you can read the node on PerlMonks.

by pjf at March 09, 2008 08:59 PM

Upgrading Trac #2 (2008.03.08 18:16)

After the migration, Trac started throwing No changeset X in repository. It took me a few minutes to figure out. The solution: resync Trac with the SVN db:

trac-admin /path/to/tracdb

by Beatnik at March 09, 2008 08:59 PM

Planet Mozilla

Michael Ventnor: Fullscreen Is Now...

Once upon a time there was a humble front-end contributor who worked on many small XUL and Javascript features for Firefox 3 like the smooth-scrolling tab bar and prefilling the find bar with the current selection. He later took on the mountainous responsibility of GTK Widget maintainer after travelling to New Zealand for his Uni holidays, but thats another story.

Anyway, in April 2007, I^H he contributed a patch to make the toolbars auto-hide themselves when in full-screen mode. It was a long and laborious process towards code review but it is now finally in the latest Firefox 3 hourly builds, and possibly in the latest nightly build.

So why is this fullscreen so incredibly awesome? For Firefox 3 we added a new read-only boolean property called window.fullScreen that can allow web applications to know whether or not you are in fullscreen mode (technically its not "new" per se, it existed in Firefox 2 but it never gave back the correct value, I just fixed that up). This can provide really great opportunities for web apps to take advantage of the new built-in fuller fullscreen. Maybe Google Presentations could start the slide show automatically when you enter fullscreen. Or maybe video sites could adjust the video size to take up the entire screen when you enter fullscreen.

Of course, I haven't forgotten my now main duty of GTK Widget maintainer. For Thunderbird users, I managed to fix the bug where dragging an image from your file manager would paste the file:// URL as text rather than embed the image. Oh, and XUL popups now properly set hints, so if you maintain a window manager, especially one with compositing, you no longer need Firefox-specific hacks; we now correctly report whether the popup is supposed to be a menu, a tooltip, or just a utility popup like Larry.

But anyway, Beta 4 is coming out soon. Like many times before, all the cool things I make just miss the beta freeze and get checked in before said beta even comes out, which makes the betas slightly less exciting than the nightlies or hourlies. Also, I hope Ted manages to turn on Profile-Guided Optimization for Linux very soon (if he hasn't done so already).

by Michael at March 09, 2008 08:59 PM

Robert Sayre: Blocker Report for March 08, 2008

Overall Status

Blocking Firefox 3: 206 bugs found.
Blocking Gecko 1.9: 175 bugs found.

Blockers fixed between 12:00am and 10:45pm

Bug 421412 Get rid of _adjustWidth hack. Patch by Edward Lee.

Bug 396548. Star icon in url bar autocomplete is partly or completely buried under scrollbar (covered, hidden). Patch by Edward Lee.

Bug 406373. Url bar results can be scrolled horizontally after scrolling vertically. Patch by Edward Lee.

Bug 421490. wpad may be dangerous, and it is on by default. Patch by Michael Ventnor.

Bug 415329. large toolbar buttons are vertically misaligned. Patch by Dão Gottwald.

Bug 417421. Loss of back forward buttons when switching between 1.8 and 1.9. Patch by Dão Gottwald.

Bug 405010. make column changes in places/library (session) persistent. Patch by Marco Bonardo.

Bug 416225. Change “Unfiled bookmarks” to “Unsorted Bookmarks”. Patch by Kurt (supernova_00).

Bug 409215. Closing tabs quickly in succession causes the close button to “get stuck” (Minefield 3.0pre3, browser.tabs.closeButtons = 1). Patch by Gavin Sharp.

Bug 412360. Download Manager remains empty, downloads don’t start, with this 3.0b2 downloads.sqlite. Patch by Edward Lee.

Bug 418961. “Save Page As” “Text Files” saves file but Downloads window doesn’t show completion. Patch by Edward Lee.

Bug 421058. Firefox won’t prompt to change stored passwords. Patch by Justin Dolske.

by rsayre at March 09, 2008 08:59 PM

Benjamin Smedberg: Has GCC Dehydra Replaced Elsa?


GCC Dehydra allows us to do analysis passes on our existing code. In the far future it may also allow us to do optimization passes. But it does not have the ability to do code rewriting, and probably won’t gain that ability any time soon. In order to be able to do C++->C++ transformations, you have to have correct end positions for all statements/tokens, not just beginning positions. GCC does not track this information, and making it do so would be a massive undertaking.

Mozilla2 still lives in a dual world where automatic code refactoring is done using the elsa/oink toolchain, while static analysis is taking place using the GCC toolchain.

by Benjamin Smedberg ( at March 09, 2008 08:59 PM

use Perl Journals

Nancy: from Lua to Perl (2008.03.09 15:13)

Some days before, Reuben Thomas (a known contributor to Lua community) announced the release of Nancy, "a simple web site builder" at the Lua mailing list.

For the dismay of Lua afficcionados, this release was not written in Lua.

Oh, and it's written in Perl. I thought it might be interesting to say why. The problem was not libraries (I used my pure-Lua stdlib and LuaFileSystem), but deployment on Windows (I use Linux). I had previously built an all-in-one binary for Windows using a cross-compiler. That worked fine but made it hard to debug on Windows as I couldn't just edit-run, and also broke nastily when the cross-compiler was upgraded. So, I switched to LuaBinaries. That enabled me in the end to deploy only pre-built binaries, but at the cost of having to install 2 binary packages, and then do manual fiddling to get .lua files run as commands by the Windows shell.

ActivePerl does all this for me, and I was already using some Perl scripts in the same system, so by rewriting Nancy in Perl I got down to "run the Perl installer" as being the prerequisites for running Nancy.

Nancy begun its life as Lua code (and that's the reason Reuben announced this at Lua mailing list for the last time — unless it be written in Lua again in the future).

Perl still has an edge ahead before some of the popular dynamical languages out there, which (I hope) is not going away anytime soon in the future.

by ferreira at March 09, 2008 08:58 PM

Unofficial Apple Weblog

Talkcast reminder, 10 pm ET tonight

Filed under: ,

If you haven't checked out last week's show yet, by all means grab a copy. We were joined by Craig Hockenberry and Gedeon Maheux from Iconfactory, who gave us the lowdown on the history of the company, the origins of Twitterrific, the coevolution of Twitter with the now-dominant Mac client, and the promise of the upcoming iPhone development explosion. Download direct, listen in your browser or subscribe to the TalkShoe feed in iTunes.

Speaking of iPhone... We are live tonight (Sunday 3/9) for this week's talkcast, 10 pm ET, talking about iPhone for enterprise and the SDK -- featuring a taped segment with Erica Sadun and Apollo IM developer Alex Schaefer, who couldn't make the regular Sunday night show but felt they had to say something after 72+ hours deep in the SDK.

Join me, Scott, Dave and Mike Schramm tonight for the social. Bring your own ice cream!

Continue reading Talkcast reminder, 10 pm ET tonight

Read | Permalink | Email this | Comments

by Michael Rose at March 09, 2008 08:57 PM

More Jim Henson classics on iTunes

Filed under:

iTunes users who also happen to be fans of a goblin David Bowie, Gelflings, Skeksis, Mystics and/or Jim Henson have reason to celebrate: two of Henson's cult classic films are now available on iTunes. The Dark Crystal and Labyrinth are now available for purchase at the iTunes Store. This comes on the heels of the Farscape and Fraggle Rock iTunes releases in January.

If you've never been able to get the cry of the Skeksis or the image of a frighteningly glam Goblin King (with fantastic hair) out of your head, pop up iTunes and make some Jim Henson magic. While you're there, you can even grab the slightly watered-down musical numbers in the Labyrinth Soundtrack to go with it, as well as a copy of The Muppet Christmas Carol, just in case the kids need some lighter fare after The Dark Crystal. Can't beat that, right?

Read | Permalink | Email this | Comments

by Brett Terpstra at March 09, 2008 08:57 PM

Macworld posts "Mac snobbery?" video

Filed under:

You may recall us posting about a recent study that found Mac users to be "Snobs." Well, Macworld has taken this study a bit further. Brian Chen, the Associate Editor, went around asking some of the staff at Macworld (including Jason Snell) what they thought about the study. They also went to the Apple store asking wandering customers outside the store what they thought about the study.
Read | Permalink | Email this | Comments

by Cory Bohon at March 09, 2008 08:57 PM

Jakob Nielsen


Company Name First in Microcontent?

March 09, 2008 08:56 PM

Perl Buzz Mechanix

Use seq or jot to do repetitive numbering

I just now had to clean up some tables in a PostgreSQL database. The prior DBA thought that it would be good to split up tables into lx1, lx2, lx3 up to lx20. After I combined all the tables together, I needed to drop the originals. I could have written a Perl program to generate a series of drop table lx1; commands to feed into the psql command-line client, but instead I used the seq tool:

$ seq -f'drop table lx%g;' 1 20
drop table lx1;
drop table lx2;
drop table lx20;

If you don't have seq on your system, as on Mac OS X, you probably have jot, as in:

jot -w'drop table lx%g;' 20 1

Then again, if you just have to do it in Perl:

perl -le'print qq{drop table lx$_;} for 1..20'

but I like to use other tools than the Swiss Army Chainsaw sometimes.

March 09, 2008 08:56 PM


German Police Raid 51 CeBIT Stands Over Patent Claims

LeCaddie writes "Last week German investigators raided 51 exhibitor stands at CeBIT, the German information technology fair in Hanover, looking for goods suspected of infringing patents. Some 183 police, customs officers, and prosecutors raided the fair on Wednesday and carried off 68 boxes of electronic goods and documents including cellphones, navigation devices, digital picture frames, and flat-screen monitors. Of the 51 companies raided, 24 were Chinese. Most of the patents concerned were related to devices with MP3, MP4, and DVB standard functions for digital audio and video, blank CDs, and DVD copiers, police said." In the US there are no criminal penalties associated with patents, and such a raid could not be conducted, especially in the absence of a court ruling of infringement.

Read more of this story at Slashdot.

by kdawson at March 09, 2008 08:40 PM

Wikileaks Calls For Global Boycott Against eNom

souls writes "The folks at Wikileaks are calling for a boycott against eNom, Inc., one of the top internet domain registrars, which WikiLeaks claims is involved in systematic domain censoring. On Feb 28th eNom shut down, one of the many Wikileaks mirrors held by a volunteer as a side-effect of the court proceedings around In addition, eNom was the registrar that shut off access to a Spanish travel agent who showed up on a US Treasury watch list. Wikileaks calls for a 'global boycott of eNom and its parent Demand Media, its owners, executives and their affiliated companies, interests and holdings, to make clear such behavior can and will not be tolerated within the boundaries of the Internet and its global community.'"

Read more of this story at Slashdot.

by kdawson at March 09, 2008 08:40 PM

Olympic Web Site Features Pirated Content

An anonymous reader writes "Despite all the emphasis on protecting Olympic copyrights in China this year, the official web site of the Beijing Olympics features a Flash game that is a blatant copy of one of the games developed at The Pencil Farm. Compare the game on the Olympic site with 'Snow Day' at The Pencil Farm."

Read more of this story at Slashdot.

by kdawson at March 09, 2008 08:40 PM

Daring Fireball


So G-Archiver is a Windows app that lets you download your archived Gmail messages. It ends up that the app emails your Gmail username and password to the author. Crazy.

by John Gruber at March 09, 2008 08:36 PM

March 08, 2008

Planet Mozillazine

Asa Dotzler: webslices and activites

Just in case the power of the Firefox platform wasn't obvious already, check out the Web Slices work from Daniel Glazman and the Activities work Mike Kaply's doing.

March 08, 2008 10:00 PM

Mac Rumors

Sun Bringing Java to iPhone

Sun announced that they are developing a Java Virtual Machine for Apple's iPhone with the newly released Software Development Kit (SDK).

"We're going to make sure that the JVM offers the Java applications as much access to the native ...

March 08, 2008 09:57 PM

iPhone SDK Limitations: Multitasking, Java, Emulators

As people delve into the details of Apple's iPhone SDK, a few interesting issues are emerging. One developer guideline that is generating some concern is from Apple's Human Interface Guidelines for iPhone:

Only one iPhone application...

March 08, 2008 09:57 PM

Planet Perl

Vanilla Perl Build 15 - Loads of new toys (14.4 MB) I'm happy to (FINALLY) release the new Vanilla Perl build 15. Vanilla Perl is the experimental Win32 Perl distribution with the mandate to do the absolute minimum amount of changes to the Perl core to get various features working. This latest experimental release contains most of the new tricks that will be in the upcoming April Strawberry Perl, and probably the biggest number of new features yet in a Vanilla release. XML::Parser This release comes with Expat and XML::Parser built in (since I still can't make XML::Parser install from CPAN itself and you can't upgrade it). So it should be possible to build a range of other stuff on top of it now (like PPM support, which is out of the scope of Vanilla). Win32::API Although it probably won't stay in Vanilla beyond this release, I've bundled in Win32::API out of the box. With Win32::API also comes (be necessity) with libwin32 bundled in as well (which is by far the biggest install from With those two installed, most of the rest of the Win32:: family should install relatively easily. Relocation This release contains experimental patches for all three configuration files that contain hard-coded paths to make them capable or handling the Perl installation being shoved around. This should also be the first release usable for people interested in creating Portable Perl type distributions for flash drives, etc. Of course, this is still an .exe installer (which Portable Perl people don't want, cause it dumps crap into the registry). This particular feature WON'T be in Strawberry Perl, but it involved adding some extra capabilities in regards to tweaking installs. libwwwperl aka LWP Because I refuse to use FTP CPAN mirrors any more (HTTP being infinitely superior in every way) Vanilla now comes with LWP out of the box. This also means that the built in CPAN mirrors can be used now, intead of it falling back on the horrible FTP defaults. Righto then... So, with Vanilla 15 working, time to move on to getting a Strawberry Beta.

Read more of this story at use Perl.

by use.perl at March 08, 2008 09:41 PM

pmtools-1.10 Release

Now at a CPAN mirror site near you — pmtools-1.10. Tom "spot" Callaway of Fedora Core let me know that the Fedora folks were concerned about the fact that pmtools was only licensed under the Perl 5 Artistic License (they were concerned about how well the Artistic License 1.0 would stand up in court). So, pmtools (starting with v1.10) is now dual-licensed like Perl (Artistic and GPL). (My other public Perl stuff is also dual-licensed.) I also added my copyright to pmtools, as I had not added my name to the copyright when I took it over. Off-hand, I don't recall why Tom Christiansen used only the Artistic License for pmtools. Anyone with a clue, please drop me a line. (That of course includes you, Tom.)

Read more of this story at use Perl.

by use.perl at March 08, 2008 09:41 PM

Slashdot Developers

Donkey Kong and Me

MBCook sends us to the blog of one Landon Dyer, who posted an entry the other day entitled Donkey Kong and Me. It describes how he was offered at job at Atari after writing a Centipede clone and ended up programming Donkey Kong for the Atari 800. It's full of detail that will be fascinating to anyone who ever programmed assembly language that had to fit into 16K, as well as portents of what was to come at Atari. "My first officemate didn't know how to set up his computer. He didn't know anything, it appeared. He'd been hired to work on Dig Dug, and he was completely at sea. I had to teach him a lot, including how to program in assembly, how the Atari hardware worked, how to download stuff, how to debug. It was pretty bad."

Read more of this story at Slashdot.

by kdawson at March 08, 2008 09:40 PM

Sun Is Porting Java To the iPhone

krquet notes an InfoWorld article on Sun's plans for the iPhone. After studying Apple's newly released SDK docs for 24 hours, Sun decided it was feasible to develop a JVM, based on Java Micro Edition, for both the iPhone and the iTouch. An analyst is quoted: "I think going forward, with the SDK, it takes out of Apple's control which applications are 'right' for the iPhone." The article doesn't speculate on how Apple might to react to such a loss of control. "Apple had not shown interest in enabling Java to run on the iPhone, but Sun plans to step in and do the job itself... The free JVM would be made available via Apple's App Store marketplace for third-party applications."

Read more of this story at Slashdot.

by kdawson at March 08, 2008 09:40 PM

Daring Fireball

The Beauty of 99¢ iPhone Apps

$.99 or $1.99 is indeed low, but I think Jens Alfke may have a point. It’s not that bigger, serious apps will sell for prices that low, but smaller, simpler apps that might otherwise have been released for free might generate real money with “cup of coffee”-level prices. It’s the App Store that makes this possible.

by John Gruber at March 08, 2008 03:35 AM

Can’t Help Falling in Love

John Siracusa:

Skilled Mac developers are uniquely positioned to be the first to market with the iPhone applications they’ve been designing in their heads since last year. They know the tools, they know the technology, they even know a lot of the APIs already, and those they don’t know look a lot like the ones they do.

by John Gruber at March 08, 2008 03:35 AM

March 07, 2008

Linux Weekly News

Bob Cringely


Do you remember Citizens' Band radio? Though established by the Federal Communications Commission in the 1950s, CB radio didn't become an overnight sensation until the 1970s when Moore's Law brought down the cost of radios to where it was economically viable to buy them solely for the purpose of breaking speed-limit laws. President Nixon, who liked to wear a blue suit and keep a cozy fire burning in his White House hearth year round no matter what the outside temperature or impact on his (our) air conditioning bill, had decided we all should drive 55 miles per hour or less to save fuel following the energy crisis of 1973. So, being true Americans, which is to say cranky and prone to complain, we en masse set out to break this new law using as our primary tool CB radio technology to warn us where Smokey was or had recently been or whether there was an eye in the sky. Criminals bound by a criminal code, we flaunted CB license restrictions (you were supposed to use your Federally assigned call sign from that license you were also supposed to have but never got) and operated under handles like "Thunderchicken" and "Boot-licker." I was "asciiboy." CB radio sales went from zero to tens of millions of units in under two years -- the highest rate of technology adoption ever seen in the U.S. before or since. Soon there was CB lore and a CB culture. CB was everywhere. When not breaking the law with it we were using CB as a huge social network to find the cheapest gas, the best hamburger or even a date for the prom. And then, quick as it started, CB was gone, worn to the bone from overuse and abuse and left to the truckers as it should have been all along. What killed CB radio was that moment when its annoyance factor exceeded its utility -- a utility already driven down by low traffic conviction rates and the eventual understanding that if everyone were a speeder then most cops wouldn't stop anyone.

I am beginning to think that Internet social networking is another CB radio, destined to crash and burn.

Social networking has a lot of problems as both a business and a cultural phenomenon. To start with there is generally no true business model. This can vary a bit from application to application but most are vying simply for eyeballs and hoping for Google ads to pay the bills until Time Warner or News Corp make them an acquisition offer they can't refuse. That might be okay for Facebook or MySpace and maybe Linked-In, but there are more than 350 general-purpose social networks out there and I will guarantee you that no more than 5 percent of those will be still operating two years from today.

If you are a social networking entrepreneur and your operation isn't among the top 10, I'd be either looking frantically for an acquirer or turning your site into a social networking aggregator, linking to many others in exactly the way the chat networks appear to be merging while still retaining their individual identities.

Then there is the annoyance factor, which for me is rapidly accelerating as the major social networks try to establish themselves as hosts for third-party applications. This would appear to be a no-brainer tactic for the two or three social networks that are likely to survive. In fact I could argue that what is more likely to survive than most social networks are the truly compelling applications that run upon them, eventually subsuming their hosts. But in the meantime there is all this annoying crap. How many groups do you have to join, how many causes do you have to support, how many silly applications do you have to run until you come to realize that you are being included TO DEATH?

My idea for the perfect Facebook app, for example, is one I call "I've Fallen and I Can't Get Up!" It's a variation on Twitter that is activated ONLY when one participant needs other participants to call 9-1-1 on his or her behalf. Maybe it could be linked to a panic button or to your cardiac pacemaker. The perfect Facebook application, then, is one you hope you'll never have to use. This is far better than the typical Facebook app, which is overused to the point where people withdraw or simply stop noticing.

It's not that I don't see value to social networks, it's that I generally don't see ENOUGH value. Yes, keeping my address book synchronized with reality is nice, but isn't that likely to be shortly absorbed into the operating system or perhaps into networked applications like Gmail and Yahoo Mail?

This trend has happened over and over as hundreds of portals came and went, leaving a few survivors. Same for hundreds of search engines, hundreds of free e-mail services, etc., etc.

Marshall McLuhan argued that obsolete communication technologies survive as art forms. This is true, I'd say, for Morse code and movable type printing and perhaps even for your venerable Rolodex or typewriter. But it isn't yet true for CB radio, nor for most Internet technologies. Maybe they aren't old enough yet to be appreciated. In the case of CB I think range of reception limits the possible population of players to something less than an artistic critical mass.

What will likely happen to social networking is that some applications will survive on a more modest basis than now (used by the trucker equivalents), others will morph into some new Next Big Thing as their more compelling sub-applications take over, and true hard-core social networkers will jump to more advanced technologies that eliminate the riff-raff. In the meantime, 70 percent or so of most social networking functionality -- the really useful functionality -- will be sucked into the dominant portal/search/e-mail/chat/social networks like MSN and Yahoo.

This next transition will happen faster than most people realize. Part of this is because Internet product cycles have been shortening for the past several years, so each generation is shorter than the one before. This hasn't mattered much because the audience has continued to expand. And even now as Internet growth in terms of new users is slowing, that's more than made up for by the shift of advertising budgets from print and broadcast to the net. So while the growth in users is decreasing, the growth in total revenue PER user is increasing. But so is the competition, hence the shorter product cycles.

The tip-off that we're nearing the end of a cycle is the flight to quality we're seeing from some of the bigger players. At Facebook, for example, you can no longer register using an e-mail address from an anonymous mail site like Mailinator, Operamail, or Countermail. Facebook demands that you take an extra three minutes and get a Yahoo Mail or AOL mail address for example. This is clearly the company pruning its subscribers in anticipation of an acquisition in the next couple quarters. There is no other reason to do it. MySpace isn't doing it despite a very real sex offender scandal, but then MySpace has already been sold and Facebook hasn't yet.

Once Facebook has been taken and one or two others, the golden era of social networking acquisitions will be over and the entrepreneurs will be headed for that Next Big Thing.

"Breaker Port 80! Do you have your ears on?"

March 07, 2008 09:58 PM

Mac Rumors

iPhone SDK Reactions and Ongoing Questions

The release of the iPhone SDK provided a lot of answers, but has also raised a number of questions, many of which will not be answerable until the iTunes App Store launches in June 2008.

The general sentiment, however, has been quite p...

March 07, 2008 09:56 PM

Mac Rumors, Page 2

DVD or CD Sharing Setup Update for Mac/PC

Apple has released DVD or CD Sharing Setup Update for Mac and PC.

This update installs software that enables remote disc sharing, system software restoration, and wireless migration with MacBook Air.

The Mac version require...

March 07, 2008 09:56 PM

Slashdot Developers

Little Demand Yet For Silverlight Developers

ericatcw writes "At its Mix08 Web development conference, Microsoft said that its Silverlight rich Internet application platform is downloaded and installed an average of 1.5 million times every day; Microsoft has a goal of 200 million installs by midyear. But Silverlight is at the beginning of a long slog towards gaining traction. Computerworld did a quick analysis of job listings at nine popular career sites and found that an average of 41 times more ads mentioned Adobe's Flash than mentioned Silverlight. As expected only 6 months after Silverlight's introduction, the number of programming books carried on was also heavily skewed in favor of Flash."

Read more of this story at Slashdot.

by kdawson at March 07, 2008 09:50 PM

Planet Perl

Catalyst: More Lessons in How Not To Write An Application

Trying to figure out the source of a method in one of our Catalyst controllers. Our controller inherited from one of our controller base classes. That, in turn, inherited from the deprecated Catalyst::Base which, in turn, does nothing but inherit from Catalyst::Controller, which inherits from three different classes. Two of those inherit from two classes each, which in turn ...

Let's see if I can figure this out our inheritance heirarchy so I can tell where that method is coming from:

        Catalyst::Base (deprecated passthrough)

Got that?

On the off chance that you're a Multiple Inheritance fanboy, I don't think I'm going to say anything right now. I'm on the verge of profanity. MI is a tool of last resort (no, I'm not saying it's always the wrong answer). Today there are so many excellent alternatives that you really have no excuse for using MI other than "I don't like change".

by Curtis Poe at March 07, 2008 09:41 PM

Planet Perl

YAPC::NA 2008 CFP Deadline Quickly Approaching

The CFP for YAPC::NA 2008 officially ends on March 15th, so get your submissions in soon. Though we actually have had an amazing number of pre-deadline submissions (typically the last few days are when the floodgates open), we could still use some more. There are spots open for talks ranging from 20 minute overviews to longer 90 minute sessions. This year, we are also doing hands-on workshops in the conference center computer lab. Any projects that want to try to recruit some new hackers should sign up for hosting one of these informal learning sessions.

Read more of this story at use Perl.

by use.perl at March 07, 2008 09:41 PM

March 06, 2008

Linux Weekly News

Focus Shift

Annotated CPAN


Net::HTTPServer does not handle large responses. To enable this support by breaking up large responses, change the _send function within: if (ref($data) eq "") { ...

to: if (ref($data) eq "") { if (length($data) > 1024) { my @data_chunks = unpack "a1024" x ((length($data)/1024)-1) . "a*", $data; foreach my $chunk (@data_chunks) { $self->_debug("SEND","_send: $chunk"); return unless defined($self->_send_data($sock,$chunk)); } } else { $self->_debug("SEND","_send: $data"); return unless defined($self->_send_data($sock,$data)); } }

by NEinwechter at March 06, 2008 09:59 PM

Josh McAdams

Perl @ Flourish

The organizers of Flourish are of course looking for attendees for their conference, but they are also looking for something else... top-notch Perl web developers. They are having a web programming showdown using a variety of languages and frameworks. Perl is on the list, but is currently under-represented. They are looking to invite the best-of-the-best in each language, preferably people who are noted contributors to the particular language or platform that they'll be developing in. Because of this demanding criteria, they are willing to talk about helping out with travel, etc. Please contact me, Josh McAdams (joshua dot mcadams at gmail dot com) if you are interested.

by jmcada at March 06, 2008 09:58 PM

Planet Mozillazine

Asa Dotzler: "activities" for firefox

If you didn't think think IE 8's "activities" were a derivative of Mozilla's microformats work then check out Mike Kapley's add-on.

March 06, 2008 09:58 PM

Gervase Markham: Breathtaking UI Award: Linksys

Six months ago I had to set up a Linksys Access Point (WAP54G) as a wireless repeater in my house, to get the wireless signal from my Wireless-G Broadband Router (WRT54G) to reach the attic. It was a painful process, and the main reason it was painful was trying to get the correct value on the repeater for the setting labelled "Remote Access Point's LAN MAC Address". This is how it knows where to send all the relayed traffic to.

How hard can this be? You go to your WRT54G router, click "Status", and there it is: a field labelled "MAC Address". Just copy that in, right? However, that's the MAC address for the wired side. So, despite the fact that the field is labelled "LAN MAC address", if you enter the MAC address the router uses on the LAN, nothing works! It's not the "LAN MAC Address" at all - it's precisely the other one, the MAC address from the Status/Wireless subtab. Doh! A "Breathtaking UI" award to Linksys, I think.

(This is a bit geeky, but I also want to document it to try and avoid anyone else having to suffer through this.)

March 06, 2008 09:58 PM

Perl Buzz Mechanix

Devel::NYTProf is the hot new profiler in town

Adam Kaplan has released a cool new profiling tool, Devel::NYTProf. It's apparently taken the formatting beauty of Devel::Cover, the code test coverage tool, and used it to identify hotspots in your code. The results are beautiful: Overview and module-level detail. There's also a report writer that provides CSV output and lets you create your own output in your own format.

I ran into a divide-by-zero error that I patched in my local copy, but other than that the results seem good. I look forward to whatever other improvements come. I'm also glad it's been released with the support of the New York Times.

March 06, 2008 09:56 PM

Other Chris Dolans

First You Need Enlightenment and Then You Need Atonement

In January, Shelray did a post about a San Francisco man suing a Catholic Hospital in Daly City for refusing to give him a sex change operation. Well apparently the hospital caved under the pressure of a court order according to an EWTN feed from CWN. This is most unfortunate but I suppose that it is encouraging that they resisted to start with. However, what is problematic is that the hospital is said to have released the following statement: “We regret any confusion that may have come from th

March 06, 2008 09:56 PM

Mac Rumors, Page 2

Apple Preparing 10.4.12 Update For Tiger?

Macenstein percolates a rumor that Apple is preparing a final update to Mac OS 10.4 "Tiger", bringing the system version to 10.4.12.

We have it on good authority (meaning this is a rumor, and “good authority” could mean anything) that...

March 06, 2008 09:56 PM

Planet Perl

Announcing IrishPulse

As I previously threatened, I’ve gone ahead and created a “Microplanet” for Irish twitterers, similar to Portland’s Pulse of PDX — an aggregator of the “stream of consciousness” that comes out of our local Twitter community: IrishPulse.

Here’s what you can do:

Add yourself: if you’re an Irish Twitter user, follow the user ‘irishpulse’. This will add you to the sources list.

Publicise it: feel free to pass on the URL to other Irish Twitter users, and blog about it.

Read it: bookmark and take a look now and again!

In terms of implementation, it’s just a (slightly patched) copy of Venus and a perl script using Net::Twitter to generate an OPML file of the Twitter followers. Here’s the source. I’d love to see more “Pulse” sites using this…

by Justin Mason at March 06, 2008 09:43 PM

Planet Perl

More companies openly supporting Perl projects

More companies are showing their support for open source projects, and I couldn't be happier about it.

Those of you following Ovid's blog on, or reading his code improvements in the perl-qa mailing list, should give thanks to the BBC for supporting his Perl work. It's not all philanthropic, of course, since the BBC wants good tools for themselves, but I love that they're letting Ovid hitch his stories to the BBC wagon. That helps give Perl some credence in the eyes of open source skeptics.

Now, as you readers of Mechanix know, Devel::NYTProf is the hot new profiler in town. Not only is the New York Times allowing code to be released, it turns out there's a blog,, where Adam Kaplan announced the module. I love that a company that's not (exactly) in the software business is blogging about their open source software work. Let's hope it's a light in the darkness that others will lend their illumination to as well.

by Andy Lester at March 06, 2008 09:43 PM

Planet Perl

Throttling qmail

This may well turn out to be another oops. Sometimes when I screw around with the mail system, it's a big win, and sometimes it's a big lose. I don't know yet how this will turn out.

Since I moved house, I have all sorts of internet-related problems that I didn't have before. I used to do business with a small ISP, and I ran my own web server, my own mail service, and so on. When something was wrong, or I needed them to do something, I called or emailed and they did it. Everything was fine.

Since moving, my ISP is Verizon. I have great respect for Verizon as a provider of telephone services. They have been doing it for over a hundred years, and they are good at it. Maybe in a hundred years they will be good at providing computer network services too. Maybe it will take less than a hundred years. But I'm not as young as I once was, and whenever that glorious day comes, I don't suppose I'll be around to see it.

One of the unexpected problems that arose when I switched ISPs was that Verizon helpfully blocks incoming access to port 80. I had moved my blog to outside hosting anyway, because the blog was consuming too much bandwidth, so I moved the other web services to the same place. There are still some things that don't work, but I'm dealing with them as I have time.

Another problem was that a lot of sites now rejected my SMTP connections. My address was in a different netblock. A Verizon DSL netblock. Remote SMTP servers assume that anybody who is dumb enough to sign up with Verizon is also too dumb to run their own MTA. So any mail coming from a DSL connection in Verizonland must be spam, probably generated by some Trojan software on some infected Windows box.

The solution here (short of getting rid of Verizon) is to relay the mail through Verizon's SMTP relay service. sends to, and let forward the mail to its final destination. Fine.

But but but.

If my machine sends more than X messages per Y time, will assume that has been taken over by a Trojan spam generator, and cut off access. All outgoing mail will be rejected with a permanent failure.

So what happens if someone sends a message to one of the 500-subscriber email lists that I host here? generates 500 outgoing messages, sends the first hundred or so through Verizon. Then Verizon cuts off my mail service. The mailing list detects 400 bounce messages, and unsubscribes 400 subscribers. If any mail comes in for another mailing list before Verizon lifts my ban, every outgoing message will bounce and every subscriber will be unsubscribed.

One solution is to get a better mail provider. Lorrie has an Earthlink account that comes with outbound mail relay service. But they do the same thing for the same reason. My Dreamhost subscription comes with an outbound mail relay service. But they do the same thing for the same reason. My account comes with an unlimited outbound mail relay service. But they require SASL authentication. If there's SASL patch for qmail, I haven't been able to find it. I could implement it myself, I suppose, but I don't wanna.

So far there are at least five solutions that are on the "eh, maybe, if I have to" list:

  • Get a non-suck ISP
  • Find a better mail relay service
  • Hack SASL into qmail and send mail through
  • Do some skanky thing with serialmail
  • Get rid of qmail in favor of postfix, which presumably supports SASL
(Yeah, I know the Postfix weenies in the audience are shaking their heads sadly and wondering when the scales will fall from my eyes. They show up at my door every Sunday morning in their starched white shirts and their pictures of DJB with horns and a pointy tail...)

It also occurred to me in the shower this morning that the old ISP might be willing to sell me mail relaying and nothing else, for a small fee. That might be worth pursuing. It's gotta be easier than turning qmail-remote into a SASL mail client.

The serialmail thing is worth a couple of sentences, because there's an autoresponder on the qmail-users mailing-list that replies with "Use serialmail. This is discussed in the archives." whenever someone says the word "throttle". The serialmail suite, also written by Daniel J. Bernstein, takes a maildir-format directory and posts every message in it to some remote server, one message at a time. Say you want to run qmail on your laptop. Then you arrange to have qmail deliver all its mail into a maildir, and then when your laptop is connected to the network, you run serialmail, and it delivers the mail from the maildir to your mail relay host. serialmail is good for some throttling problems. You can run serialmail under control of a daemon that will cut off its network connection after it has written a certain amount of data, for example. But there seems to be no easy way to do what I want with serialmail, because it always wants to deliver all the messages from the maildir, and I want it to deliver one message.

There have been some people on the qmail-users mailing-list asking for something close to what I want, and sometimes the answer was "qmail was designed to deliver mail as quickly and efficiently as possible, so it won't do what you want." This is a variation of "Our software doesn't do what you want, so I'll tell you that you shouldn't want to do it." That's another rant for another day. Anyway, I shouldn't badmouth qmail-users mailing-list, because the archives did get me what I wanted. It's only a stopgap solution, and it might turn out to be a big mistake, but so far it seems okay, and so at last I am coming to the point of this article.

I hacked qmail to support outbound message rate throttling. Following a suggestion of Richard Lyons from the qmail-users mailing-list, it was much easier to do than I had initially thought.

Here's how it works. Whenever qmail wants to try to deliver a message to a remote address, it runs a program called qmail-remote. qmail-remote is responsible for looking up the MX records for the host, contacting the right server, conducting the SMTP conversation, and returning a status code back to the main component. Rather than hacking directly on qmail-remote, I've replaced it with a wrapper. The real qmail-remote is now in qmail-remote-real. The qmail-remote program is now written in Perl. It maintains a log file recording the times at which the last few messages were sent. When it runs, it reads the log file, and a policy file that says how quickly it is allowed to send messages. If it is okay to send another message, the Perl program appends the current time to the log file and invokes the real qmail-remote. Otherwise, it sleeps for a while and checks again.

The program is not strictly correct. It has some race conditions. Suppose the policy limits qmail to sending 8 messages per minute. Suppose 7 messages have been sent in the last minute. Then six instances of qmail-remote might all run at once, decide that it is OK to send a message, and send one. Then 13 messages have been sent in the last minute, which exceeds the policy limit. So far this has not been much of a problem. It's happened twice in the last few hours that the system sent 9 messages in a minute instead of 8. If it worries me too much, I can tell qmail to run only one qmail-remote at a time, instead of 10. On a normal qmail system, qmail speeds up outbound delivery by running multiple qmail-remote processes concurrently. On my crippled system, speeding up outbound delivery is just what I'm trying to avoid. Running at most one qmail-remote at a time will cure all race conditions. If I were doing the project over, I think I'd take out all the file locking and such, and just run one qmail-remote. But I didn't think of it in time, and for now I think I'll live with the race conditions and see what happens.

So let's see? What else is interesting about this program? I made at least one error, and almost made at least one more.

The almost-error was this: The original design for the program was something like:

  1. do
    • lock the history file, read it, and unlock it
    until it's time to send a message
  2. lock the history file, update it, and unlock it
  3. send the message
This is a classic mistake in writing programs that run concurrently and update a file. The problem is that process A update the file after process B reads but before B updates it. Then B's update will destroy A's.

One way to fix this is to have the processes append to the history file, but never remove anything from it. That is clearly not a sustainable strategy. Someone must remove expired entries from the history file.

Another fix is to have the read and the update in the same critical section:

  1. lock the history file
  2. do
    • read the history file
    until it's time to send a message
  3. update the history file and unlock it
  4. send the message
But that loop could take a long time, during which no other qmail-remote process can make progress. I had decided that I wanted to try to retain the concurrency, and so I wasn't willing to accept this.

Cleaning the history file could be done by a separate process that periodically locks the file and rewrites it. But instead, I have the qmail-remote processes to it on the fly:

  1. do
    • lock the history file, read it, and unlock it
    until it's time to send a message
  2. lock the history file, read it, update it, and unlock it
  3. send the message
I'm happy that I didn't actually make this mistake. I only thought about it.

Here's a mistake that I did make. This is the block of code that sleeps until it's time to send the message:

          while (@last >= $msgs) {
            my $oldest = $last[0];
            my $age = time() - $oldest;
            my $zzz = $time - $age + int(rand(3));
            $zzz = 1 if $zzz  1;
       #    Log("Sleeping for $zzz secs");
            sleep $zzz;
            shift @last while $last[0] < time() - $time;
The throttling policy is expressed by two numbers, $msgs and $time, and the program tries to send no more than $msgs messages per $time seconds. The @last array contains a list of Unix epoch timestamps of the times at which the messages of the last $time seconds were sent. So the loop condition checks to see if fewer than $msgs messages were sent in the last $time seconds. If not, the program continues immediately, possibly posting its message. (It rereads the history file first, in case some other messages have been posted while it was asleep.)

Otherwise the program will sleep for a while. The first three lines in the loop calculate how long to sleep for. It sleeps until the time the oldest message in the history will fall off the queue, possibly plus a second or two. Then the crucial line:

            shift @last while $last[0] < time() - $time;
which discards the expired items from the history. Finally, the call to load_policy() checks to see if the policy has changed, and the loop repeats if necessary.

The bug is in this crucial line. if @last becomes empty, this line turns into an infinite busy-loop. It should have been:

            shift @last while @last && $last[0] < time() - $time;
Whoops. I noticed this this morning when my system's load was around 12, and eight or nine qmail-remote processes were collectively eating 100% of the CPU. I would have noticed sooner, but outbound deliveries hadn't come to a complete halt yet.

Incidentally, there's another potential problem here arising from the concurrency. A process will complete the sleep loop in at most $time+3 seconds. But then it will go back and reread the history file, and it may have to repeat the loop. This could go on indefinitely if the system is busy. I can't think of a good way to fix this without getting rid of the concurrent qmail-remote processes.

Here's the code. I hereby place it in the public domain. It was written between 1 AM and 3 AM last night, so don't expect too much.

by Mark Jason Dominus at March 06, 2008 09:43 PM

Surfin Safari

The Acid 3 Test

The Acid 3 Test has been officially released. The test has been in development for some time, with much of that development happening in the open.

The Acid 3 test is far more complex than the Acid 2 test. It covers a wider range of standards and consists of many more individual tests. Browsers have to render a sequence of boxes that display dynamically in a stairstep pattern. For every cluster of tests passed successfully, the boxes will fill in with a color, which signifies that all of the tests covered by that block have passed.

If you run Acid 3 on the shipping versions of current browsers (Firefox 2, Safari 3, Opera 9, IE7), you’ll see that they all score quite low. For example Safari 3 scores a 39/100. This percentage score is a bit misleading however. The situation with all four browser engines really isn’t that bad.

You can think of the Acid 3 test as consisting of 100 individual test suites. In order for a browser engine to claim one of these precious 100 points, it has to pass a whole battery of tests around a specific standard. In other words it’s like the browser is being asked to take 100 separate exams and score an A+ on each test in order to get any credit at all.

The reality is that all of the browsers are doing much better than their scores would have you believe, since the engines are often passing a majority of the subtests and experiencing minor failures that cost them the point for that section.

Shipping Safari scores a 39/100 with some significant rendering errors. We’ve been working hard since the test surfaced and are pleased to report that we’ve entered the “A” range on the test with a score of 90/100.

So what did we fix to gain so many points?

Bug 17064 has all the details, but here are the highlights.

Support for CSS3 Selectors
We added support for all of the remaining CSS3 selectors. These include selectors like nth-child, nth-of-type, last-child, last-of-type, etc. These selectors were already implemented in KHTML, and the KHTML developers had even kindly provided patches for us in the relevant WebKit bugs. Therefore it was a simple matter of taking those patches, updating them to the WebKit codebase, and then merging them in. A big thanks to the KHTML developers for their hard work in this area.

Parsing Bugs
WebKit had a number of minor parsing bugs that Acid 3 targeted. The boxes did not render properly because of an obscure parsing bug that the test exploited (thanks, Hixie). In addition a number of other parsing bugs kept us from completely passing individual tests. We have updated our parser to be much closer to the HTML5-specified parsing rules.

WebKit has also never parsed DOCTYPEs before. I re-wrote WebKit’s DOCTYPE parsing to match the HTML5 specification, and so now if you put a DOCTYPE into your page it will be present in the DOM. In addition many bugs centered around proper mode resolution (quirks vs. strict) have now been fixed. You can document.write a DOCTYPE for example in a new document and have the correct mode be selected.

Acid3 has many SVG tests. We’ve been hard at work making these tests pass. In particular SVG font support and other aspects of the SVG DOM have been tested. Many of the remaining 10 points are SVG failures. We’ll be working on SVG animation in order to pass the last few SVG tests.

Acid3 tests a lot of DOM level 2 features, like traversal and ranges. It particularly focuses on the “liveness” of objects, e.g., making sure everything updates properly when you dynamically change a document by adding/removing nodes. Most of our failures in this area had to do with not behaving properly in the presence of these dynamic changes (even though we tended to pass the more static tests).

Now that we’re closing in on 100%, we’ll be blogging about each fix as it happens, so that you can follow our progress from the blog.

by Dave Hyatt at March 06, 2008 08:29 PM

March 05, 2008

Aristotle Pagaltzis

No credit where no credit is due

John Gruber:

I do think the IE team deserves credit for having floating the idea for opt-in version targeting rather than just going ahead and implementing it.

Err, “floated the idea?” I thought what I read was an announcement of fait accompli. At no time did it strike me as though Microsoft left the issue open-ended. That they subsequently revoked their proclaimed decision came out of left field; would this have been the case if what they first did was in fact merely “floating the idea?”

I’m glad that someone inside Microsoft apparently somehow managed to overrule someone else (whoever the people involved are), but I can find no way to interpret Microsoft’s initial course of action as commendable.

Furthermore, the question Eric Meyer asked is still open: even though Microsoft reneged on the most objectionable part of the announcement, the fact that IE 8 will have three rendering modes, including a frozen-in-time one with all its implications for competitors, still stands.

March 05, 2008 10:47 PM

Linux Weekly News

Adriano Ferreira

Abusing "Memoize"

A few days ago, I was writing a code (namely the Path-Classy dist) and stared at the code that produced the file size in raw bytes or "humanized" (28300 or 28K).

sub _format_size {
  my ($sz, $opt) = @_;

  my $format = $opt->{format};
  if ( $format eq 'h' ) {
    require Numbers::Bytes::Human;
    return Number::Bytes::Human->new->format( $sz );
  else { # raw bytes
    return $sz;

Of course, loading Number::Bytes::Human and creating a instance every time $f->size({ format => 'h' }) was invoked seemed overkill. But saving the N::B::H into a class/instance variable seemed overkill too: it has nothing to do with Path::Classy (which are Path::Class ) objects but for that instant relationship to format a file property, size.

Hey, that's a chance to use memoization, splitting the formatter creation into a function and then memoizing it (so that we don't need to create a [reusable] object with the same capabilities over and over), we come to this code.

use Memoize;

sub _size_formatter {
  require Number::Bytes::Human;
  return Number::Bytes::Human->new;

sub _format_size {
  my ($sz, $opt) = @_;

  my $format = $opt->{format};
  if ( $format eq 'h' ) {
    return _size_formatter->format( $sz );

That looked elegant to me. To make it even more tight (and to require yet another CPAN module ;-) ), using Attribute::Memoize seemed right. It avoids the need to repeat the function name in the memoize call and it anticipated the wrapping up of the sub to BEGIN time (a free bonus of Attribute::Handlers in the backstage).

use Attribute::Memoize;

sub _size_formatter :Memoize {
  require Number::Bytes::Human;
  return Number::Bytes::Human->new;

That's it! Efficient code, localized behavior, no need for extra variables. Will people understand that for maintenance? I hope so.

by ferreira at March 05, 2008 09:58 PM

Adam Kennedy

Win32::File::Object - Rounding out the Win32 "experience"

I've had pretty much all the basic modules I need for a while now, which has put a damper on my release rate. No bad thing, since when you are looking after 100+ you tend to end up doing a lot more maintenance and feature additions than new coding.

I'm by and large completely happy coding Perl on Unix now.

Unfortunately, as I start to do more coding on Windows (in this case, funky Perl::Dist internals magic) I find myself back in the past a bit.

Win32::File, for example, is a horrible piece of API ugliness. It's all CamelCase and return-by-param and bit fields. Ugh...

So here I am again writing simple usability wrappers about code that does the right thing but makes you feel dirty while doing it.

Win32::File::Object is a wrapper around Win32::File, which is basically only a thin Perl/XS wrapper around the raw C API.

So now if you have some code that needs to remove a readonly flag, you can just go...

Win32::File::Object->new('file.txt', 'autowrite')->readonly(0);

The only downside of this module is that my release code can't deal with Windows code, so I'm stuck with an absolutely tortuous release process.

And given the state of Win32:: I've got a feeling this won't be the first Win32:: module I'm going to be forced to write to feel like a human being when I'm coding on Win32.

by Alias at March 05, 2008 09:57 PM

Perl Buzz Mechanix

The worst way to shorten names

Dropping vowels to shorten names is a terrible practice. Quick, someone give me an idea what $hdnchgdsp means, an Actual Variable from some Bad Code I'm working on today.

It's not just variables names, either. Filenames often need to be shortened, but dropping vowels is not the way to do it. You're left with unpronounceable names that are annoying to type.

The key to effective abbreviation is not removal of letters from the middle of the words, but from the end. Sometimes, it doesn't make sense to shorten a word at all, like "post". If you have a file that is supposed to "post audit transactions", call it "post-aud-trans" or "post-aud-trx", not "pst_adt_trns".

March 05, 2008 09:56 PM

Planet Perl

hiveminder integration with jott

Jott is a really neat service that lets you Do Stuff via your cell phone. The default Stuff you can do is "send email and SMS" and "setup a reminder." There's also a very simple API for writing your own applications (called Jott Links). It works something like this:

  1. you call the toll-free Jott number
  2. you speak the name of the Jott Link you've set up
  3. you speak a message
  4. Jott issues a web request with data including your id and the message
  5. the service does something and replies to Jott
  6. Jott sends you a reply

There are Jott Links for Twitter and other things that I don't care about. There isn't one for Hiveminder. Zak Greant made a video demonstrating Hiveminder and Jott together, which has Jott send mail to the task-by-email interface of Hiveminder. This isn't bad at all, but it puts all kinds of crap into your task, because Jott sends pretty chatty email.

I wrote a Jott Link service in about ten minutes (much of which was test time, waiting for Jott to transcribe my messages). It uses and Net::Hiveminder to create a very concise task. I need to add more features to it, but I'm in no rush. I am secretly hoping that the guys at Best Practical will write a much better version, complete with a user setup link, so that everyone can use their link, rather than running his own, each on a different server.

Here's my code:

use strict;
use warnings;
BEGIN { $ENV{HOME} = '/home/rjbs' }
use CGI qw(:standard);
use Net::Hiveminder;

my ($pw, $key) = `cat /home/rjbs/.hiveminder`;
chomp($pw, $key);

my $hm = Net::Hiveminder->new(
  email    => '',
  password => $pw,

my $user_key = url_param('userKey');
my $message  = url_param('message');

die unless lc $user_key eq lc $key;
$hm->create_task("$message\n via");

print "Content-type: text/plain\n\nCreated.";

Obviously, this is a horrible hack. Still, it means I can open my phone, hold down 5, and dictate todo items right into Hiveminder.

There are a lot of little problems with Jott, some of which strike me as significant usability issues, but they're all very fixable, and I look forward to seeing them fixed. I'll write more about them later. Here's the one that irked me the most last night: Jott says that to write a Jott Link, you should expect an HTTP POST. You do, in fact, get a POST, but all of the data is in the URL query string, not in the content of the request. Huh?

Well, whatever. All their problems are fixable, and the service looks like it will be great.

by Ricardo Signes at March 05, 2008 09:42 PM

Planet Perl

Test::Aggregate 0.07

I've just uploaded the new Test::Aggregate. The only change is that it sets the $ENV{TEST_AGGREGATE} variable to true (for VMS users: and explicitly deletes it in an END block). This allows you to do this:

die "Cannot use $0 in aggregated tests"

Blew a chunk of time yesterday trying to debug why the aggregated tests were failing. Now I can add that to some code to ensure that I'll know immediately next time.

by Curtis Poe at March 05, 2008 09:42 PM

Planet Perl

Fun with IMAP

So I've been playing with IMAP lately, processing a folder of emails to process. It has been kind of interesting (to say the least).

Those of you who follow my CPAN uploads know I created Net::IMAP::Simple::NB, which is a subclass of Net::IMAP::Simple but using non-blocking I/O. The idea for that originally was to create a webmail system for AxKit2, but it was also fun learning how IMAP works.

There are some really interesting corner issues in IMAP that surprise me. For example an IMAP server is expected to be able to parse MIME messages, and be able to provide different components of the body as requested. This seems odd to me as frankly this should be a client task - surely this slows IMAP servers down? Also when you ask for the body structure it maps it in a very odd manner - though perhaps its useful for clients - there seems to be a lot of structure data there that isn't useful. There are some other odd choices too, like dates are provided as "DD-MON-YYYY" rather than the more ISO compliant "YYYY-MM-DD" format, and email addresses are provided pre-parsed, which means if your IMAP server gets it wrong you're screwed (though I guess that isn't too common).

On the other hand there are some nice things too, like IMAP provides most of its data in an S-expressions-like format, which is quite easy to parse in perl. The RFC is also not as horrible as I had once thought, so decoding various things is reasonably easy. On the other hand, it seems Net::IMAP::Simple is a bit too simplistic, in that it doesn't parse the output formats properly, and honestly doesn't have enough methods in it (I've added 8 methods just for my one simple app).

I'll have to consider contacting the author about patches. Though I'm unsure right now if I want to have too much to do with it in the long term.

by Matt Sergeant at March 05, 2008 09:42 PM

Planet Perl

Google’s CAPTCHA - not entirely broken after all?

A couple of weeks ago, WebSense posted this article with details of a spammer’s attack on Google’s CAPTCHA puzzle, using web services running on two centralized servers:

[…] It is observed that two separate hosts active on same domain are contacted during the entire process. These two hosts work collaboratively during the CAPTCHA break process. […]

Why [use 2 hosts]? Because of variations included in the Google CAPTCHA image, chances are that host 1 may fail breaking the code. Hence, the spammers have a backup or second CAPTCHA-learning host 2 that tries to learn and break the CAPTCHA code. However, it is possible that spammers also use these two hosts to check the efficiency and accuracy of both hosts involved in breaking one CAPTCHA code at a time, with the ultimate goal of having a successful CAPTCHA breaking process.

To be specific, host 1 has a similar concept that was used to attack Live mail CAPTCHA. This involved extracting an image from a victim’s machine in the form of a bitmap file, bearing BM.. file headers and breaking the code. Host 2 uses an entirely different concept wherein the CAPTCHA image is broken into segments and then sent as a portable image / graphic file bearing PV..X file headers as requests. […]

While it doesn’t say as such, some have read the post to mean that Google’s CAPTCHA has been solved algorithmically. I’m pretty sure this isn’t the case. Here’s why.

Firstly, the FAQ text that appears on “host 1″ (thanks Alex for the improved translation!):



If you cannot recognize the image or if it doesn’t load (a black or empty image gets displayed), just press Enter.

Whatever happens, do not enter random characters!!!

If there is a delay in loading images, exit from your account, refresh the page, and log in again.

The system was tested in the following browsers: Internet Explorer Mozilla Firefox

Before each payment, recognized images are checked by the admin. We pay only for correctly recognized images!!!

Payment is made once per 24 hours. The minimum payment amount is $3. To request payment, send your request to the admin by ICQ. If the admin is free, your request will be processed within 10-15 minutes, and if he is busy, it will be processed as soon as possible.

If you have any problems (questions), ICQ the admin.

That reads to me a lot like instructions to human “CAPTCHA farmers”, working as a distributed team via a web interface.

Secondly, take a look at the timestamps in this packet trace:


The interesting point is that there’s a 40-second gap between the invocation on “Captcha breaking host 1″ and the invocation on “Captcha breaking host 2″. There is then a short gap of 5 seconds before the invocations occur on the Gmail websites.

Here’s my theory: “host 1″ is a web service gateway, proxying for a farm of human CAPTCHA solvers. “host 2″, however, is an algorithm-driven server, with no humans involved. A human may take 40 seconds to solve a CAPTCHA, but pure code should be a lot speedier.

Interesting to note that they’re running both systems in parallel, on the same data. By doing this, the attackers can

  1. collect training data for a machine-learning algorithm (this is implied by the ‘do not enter random characters!’ warning from the FAQ — they don’t want useless training data)

  2. collect test cases for test-driven development of improvements to the algorithm

  3. measure success/failure rates of their algorithms, “live”, as the attack progresses

Worth noting this, too:

Observation*: On average, only 1 in every 5 CAPTCHA breaking requests are successfully including both algorithms used by the bot, approximating a success rate of 20%. The second algorithm (segmentation) has very poor performance that sometimes totally fails and returns garbage or incorrect answers.

So their algorithm is unreliable, and hasn’t yet caught up with the human farmers. Good news for Google — and for the CAPTCHA farmers of Romania ;)

by Justin Mason at March 05, 2008 09:42 PM

Planet Perl

Perl Foundation needs new members

The Perl Foundation needs new blood. Jim Brandt writes:

Have you ever wanted to get involved in The Perl Foundation, but didn't know how? Well, now's your chance. I'm pleased to announce open self-nominations for the following TPF roles:

You can follow the links above to read descriptions of each of the positions. If you think you're a good fit for one or more of them, send me an email at cbrandt at perlfoundation dot org. I'll then invite you to a dedicated wiki we have set up just for the election.

Once you join the wiki, you'll set up a page to post all of your experience and answer the questions provided in each section above. The wiki is private, but you'll be able to see the other candidate pages, and they'll see yours.

The deadline to get all of your information in is midnight next Tuesday, March 11. Our committees elect their members, so the Conferences Committee will be voting on the CC chair and the Steering Committee will vote on the chair and PR positions. After we have a chance to look over everyone's information, we vote and select our newest members.

You only have a week, so don't wait too long. I look forward to hearing from you.

Karen Pauley is stepping up to run for Steering Committee chair, so how about you? Maybe that's a spot you'd like to work on, or maybe public relations is more up your alley. This is your chance to help lead TPF lead Perl and Perl development.

Astute followers of TPF will note that the PR spot is open, a spot that I once held. Yes, I am no longer doing PR for TPF. I've done that job for a while, and now I'm moving on to do other things, not least of which is this little news called

by Andy Lester at March 05, 2008 09:42 PM

March 04, 2008

Annotated CPAN


Net::HTTPServer also enables client side certificate checking by default without any built in interface to change this.

I've added an option to new() to set this on the fly, but as a workaround see line 825 of and change SSL_verify_mode to desired setting:

0x00 - no verification 0x01 - verify peer certificate 0x02 - fail verification if no peer certificate exists; ignored for clients 0x04 - verify client once

for more details on these options see:

by NEinwechter at March 04, 2008 09:58 PM

Other Chris Dolans

So, about that freedom of religion mentioned in the Constitution...

Guess it's another case of all animals being equal, some are more equal than others. Phooey! Daly City, CA, Mar 4, 2008 / 04:19 am (CNA).- A Catholic hospital that refused to allow its facilities to be used for breast implant surgery on a man that had undergone a sex-change operation will now allow the procedure, the California Catholic Daily reports. In 2006 a doctor told Charlene Hastings, 57, that Seton Medical Center in Daly City would not allow him to perform breast-enhancement surgery on

March 04, 2008 09:56 PM

Slashdot Apple

Paypal Advises Users To Stop Using Safari

eldavojohn writes "Over concerns for lack of an anti-phishing mechanism for Safari, Paypal is telling its Mac users to use another browser. An author from Ars Technica reveals that he has been using Camino and has fallen victim to a Paypal related phishing scam via e-mail so this story must hit home for him. 'Currently the Apple browser does not alert users to sites that could be phishing for your info, and it lacks support for Extended Validation. PayPal is, of course, a popular site among phishers in their neverending search for personal information, user IDs, and passwords. While it's not entirely fair singling out Safari (other Mac browsers like Camino also lack this support), it is perhaps at least a helpful reminder of the threat.'"

Read more of this story at Slashdot.

by Zonk at March 04, 2008 09:50 PM

Planet Perl

hiveminder and imap, now sharing a bed

Today, Best Practical announced IMAP access to Hiveminder. It's way cool, and I'm sure I'll end up making a lot of improvement to my mutt configuration tools to make the most of it. You can check out their blog post or documentation for more information, but basically you point your IMAP client at Hiveminder and you can see your todo list. You can drop new tasks (in the form of email from elsewhere) into inbound folders and you can move existing tasks into other folders to cause them to become hidden or complete. There's a bit more to it, but that's the gist.

My IMAP client of choice is OfflineIMAP, as I've said many times before. It's the easiest way for me to use mutt with IMAP, whether online or off. Unfortunately, it has a really stupid bug. Every message in an IMAP account has a unique id (the UID), which is useful for doing synchronization. It lets you figure out that you've moved a message from one place to another in your offline store. OfflineIMAP doesn't seem to keep the same UID on messages that have moved from one folder to another, which made it impossible to use the IMAP interface to mark a message done or hidden.

As usual, the guys at Hiveminder were quick to sort this out, making their correct software cope with my twitchy software.

Now, the folders in which Hiveminder presents your tasks are (I am told) great for users of GUI MUAs, where they form a nice hierarchy of folders that you can drill down through. Here's a summary of the folder layout:

  Hide for
      01 day
      01 month
Braindump mailboxes
    All tasks
    Everyone else's tasks
    Up for grabs

Here's what they look like as directories:

Actions/Hide for/Days../01 day
Actions/Hide for/Months../01 month
Braindump mailboxes/[]
Groups/pep/All tasks
Groups/pep/Everyone else's tasks
Groups/pep/Up for grabs

The amount of typing needed to move things around between these folders is a drag. Fortunately, OfflineIMAP makes it really simple to map Hiveminder's IMAP folders into a nice, shallow, easy to type hierarchy. With my OfflineIMAP configuration, it looks like this:

. /groups.pep.avail
. /take

I need to do a bit of work to make WhichConfig check $0 (or something) to notice that I want to use Hiveminder, rather than the "normal" mail available to it. Even without having done that, the IMAP interface is pretty fantastic. I see a lot of weird Maildir tricks in my future. Until I have some to publish, here's my OfflineIMAP configuration for use with Hiveminder:

.offlineimap :

pythonfile = ~/.offlineimap/

[Account hiveminder]
localrepository = hiveminder_maildir
remoterepository = hiveminder_imap

[Repository hiveminder_imap]
type = IMAP
remotehost =
ssl = yes
remoteuser =
remotepass = PASSWORD

nametrans    = lambda foldername: hm_nametrans(foldername)
folderfilter = lambda foldername: hm_folderfilter(foldername)

[Repository hiveminder_maildir]
type = Maildir
localfolders = ~/Mailhive

This relies on a few Python functions stored in another file: :

import re

hide_re = re.compile('^Actions/Hide')
spec_re = re.compile('(?P<n>\d\d) (?P<units>days?|months?)$')

def hm_folderfilter(folder):
  if folder in ('Actions', 'Groups'): return False

  if and not return False

  return True

def hm_nametrans(folder):
  if folder == 'Actions/Completed': return 'done'
  if folder == 'Actions/Take': return 'take'
  if folder == 'Actions/Take': return 'take'

  folder = re.compile('Braindump mailboxes').sub('braindump', folder)

    spec  =
    n     = int('n'))
    units ='units')

    return 'hide/%s%s' % (n, units[0:1])

  if re.compile('^Groups').search(folder):
    folder = re.compile('All tasks').sub('all', folder)
    folder = re.compile('Up for grabs').sub('avail', folder)
    folder = re.compile("Everyone else's tasks").sub('others', folder)

  return folder.lower()

by Ricardo Signes at March 04, 2008 09:42 PM

Planet Perl6

Jesse Vincent: We've released the code used to run

As part of a recent project to modernize and improve, we took the time to clean up and better abstract the various plugins we use on the backend. We've also (finally) moved all the RT extensions that make up the UI to a public SVN repository.

You can get at the code via svn://

We use the following extensions.

For authentication:
* RT-Authen-PAUSE
* RT-Authen-Bitcard
* RT-Authen-OpenID

CPAN specific UI and public bug tracking:
* RT-BugTracker
* RT-BugTracker-Public
* RT-Extension-rt_cpan_org

* RT-Extension-MergeUsers
* RT-Extension-QuickDelete

We also have a set of tools which import info from the PAUSE and
other sources into RT's Database, but we still need to clean those up a bit (removing hardcoded passwords, little things like that) before we can publish them.

If you've been hankering for a new feature in, now's the time to start sending patches. After 3 good patches, we'll grant you a commit bit to the extensions. You can start sending your patches to the address listed on the front page of


March 04, 2008 09:42 PM

Planet Perl

I've put up a quick site with the results of Acme::ReturnValue:

This page shows that Acme::ReturnValue is far from perfect because it contains a whole lot of false positives. But there are also some very funny things to be found.

I'm not sure if I'll spend much more time on Acme::ReturnValue, so I doubt that the website will see any improvements (filters, sorting, links to source code, ..). But I do plan to look at Perl::Critic::Policy::Modules::RequireEndWithOne, as suggested by Chris Dolan.

And I will set up a cronjob to generate the site (but probably only once a week - I want to spare those cycles for cpants...)

by Thomas Klausner at March 04, 2008 09:42 PM

Planet Perl

Module Updates

I've been a rather slack CPAN author for the last couple of years and haven't been updating my modules as much as I should.

But over the weekend, whilst updating the Teach-In slides for the UKUUG conference I discovered the new CPAN testers matrix and, in particular, the appalling test results for the current version of Symbol::Approx::Sub.

Obviously having major test failures in such a crucial module is a terrible state of affairs so I spent some time looking at the problem last night.

Luckily it was a relatively easy fix. It was just a test which had been written by someone (me!) whose knowledge of Perl had temporarily left them. Fixing it was simple enough, and I was able to release the first new version of Symbol::Approx::Sub for over two years. I also switched the distribution from ExtUtils::MakeMaker to Module::Build and made a few other tweaks which have improved its kwalitee.

And this morning, I saw a much happier set of test results. Which was nice.

Whilst poking around in my test results, I noticed that WWW::MakeAShorterLink was also failing far too many tests. It turns out that this is because the MASL web site no longer exists. Or, rather, it redirects to TinyURL. So I've submitted a deletion request for WWW::MakeAShorterLink. It will be removed from CPAN in the next couple of days. All of your URL-shortening needs will be handled by WWW::Shorten. And, yes, next on my list is to fix the problems in that distribution's test plan.

Many thanks must go to the CPAN testers whose is so important in revealing my inadequacies as a programmer.

by Dave Cross at March 04, 2008 09:42 PM

Planet Perl

Quick Test Hack of the Day

As part of our ongoing effort to maintain our test suite's performance, I've just added the following quick hack to source control (it needs a lot of work):

#!/usr/bin/env perl

use strict;
use warnings;
use App::Prove::State;
use List::Util 'sum';
use Lingua::EN::Numbers 'num2en';

my $prove = '.prove';
unless (-f $prove && -r _) {
    die "Cannot find or read $prove file";

my $state      = App::Prove::State->new({ store => $prove });
my $generation = $state->{_}{generation};
my $tests      = $state->{_}{tests};

my $total   = sum(map { $_->{elapsed} } values %$tests);
my $minutes = int($total / 60);
my $seconds = int($total % 60);

my $num_tests = shift || 5;

if ($num_tests > keys %$tests) {
    $num_tests = keys %$tests;

my $num_word = num2en($num_tests);

my %time_for;
while (my ($test, $data) = each %$tests) {
    $time_for{$test} = $data->{elapsed};

my @sorted_by_time_desc
        = sort { $time_for{$b} <=> $time_for{$a} } keys %time_for;

print "Generation $generation\n";
print "Total runtime approximately $minutes minutes $seconds seconds\n";
print "\u$num_word slowest tests:\n";
for (0 .. $num_tests) {
    my $test = $sorted_by_time_desc[$_];
    print "\t$time_for{$test} seconds -> $test\n";

Basically, if you use the '--state=save' option with prove, it will save the state of your tests in a .prove file. This code reads the file, tells you which generation the file is, total test suite run time in minutes and seconds and your 5 slowest tests. Pass it a number and it will tell you the X slowest tests.

Update. Here's the output from the current branch I'm working on (a slightly updated version from above):

Generation 18
Number of test programs: 58
Total runtime approximately 17 minutes 35 seconds
Five slowest tests:
        482.732247114182 seconds -> t/acceptance.t
        234.499103069305 seconds -> t/aggregate.t
        96.313854932785 seconds -> t/standards/strict.t
        66.6500070095062 seconds -> t/unit/db/migrations.t
        56.7010760307312 seconds -> t/unit/piptest/pprove/testdb.t
        13.5212490558624 seconds -> t/unit/api/builder/brand-promotions.t

by Curtis Poe at March 04, 2008 09:42 PM

Planet Perl

"Boolean" or "boolean"?

In a recent article I wrote:

... a logical negation function ... takes a boolean argument and returns a boolean result.
I worried for some time about whether to capitalize "boolean" here. But writing "Boolean" felt strange enough that I didn't actually try it to see how it looked on the page.

I looked at the the Big Dictionary, and all the citations were capitalized. But the most recent one was from 1964, so that was not much help.

Then I tried Google search for "boolean capitalized". The first hit was a helpful article by Eric Lippert. M. Lippert starts by pointing out that "Boolean" means "pertaining to George Boole", and so should be capitalized. That much I knew already.

But then he pointed out a countervailing consideration:

English writers do not usually capitalize the eponyms "shrapnel" (Henry Shrapnel, 1761-1842), "diesel" (Rudolf Diesel, 1858-1913), "saxophone" (Adolphe Sax, 1814-1894), "baud" (Emile Baudot, 1845-1903), "ampere" (Andre Ampere, 1775-1836), "chauvinist" (Nicolas Chauvin, 1790-?), "nicotine" (Jean Nicot, 1530-1600) or "teddy bear" (Theodore Roosevelt, 1858-1916).
Isn't that a great paragraph? I just had to quote the whole thing.

Lippert concluded that the tendency is to capitalize an eponym when it is an adjective, but not when it is a noun. (Except when it isn't that way; consider "diesel engine". English is what it is.)

I went back to my example to see if that was why I resisted capitalizing "Boolean":

... takes a boolean argument and returns a boolean result.
Hmm, no, that wasn't it. I was using "boolean" as an adjective in both places. Wasn't I?

Something seemed wrong. I tried changing the example:

... takes an integer argument and returns an integer result.
Aha! Notice "integer", not "integral". "Integral" would have been acceptable also, but that isn't analogous to the expression I intended. I wasn't using "boolean" as an adjective to modify "argument" and "result". I was using it as a noun to denote a certain kind of data, as part of a noun phrase. So it is a noun, and that's why I didn't want to capitalize it.

I would have been happy to have written "takes a boolean and returns a boolean", and I think that's the controlling criterion.

Sorry, George.

by Mark Jason Dominus at March 04, 2008 09:42 PM

Perl Foundation

TPF Needs You: Nominations Open for Several TPF Roles

Have you ever wanted to get involved in The Perl Foundation, but didn't know how? Well, now's your chance. I'm pleased to announce open self-nominations for the following TPF roles:

You can follow the links above to read descriptions of each of the positions. If you think you're a good fit for one or more of them, send me an email at cbrandt at perlfoundation dot org. I'll then invite you to a dedicated wiki we have set up just for the election.

Once you join the wiki, you'll set up a page to post all of your experience and answer the questions provided in each section above. The wiki is private, but you'll be able to see the other candidate pages, and they'll see yours.

The deadline to get all of your information in is midnight next Tuesday, March 11. Our committees elect their members, so the Conferences Committee will be voting on the CC chair and the Steering Committee will vote on the chair and PR positions. After we have a chance to look over everyone's information, we vote and select our newest members.

You only have a week, so don't wait too long. I look forward to hearing from you.

by Jim Brandt at March 04, 2008 01:57 AM

March 03, 2008

Focus Shift

CPAN Testers, Clotho

Homestar Runner

Mac Rumors, Page 2

Woz on MacBook Air, 3G iPhone... Reporters

Apple's co-founder, Steve Wozniak, spoke at a broadband conference in Australia. In a Q&A session with journalists, Wozniak spent some time relating his thoughts about some of Apple's newest products.

In general, he had similar though...

March 03, 2008 09:56 PM

Slashdot Apple

Woz Dumps on MacBook Air, iPhone, AppleTV

AcidAUS writes "Apple co-founder Steve Wozniak heaped less than lavish praise on the company's iPhone, MacBook Air and Apple TV products when visiting Sydney this morning. Wozniak said he was puzzled by the lack of 3G support on the iPhone and that he didn't believe the MacBook Air would be a hit."

Read more of this story at Slashdot.

by CmdrTaco at March 03, 2008 09:40 PM

Planet Perl

more code for mutt on osx

I have a fairly complicated mutt configuration. It could probably do with more streamlining, but it's pretty easy for me to update, because of the way I generate it.

Some of it, of course, comes from Addex. That's only some of it, though. Namely, the folder hooks, folder subscriptions, and a lot of the aliases. That leaves a lot of things unconfigured: default headers, folder names and locations, connection methods, helper programs (i.e., the mailcap), OpenPGP and S/MIME config, keybindings, colors, and all sorts of other little things.

A lot of these I really do want to set myself, once, by hand. I want the same basic colors everywhere, for example. A lot of other things vary from host to host. On the server to which mail mail is delivered, my mail is laid out in Courier-style Maildirs, so my inbox is in ~/Maildir/{cur,new,tmp} and one of my folders is ~/Maildir/cpan/{cur,new,tmp} and so on. On my laptop, where I sync that mail with OfflineIMAP, I end up with my inbox in ~/Maildir/INBOX/{cur,new,tmp}. Some folders are renamed, others are omitted. That affects save hooks, folder hooks, folder subscriptions, and other settings.

At work, I have an entirely different set of folders, as well as a different From header, a different sig, and other different settings. On all my machines, I have different helper applications. On my workstation at work, which I use only via ssh, I can't open images. On my laptop, I need to use a wrapper around Elsewhere, I might want to use Firefox. On some machines, I want HTML rendered with lynx, and if there's no lynx, html2text will do, and so on.

So, a lot of my mutt configuration is generated for me by little programs, either when I run mutt or when I deploy its configuration to my homedir from a git checkout.

Since it's important to know what machine I'm running on, I have a module called WhichConfig. It exports a routine, which_config that tells me what configuration to use. For the most part, this is either a hostname or "default." It works like this:

  1. if the hostname is a known hostname, use that config
  2. if we find a known string in ifconfig, use the associated config
  3. use default config

The ifconfig check is pretty crude, but very, very effective. I look for the MAC address on hosts for which I control the hardware and IP address on hosts that I don't. It's easy to change the way the test works, but so far this has always worked. Many of the rest of my tools rely on WhichConfig.

The first application is simple; my muttrc contains this line:

source `~/.mutt/which-config`

which-config just prints out a filename based on the appropriate config. That file contains settings that I just want to set by hand on each host.

A more interesting (but still very simple) helper script is folder-finder. It finds all the relevant maildirs for the current configuration and subscribes to them. It knows how to find both Courier-style and OfflineIMAP-style folders and normalize their names. It runs every time I run mutt, so that it will find folders that have been recently created. Unfortunately, mutt can't include the multi-line output of a script via the "source" directive or backticks mechanism, so I end up with this in my muttrc:

source `~/.mutt/folder-finder > ~/.mutt-folders; echo ~/.mutt-folders`

This minor inelegance is definitely worth the benefits.

Finally, there's make-mailcap. This program looks at WhichConfig and looks for known useful commands in $PATH, then reads in /etc/mailcap and dumps an output file into ~/.mutt/mailcap. This file is used as the mailcap file, which mutt uses to figure out how to view or print attachments. This is useful for dumping HTML mail to text (when it has no useful text alternative), or for opening pictures and PDFs in Preview, xv, or xpdf. Over time, I imagine I'll add more and more helpers to make-mailcap, but the most useful one is osx-preview-img. When mutt uses a helper program to open an attachment, it generally sees a specification like "lynx -dump -force_html '%s'" and replaces the %s with the name of a temporary file, which is deleted after the command exits.

In MacOS X, the way to open a file in a GUI application is usually to use the open command, like this:

$ open -a Preview some-image.jpg

The problem is that open exits nearly instantly, having send a request to Preview. mutt then deletes the temporary file, and Preview sends a SIGWTF. My helper program copies the tempfile to another location and has Preview open that. It never cleans up that tempfile, but since it's under /tmp, I know the OS will clean it up on reboot. In the future, I may look at using Mac::Glue to write a helper that won't leave clutter in /tmp, but I'm not too worried about it for now.

All of this stuff has been so useful to me that I feel like I should bundle it up and drop it on the CPAN, but I'm not sure whether (or how) anyone else would find much of it useful. I think I need to work more on it and see if it can be turned into a simple module to attach plugins to, sort of like Addex, but just for mutt configuration.

by Ricardo Signes at March 03, 2008 09:22 PM

Planet Perl

Lessons in workshop organization from Frozen Perl 2008

Dave Rolsky has written up a recap of Frozen Perl from the organizers' point of view. Some interesting tidbits:

  • 2/3rds of FP2008 expenses were paid by sponsors, keeping attendee cost low
  • Some sponsors are interested in the tax deduction; some see it as a marketing expense
  • With very low ticket prices, each additional attendee ends up being a net loss
  • A potential solution to the lightning talk machine dance could be a KVM.
  • Income $7,190 - Expenses $6,213.43 = $976.57 overage

The workshop came together beautifully. I was very impressed with what Dave & Co. pulled together.

by Andy Lester at March 03, 2008 09:22 PM

Planet Perl

Uniquely-decodable codes revisited

[ This is a followup to an earlier article. ]

Alan Morgan wrote to ask if there was a difference between uniquely-decodable (UD) codes for strings and for streams. That is, is there a code for which every finite string is UD, but for which some infinite sequence of symbols has multiple decodings.

I pondered this a bit, and after a little guessing came up with an example: { "a", "ab", "bb" } is UD, because it is a suffix code. But the stream "abbbbbbbbbb..." can be decoded in two ways.

After I found the example, I realized that I shouldn't have needed to guess, because I already knew that you sometimes have to see the last symbol of a string before you can know how to decode it, and in such a code, if there is no such symbol, the decoding must be ambiguous. The code above is UD, but to decode "abbbbbbbbbbbbbbb" you have to count the "b"s to figure out whether the first code word is "a" or "ab".

Let's say that a code is UD+ if it has the property that no two infinite sequences of code words have the same concatenation. Can we characterize the UD+ codes? Clearly, UD+ implies UD, and the example above shows that the converse is not true. A simple argument shows that all prefix codes are UD+. So the question now is, are there UD+ codes that are not prefix codes? I don't know.

[ Addendum 20080303: Gareth McCaughan points out that { "a", "ab" } is UD+ but not prefix. ]

by Mark Jason Dominus at March 03, 2008 09:22 PM

Jonathan Rockway

Sorry about the Angerwhale bugs

I've noticed a few bugs in Angerwhale these days that are annoying people. For some reason, the CAPTCHA is really hard to guess (it has to be a bug, I'm sure that I'm typing it in correctly), and of course Crypt::OpenPGP is choking on UTF-8 regularly. I found it ironic that I couldn't use my own perl software to post a rant about people misusing the perl UTF-8 flag. (Not signing the post fixed the problem; my code is mostly correct, but the modules I use are broken...)

Anyway, work on Angerwhale has been slow-going because Crypt::OpenPGP doesn't work on 5.10. This means I can't run the test suite, among other things. I need to get rid of that broken module anyway, so I will sometime this week. Then I can start actively fixing the Angerwhale weirdness and push out a new version.

For now, sorry for the brokenness. It will be fixed Real Soon Now.

by Jonathan Rockway ( at March 03, 2008 09:22 PM

Lawrence Watt-Evans

Class is in Session

Back in 2001, I posted a bunch of mini-essays about class in the United States in my newsgroup on SFF Net — six of them in all, though I’d originally planned on seven to nine; I got distracted before I finished.

I’m planning to repost them here, somewhat edited and updated, as much for my own amusement as anything else, but I welcome comments.

I don’t have a hard and fast schedule for when they’ll appear here, but I thought I’d let any readers know they’re coming.

by lawrence at March 03, 2008 06:33 AM

March 02, 2008

Planet Perl

Time::Piece 0.13 released

Some of you may know that Time::Piece became part of perl 5.10. Anyone one of the things discovered was that I accidentally dropped a BSD copyright off one of the XS functions. This is now added back in. I also added an add_months() and add_years() set of functions, to make date arithmetic a bit easier.

This was interesting seeing what happens with the edge-case dates. It seems that when you do 31st March + 1 month you end up with 1st May. This mirrors what other date libraries appear to do. I documented the gotcha.


by Matt Sergeant at March 02, 2008 09:42 PM

Jonathan Rockway

Fuck the internal representation

I often see people (including myself) write code like this:

utf8::encode($data_to_print) if utf8::is_utf8($data_to_print);

This results in irritating bugs, because it's incorrect and doesn't even make sense.

Perl can store text as either latin-1 or utf8 internally. For a string like ほげ, the internal representation will be utf8, because you definitely can't represent Japanese in latin-1. However (and this is where problems crop up), something like ü (written as "\xfc") will be represented as latin-1, even if you use utf8.

This is not something that should concern you, but when you check utf8::is_utf8, you've just made Perl's internals your problem. You want to convert to utf8 regardless of the internal representation, but your code only converts if the string is already utf8. If the string isn't utf8, you're saying you don't want to convert it? What!?

The key is to drop the if condition. Always encode to utf8 if you want utf8!

print {$the_web_browser} Encode::encode('utf8', $some_string);

Please stop checking utf8::is_utf8. Fuck the internal representation!

by Jonathan Rockway ( at March 02, 2008 09:42 PM

March 01, 2008

Adam Kennedy

Allocating a timeslice to PITA

With all the changes for the Strawberry April release mostly working now (I just need to generate the beta release now) and my PITA talk at the Go Open conference in Norway officially in the program, it's time again to try and make the next push on getting PITA running actual productive tests.

The good news is that I think I now have enough information together to generate live testing images. After some consulting with various sysadmin types, we've come up with the following.

To turn a system image into a PITA image, we'll be using a hook into SysV init.

This is in the form of an S98PITA that runs just before logins are enabled, but after networking and all services are running. And, more importantly, after the "injector" (payload) disk image has been mounted already.

The PITA init script will look for the image.conf config file in the root of the mount directory.

If the config file exists, the script assumes the system is running in testing mode, and will spawn the PITA::Image image manager object and run it, which will then do the testing or other task.

If the config file does NOT exist, the init script assumes that the image is being booted in "maintenance mode", and shortcut to null, allowing normal boot up of the system.

Obviously this only works with SysV Init, but that covers the scode of the initial OS we want to get running.

This solution does, however, allow a system image to be easily maintained and update, as you can just boot the image up as a regular VM and it should work completely normally.

Only if it discovers the payload does the system switch to fully automated mode, run the tests, then shut itself down.

You can see the current prototype of the init script here...

If you'd like to assist setting me up some images (since I'm not an amazing sysadmin) I'll try to hang out on #pita as much as possible.

Any sysadmin one-off help to set up an OS image would be greatly appreciated.

by Alias at March 01, 2008 09:57 PM

use Perl journals

Planet Perl

Dutch Perl Workshop, part 2

After staying at Wendy and Liz' (and visting a cave (!) in the Dutch mountains (!!)) I stayed a night at Mark & Cleos place.

Their 1.5 years old son Tycho is very cute (but I'm still happy that my kids are already older...). I managed to get most of my slides done while staying there.

On Thursday evening we prepared the venue for the Workshop (including setting up Wendys huge collection of Perl books). Then a aprox 10 attendees had some chinese food at Marks place. Then we went back to the venue, for more preparation, Fluxx and Whisk(e)y.

A tiny bit after midnight I was done with all my slides (even for the talk I only agreed upon a few hours ago, and a lightning talk), so I started working on Acme::ReturnValue. After finishing a first version I want to bed way to late.

The workshop itself was very nice. Jonathans talk on Perl6 Internals was very interesting (and it prompted me to install Perl6 on my laptop - hard to belive, but things like

perl6 -e 'say "Hello World!"'

I used my new wireless presenter thingy to remote-control my computer during my presentation, which was very nice.

Here are my talks (and their slides):

The evening was spend (as usual) with Fluxx, Whisk(e)y and Cake. I very much enjoyed my stay in the Netherlands. Everybody was very hospitable and I had a lod of fun speaking fake dutch

But I also look forward to beeing home again and spend some time with my family...

by Thomas Klausner at March 01, 2008 09:41 PM

Planet Parrot

chromatic: The Difference Between a Program and a Script

The difference between a program and a script isn't as subtle as most people think. A script is interpreted, and a program is compiled.

Of course, there's no reason you can't write a compiler that immediately executes the compiled form of a program without writing compilation artifacts to disk, but that's an implementation detail, and precision in technical matters is important.

Though Perl 5, for example, doesn't write out the artifacts of compilation to disk and Java and .Net do, Perl 5 is clearly an interpreter even though it evaluates the compiled form of code in the same way that the JVM and the CLR do. Why? Because it's a scripting language.

Okay, that's a facetious explanation.

The difference between a program and a script is if there's native compilation available in at least one widely-used implementation. Thus Java before the prevalence of even the HotSpot JVM and its JIT was a scripting language and now it's a programming language, except that you can write a C interpreter that doesn't have a JIT and C programs become scripts.


Of course, if someone were to write an extra optimizer step for Perl 5 to evaluate certain parts of the optree and generate native code in memory on certain platforms without writing it out to disk (uh oh...) and then execute that code under certain conditions, all Perl 5 scripts would automatically turn into programs.

You know, like .pmc files, or Python's .pyc files. Uh.

As well, if more people use Punie (Perl 1 on Parrot) this year than native Perl 1 -- a possibility -- then Perl 1 scripts automatically become Perl 1 programs becaues Punie can use Parrot's JIT. I don't know if this powerful upgrade from script to program is retroactive, but I see no reason why not.

Perl 5 scripts were briefly programs while Ponie was viable, but the removal of the code from the Parrot tree has now downgraded them back to scripts. We apologize for the inconvenience.

To summarize, if you have a separate compilation step visible to developers, you have programs. If not, you have scripts. An exception is that if you have a separate, partial compilation step at runtime and not visible to users, then you may have programs. The presence of one implementation that performs additional compilationy thingies at runtime instantly upgrades all scripts to programs, while the presence of an interpreter for a language in which people normally write programs, not scripts, does not downgrade programs to scripts. Program-ness is sticky.

I hope this is now clear.

Ironically some JavaScript implementations have JITs, so the colloquial name of the language should change from JavaScript to JavaProgram.

Script bad, four-legs good.

March 01, 2008 09:41 PM

February 29, 2008

Bob Cringely

Azul Means (Big) Blue

In a triumph of PR right up there with suggesting that Intel executives ever badgered Microsoft executives into doing anything, IBM this week introduced a new generation of mainframe computers. The IBM System z10 is smaller, faster, cooler, has more memory, more storage -- more of everything in fact -- and all that is crammed into less of everything than was the case with the z9 machine it replaces. Touted as more of a super-duper virtualization server than traditional big iron, the only problem with the z10 is that every bit of its superior performance can be easily attributed to Moore's Law. The darned thing actually should be faster than it is. There's a mainframe revolution going on all right, but it's not at IBM. The real mainframe revolt is taking place inside your generic Linux box, as well as at an outfit called Azul Systems.

I'm perfectly happy for IBM to introduce a great new mainframe computer. It's just that the 85 percent faster, 85 percent smaller and a little bit cheaper z10 is coming three years after the z9, and Moore's Law says sister machines that far apart ought to be 200 percent faster, not 85 percent -- a fact that IBM managed to ignore while touting the new machine's unsubstantiated equivalence to 1,500 Intel single-processor servers.

Where were the hard questions? Did anyone do the math? The tricked-out z10 that's the supposed equivalent of 1,500 beige boxes costs close to $20 million, which works out to $13,333 per beige box -- hardly a cost savings. Even taking into account the data center space savings, power savings, and possibly (far from guaranteed) savings on administration, the z10 really isn't much of a deal unless you use it for one thing and one thing only -- replacing a z9.

So the newfangled mainframe is really just an oldfangled mainframe after all, which I am sure is comforting for folks who like to buy oldfangled mainframes.

But those sketchily described IBM benchmarks are, themselves, dubious. IBM never fully explains its own benchmarks nor does it even allow others to benchmark IBM mainframe computers. So nobody really knows how fast the z10 is or how many Intel boxes it can replace if those boxes are actually DOING something.

Remember the stories folks like me wrote a few years back about an earlier IBM mainframe running 40,000+ instances of SUSE Linux under VM on one machine? I wonder how many of those 40,000 parallel Linux images were simultaneously running Doom? My guess is none were.

Far more interesting to me is the vastly increasing utility of Linux as what I would consider a mainframe-equivalent operating system, primarily due to the open source OS's newfound skill with multiple threads that goes a long way toward making efficient use of those multi-core processors we all are so excited to buy yet barely use.

As I wrote a few weeks ago in a column on semiconductor voltage leakage of all things, all this multi-core stuff is really about keeping benchmark performance up while keeping clock speeds down so the CPUs don't overheat. Unlike the benchmark programs, most desktop applications still run on a single processor core and have no good way to take efficient advantage of this extra oomph.

But that's changing. Linux used to be especially bad at dealing with multiple program threads for example -- so bad the rule of thumb was it simply wasn't worth even trying under most conditions. But that was with the archaic Linux 2.4 kernel. Now we have Linux 2.6 and a new library called NPTL or Native POSIX Thread Library to change all that.

NPTL has been in the enterprise versions of Red Hat Linux for a while, but now it is here for the rest of us, too. With NPTL, hundreds of thousands of threads on one machine are now very possible. And where it used to be an issue when many threads competed for data structures (think about 1,000 threads all trying to update a hash table), we now have data structures where no thread waits for any other. In fact, if one thread gets swapped out before it's done doing the update, the next thread detects this and helps finish the job.

The upshot is superior performance IF applications are prepared to take advantage.

"My e-mail application runs on a four-core Opteron server," says a techie friend of mine, "but I've seen it have over 4,000 simultaneous connections - 4,000 separate threads (where I'm using "thread" to describe a lightweight process) competing for those four CPU's. And looking at the stats, my CPUs are running under five percent almost all the time. This stuff really has come a long way."

But not nearly as far as Azul Systems has gone in ITS redefinition of the mainframe -- extending further than any other company, as far as I can tell, models for thread management and process concurrency.

Azul makes custom multi-core server appliances. You can buy a 14u Azul box with up to 768 processor cores and 768 gigabytes of memory. The processors are of Azul's own design, at least for now.

But what's a server appliance? In the case of Azul, the appliance is a kind of Java co-processor that sits on the network providing compute assistance to many different Java applications running on many different machines.

Java has always been a great language for writing big apps that can be virtualized across a bunch of processors or machines. But while Java was flexible and elegant, it wasn't always very fast, the biggest problem being processor delays caused by Java's automatic garbage collection routines. Azul handles garbage collection in hardware rather than in software, making it a continuous process that keeps garbage heap sizes down and performance up.

Language geeks used to sit around arguing about the comparative performance of Java with, say, C or C++ and some (maybe I should actually write "Sun") would claim that Java was just as fast as C++. And it was, for everything except getting work done because of intermittent garbage collection delays. Well now Azul -- not just with its custom hardware but also with its unique multi-core Java Virtual Machine -- has made those arguments moot: Java finally IS as fast as C++.

But for that matter there is no reason to believe that Azul's architecture has to be limited to Java, either, and can't be extended to C++, too.

To me what's exciting here is Azul's redefinition of big iron. That z10 box from IBM, for example, can look to the network like 1,500 little servers running a variety of operating systems. That's useful to a point, but not especially flexible. Azul's appliance doesn't replace servers in this sense of substituting one virtualized instance for what might previously have been a discrete hardware device. Instead, Azul ASSISTS existing servers with their Java processing needs with the result that fewer total servers are required.

Servers aren't replaced, they are made unnecessary at a typical ratio of 10-to-one, according to Azul. So what might have required 100 blade servers can be done FASTER (Azul claims 5-50X) with 10 blade servers and an Azul appliance. Now that Azul box is not cheap, costing close to $1,000 per CPU core, but that's comparable to blade server prices and vastly cheaper than mainframe power that isn't nearly as flexible.

And flexibility is what this is all about, because Azul's assistance is provided both transparently and transiently. Java apps don't have to be rewritten to accept assistance from the Azul appliance. If it is visible on the network, the appliance can assist ANY Java app, with that assistance coming in proportion to the amount of help required based on the number of cores available.

Now imagine how this would work in a data center. Unlike a traditional mainframe that would take over from some number of servers, the Azul box would assist EVERY server in the room as needed, so that you might need a big Azul box for every thousand or so servers, with that total number of servers dramatically diminished because of the dynamically shared overhead.

This is simply more efficient computing -- something we don't often see.

There are other concurrency architectures out there like Appistry (which I wrote about back when it was called Tsunami before we unfortunately HAD a Tsunami -- what sort of marketing bad luck is that?). But where Appistry spreads the compute load concurrently across hundreds or thousands of computers, Azul ASSISTS hundreds or thousands of servers or server images with their compute requirements as needed.

Bear Stearns runs its back office with Azul assistance, but many customers use Azul boxes to accelerate their websites.

Since I am not a big company guy who cares very much about what big companies do, what I see exciting about Azul's approach is how it could be applied in the kinds of data centers where I am typically renting either virtual or dedicated servers. If an Azul box were installed on that network, my little app would instantly and mysteriously run up to 50 times faster.


February 29, 2008 09:58 PM


Perl & The Leap Year Day Babies

The Register today (29th Feb 2008), has highlighted an all too common issue for several thousand people. Their birthdays fall on the leap day of a leap year. To emphasise their plight they have written a snippet of perl code to show how easy it is to get the number of days in a year. Obviously it might be a little more robust if they use something like DateTime, but the general rule is there. They have now taken on Toys R Us and Microsoft to fix the problem in their websites and software respectively. I wish them luck :)

by barbie at February 29, 2008 09:57 PM

Nicholas Clark

spaces is a waste of space

So, it seems that every time I switch workspace, Spaces helpfully decides that I want Finder as the front most application. How useful.

This makes Spaces a waste of space.

Dear lazyweb, which virtual desktop system is useful?

by nicholas at February 29, 2008 09:56 PM

Other Chris Dolans

A northern Uganda reading list

I am often asked for recommended reading on the war in northern Uganda. The literature is vast, but a few works on culture, politics and history stand out. For history and analysis of the war, this ACORD volume presents the evolution of the war (and previous attempts at peace) from the perspective of numerous Ugandans. Also very good is the background material in this report by Tim Allen. This report from the Refugee Law Project (RLP) at Makerere University provides another fine analysis of the

February 29, 2008 09:56 PM

Planet Parrot

chromatic: Perl 6 Design Minutes for 27 February 2008

The Perl 6 design team met by phone on 27 February 2008. Larry, Allison, Patrick, Will, Jerry, Jesse, Nicholas, and chromatic attended.


  • very busy with my day job right now
  • clarified that multis and protos are automatically exported by default
  • assumed that there's is export on them
  • you have to declare them with my to get non-exported versions
  • made some changes and defined something called interface versions
  • subset of the version number
  • the patchlevel doesn't matter when you require something with language tweaks
  • only the interface version
  • doing a lot of cleanup of
  • dekludging various things
  • made a separate regular expression grammar
  • derived from the Perl grammar
  • allows us to override things like whitespace rules
  • we use derivation for its original intent
  • did a lot of work on the gimme program that translate that
  • cleanups came from noticing badness when I tried to run the Perl 5
  • plenty of feedback from Patrick, Jonathan, and the rest of the gang
  • added some rules to to add hooks for having an interactive parser that knows when you're done with user input
  • the vws rule for vertical whitespace


  • the Parrot release went very smoothly
  • compliments to everyone who put together release notes and updated things for me
  • spent the weekend in Brussels at FOSDEM 2008
  • my Perl 6 talk seems to have been well received
  • lots of compliments and comments and renewed enthusiasm
  • spent some time on the plane looking into getting Rakudo to use Parrot's HLL directives
  • it'll take some refactoring to get some of the classes working there
  • just methods and the way things get stored in namespaces


  • let's create a branch for that


  • that's a good idea
  • probably just a branch to play in, then switch over in the trunk
  • probably doable incrementally
  • did some work on trying to improve the state of Unicode in Parrot
  • want to use more Unicode in Rakudo
  • get string tests passing, use French quotes
  • I'm a little concerned that applying the patch will slow things down until we can do things in something other than UTF-8
  • otherwise applying patches and keeping up with the excellent work done by Jonathan, Jerry, and others
  • all of the changes have been really nice lately


  • working on the security PDD
  • have a long list of features that we I include
  • working on deciding a necessary and sufficient set of security features for the 1.0 release
  • need the most useful features for our target contexts and target languages
  • otherwise we could spend three years implementing security features


  • enjoying some peanut chocolate-coated candies
  • updated p6doc before the release
  • I don't think anyone's really using it yet though
  • removed some deprecated compiler directives from Rakudo's grammar
  • now that we have fudge working
  • working on a patch to allow you to write Rakudo runtime libraries in Perl 6
  • Zev Benjamin sent the patch to the list
  • it had some bugs, but most of those are fixed
  • there seems to be one cross-compiler problem remaining
  • made some progress on a YAML dumper to use for dumping AST match objects
  • committed a config patch to detect gettext so we can work toward internationalizing Parrot


  • talked to Mitchell Charity about the state of Pugs
  • he's looking into a way to extract a standardized AST for all of the various Pugsian implementations for anyone to play with different backends
  • a little glue around the kp6 AST to target from either end
  • hopefully let the various folks in the Pugs community actually interoperate
  • instead of having a half-dozen half-implemented full stacks hanging around


  • working on GC problems
  • have a workaround I think fixes things
  • sort of expensive, but we need to rethink part of our strategy
  • workaround will probably stick around until we revise the GC in a couple of months
  • did some profiling; think I'll tackle PIR profiling next


  • found a bug in Perl 1 configure and patched it


  • do you have someone to bounce your security ideas off of?
  • it would help me to have this more visible
  • I don't want it to slow you down


  • this is just the initial draft
  • the whole list will get to see and review the draft
  • or do you want to see the mental process of what I consider and discard?


  • I just wonder if you would have an easier time deciding what we need for 1.0 if you could discuss pros and cons with someone


  • I've been trying to write the PDD as a single coherent set of things
  • haven't written pros and cons within the PDD
  • otherwise it'll end up about 20 pages long
  • so many different approaches for the same thing


  • years ago, docs/dev/ was the place for those


  • I'll probably push the current document out today or tomorrow
  • we'll start a series of discussions about various different topics
  • a lot of it depends on what language implementors and application designers want
  • the biggest thing I want is people asking for missing features and telling me they don't want other features
  • what I'm doing is the core seed of that process


  • hopefully interested people will read these minutes or a weblog post


  • I'll do my usual post to the mailing list


  • maybe you could post it to your journal


  • which journal?
  • I've been thinking of setting up a dedicated Parrot blog

February 29, 2008 09:42 PM

Planet Perl


FOSDEM last weekend was huge - 4000 geeks and hundreds of speakers. Lots of interesting talks in the hallways and I particularly liked the JRuby talk as an example of how an open source project can continue without its founders. I really didn't like Patrick's Perl 6 talk: a lot of it was along the lines of "Perl 5 doesn't have this, but Perl 6 will" with examples which Perl 5.10 actually has, or "Perl 6 has feature X (e.g. threads) built in from the beginning" which is completely untrue. It was a bit sad really, but at least the room was mostly full so people haven't completely written off Perl.

by Leon Brocard at February 29, 2008 09:42 PM

Planet Perl

On the effects of lowering your SpamAssassin threshold

So I was chatting to Danny O’Brien a few days ago. He noted that he’d reduced his Spamassassin “this is spam” threshold from the default 5.0 points to 3.7, and was wondering what that meant:

I know what it means in raw technical terms — spamassassin now marks anything >3.7 as spam, as opposed to the default of five. But given the genetic algorithm way that SA calculates the rule scoring, what does lowering the score mean? That I’m more confident that stuff marked ham is stuffed marked ham than the average person? That my bayesian scoring is now really good?

Do people usually do this without harmful side-effects? What does it mean about them if they do it?

Does it make me a good person? Will I smell of ham? These are the things that keep me awake at night.

It’s a good question! Here’s what I responded with — it occurs to me that this is probably quite widely speculated about, so let’s blog it here, too.

As you tweak the threshold, it gets more or less aggressive.

By default, we target a false positive rate of less than 0.1% — that means 1 FP, a ham marked as spam incorrectly, per 1000 ham messages. Last time the scores were generated, we ran our usual accuracy estimation tests, and got a false positive rate of 0.06% (1 in 1667 hams) and a false negative rate of 1.49% (1 in 67 spams) for the default threshold of 5.0 points. That’s assuming you’re using network tests (you should be) and have Bayes training (this is generally the case after running for a few weeks with autolearning on).

If you lower the threshold, then, that trades off the false negatives (reducing them — less spam getting past) in exchange for more false positives (hams getting caught). In those tests, here’s some figures for other thresholds:

SUMMARY for threshold 3.0: False positives: 290 0.43% False negatives: 313 0.26%

SUMMARY for threshold 4.0: False positives: 104 0.15% False negatives: 1084 0.91%

SUMMARY for threshold 4.5: False positives: 68 0.10% False negatives: 1345 1.13%

so you can see FPs rise quite quickly as the threshold drops. At 4.0 points, the nearest to 3.7, 1 in 666 ham messages (0.15%) will be marked incorrectly as spam. That’s nearly 3 times as many FPs as the default setting’s value (0.06%). On the other hand, only 1 in 109 spams will be mis-filed.

Here’s the reports from the last release, with all those figures for different thresholds — should be useful for figuring out the likelihoods!

In fact, let’s get some graphs from that report. Here is a graph of false positives (in orange) vs false negatives (in blue) as the threshold changes…

and, to illustrate the details a little better, zoom in to the area between 0% and 1%…

You can see that the default threshold of 5 isn’t where the FP% and FN% rates meet; instead, it’s got a much lower FP% rate than FN%. This is because we consider FPs to be much more dangerous than missed spams, so we try to avoid them to a higher degree.

An alternative, more standardized way to display this info is as a Receiver Operating Characteristic curve, which is basically a plot of the true positive rate vs false positives, on a scale from 0 to 1.

Here’s the SpamAssassin ROC curve:

More usefully, here’s the ROC curve zoomed in nearer the “perfect accuracy” top-left corner:

Unfortunately, this type of graph isn’t much use for picking a SpamAssassin threshold. GNUplot doesn’t allow individual points to be marked with the value from a certain column, otherwise this would be much more useful, since we’d be able to tell which threshold value corresponds to each point. C’est la vie!

(GNUplot commands to render these graphs are here.)

by Justin Mason at February 29, 2008 09:42 PM

Planet Perl

SVN::Notify 2.70: Output Filtering and Character Encoding

I’m very pleased to announce the release of SVN::Notify 2.70. You can see an example of its colordiff output here. This is a major release that I’ve spent the last several weeks polishing and tweaking to get just right. There are quite a few changes, but the two most important are imporoved character encoding support and output filtering.

Improved Character Encoding Support

I’ve had a number of bug reports regarding issues with character encodings. Particularly for folks working in Europe and Asia, but really for anyone using multibyte characters in their source code and log messages (and we all do nowadays, don’t we?), it has been difficult to find the proper incantation to get SVN::Notify to convert data from and to their proper encodings. Using a patch from Toshikazu Kinkoh as a starting-point, and with a lot of reading and experimentation, as well as regular and patient tests on Toshikazu’s and Martin Lindhe’s production systems, I think I’ve finally got it nailed down.

Now you can use the --encoding (formerly --charset), --svn-encoding, and --diff-encoding options—as well as --language—to get SVN::Notify to do the right thing. As long as your Subversion server’s OS supports an appropriate locale, you should be golden (mine is old, with no UTF-8 locales :\). And if all else fails, you can still set the $LANG environment variable before executing svnnotify.

There is actually a fair bit to know about encodings to get it to work properly, but if you use UTF-8 throughout and your OS supports UTF-8 locales, you shouldn’t have to do anything. You might have to set --language in order to get it to use the proper locale. See the new documentation of the encoding support for all the details. And if you still have problems, please do let me know.

Output Filtering

Much sexier is the addition of output filtering in SVN::Notify 2.70. I got pretty tired of getting feature requests for what are essentially formatting modifications, such as this one requesting support for KDE-style keyword support. I myself was using Trac wiki syntax in commit messages on a recent project and wanted to see them converted to HTML for messages output by SVN::Notify::HTML::ColorDiff.

So I finally sat down and gave some though on how to implement a simple plugin architecture for SVN::Notify. When I realized that it was generally just formatting that people wanted, it became simpler: I just needed a way to allow folks to write simple output filters. The solution I came up with was to just use Perl. Output filters are simply subroutines named for the kind of output they filter. They live in perl packages. That’s it.

For example, say that your developers write their commit log messages in Textile, and rather than receive them stuck inside <pre> tags, you’d like them converted to HTML. It’s simple. Just put this code in a Perl module file:

package SVN::Notify::Filter::Textile;
use Text::Textile ();

sub log_message {
    my ($notifier, $lines) = @_;
    return $lines unless $notify->content_type eq 'text/html';
    return [ Text::Textile->new->process( join $/, @$lines ) ];

Put the file, SVN/Notify/Filter/ somewhere in a Perl library directory. Then use the new --filter option to svnnotify to put it to work:

svnnotify -p "$1" -r "$2" --handler HTML::ColorDiff --filter Textile

Yep, that’s it! SVN::Notify will find the filter module, load it, register its filtering subroutine, and then call it at the appropriate time. Of course, there are a lot of things you can filter; consult the complete documentation for all of the details. But hopefully this gives you a flavor for how easy it is to write new filters for SVN::Notify. I’m hoping that all those folks who want featurs can now stop bugging me and writing their own filters to do the job, and uploading them to CPAN for all to share!

To get things started, I scratched my own itch, writing a Trac filter myself. The filter is almost as simple as the Textile example above, but I also spent quite a bit of time tweaking the CSS so that most of the Trac-generated HTML looks good. You can see an example right here. Thanks to a number of bug fixes in Text::Trac, as well as Trac-specific CSS added via a filter on CSS output, it works beautifully. If I’m feeling motivated in the next week or so, I’ll create a separate CPAN distribution with just a Markdown filter and upload it. That will create a nice distriution example for folks to copy to creat their own. Or maybe someone on the Lazy Web Will do it for me! Maybe you?

I wish I’d thought to do this from the beginning; it would have saved me from having to add so many features/cruft to SVN::Notify over the years. Here’s a quick list of the features that likely could have been implemented via filters instead of added to the core:

  • --user-domain: Combine the SVN username with a domain for the From header.
  • --add-header: Add a header to the message.
  • --reply-to: Add a specific header to the message.
  • SVN::Notify::HTML::ColorDiff: Frankly, looking back on it, I don’t know why I didn’t just put this support right into SVN::Notify::HTML. But even if I hadn’t, it could have been implemented via filters.
  • --subject-prefix:: Modify the message subject.
  • --subject-cx: Add the commit context to the subject.
  • --strip-cx-regex: More subject context modification.
  • --no-first-line: Another subject filter.
  • --max-sub-length: Yet another!
  • --max-diff-length: A filter could truncate the diff, although this might be tricky with the HTML formatting.
  • --author-url: Modify the metadata section to add a link to the author URL.
  • --revision-url: Ditto for the revision URL.
  • --ticket-map: Filter the log message for various ticketing system strings to convert to URLs. This also encompasses the old --rt-url, --bugzilla-url, --gnats-url, and --jira-url options.
  • --header: Filter the beginning of the message.
  • --footer: Filter the end of the message.
  • --linkize: Filter the log message to convert URLs to links for HTML messages.
  • --css-url: Filter the CSS to modify it, or filter the start of the HTML to add a link to an external CSS URL.
  • --wrap-log: Reformat the log message for HTML.

Yes, really! That’s about half the functionality right there. I’m glad that I won’t have to add any more like that; filters are a much better way to go.

So download it, install it, write some filters, get your multibyte characters output properly, and enjoy! And as usual, send me your bug reports, but implement your own improvements using filters!

by David Wheeler ( at February 29, 2008 09:42 PM

Slashdot Apple

Mac OS X Secretly Cripples Non-Apple Software

spikedLemur writes "Vladimir Vukicevic of the Firefox team stumbled upon some questionable practices from Apple while trying to improve the performance of Firefox. Apparently, Apple is using some undocumented APIs that give Safari a significant performance advantage over other browsers. Of course, "undocumented" means that non-Apple developers have to try and reverse-engineer these interfaces to get the same level of performance. You really have to wonder what Apple is thinking, considering the kind of retaliation Microsoft has gotten for similar practices.

Read more of this story at Slashdot.

by Soulskill at February 29, 2008 09:40 PM

Parrot Blog

What is Parrot?

Parrot is a virtual machine for dynamic languages like Python, PHP, Ruby, and Perl. A dynamic language is one that allows things like extension of the code base, subroutine and class definition, and altering the type system at runtime. Static languages like Java or C# restrict these features to compile time. If this sounds like an edgy idea, keep in mind that Lisp, one of the prime examples of a

by Allison at February 29, 2008 11:19 AM

February 28, 2008


UKUUG Spring 2008 Conference: 31 Mar - 2 Apr

The UKUUG Spring 2008 Conference will be held at the Birmingham Conservatoire (Birmingham, UK) from 31st March to 2nd April 2008. Monday features 3 full day tutorials, with Tuesday and Wednesday taken up by shorter technical presentations. You can see the current schedule here.

Birmingham Perl Mongers are helping to coordinate the event, with several Perl Mongers from around the UK offering to present talks. Dave Cross will be holding a one-day Perl tutorial of his Teach-In session, with Matt S Trout, Tom Hukins, Mike Whitaker, Daniel Giribet, Barnabas Aspray, Mark Gledhill, Robin Doran, Brian McCauley, Jon Allen and me presenting technical talks discussing Perl.

The event is a UKUUG event and there are discounted rates for UKUUG members. You can attend just a tutorial, just the technical talk days or the whole 3 days. See Payment Details for all the options and prices. For those travelling from further afield who would like to know of some local hotels, the Accommodation page lists several nearby hotels. The conference venue is situated at the west end of New Street and is within 5-10 minutes walk of several hotels, including all those available during YAPC::Europe in 2006. Both GUADEC and PyConUK were held there in 2007, and proved a very suitable venue.

The Early Bird rates for the event are due to end on March 10th, so if you're thinking of coming along, please book soon to take advantage of the reduced rates.

by barbie at February 28, 2008 09:57 PM

use Perl journals

Planet Perl

Retries in Net::Amazon::S3

One of the slight issues with Amazon's Simple Storage Service is that by design sometimes the service returns a HTTP 500 Internal Server Error response and the client should retry the request. Previously, applications which use my Net::Amazon::S3 module, such as Brackup, had to handle the retries themselves - but no more! With the magic that is LWP::UserAgent::Determined you can now pass a retry option into the version 0.42 of Net::Amazon::S3 and it will handle the retries with exponential backoff for you.

by Leon Brocard at February 28, 2008 09:21 PM

Mozilla DevNews

flag changes coming for this week

To facilitate the triage we’re going to be doing this week for Fx3/1.9 we’ll be making some changes to various flags.  There’s a few goals here:

* Identifying the set of bugs that will absolutely block the release of Firefox 3
* From those bugs, identify the set of bugs that we need to ship in a beta to get wider testing before ship.
* Ensure that bugs we won’t get done for this release don’t get lost in the shuffle.

In order to do this, we are going to work against the following plan, starting Real Soon Now:

* The current blocking1.9 flag will be renamed to tracking1.9 on a temporary basis.
* A new blocking1.9 flag will be created, along with a wanted-next flag to track bugs that won’t make 1.9.0 but should be tracked.
* All b4 blockers will move over to the new blocking flag immediately.
* All outstanding nominations against the old blocking flag will be migrated as well.
* Drivers will triage all of the open bugs marked as tracking1.9+, moving flags to one or more of blocking1.9, wanted-next, or wanted1.9.0.x as appropriate.  the tracking1.9 flag will be cleared as we go.
* When there are no bugs with the tracking1.9 flag left, we’ll obsolete the flag and rename it to blocking1.9 so historical queries continue to work.

For developers and triagers:

Please don’t be alarmed if your P1/P2 bugs no longer appear as blockers, we’ll be retriaging aggressively and plan to be complete this week.  If you have opinions on your bugs, please add comments making your recommendations for drivers.

The new blocking1.9 should be used like the old one, both for nominating blockers for beta 4 and for final.  If a bug was previously marked as a blocker but hasn’t been retriaged, please nominate again to expedite the process.

For questions or feedback, please see the matching post in dev.planning.

by mconnor at February 28, 2008 01:01 AM

February 27, 2008

José Castro Tech Meeting #8

Yet another tech meeting! Today!

Yeah, yeah, I know it's short notice, but even if this doesn't reach potential attendees in time, at least we're putting the word out there of what we're doing.

The meeting takes place today, starting at 21:30, on the IST facilities in Lisbon (Alameda).

The talks:

        * Namespaces, typeglobs, closures and references, by Daniel Ruoso
        * DBI-Link 3.0, by David Fetter
        * Wrap-up && upcoming events (workshops, training, etc.), by José Castro

Attendance is free.

Join our mailing list if you need more details on how to find us.

by cog at February 27, 2008 10:00 PM

Portuguese Perl Workshop 2008 :: Call for Talks

This is the official Call For Talks for the very first Portuguese Perl Workshop.

We are now accepting talk proposals in English or in Portuguese that are 5, 20 or 40 minutes long.

The deadline for talk submission if April 30th, but don't you go around waiting, do it now!

by cog at February 27, 2008 10:00 PM

Adam Kennedy

Goodbye USA

Most of the business and economics people I respect have been saying for a couple of years now that the US economy is "cactus". The first people to put their balls on the line were saying this in 2004, anticipating the like effects of the massive stimulation caused by the interest rate falls of the time.

Through 2005 and 2006, opinion start to line up behind the the position that the scenario was becoming inevitable, with no escape options left.

The housing bubble collapse, and resulting world credit squeeze, was merely the trigger.

The underlying cause of the whole situation is a problem called a "triple deficit".

The idea of the triple deficit is that the health of a country's economic, and the risk of various policy actions, can be determined by examining 3 main cash flow indicators in a combined fashion.

1. Public Accounts (Government Surplus/Deficit)

2. Private Accounts (Citizen and Corporate Surplus/Deficit)

3. Trade Accounts (Trade Surplus/Deficit)

While deficits are generally seen as "bad", the triple deficit concept suggests that deficits in individual elements can be benign if they are balanced by the other elements.

Under these rules, a high-exporting country like Germany or China can make a decision to spend big and run up big government debts if it needs to, because it is healthy in overall terms.

The dangerous scenario from which negative consequences seem to always result is the situation in which you simultaneously have public debt, private debt, AND trade debt. The longer it lasts, and the higher the debt levels (in relative terms of course) the worst the final outcome.

For more background, there is a very interesting recent paper produced by the Budapest College of Management, looking at the state of Hungary's current triple-deficit as well. (PDF file)

Ever since the dot-com crash the US has been running with a high government deficit (now close to but not quite record levels in GDP terms), a high private deficit (made worse by the low interest rates and resulting credit and housing glut) and a high trade deficit (thanks to China and Walmart-and-friends).

The initial inevitable consequences of this are in full swing now. The large fall in the US dollar is by now obvious to all and sundry.

Warren Buffet made a major bet on this move a while back, moving a vast sum of money into the Brazillian currency. (a strong growing energy-independant democracy with high resources)

Buffet is particular interesting to watch because the cash pile he is sitting on is so large that he is unable to invest in short term events without his moves affecting those markets. As economic entities get larger, their performance inevitably approaches the performance of the economy as a whole.

So he is limited to betting mainly on country-scale and long term trends.

The current fall helps address the manufactured goods component of the trade deficit in particular, because it effectively imposes a trade tariff, making local manufacturing more competitive against foreign manufacturing.

Buffet recently bought a giant US generalized manufacturing conglomerate, effectively betting on US manufacturing as a whole.

Unfortunately, here is where things get ugly.

Although the currency fall helps manufacturing, there's lag involved, particularly in areas where manufacturing has largely died domestically. Thing textiles, toys and light bulbs. Industries you can't just bootstrap overnight.

Worse, the US also has a huge energy deficit, which can't be as easily correct by a drop in the US dollar. In fact, since energy prices controlled by supply/demand at a global level, the fall in the US dollar results in a very significant price spike in the cost of energy, above and beyond the underlying increases in energy prices.

The combination of rising import prices on household expenses and rising energy prices together creates a major risk of one of the most dangerous economic beats, "stagflation".

Stagflation is so dangerous because there's very little you can do about it. The Reserve Banks, whose normal job it is to control inflation, has one big weapon. Interest rates.

Under normal circumstances, with inflation driven by excessive economic activity, a rise in interest rates dampens this activity, and helps bring inflation undercontrol.

In stagflation, inflation is high DESPITE the economy being weak. Interest rate rises have less of an effect on stagflation and can easily be pushed too far (the effect of 15%+ home loan rates and the resulting recession from the 80s is burned into the Australian racial memory).

And with a triple-deficit in play, some of the other safety values are missing as well. Governments, already cash-strapped, can't simply spend big to help the country past the problem.

And thus, the three deficits, although resulting from separate causes, combine together in a devastating fashion. The Private Debt triggers the problem, the Trade Debt creates the stagflation, and the Public Debt prevents countermeasures.

As you can see at that first link, we now have the clearest evidence yet that the US economy is in bad enough shape to kick off stagflation, and that it's probably happening right now.

So it appears the US economy is indeed cactus.

You have my sincerest condolences, living under stagflation is not fun.

by Alias at February 27, 2008 10:00 PM

Josh McAdams

YAPC::NA Website Banners

The folks over at PlainBlack were nice enough to offer up some graphic design assistance and created a set of banners for people to help promote YAPC::NA 2008. Please feel free to use these banners and li nke to this site to help spread the word about YAPC.

by jmcada at February 27, 2008 09:59 PM

Mozilla DevNews

Thunderbird security and stability release now available

As part of Mozilla Corporation’s ongoing stability and security update process, Thunderbird is now available for Windows, Mac, and Linux as a free download from

Due to the security fixes, we strongly recommend that all Thunderbird users upgrade to this latest release.

If you already have Thunderbird 2.0.0.x, you will receive an automated update notification within 24 to 48 hours. This update can also be applied manually by selecting “Check for Updates…” from the Help menu.

For a list of changes and more information, please review the Thunderbird Release Notes.

Please note: If you’re still using Thunderbird 1.5.0.x, this version is no longer supported and contains known security vulnerabilities. Please upgrade to Thunderbird 2 by downloading Thunderbird from

by ss at February 27, 2008 07:09 AM

Firefox 3 Beta 4 starts baking tonight

At today’s Firefox 3 / Gecko 1.9 meeting we reviewed the remaining number of P1 and P2 blockers on our lists, and decided that we would go ahead with tonight’s Firefox 3 Beta 4 code freeze tonight at 11:59pm PST and then bake nightly builds for a few days before handing off the code to the Build and Quality Assurance teams.

During the baking period, all Firefox 3/ Gecko 1.9 component owners have been asked to triage their blocker nomination and blocking bug lists by Friday noon PST in order to determine:

  • which bugs, if any, require a beta release vehicle
  • which bugs, if any, need to block the final release of Firefox 3

Mike Connor has posted criteria to be used when assigning priorities to blocking bugs. If possible, bug owners should add an estimate of the time required and precieved difficulty of fixing a bug.

Tree management after tonight’s freeze

After tonight’s freeze we’ll be using the same process we used for the last beta. The tree will be closed to bake, and during that time we would appreciate your help in regression spotting and fixing. The only bugs that can land during this baking period are those marked with the “approval1.9b4+” flag.

Please note that if you believe a bug should block the release of Firefox 3 Beta 4, please make sure it is either marked or nominated as a P1 blocker and set the target milestone to “Firefox 3 beta 4″ or “mozilla1.9beta4″. We are currently frozen for localization work, so no new strings will be accepted at this time. You may wish to mark bugs with the following keywords:

  • “relnote” will nominate that bug for entry in the Firefox 3 Beta 4 release notes
  • “late-compat” will indicate that the bug might affect add-on compatibility
  • “dev-doc-needed” will indicate that developer documentation is required

After this Friday, we will have more information about the delivery schedule for this beta. Look for announcements here and on the group.

by beltzner at February 27, 2008 07:09 AM

February 26, 2008

David Landgren

Stalling the pipeline in the checkout queue

I was in the supermarket the other day after work. I had a number of essentials in my basket and I was itching to get home.

Big problem: which queue to choose? Having learnt about Queuing Theory at school, and knowing that single queue-multiple consumer is as efficient as it gets, it's always an agonizing decision. You have to balance a number of factors: how many people in the queue, how many items do people want to buy, do they look impatient or vagued out. It's better to be behind a person buying 10 of one thing, than one item of ten different things. And, although it pains me to admit it, old people are Bad News. Statistically, you'll waste 30 seconds to five minutes with them in front of you.

So I was pondering this the other day, and reflecting on my worldview, how I tend to algorithmatise things (figuring out the shortest path between the four shops I need to go to, establishing contigency plans in case a shop doesn't have a product I need, that sort of stuff. When house-cleaning I try to keep my hands full. I hate going into room A to fetch something for room B, and realising there was something in room B which should be tidied away in room A). Geeking out, basically.

And as I stood there ruminating on this, I was idly watching the woman at the front of the line, and became more and more alarmed. She was just stacking up the products that the cashier swiped...but not putting them into bags. I couldn't figure out what she was doing, but figured it was bad news for me. And on and on it went, until the cashier had checked out every last item. Then she handed over her credit card, had it swiped, punched in her pin, and only once she had received her docket did she begin to bag up the stuff she'd bought. And I thought "You f5cking moron: can't you deal with asynchronous events?" Because the cashier couldn't start checking out the items of the next person until she'd cleared the decks. Which took a non-trivial amount of time, during which no other work could be done.

Meantime I note that the people who were at the ends of the other queues are now close to being served, and I've still got two people in front of me. But I'm in too deep at this point to bear the cost of cutting my losses and requeuing on another line.

The next person went through without a hitch: a few items, had cash ready, out straight away.

Then the person in front of me went through. Seemed to be okay: started bagging up the goods as soon as they came through, but she had a fair number of things to buy. Then it turns out that she has a Method. All the fruit goes together, the stuff that requires Refrigeration goes together, tins kept apart from packets and so on. And the cashier is done quickly and announces the price. But does she do anything? Noooooooooo! She just keeps putting stuff in bags. And the cashier, who is polite (the Customer is always Right and all that) says nothing.

At this point I just take a deep breath and resign myself. The people who were at the ends of the other queues are all long since gone. At times like this I can't help thinking that a lot of what we learn in Computer Science is applicable to the Real World. And one of the cardinal sins is stalling the pipeline. When you have people queued up to do something, you want to get in and get out as fast as possible, just like an instruction on a CPU. Because wait states are just time lost. Gone, never to come back.

I really, really hate when that happens.

by grinder at February 26, 2008 09:56 PM

Another fun (?) SQL puzzle

So, I have a database with a particularly nasty design decision. We have people who belong to cost centres, usually only one, but sometimes with a prorata on two cost centres. The programmer responsable for creating the table denormalised things, so rather than having

    EMP1  UNIT1 50%
    EMP1  UNIT2 50%
    EMP2  UNIT3 100%
    EMP3  UNIT1 100%

we have something that looks like

    EMP1   UNIT1   UNIT2    50   50
    EMP2   UNIT3   null    100    0
    EMP3   UNIT1   null    100    0

That is, both cost centre ids in the same table, the second one usually null. It is a given that there will never be more than two. This table is of course an utter bitch to work with. Turns out we can cheat a bit, by only keeping track of the rate of the first centre, the second is just 100-first (which also helps cut down round-offs). Let us create a table to play with:

create table t1 (
   id_person varchar(10),
   rate      number(5,2),
   unit1     varchar(3),
   unit2     varchar(3),
   val1      number(10),
   val2      number(10)
insert into t1 values ('alice',   1, 'U1', null,   10,   20);
insert into t1 values ('bob',     1, 'U2', null,    4,    8);
insert into t1 values ('carol', 0.5, 'U1', 'U2',  300,  600);
insert into t1 values ('david', 0.2, 'U1', 'U3', 6000, 8000);

Now I want the sum the values val1 and val2 by unit, keeping in mind that for 'david', VAL1 6000 * 0.2 = 1200 is summed to U1, and the difference, 4800, to U3. Similarly, for VAL2, 1600 to U1 and 6400 to U3. In other words, I want the following result set:

    U1 1360 1920
    U2  154  308
    U3 4800 6400

Now the only way that I can see is to:

  1. Sum the value proratas for all people on their first cost centre. If they have one centre, they get the full hit, otherwise it's prorata'ed between it and the second.
  2. Union the above with the people having two centres, by subtracting the prorata of the first centre from the total value to arrive at the second prorata (to minimise roundoff errors, otherwise the sum of both centres will lose a cent compared with the initial sum from time to time).
  3. Treat all that as a derived table, and sum the results.

This gives the following:

    ,sum(V1) V1_TOT
    ,sum(V2) V2_TOT
from (
         unit1            UNIT
        ,sum(val1 * rate) V1
        ,sum(val2 * rate) V2
    group by
    union select
         unit2                   UNIT
        ,sum(val1 - val1 * rate) V1
        ,sum(val2 - val2 * rate) V2
        unit2 is not null
    group by
) S
group by S.UNIT
order by S.UNIT

That's pretty ugly. Is there a better way?

by grinder at February 26, 2008 09:56 PM

Bitten by glob crypto context

/me is annoyed

I just spent a while chasing a stupid bug. I have an big log directory that I have to clean up. The number of files caused the shell's wildcard expansion to fail. So I wrote some perl to move things around.

And it didn't do anything. To cut a long story short, I needed the total number of files in the directory. So I had something along the lines of:

perl -le 'print scalar(glob("*"))'

That does not return the number of files. It returns the name of the first file. Or the last. I don't care.

You have to force array context and throw it away:

perl -le 'print scalar(()=glob("*"))'

This prints 31192. I wish Perl didn't do this. Nice interview question though, I guess.

by grinder at February 26, 2008 09:56 PM

use Perl journals

Planet Perl

Trip to FOSDEM &amp; Dutch Perl Workshop, part 1

After the nice 0100000 party on Thursday (and a nice loot) I took the sleeper train to Köln on Friday night. By some very lucky coincidence I got a 4-person compartment on my own - yay!

The next day I walked a bit through the central area of Köln (around the Cathredral). Quite nice for a german city... I discovered a space invader and a fake medevial castle on a boat (some kind of museum).

In Brussels, I went straigth to FOSDEM where I met a few Perl people (Mark, Juerd, Leon, ..) at the Perl 6 talk. I spend most of the day talking with them. In the evening we had yet another birthday "party" (together with Leon) - and to my big surprise I discovered that I actually like Cherry Beer (because it doesn't taste like beer I guess)

Sunday night I drove with Wendy & Liz to their place, where I'm staying now. It's very nice and they are very hospitable. Yesterday Jonathan arrived from Kiev, and we did a small bicycle tour around the neighbourhood. I'm switching between working, preparing slides, chatting & playing Fluxx. Very nice...

by Thomas Klausner at February 26, 2008 09:42 PM

Planet Parrot

chromatic: Hasty Generalizations Make Wastey Generalizations

... what I'm seeing in Ruby is that the many ways have been transformed into idioms and guidelines. There are no hard rules, but the community have evolutionary evolved idioms that work and found out many of the ways that doesn't work.

Ruby has almost all of the flexibility of Perl to do things in different ways. But at the end of the day, none of the Perl problems tend to show up. Why is this?

Ola Bini, Language design philosophy: more than one way?

Why? Probably because you're not a very good Perl programmer.

A better question is "Why do programmers experienced with a language so often fail to have the maintainability problems that plague novices?" That might have led nicely into a discussion of idioms and the evolution of good style in a language which encourages such things.

See also the discussion why Java fans luuurve their IDEs and can't understand why those of us who can go through the TDD cycle once or twice before Eclipse finishes loading the whole project think that Java's syntax might be a touch verbose. Another fun discussion is "Why don't you Lunix types make one-click installers you can just download and click to install?"

I suppose only the familiar is awesome, and the unfamiliar is stupid and scary.

February 26, 2008 09:42 PM

Joshua Wehner

On the need for game criticism

Greg Costikyan has been saying this for a decade or more, but this is well-written at least:

The truth is that, for the most part, we don’t have anything like game criticism, and we need it—to inform gamers, to hold developers to task, and to inform our broader cultural understanding of games and their importance and impact on our culture.

We need our own Pauline Kaels and John Simons—and we need to ensure that when they appear, no one insists that they attach a damn numerical score to their writing, because that is wholly irrelevant to the undertaking of writing seriously about games.

Tagged: ,

by Joshua Wehner ( at February 26, 2008 09:10 AM

February 25, 2008

Barbie Technical Meeting - Wed 27th Feb 2008

Event:   Technical Meeting
Date:    Wednesday 27th February 2008
Times:   from 7pm onwards (see below)
Venue:   The Victoria, 48 John Bright Street, Birmingham, B1 1BN.

  • Monotone: Distributed Peer-To-Peer revision control system. A natural successor to CVS [Tony Cooper]
  • Developing Perl GUIs Using Glade and Gtk2 [Tony Cooper]


This month we're featuring a special guest night with Tony Cooper coming along to give us two talks. The first looks at the VCS Monotone, and the second looks at creating GUI tools with Perl, Glade and Gtk2.

Once again we'll be at The Victoria this month. The pub is on the corner of John Bright Street and Beak Street, between the old entrance to the Alexandra Theatre and the backstage entrance. If in doubt, the main entrance to the Theatre is on the inner ring road, near the Pagoda roundabout. The pub is on the road immediately behind the main entrance. See the map link on the website if you're stuck.

As always entry is free, with no knowledge of Perl required. We'd be delighted to have you along, so feel free to invite family, friends and colleagues ;)

We'll be in the venue from about 6.30pm, and have booked The Boardroom for the night. Order food as you get there, and we'll aim to begin talks at about 8pm. I expect talks to finish about 9.30pm, with plenty of time for discussion and planning for meetups over the weekend in London.

Venue & Directions:

The Victoria, 48 John Bright Street, Birmingham, B1 1BN (Tel: 0121 633 9439)
- Pub Details
- Picture
- Google Map

The venue is approximately 5-10 minutes walk from New Street station, and about the same from the city centre. On street car parking is available see full details and directions on the website.


These are the rough times for the evening:

  • food available until 7.30pm
  • talks: 8.00-10.00pm
  • pub closes: 11.00pm

Please note that beer will be consumed during all the above sessions ;)

by barbie at February 25, 2008 09:57 PM

Homestar Runner

Randal Schwartz

I made MacOSX Hints today!

Rob Griffiths IM'ed me saturday while I was sitting at ATL airport, asking what my day rates were.

My normal reply was "depends on the task", and asked him what he had in mind. As he described it, it fleshed out to all of 10 lines in my head, so I said "well, buy me lunch and we'll call it even". He couldn't believe that it could be that short to create or to write.

Ten minutes later, I showed him the code that he added to a hint for today about renaming old iChat logs.

Hadn't tried it on my own data, but told him "it should probably work". I'm pretty good at previewing code in my head. :) He tried it, and it worked fine for his data. Yeay.

So there I am, famous again. And got a free lunch for 10 minutes work. Not bad.

by merlyn at February 25, 2008 09:55 PM

Planet Perl

February 24, 2008

Aristotle Pagaltzis

You know what’s tough?

Forget Markup Barbie… I want Unicode Barbie. When you pull her string, she says “text is hard.”

February 24, 2008 11:55 PM

Michael Schwern

That damned Test::More threading test

I did it. I finally killed that damned threading test in Test::More. is_deeply_fail.t will no longer run unless AUTHOR_TESTING is set.

For those who don't know, that test would tickle intermittent threading bugs in certain vendor supplied versions of perl. The 5.8.6 OS X ships with and most Redhat derivatives are vulnerable, but it would only fail about one in a hundred times. I don't know what the problem is, I suspect it's from vendors pulling in bleadperl patches but I haven't confirmed. Nobody's put the time into it to find out.

Since there's nothing I can do about it, and it was just holding up CPAN installations, I turned the test off. Done.

by schwern at February 24, 2008 09:57 PM

Jakob Nielsen


Top-10 Application-Design Mistakes

February 24, 2008 09:56 PM

Nicholas Clark

who are you and what have you done with the real politicians

The Home Office said a mandatory database "would raise significant practical and ethical issues".

Home Office minister Tony McNulty told BBC that a national database was not a "silver bullet" and that it would raise practical as well as civil liberties issues.

"How to maintain the security of a database with 4.5m people on it is one thing," he said.

"Doing that for 60m people is another."

Politicians listening to reason and experts and not going to do something (that can be spun as doing something useful) because it's impractical? Who are you and what have you done with the real politicians?

by nicholas at February 24, 2008 09:56 PM

Planet Perl

Catalyst Book Review

I wrote a review of "Catalyst" by Jonathan Rockway. You can read it (the review, not the book) on my web site.

Executive summary: I didn't like it much.

by Dave Cross at February 24, 2008 09:41 PM

February 23, 2008

Planet Perl

Domain names not for sale

We regularly get inquiries about the, etc domains like the following:

We are interested in purchasing your domain name. If interested, please let me know what it takes to buy it.

If agreeable, we can finalize the deal through Monday.

Our typical response:

Hi $spammer,

One billion USD. Non-sequential twenty dollar bills preferred, but not required.

You pay the fees.


- ask

p.s. no, it's not really for sale.

by Perl NOC Log at February 23, 2008 09:41 PM

February 22, 2008

Bob Cringely


If you have ever seen my show Triumph of the Nerds well then you've also seen my car, a 1966 Ford Thunderbird convertible very similar to the car used in the movie Thelma & Louise (I play the role of Thelma). It is in almost every way a fabulous car. It's going up in value, for one thing. It looks cool. It goes like hell with its 428 cubic-inch V-8 engine. It is heavier than anything else on the road, so in a collision with anything less than a dump truck I win. And thanks to analog technology that handily predates the Clean Air Act, it somehow manages to do all this while getting 22 miles per gallon on the highway, 16 in town. Everything is good about my T-Bird, in fact, except for its wires. My car has bad wires. And shortly YOUR car will have bad wires, too, as will everything else you own that has soldered electrical connections. Everything. Prepare to share my pain.

My T-Bird was built at the absolute apex of 20th century electromechanical automotive technology. A convertible, it has a fully automatic electric top that relies on eight electrical relays firing in sequence to put the top up or down. Here's the typical (and inevitable) failure mode. I'm at the beach with the top down. It starts to rain. Quickly I run to the car, start it, and hit the button to raise the top. First the suicide trunk lid opens until it is fully vertical. Next the electric tonneau cover opens until it is vertical, too. Then the canvas top begins to retract, raising until it, too, is vertical, at which point everything grinds to a halt and I drive my car home in the pouring rain at five miles per hour, traffic honking behind me, and all three broken parts sticking eight feet into the sky.

Victim to a succession of good and bad mechanics, some well-intentioned but all in it for the money, I have spent thousands of dollars over the years replacing electrical parts -- window motors, switches, relays for both the top and the sequential tail lights -- all to little avail. New parts failed as quickly as old parts. Eventually I abandoned all hope of viewing my car as a restoration and replaced the relays with brilliant little computers from British Columbia. Now the hydraulics worked beautifully but all it really meant was that the top no longer failed in mid-sequence: it would either work fine or not at all.

When you've replaced everything else the problem has to be with what's left, which in the case of my car was the wires, themselves. Over the years the wires had somehow corroded inside their insulation and the terminals had lost their mojo. I had been replacing perfectly good switches and motors (and knowledgeable folks had been selling me switches and motors) that would have been helped more by simply replacing the terminals or, better still, the wires. Some experts think Ford just got a bad batch of wire back in 1966 -- that this problem is isolated -- but I don't care. So what if my car is two years older than my wife? All her parts seem to be working just fine, why shouldn't my T-Bird?

Which brings me to you, or rather to all of your soldered devices that are two years old or less. Most of these are now assembled using solder joints that have no lead in an effort to save our groundwater and our health. The fact that the lead has been generally replaced with silver or bismuth, both of which are actually greater health risks than lead, well we'll leave that one for Ralph Nader if he decides not to run for President. The longer-term trend is toward all-tin connections, anyway, but they don't work very well, either.

I wrote a column about this back in 2004 (it's in this week's links) that was heavy on information and therefore low on readership. Everything in that column has come to pass and more. Where's my Pulitzer Prize?

Costs have gone up, mean time between failures (MTBF) has gone down (accelerated MTBF tests, which are the only MTBF tests we do anymore, don't reliably pick this up, by the way), and reliability has suffered. Since we don't fix things anymore, it’s hard to say whether your gizmo failed because of bad solder or not, but the problem is becoming worse as a greater percentage of total circuits in use have lead-free solder. The military was especially concerned, even before the whisker crisis.

We're talking about tin whiskers, single crystals that mysteriously grow from pure tin joints but not generally from tin-lead solder joints. Nobody knows how or why these whiskers grow and nobody knows how to stop them, except through the use of lead solder. Whiskers can start growing in a decade or a year or a day after manufacture. They can grow at up to nine millimeters per year. They grow in any atmosphere including a pure vacuum. They grow in any humidity condition. They just grow. And when they get long enough they either touch another joint, shorting out one or more connections, or they vaporize in a flash, creating a little plasma cloud that can carry for an instant hundreds of amps and literally blow your device to pieces.

Since 2006 we have been exclusively manufacturing soldered connections thousands of times more likely to create tin whiskers than previous generation joints made with tin-lead solder. Because of the universal phase-in of the new solder technology and the fact that the solder technologies can't reliably be mixed (old solders mess with new solder joints in the same device through simple outgassing) this means that it is practically impossible to use older, more reliable technology just for mission-critical (even life-critical) connections. So we're all in this tin boat together.

Some experts confidently say that the disparity of joint reliability we are seeing today will go away and that the new joints will become as reliable or even more reliable than the old tin-lead joints as we gain experience with the new processes. What's disturbing, though, is that these experts don't actually know how this increased reliability is likely to be achieved. Just like extrapolating a Moore's Law curve to figure out how fast or how cheap technology is likely to be a decade from now, they have no idea how these gains will be made, just confidence that they will be.

What if the experts are wrong?

Tin whiskers can take out your iPod or your network. They can stop your car cold. They can take down an entire airport or Citibank. They are much more common than most people -- even most experts -- think. The reason for this is that most tin whiskers can't even be seen.

"Maybe it is worth adding," said one expert who prefers to remain anonymous, "that whisker diameters range from 0.1 um to 10 um, while the diameter of a human hair is 70 um to 100 um --- so the largest whisker is only some 15 percent of the diameter of a thin hair, and most are less than 5 percent. A good fraction (of these are) so thin that light waves just pass them by, scattering a bit but not reflecting. So the optical microscope images that (typically used to illustrate whiskers) show only a small fraction of what is really there. Scanning electron microscope (SEM) images are a bit better, but only show a small zone of the sample; also, not many folks are able to acquire SEM images of their equipment. So all too many folks have the idea that whiskers are something that happens to someone else, but never to them. This is an expensive misconception."

What I wonder is whether a cost-benefit analysis of this solder technology changeover was ever done? I haven't seen one.

And if you think this problem is minor, I have been told that just the cost of changing to lead-free solder stands right now at $280 BILLION and climbing. That cost is borne by all of us.

Maybe dumping lead solder was absolutely the right thing to do. Maybe it was absolutely the wrong thing to do. The truth is we haven't the slightest idea the answer to that question and anyone who claims to know is wrong. We didn't know what would happen when we started this and we don't know what we'll get out of it, either, or whether it will be worth the cost. All we know for sure is that a bumpy ride lies ahead.

Fortunately I have new shock absorbers (and a new wiring harness) on my T-Bird.

February 22, 2008 09:58 PM

Aristotle Pagaltzis

Lost in translation

Eric Lippert :

I understand that there is an inherent and pervasive bias in pure-text communication which makes statements intended to be good-humoured sound sophomoric, makes statements which were intended to be friendly sound smarmy, makes statements which were intended to be enthusiastic sound brash, makes statements intended to be helpful sound condescending, makes statements which were intended to be precise and accurate sound brusque and pedantic, makes statements which were intended to be positive sound neutral, and makes statements which were intended to be neutral seem downright hostile.

by Aristotle at February 22, 2008 09:56 PM

Shout it from the rooftops!

From List::Maker’s Changes file:

0.0.4  Sat Feb  9 11:08:51 2008

    * Made globbing magical only in those source files that explicitly load
      the module (thanks Steffen)

W00t! Now I can actually use the module instead of making sad eyes and letting out a wistful sigh when I think of it.

by Aristotle at February 22, 2008 09:56 PM

Planet Perl

Making URI work with Business::ISBN 2.x

If you have Business::ISBN 2.x installed and you try to install URI, you'll probably get stopped at the `make test` stage. Some of the method names changed to support ISBN-13, but URI up to 1.35 hasn't caught up yet. Unless you're using the obscure ISBN scheme in URLs, you don't really care that it breaks save that it doesn't install nicely. You can force install URI and be just fine (or install it without Business::ISBN already installed).

I've posted the patch for URI to RT so URI can work with either major version of Business::ISBN back to Perl 5.004. It renames a couple of methods in URI::urn::isbn, but still works with the older names (with a warning) too.

by brian d foy at February 22, 2008 09:21 PM

February 21, 2008

Beautiful Code

Quality Begs for Object-Orientation

Many people are dabbling in functional programming these days. Haskell is more popular than it ever has been, OCaml has it's adherents, and we are starting to see common functional idioms spread throughout the industry.

Why am I not happy?

Here's why. I think that most functional programming languages are fundamentally broken with respect to the software lifecycle. I realize that's a bold statement. Let me back it up.

Imagine these lines of code in any object-oriented language (I'll use Java here because it is familiar to most people, even if they dislike it):

public class X {
    public void method() {

Class X has a method named badMethod. The method isn't bad because it does something awful while the system is running; it's bad because it does something painful during testing. It could be anything. The method could make a call to our production database and update it, or it could communicate with another system across a socket. It could even touch some low level hardware that causes a mechanical machine arm to do something that it shouldn't be doing over and over again while we are testing.

In an ideal world, people would design their systems so that classes and clusters of classes could be tested independently; the industry is slowly rediscovering the utility of unit testing. But, stuff happens. People make mistakes. They think that they've got it all under control until they discover that they have a big wad of code that they can't easily change and don't understand. At that point, they wish that they could write little tests that help them understand what the hell their code does before and after they change it.

The nice thing, so far, is that most of the object-oriented languages out there leave you an “out.” You can use the features that were built in to provide flexibility to give yourself enough maneuverability to test. In short, we can do this:

public class TestableX extends X {
    void badMethod() {
        // do nothing

We can override functionality and build ourselves a wedge that makes testing easy.

The fact that badMethod is a non-final, override-able method makes it something I call a seam. A seam is a place where you can substitute one piece of functionality for another without editing. Most languages provide seams. The C programming language is rich with them. You can use the preprocessor, function pointers, and link substitution to replace awkward functionality during testing, but it isn't quite as easy as it is in OO.

Virtual function calls in OO languages are a common seam. Java is easy. C++ is a bit more awkward. Ruby and Python are a breeze. The power of these seams is in the fact that you can get between around around the pieces of your application when testing. It isn't just a big hard-coded mass.

What about Haskell, OCaml, and Erlang?

Yes, you can provide alternative modules to link against, but it's clunky. Sure, you can use virtual in OCaml, but who really organizes all of their OCaml code in classes?

Haskell is a bit nicer, most of the code that you'd ever want to avoid in a test can be sequestered in a monad, and I expect that half of the Haskellers reading this will argue that functional purity obviates any need to unit test; it can all be done in QuickCheck. I hear you, but there's distance between here and there and that distance can be a quagmire.

No, the fact is, the late-binding that OO languages provide makes code written in them more easily recoverable. And, this is important because entropy happens. Count on it.

by Michael Feathers at February 21, 2008 10:16 PM

Planet Perl6

perl6.announce: Parrot 0.5.3 "Way of the Parrot" released! by Patrick R. Michaud

On behalf of the Parrot team, I'm proud to announce Parrot 0.5.3
"Way of the Parrot." Parrot ( is a virtual
machine aimed at running all dynamic languages.

Parrot 0.5.3 can be obtained via CPAN (soon), or follow the
download instructions at
For those who would like to develop on Parrot, or help develop
Parrot itself, we recommend using Subversion or SVK on the
source code repository to get the latest and best Parrot code.

Parrot 0.5.3 highlights:

The Perl 6 on Parrot compiler has now been given the name
"Rakudo Perl". More details on the new name are available
from . In addition,
Rakudo now has more support for objects, classes, roles, etc.,
and a better interface to the official Perl 6 test suite.

More languages are being converted to use the Parrot Compiler

Parrot 0.5.3 News:
- Documentation
+ PDD09 (garbage collection) - approved
+ PDD28 (character sets) - draft started
+ added function documentation to some core functions
+ PCT beginners guide, optable guide and PAST nodes guide, bug fixes
- Compilers
+ IMCC: plugged various memory leaks and other cleanups
+ PCT:
. add "attribute" as a scope variant to PAST::Var nodes
. add 'shift' and 'pop' methods to PAST:: nodes
+ NQP: add '=:=' op, tests for scalar and list contextualizers, \x escapes
- Languages
+ APL: reimplementation with PCT
+ Cardinal (Ruby): reimplemention with PCT
+ Ecmascript: reimplementation with PCT
+ lolcode: improved expression parsing, ifthen, IT, YARN
+ lua:
. aligned with Lua official release 5.1.3.
. added initial PCT-based implementation.
+ Punie (Perl 1): refactor to use standard PCT-based filenames
+ Pynie (Python): add functions
+ Rakudo (Perl 6):
. rebranded, formerly known as 'perl6'
. passes many more official Perl 6 Specification tests
. added 'perl6doc' utility
. oo including meta?classes, objects, methods, attributes, role composition
. match variables, while/until statements, traits
. many new methods for Str, List, Hash, Junction
- Implementation
- Deprecations
+ PCCINVOKE syntax for named arguments using []; use () instead.
+ see DEPRECATED.pod for details
- Miscellaneous
+ pbc_to_exe refactored for code reduction, portability, and maintainability
+ various bug fixes
+ #line directives added to generated JIT files, improving debugging
+ consting, attribute marking, refactoring, warnings cleanup

The next scheduled Parrot release will be on March 18, 2008.

Thanks to all our contributors for making this possible, and our
sponsors for supporting this project.


February 21, 2008 10:00 PM

Nicholas Clark

terminals for OS X?

Dear lazyweb,

Given that genuine VT102 terminals are not that practical to lug around, what is the "best" terminal emulator for OS X? I realise that as all are made of software, all will be hateful, but I was hoping that some might be less hateful than others.

by nicholas at February 21, 2008 09:56 PM

Planet Perl

SlideShare Perl Goodness

I've joined SlideShare and uploaded the 17 talks for which I have slides readily available. I'm still playing with the service, and although Andy Armstrong pointed out that there is a Perl group, I didn't find any Perl events. I have fixed that by adding the right stuff for the talks I have:



Add your own events and groups even if you don't have slides for them yet! If you need help remembering dates, use The Perl Review's Community Calendar.

by brian d foy at February 21, 2008 09:41 PM

February 20, 2008

Planet Perl

Three levels of Perl/Unicode understanding

(Editorial: Don't frontpage this post, editors. I write it down here to summarize my thought, wanting to get feedbacks from my trusted readers and NOT flame wars or another giant thread of utf-8 flag woes)

I can finally say I fully grok Unicode, UTF-8 flag and all that stuff in Perl just lately. Here are some analysis of how perl programmers understand Unicode and UTF-8 flag stuff.

(This post might need more code to demonsrate and visualize what I'm talking about, but I'd leave it as a homework for readers, or at least thing for me to do until YAPC::Asia if there's a demand for this talk :))

Level 1. "Take that annoying flag off, dude!"

They, typically web application developers, assume all data is encoded in utf-8. If they encounter some wacky garbaged characters (a.k.a Mojibake in Japanese) which they think is a perl bug, they just make an ad-hoc call of:

to take the utf-8 flag off and make sure all data is still in utf-8 by avoiding any possible latin-1-utf8 auto upgrades.

This is level 1. Unfortunately, this works okay, assuming their data is actually encoded only in utf-8 (like database is utf-8, web page is displayed in utf-8, the data sent from browsers is utf-8 etc.). Their app is still broken when they call things like length(), substr() or regular expression because the strings are not UTF-8 flagged and those functions don't work in Unicode semantics.

They can optionally use "use encoding 'utf-8'" or CPAN module encoding::warnings to avoid auto-upgrades at all, or catch such mistakes, or use Unicode::RecursiveDowngrade to turn off UTF-8 flag on complex data structure.

Level 2. "Unicode strings have UTF-8 flags. That's easy"

They make an extensive use of Encode module encode() and decode() to make sure all data in their app is UTF-8 flagged. Their app works really nice in Unicode semantics.

They sometimes need to deal with UTF-8 bytes in addition to UTF8-flagged strings. In that case, they use some hacky modules named ForceUTF8, or do things like

utf8::encode($_) if utf8::is_utf8($_)
to assume that "Unicode strings should have UTF-8 flagged, and those without the flag are assumed UTF-8 bytes."

This is Level 2. This is a straight upgrade from Level 1 and fixes some issues of Level 1 (string functions not working in Unicode semantics, etc.), but it's still too UTF-8 centric. They ignore why perl5 treats strings this way, and still hate SV Auto-upgrade.

To be honest I was thinking this way until, like early 2007. There's a couple of my modules on CPAN that accepts both UTF-8 flagged string and UTF-8 bytes, because I thought it'd be handy, but actually that breaks latin-1 strings if they're not utf-8 flagged, which is rare in UTF-8 centric web application development anyway, but still could happen.

I gradually have changed my mind when I talked about how JSON::Syck Unicode support is broken with Marc Lehmann, and when I read the tutorial by and attended to the Perl Unicode tutorial talk by Juerd Waalboer in YAPC::EU.

Level 3. "Don't bother UTF-8 flag"

They stop guessing if a variable is UTF-8 flagged or not. All they need to know is that a string is whether bytes or characters, by checking how a scalar variable is generated.

If it's bytes, use decode() to get Unicode strings. If it's characters, don't bother if it's UTF-8 flagged or not: if it's not flagged they'll be auto-upgraded thanks to Perl, so you don't need to know the internal representations.

So it's like a step back from Level 2. "Get back to the basic, and think why Perl 5 does this latin-1 to utf-8 auto upgrades."

If your function or module needs to accept strings that might be either characters or bytes, just provide 2 different functions, or some flag to explicitly set. Don't auto-decode bytes as utf-8 because that breaks latin-1 characters if they're not utf-8 flagged. Of course the caller of the module can call utf8::upgrade() to make sure, but it's just a pain and anti-perl5 way.

There's still a remaining problem with CPAN modules, though. Some modules return strings in some occasion and not otherwise. For instance, $c->req->param($foo) would return UTF-8 flagged string if Catalyst::Plugin::Unicode is loaded and bytes otherwise. And using utf8::is_utf8($_) here might cause bugs like described before.

Well, in C::P::Unicode example, actually not. using C::P::Unicode guarantees that parameters are all utf-8 flagged even if the characters contain latin-1 range characters. Not using the plugin guarantees the parametes are not flagged at all. So it's a different story.

(To be continued...)

by Tatsuhiko Miyagawa at February 20, 2008 09:41 PM

Planet Perl

I'm now on SlideShare

So, I have another web 2.0 account thingy. I uploaded my talks to Slideshare. There's probably some way to connect to other Perl people or somesuch on there.

by brian d foy at February 20, 2008 09:41 PM

February 19, 2008

Homestar Runner

Planet Perl

Submit your talks to YAPC::Asia 2008

YAPC::Asia 2008 proposal deadline is 2/25, one week away. Submit your talk now. We welcome JavaScript related talks as well as anything Perl.

by Tatsuhiko Miyagawa at February 19, 2008 09:22 PM

Planet Perl

Working in the cloud

I've just submitted this talk to YAPC::Asia and will submit it to YAPC::Europe:

We are from the internet - we know the value of open source. Hardware and storage is unfortunately real, but you can outsource it all. This talk will guide you through how to exploit cloud computing today to make you happier and more efficient.

by Leon Brocard at February 19, 2008 09:22 PM

Planet Perl

goodbye cpan-testers, hello cpan-uploads

Today, at 4:11pm Pacific Standard Time, an era (or at least 9 years) ended.  The cpan-testers mailing list, recipient of a all CPAN tests submitted for CPAN testers processing, no longer resends all of those emails to its 50+ subscribers.  The last message to be distributed via email should have been #1049514.  Further messages will be kept in the archive, (also home to RSS and Atom feeds).  Eventually, we're going to transfer to a proper database backed system that doesn't use email at all.

Several people noted that they used cpan-testers to receive notification of new uploads to CPAN.  We've created the cpan-uploads mailing list to receive these notifications.     Archive/RSS/Atom is at  You can subscribe by sending a note to cpan-uploads-subscribe at

by Perl NOC Log at February 19, 2008 09:22 PM

February 18, 2008

Beautiful Code

Code inspections simplified

It's hard to remember to do simple code inspections--the oldest quality technique in the software field--amid the welter of graphical tools, measurement tools, and other fancy tricks the industry has thought up. Code inspections make sense. If you find a flaw during a program run and debug it, you've fixed just one bug. Only a code inspection can fix the potentially hundreds of other similar bugs.

But code inspections are a headache, because logic and consistency are hard to determine. Miska Hiltunen is trying to make them more agreeable by rigidly limiting what you have to look for, and assuring developers that they can get through each inspection in just about an hour. His Tick-the-Code site lists extremely simple things that pop out of poorly constructed code right away, and that supposedly warn you of the risk of deeper problems. Things to look for include unchecked parameters, deeply nested structures, duplicate code, unnecessary comments, unfinished code, and poorly named variables.

How is this relevant to Beautiful Code? A chapter in that book by Laura Wingerd and Christopher Seiwald of Perforce focuses our attention on just such superficial aspects of source code. Simply lining up the code for different cases to show their similarities and differences, these authors claim, can prevent associated bugs. They show how a violation at one stage of one of their principles--deep nesting of control structures, which they, like Hiltunen, try to avoid--coincided with a sharp uptick in errors.

Will Hiltunen's list of simple rules help programmers avoid real bugs? Or is it a focus on trivia that distracts programmers from dealing with real problems in their design and algorithms? Testing and time will tell.

Perhaps we can look at the endeavor this way: design and algorithms are certainly the most important drivers of quality and good performance. But design mostly takes place outside of and before coding, while algorithms are coded by experts who provide them to the rest of us in packages. Most of us who code are cobbling together small programs with lots of glue from standard libraries. Checking for trivial coding inconsistencies may uncover a lot of the problems we need to find.

by Andy Oram at February 18, 2008 12:02 AM

February 17, 2008

Joshua Wehner

Obscure Rails bug: respond_to format.any

I found an odd bug in Rails today. Odd, in the sense that it's not so much broken, as working in a way that's different than one would expect.

In a controller, one uses respond_to to present the appropriate response, as determined by the requested mimetype. If you want to respond to a whole clump of mimetypes in the same way, you might expect format.any to act as a catch-all for all the types you didn't already address.

So, for example, if we're writing an authentication system, we want web browsers redirected to the login page. But for non-browsers (eg, curl asking for XML, or Ajax asking for JSON, or some API asking for a vcard, whatever), it doesn't make any sense to direct them to a login page. We should ask them to use http basic authentication.

Here's the way this is handled by the current version of restful_authentication:

def access_denied
  respond_to do |format|
    format.html do
      redirect_to new_<%= controller_singular_name %>_path
    format.any do
      request_http_basic_authentication 'Web Password'

Except, this doesn't actually work. If you make a request for a non-html mimetype, you'll get a 406 ("that format doesn't work here anymore"), not a 401 ("unauthorized").

Presently, format.any actually looks something like this:

def any(*args, &block)
  args.each { |type| send(type, &block) }

And, if you dig around a little in the mime_responds tests, you'll see that you're supposed to call #any like so:

respond_to do |type|
  type.html { render :text => "HTML" }
  type.any(:js, :xml) { render :text => "Either JS or XML" }

Which, effectively, makes #any useless as a high-level catch-all for things like #access_denied. It's interesting that you can use it as a sort of multi-type, but that hardly seems the most common application. (Given the scarce documentation and meta-magic shenanigans in MimeType::Responders, I kinda doubt #any is used all that often. I only know about it because of restful_authentication.)

I've created a patch that changes #any's signature. It can now take 0 or any number of arguments. In the case where it has zero arguments, it assumes the mimetype requested (via the Rails-standard format parameter) or the first allowed mimetype (set by the request headers). In other words, it allows code like #access_denied, above from restful_authentication, to work as intended.

If you can, please take a moment to +1 the patch.

Tagged: , ,

by Joshua Wehner ( at February 17, 2008 04:39 PM

Aristotle Pagaltzis

Roy T. Fielding has a posse

… err, I mean, has a weblog.

Welcome aboard, Roy.

February 17, 2008 07:48 AM

February 16, 2008

Randal Schwartz

February 15, 2008

Randal Schwartz

Planet Perl

10000+ tables in one MySQL database

Once in a while I hear people talking about using thousands or tens of thousands of tables in one MySQL database and often how it “doesn’t work”. There are two things to say to them:

  • Are you nuts?!
  • Sure it works

I’ll elaborate a little on both …

Why’d you do that? Are you nuts?!

In most cases when extraordinarily many tables are brought up the “correct answer” is: Fix your schema to not duplicate the same table layout for each customer/user/site/…!

Once in a while though there are good reasons to have way too many lots of tables. Even “takes too long to fix the application now” can be a good enough answer sometimes.

My use case was to use the many tables as an extra “index” for a situation that a regular index couldn’t cover. Tens of thousands of tables, here we come.

Nova Cimangola Cement Plant

Sure it works, just configure it right!

… which is easy!

  • In your startup script (/etc/init.d/mysql with the MySQL RPMs), add “ulimit -n 30000” somewhere near the top to allow mysqld to have 30000 open files (and sockets).

  • In your mysql configuration, add something like the following - adjust the number as appropriate.

    set-variable = table_cache=12000

This will let MySQL keep up to 12000 tables open. The default limit is much too low and the system will spend all its time closing and opening the files. The other few thousand handles are free for database connections or whatever. You surely can tune the numbers more, but I haven’t needed to be more specific yet. MySQL uses two filehandles per open table (for MyISAM, it depends on the table type…)

Flushing the tables

One curious thing you’ll run into is that MySQL can take forever (read: hours!) flushing thousands of tables that have been changed if you do it with a simple “flush tables” or when you are shutting down mysql. That’s of course not “hmn, how curious” but rather insanely frustrating if you were going for a quick restart. This occasionally seems to happen with InnoDB tables too, but in particular with our large MyISAM system (we use fulltext indexes, hence MyISAM) this is a big issue.

With MyISAM tables, you also have a lot of cleaning up to do if the system crashes one way or another with thousands of tables open.

There’s an easy-ish solution to both these problems, though! Just flush the tables individually before the shutdown command and on a regular basis to mitigate the issue if it crashes. Remember the system or MySQL can crash for all sorts of reasons. Recently we had a motherboard with a BIOS or hardware bug that made it unstable after adding more than 16GB memory. On another box, one of the memory sticks went bad so suddenly it came up with 4GB memory less than previously. With MySQL carefully tuned to use all the memory (it was an InnoDB-only installation) it’d try using all 24GB memory and get killed by the kernel when it got above 20! Yeah, that one took some head scratching before I figured it out.

Below is a small program that’ll go through the database twice flushing all tables in all databases and then end with a regular “flush all”. We go through the database twice just in case the first flush took so long that a lot of tables got opened again. Two works for me, depending on your needs you might make it an option. Or a fancy version would check how many open tables are at the end of the run and go through it again if too many are open (and abort with an error if they open faster than they can get closed!). The final “flush tables” worked for me in getting everything closed just before the script exits (and the shutdown or whatever starts).

use strict;
use warnings;
use Getopt::Long qw(GetOptions);
use DBI;

my %args = (
            verbose => 0,
            user     => $ENV{USER},
            hostname  => '',
            port     => 3306


my $dbh = DBI->connect("dbi:mysql:hostname=$args{hostname};port=$args{port}",
                        $args{user}, $args{password})
  or die DBI->errstr;

my @dbs = $dbh->func('_ListDBs');

for my $db (@dbs) {
  next if uc($db) eq 'INFORMATION_SCHEMA';
  $dbh->do("use $db");
  my $tables = $dbh->selectcol_arrayref("show tables");
  for (1..2) {
    for my $table (@$tables) {
      print "flushing $db.$table\n";
      $dbh->do("flush table $table");

print "flushing all\n";
$dbh->do("flush tables");

by Ask Bjørn Hansen at February 15, 2008 09:41 PM

February 14, 2008

Josh McAdams

YAPC::NA 2008 Call for Participation

The Chicago Perl Mongers are excited to officially open the call for participation for YAPC::NA 2008. To submit your proposal, visit the YAPC site, create an account, and let us know what you'd like to talk about. Submissions will be accepted through March 15th 2008, so get yours in soon.

We are currently accepting proposals for conference talks with durations of 20, 45, 70, and 95 minutes. These talks can be directed at any level of Perl programmer, from the noobies to seasoned Perl veterans. If you want to show off an amazing hack or new framework that youve been involved with, this could be your chance. Possibly you just want to contribute to the community by giving an introductory talk on regular expressions or subroutines; we intend on having something for everyone this year.

If 20 minutes is a too intimidating for you right now or if you just dont have enough material to fill up that much time, dont fret, we'll be opening the call for lighting talks soon. These 5-minute mini-presentations are a great way to get a quick point across and to get some experience in presenting in front of a crowd. Keep watching this news source for more information about the lighting talks.

This year we are also planning on introducing more hands-on workshop-style tracks to the conference. These sessions will typically be a little longer than a normal presentation and will be much more informal. During the workshops, conference attendees will be able to interact with presenters to actually do things like compile Parrot or create a hello world program in Perl 6. If you are involved in a project and would like to host a workshop, please contact Josh McAdams directly at joshua dot mcadams at gmail dot com.

by jmcada at February 14, 2008 10:01 PM

Adriano Ferreira

Wanna break some dists?

An easy recipe to do this is to include a dependency on a module version which only development releases reached that far.

That will provoke installations by the CPAN shell to fail complaining about a bad dependency. These actually will generate NA test reports because of dependencies which could not be satisfied.

I saw such an example the other day. The dist KSx-Analysis-StripAccents declared a dependency on 0.2 version of KinoSearch . The latest stable release of KinoSearch is 0.162 and the current devel release is 0.20_05. That filled CPAN Testers with NA reports on SPROUT's module.

Note that this is not a major fault from author's part. It is just how the toolchain works nowadays. There is no automated way to have a dependency on development versions, which seems a good thing, but which cannot be circumvented (unless it is done manually).

Maybe, that has some resemblances with declaring dependencies on third-party modules which are not in CPAN (like SVN::Core and modules in the list kept by Module::ThirdyParty, and company-specific code).

by ferreira at February 14, 2008 09:59 PM

Planet Perl6

Jesse Vincent: Shipwright - our new code distribution system

Like any opensource software shop, we distribute the source code
for our software. How's that for the obvious statement of the decade?

Actually, I can beat it. It's a pain in the neck for end users to
collect and install all of the dependencies for our software.

And now I'm going to one-up myself again. Customers often build
our software against untested versions of libraries, making debugging

RT, our flagship product, depends on 124 separate packages, 114 of
them CPAN libraries. While CPAN has pretty good support for recursively
installing dependencies, it's not perfect and can be time consuming
and confusing for end users. And when it doesn't work right, as can
happen when a module author makes an incompatible change, debugging
requires a wizard.

We've built a new source (and binary) packaging system called
Shipwright. Shipwright allows you to track all of your package's
dependencies in a version control repository like SVN or SVK as
well as build order and build instructions.

It comes with tools for importing Perl modules, C libraries and
other dependencies from CPAN, upstream version control repositories
and tarballs. When it can discover dependency information (as it
can for Perl modules), Shipwright will automatically import the
current versions of all listed dependencies if the repository doesn't
already contain sufficient versions.

Shipwright can automatically set up build instructions for projects
using autoconf as well as projects using Perl's MakeMaker,
Module::Install and Module::Build mechanisms. If necessary, you
can customize the build instructions and dependency ordering after
you import a package.

When it's time to ship your project to your end users, all you need
to do is take a snapshot of your Shipwright repository and send it
out. To build your project, an end user just needs to run
"./bin/shipwright-build". If they want to, your users can choose
to skip certain dependencies (if they want to use system versions)
or specify an installation path. By default, Shipwright builds
fully relocatable binary distributions into a temporary directory
and users can move them into place or copy them to any number of
hosts with the same base system libraries -- Shipwright automatically
wraps all your binaries and scripts so that they can find the
Shipwright versions of their dependencies, no matter where you move
the installed distribution. Shipwright also comes with sh and tcsh
scripts you can 'source' to add an installed distribution's libraries
to your current environment.

At Best Practical, we've configured most of our Shipwright distributions
to bundle everything above libc. Perl, Subversion and GD are just
some of the packages we distribute as part of these relocatable
builds. We now have a single-command tool to build, link and install
Subversion, SVK and all their dependencies (including APR, Neon,
Perl and a bunch of others). With a single command, we downloaded,
extracted, checked in and tested Tatsuhiko Miyagawa's Plagger Feed
Aggregator and all 134 perl modules it depends on. After that, a
single command built a full binary distribution of Plagger, ready
for deployment on any Mac OS X system.

I'm quite proud to release Shipwright 1.0 today. I designed Shipwright
with sunnavy, one of the hackers here at Best Practical. He's
responsible for almost all of the project's implementation to date,
though we're eager to have additional developers join us going forward.

If you're interested in Shipwright, download 1.0 from and subscribe to the Shipwright
mailing list by emailing

You can always get the latest version of the Shipwright source code
with this command:

svn co svn://

February 14, 2008 09:41 PM

February 13, 2008

Adriano Ferreira

What's better? -Ilib or -Mblib?

When testing/playing with a distribution, one usually runs:

$ perl Makefile.PL; make
$ perl -Mblib
# or (with tests)
$ prove -b test.t

Sometime the make (or ./Build) gets annoying and a shortcut is nice:

$ perl -Ilib
# or
$ prove -l test.t

However, there are a bunch of reasons not do that. Among them:

  • -Ilib won't work for modules with XS parts (it will use installed XS components or fail to load)
  • the current build settings may establish an environment different from the current lib/ layout (with modules not in the MANIFEST and things like that)

At the end, we conclude that working under -Mblib is safer (and closer to release conditions) than playing with -Ilib.

by ferreira at February 13, 2008 09:58 PM

Elements of Access Control

Some data is private. Other data, less so. Secure applications make it possible--and easy--to keep user data visible to the right people and invisible to the wrong people. Vladi Belperchinov explains how access control works and demonstrates with working code suitable for implementing your own access controls.

by Vladi Belperchinov-Shabanski at February 13, 2008 09:58 PM

February 12, 2008

David Golden

CPAN 1.92_56 adds "trust_test_report_history" option

I'm proud of this new config option I added to trust_test_report_history.

When this option is set and the latest version of CPAN::Reporter is installed, then won't run tests on a distribution that has already passed tests on that platform and perl, but will use the last test result for that distribution instead.

Where this comes in handy is "build_requires" prerequisites. If a build_requires prereq is not installed, will download, build and test it and then include it in PERL5LIB (if it passes its tests) for the rest of that session. But in any future session, the next time a distribution has that prerequisite, does the exact same thing all over again. But with "trust_test_report_history", the test is only run once.

This may not have a big impact for day-to-day use, but it should save a lot of time and processor cycles for smoke testing.

-- dagolden

by dagolden at February 12, 2008 09:56 PM

Aristotle Pagaltzis

T-2D for the 10th German Perl Workshop

Tomorrow at this hour I’ll be asleep 400km from home.

by Aristotle at February 12, 2008 09:56 PM

Yanick Champoux

Thinking about taking over NetPacket

At $work, an application that I wrote (remora, a companion application to Wireshark) is extensively using NetPacket. NetPacket is very handy but, alas, has some bugs, and seem to be orphaned (the latest update is from 2003). I've tried to poke the maintainers, but Stephanie Wehner's email is no longer working, and Tim Potter didn't reply yet (although, to be fair, I only began to poke last week).

Bottom line, I'm playing with the idea of taking over the module so that I can churn a new version with the bug fixes. So if anyone out there is in contact with Stephanie or Tim, can you let them know a madman is nefariously organizing a coup? Thanks. :-)

by Yanick at February 12, 2008 09:55 PM

Perl Foundation Speed Improvements in Place

A while back, around November 2007, there was some discussion about performance problems with to the point that some found it to be almost unusable. I bring this up here because there were some suggestions that perhaps TPF could buy some new hardware. If you scroll to the bottom, you'll see Jesse Vincent jumped in and said he thought the performance wasn't a hardware problem and he could make some changes, but he needed help locating the trouble spots.

I'm happy to report that Jesse's team, led by Ruslan Zakirov, has implemented some changes and performance seems to be much better now. Even better, many of the changes made for have filtered into the regular RT codebase as of RT 3.6.6. Jesse also told me they are working to publish all the bits of that are still
locked away so that the perl community can contribute more actively.

I just wanted to say thanks to Jesse (and Ruslan) for following through on the fixes. I also want to thank Adam and others for pointing out the problems so we could address them. A public service isn't really a service if people can't use it.

Note: I applied some updates after I first published this.

by Jim Brandt at February 12, 2008 06:39 PM

February 11, 2008

Beautiful Code

Model Checking creators win Turing Award

The Association for Computing Machinery has given it\s highly prestigious A.M. Turing Award to the researchers credited for inventing Model Checking: Edmund M. Clarke, E. Allen Emerson, and Joseph Sifakis.

I believe it was in the 1960s that a few computer science pioneers such as Edsger Dijkstra suggested checking computer programs through formal proofs. For instance, it's obvious you'd better be careful if you write code such as:

if ( var > 0 )
else if ( var = 0 )

Any programmer looking at that has to ask: what does the program do if var is less than 0? Is it OK if the program just falls through to the next statement? If not, can you be sure that var can never be less than 0 when the program reaches this point? These sort of questions are what formal proofs are supposed to expose and resolve.

Formal proofs looked great for academic exercises, but quickly became untenable when applied to real-life applications because of the explosion of possible states. The same originally was true for Model Checking when it was invented in the 1980s.

Another problem with these systems is that they beg the question of whether a program is correct. You can't run a proof without specifying your requirements in a highly formal manner, and the formal statement could just as easily have a bug as the program you want to check, a qui custodiat custos situation.

Gradually these problems were overcome to enough of an extent that Model Checking proves useful in a wide range of situations nowadays, and a huge number of products support it. It's particularly useful in hardware, probably because you're not facing the irony of using code to check code (the qui custodiat custos situation).

So computer science can solve some of the big problems in quality. Congratulations to the honored researchers.

by Andy Oram at February 11, 2008 11:28 PM

Surfin Safari

The Star Seven Hack

For those of you using the star seven CSS hack to target current or older versions of WebKit, this parsing bug has been closed in the latest WebKit nightlies. Acid3 specifically tests for this, so any browser that wants to be compliant with Acid3 will have to fix this CSS parsing bug.

For more information about this hack, see:

by Dave Hyatt at February 11, 2008 10:09 PM

José Castro

Portuguese Perl Workshop 2008

It's true! It's going to happen!

June 6th and 7th (a Friday and a Saturday), in Braga, Portugal.

brian d foy is going to be there and he will also be lecturing two days of Intermediate Perl Programming on the 4th and on the 5th (and we could also tell you which days of the week those are, but instead we'll just let you guess). Other national and foreign speakers are also expected (there's already some movement on DOPPLR).

What did you say? A website? Of course we have a website, don't be ridiculous... Now, where did we put it? Ah, here it is!

You may want to subscribe our feed, since that's the place where the CFP and other announcements are supposed to show up.

Also, spread the word!

See you in Braga ;-)

by cog at February 11, 2008 09:58 PM

Planet Perl

No more email delivery of cpan-testers

Dear cpan-testers recipients,

  Effective Monday night, Feb 11th, 2008, after over a million test reports[1], we will no longer be supporting the delivery via email of cpan-testers test reports.  With an influx of over 3000 messages a  day, this was causing us to deliver almost 200,000 outbound messages, most of which nobody read.

cpan-testers test report submission is unaffected by this change.[2]

If you are currently subscribed to cpan-testers, you'll be unsubscribed, and your mail server will breathe a sign of relief.

  You can find test reports at:

Why are we doing this?  Things were chugging along smoothly, except every few weeks we'd have a problem where a recipient's mail server would stop accepting mail, and we'd very quickly end up with a large backlog of thousands of messages waiting to be delivered.  This would slow down delivery for all of our mailing lists.  Recently, this has been happening more and more often.  We analyzed the
problem, and came to the conclusion that the best solution was to discontinue outbound email.  This will let us focus more time on maintaining more important things.

If you have something that is dependent on receiving all of these emails, please let us know.




[2]  There are some volunteers working on a new system that will take email out of the picture altogether, creating a faster, more streamlined, and more consistent test database.

by Perl NOC Log at February 11, 2008 09:42 PM

Planet Perl

Mac OS X CD-ROM File Systems WTF?

Didn’t it used to be the case that when you used the Mac OS X Finder to burn a CD-ROM that you could then mount that CD-ROM on a Windows box? In the last few months, I’m suddenly finding that this is no longer the case. So now I have to use hdiutil to convert a .dmg file to the Joliet and ISO9660 file systems:

hdiutil makehybrid -o image.iso -joliet -iso image.dmg

And then I could burn a CD readable on Windows. What the fuck? I burned three CDs that were then useless to me before I finally dug up this hint. And I had this problem with CDs burned by Tiger, too, last summer, so it’s not just Leopard. It seems to me that Mac OS X should always default to building a hybrid CD that’s then readable by Windows, Linux, and everything else. Why doesn’t it?

by David Wheeler ( at February 11, 2008 09:42 PM

Jonathan Rockway

Adding methods at runtime

Something people often want to do is add methods to a specific instance of a class. For example, if you have a web request, you might want to introspect it and add a "deserialize" method if it's a REST request with serialized data. However, you don't want other instances of the Request class to have that method. In this article, we'll see how such a thing is possible.

Let's start with a simple (and contrived) example:

package Foo;
use Moose;
has 'value' => (is => 'ro', isa => 'Any');

You can use the class like this:

my $foo = Foo->new( value => 'Hello' );
say $foo->value; # Hello

It sure would be nice to say $foo->say though. Let's write a role that implements the say method:

package Say;
use Moose::Role;
sub say { say shift->value }

Right now, this role doesn't do much:

$foo->can('say');  # undef
$foo->does('Say'); # undef
$foo->say;         # dies

To make $foo do Say, we need to apply the Role. If we were applying the role to every instance of the Foo class, we would say:

package Foo;
with 'Say';

Then Foo->new(value => '...')->say would work.

We only want to apply Say to a specific instance, however. Fortunately, that is possible:

$foo->say;         # Hello 
$foo->can('say');  # CODE(0xc0ffee)
$foo->does('Say'); # true

my $bar = Foo->new;
$bar->can('say');  # no
$bar->does('say'): # false

That's all there is to it. Applying Say to every instance is also possible at runtime:


Let's look at a more complex example:

package Integer;
use Moose;
has 'value' => (is => 'ro', isa => 'Int');

sub one_less {
    my $self = shift;
    return (blessed $self)->new( 
        value => $self->value - 1

sub multiply_by { 
    my ($self, $other) = @_;
    return (blessed $self)->new( 
        value => $self->value * $other->value
sub is_zero { shift->value == 0 }

sub say { say $_[0]->value; $_[0] }

Here we have a basic Integer class. You can do things like:

my $two = Integer->new(value => 2)->say;  # 2
my $four = $two->multiply_by($two)->say;  # 4
my $zero = $two->one_less->one_less->say; # 0
say "is zero" if $zero->is_zero;          # is zero

Straightforward. Now let's say we want to add a factorial method. We again begin by creating a Factorial role:

package Factorial;
use Moose::Role;

requires 'is_zero';
requires 'multiply_by';
requires 'one_less';

sub factorial {
    my $number = shift;
    return Integer->new( value => 1 ) if $number->is_zero;
    return $number->multiply_by($number->one_less->factorial);

Notice that this time we make sure we have all the methods that factorial requires by using the requires keyword. This is checked when we apply the role.

Let's do that:

my $ten = Integer->new(value => 10);
eval { say $ten->factorial } or say "dies"; # dies

$ten->factorial->say; # 362880

my $ten2 = Integer->new(value => 10);
$ten2->factorial->say; # dies

It works just like you'd expect. However, we are doing something tricky. Let's take a look at the one_less method. It takes the current value, subtracts 1, and then wraps up the result in another Integer object.

But, you'll note that instead of Integer->new, we say (blessed $self)->new. That's because to calculate the factorial, the result of one_less also needs to does('Factorial'). But, role application only affects one instance, so just saying Integer->new would fail.

The tricky bit is in the implementation of runtime role application. Basically, when you apply a role at runtime, this happens:

sub apply_role_to($invocant) {
    { package Some::Dynamic::Package::1;
      use Moose;
      extends 'The::Original::Class';
      with 'The::Role::You::Just::Applied';

    $invocant = bless $class, 'Some::Dynamic::Package::1';

That's not valid Perl, but the idea holds. Whatever you passed to apply is reblessed into a dynamically generated package that isa the original class. When we say:

(blessed $self)->new( value => ... );

instead of:

Integer->new( value => ... );

we're making sure that the Integer we return is in that dynamically-generated class with the role applied to it. That way if we call one_less on a class that does Factorial, the instance we return can also do Factorial.

The key thing to take away is that it's possible, easy, and clean to add methods (via roles) to specific instances of classes. However, you do need to make sure your class isn't working against, like our Integer class would be if we just returned Integer->new.

Footnote 1

Incidentally, did you know you can modify a method's invocant? Try this sometime:

package Foo;
sub go { say 'Foo::go'; $_[0] = 'Bar'; }

package Bar;
sub go { say 'Bar::go'; $_[0] = 'Foo'; }

my $class = 'Foo';
$class->go; # Foo::go
$class->go; # Bar::go
$class->go; # Foo::go

This is a great way to ensure that your code is completely unmaintainable. But it's also good for implementing runtime role application.

by Jonathan Rockway ( at February 11, 2008 09:42 PM

Perl Foundation Updates

Thanks to some help from Will Willis and Jeremy Fluhmann, of the Perl Foundation conferences committee, has a few new items. Specifically, we've included ads from the Perl community ad server provided by Gabor Szabo and a new Workshops page that describes how to organize a workshop and what TPF can do to help.

by Jim Brandt at February 11, 2008 06:01 PM

February 10, 2008

Jakob Nielsen


User Skills Improving, But Only Slightly

February 10, 2008 09:56 PM

Yanick Champoux

Git's the nightclub, Perltidy's the bouncer

I finally wrapped my CVS-encrusted mind around Git's hooks. Huzzah! The biggest hurdle, really, was realizing that there is no spoon.

Anyway, as I'm an unsalvageable slob who always forget to run perltidy before committing changes, I've written a pre-commit hook that makes sure that all Perl files to be committed are all clean, neat and tidy (and aborts the commit and chides me if they are not):


use Perl6::Slurp;

my $status = slurp '-|', 'git-status';

# only want what is going to be commited
$status =~ s/Changed but not updated.*$//s;

my @dirty =
  grep { !file_is_tidy($_) }                   # not tidy
  grep { /\.(pl|pod|pm|t)$/ }                  # perl file
  map  { /(?:modified|new file):\s+(\S+)/ }    # to be commited
  split "\n", $status;

exit 0 unless @dirty;                          # Alles gut

warn "following files are not tidy, aborting commit\n",
     map "\t$_\n" => @dirty;

exit 1;

### utility functions ###############################################

sub file_is_tidy {
    my $file = shift;

    my $original = slurp $file;
    my $tidied = slurp '-|', 'perltidy', $file, '-st';

    return $original eq $tidied;

by Yanick at February 10, 2008 09:55 PM

February 09, 2008

Michael Schwern

Critical and Significant Dates

Speaking of 2038, J R Stockton wrote up an enormous and comprehensive list of Critical and Significant Dates. The original site has, alas, been knocked out but the Wayback Machine remembers all.

It's a fascinating look back at historical date and time related crises as well as possible future ones. 2038 is, of course, on there but there are hundreds more between now and then. Not just computing problems, but multiple ends of the world ranging from Mayan predictions to near-misses by asteroids. The last crisis point to pass was 2008-01-19 when 30 year look aheads fail. Next up is an unusually early Easter, 2008-03-23.

Not so exciting but what about 2010 when a lot of not particularly robust Y2K fixes will fail and 2019 when yet more will fail? Various dates used as magic marker values happen. 2009-09-09 (09/09/09) and 2011-11-11 (11/11/11). 2008-12-31 is coming up, the 366th day of the year which has caused major failures in the past. 2015-09-05 is when Apollo/HP 32 bit machines run out of time.

After 2025 the pace of systems failing accelerates. Quickbooks starts to die in 2025. 2028 overflows systems that store the year as 1900 + signed byte. More Y2K fixes break in 2028 and 2029. MSDOS file dates start to fail in 2030. Palm Pilots die in 2031. Microsoft's Y2K compliance ends at 2035...

Looking far, far into the future, around the year 300 billion 64 bit time_t runs out. Finally, in the year 2^1E80, it becomes impossible to express the date as the size of the year in binary is larger than the number of particles in the universe.

But by then I think we can safely assume we'll all have migrated to a 1e160 particle universe.

by schwern at February 09, 2008 09:57 PM

February 08, 2008

Surfin Safari

querySelector and querySelectorAll

A familiar and unpleasant sight in web applications is fragile code traversing the DOM to get to certain elements or collections of elements. Chains of getElementById("something").parent.parent are all too common, hurting both readability and flexibility. As a result, many javascript libraries have implemented functions to use the powerful CSS selector system to look up DOM nodes.

Continuing the trend of standardizing and speeding up commonly used functionality from these libraries, WebKit now has support for the new W3C Selectors API, which consists of the querySelector and querySelectorAll methods. Hopefully libraries will begin to adopt this new functionality to provide performance improvements while remaining compatible with older browsers.

Some examples of how it could be used:

   * Get all the elements with class "hot" (duplicating getElementsByClassName)
   * A common use for this is as a toggle;
   * for example, a search feature might tag results with a class

   * Get the currently hovered element

   * Get every other element in the <li> with id "large"
   * This is mostly useful for doing "zebra stripe" alternating rows.
   * Once CSS3 becomes more widespread, doing this directly via CSS will be more practical

What would a new API like this be without benchmarks? The mootools project has conveniently created a wonderful test and benchmark suite for just this sort of functionality. A version of it that has been modified to test querySelectorAll as well as three common javascript libraries is available at Please note that many of the tests will only work in a build of WebKit from February 7th or later.

by David Smith at February 08, 2008 06:51 AM

February 07, 2008

Michael Schwern

Perl is now Y2038 safe

They said it couldn't be done. They said it SHOULDN'T be done! But I have here a working 64 bit localtime_r() on a machine with just 32 bits of time_t. Time zones, daylight savings time... it all works.

$ ./miniperl -wle 'print scalar localtime(2**35)'
Mon Oct 25 20:46:08 3058
Perl will be Y2038 safe. And yes, I'm going to get it backported to 5.10.

The underlying C functions are solid, but I just sort of rammed them down perl's throat because it's 5am. Here's the patch for the intrepid.

The underlying C implementation is a heavily modified version of the code from written by Paul Sheer. He came up with the same basic algorithm I did:

1) Write a 64 bit clean gmtime(), that's a SMOP and Paul did that.
2) Run your time through this new gmtime_64().
3) Change the year to a year between 2012 and 2037.
4) Run it through the 32 bit system localtime() to get time zone stuff.
5) Move the year back to the original.

The trick is using a 32 bit safe year that has the same properties as the real year. This means same leap year status and same calendar layout. Had to do some tricky Gregorian calendar math aided by Graham, Nick and Abigail who realized there's a 28 year cycle within the larger 400 year Gregorian cycle and Mark Mielke who provided a big table of 64 bit localtime() results to test against. There's also some edge cases around New Year's, but they're all taken care of.

This approach will break when daylight savings time changes, but I'd rather be off by an hour than 137 years. The full Perl patch will always prefer the system's 64 bit localtime() if one is available. As more machines upgrade time_t this hack will be used less.

The nice part is this code isn't specific to Perl and can be used to fix up any other C-based Unix program.

by schwern at February 07, 2008 09:57 PM

February 04, 2008

Planet Perl

Winter Creek


        A small creek frozen over that I found on the drive home yesterday. The
        utter silence while taking this photograph was perfect, broken by the
        distant screech of an owl.

Original here

by Matt Sergeant at February 04, 2008 09:42 PM

Planet Perl

Need Suggestions for IMAP Solution and Migration

For the last several years, I’ve run a Courier-IMAP mail server for all of the mail for this site, Kineticode, Strongrrl and other domains. We mainly used on Mac OS X to communicate with the server, and it worked really well. Today, Julie has over 3 GB of mail data, and I have around 1.5 GB, all managed via IMAP.

Recently, I decided it was time to move the mail elsewhere. I’ve been meaning to do it for a while, primarily because the server I was using is now used for the Bricolage project, and because I never set up any spam filtering. Julie was suddenly getting 100s of spam messages in her inbox. (It really didn’t help that she was still using Panther.) So on the advice of a good friend who had been evaluating various mail services—and who for now shall go nameless and therefor blameless—I moved all of our mail to FuseMail.

At first this seamed like a pretty good solution. Our spam rates went way down, I could set up unlimited mail lists, aliases, and forwards, and there was a migration tool that automated moving all of our existing mail from the old IMAP server to the new one. There were some glitches with the migration tool, but in the end all of our mail was moved and in tact.

But that’s when I started to notice the issues. To summarize:

  • Mail put into the Sent Items folder by was marked as unread. This didn’t happen on the old server, and apparently has something to so with how FuseMail names the sent folder: Sent Items rather than Sent Messages.
  • is syncing constantly. Even once it had successfully synced the all of our email in all of our IMAP folders (which took days, it is syncing all the time, to the extent that I am sometimes waiting for up to a minute to read a mail when I double-click it, because there are all these other threads doing stuff and taking up all the resources. It can take several minutes for mail I’m sending to be sent (though that might be a delay in copying the message to the Sent Items folder rather than the actual sending).
  • Deleting mail takes forever! This is probably the same issue as the syncing problem, but when I delete 1000s of messages from my Junk mail folder, it runs forever, and all other activities are delayed eve further. It turns out to be much more efficient to empty the Junk and Deleted Items folders using the webmail interface. And even then, can take a while to delete locally-cached items from the folder when it syncs.
  • Suddenly, Julie is getting a lot less spam. She went from several hundred messages showing up in her Junk mailbox a few days ago to just five on Friday and two yesterday—one of which was a false positive). As she had been expecting a message from someone that she never got, this naturally made her very suspicious. Where is all the spam? Is she getting all of her mail?
  • Since FuseMail uses a mailbox named Sent Items instead of the traditional Sent Messages for all sent mail, I asked if they could move the 1.8 GB of messages from Julie’s Sent Messages to their Sent Items, since would just choke on such a task. Though my request was escalated to the FuseMail developers, the answer came back no. Which I guess means that they’re not using Maildir, because in that case it would be a cinch, n’est pas?
  • Backups are not really feasible. Of course FuseMail has its own backup regimen, but if I ever want to move elsewhere or deal with some sort of catastrophic failure, I want my own backups. There is no rsync service available for this (remember: no maildir), so I have to use the IMAP interface. I’ve been trying for the past two weeks to get Offline IMAP to back up all of Julie’s and my mail, but it keeps choking. It gets a little further every time I run it; eventually it will get it all. But this only allows me to backup those accounts for which I happen to have a password. I have accounts set up for a few other users, but don’t have access to their passwords, so I can’t back them up. This does not make for very good support for corporate backup and retention policies.
  • Mail forwarded by FuseMail has its Return-Path header modified. This made RT break until I hacked it to ignore that header (which is its by-default preferred header for identifying senders.

So I’m pretty fed up. It took me a week to get all of our mail on FuseMail, and now I’m looking at moving it off again (once OfflineIMAP finishes a full sync). Grr. I’m considering finding a virtual host somewhere and setting up my own IMAP server again, but then I have the spam problem again. So then I could use a forwarding service like Pobox, or I can set up my own spam filtering (something I had hoped never to get into managing myself). My old IMAP server required very little maintenance, which was nice, but then the span filtering stuff always seemed daunting. Don’t you have to update things all the time?a

But before I go off and do something else, and unlike before I moved to FuseMail, I wanted to get an idea what other folks are doing? Do you use IMAP? Do you use it to manage a shitload (read: Gigabytes) of mail? Do you get very little spam and still get all of your valid mail? Are IMAP folder maintenance actions fast for you (in in particular)? Are you paying a not-unreasonable amount of money for your setup? If you answered yes to all of these questions, please, for the love of all that is good in this world, tell me how you do it. I’m looking for something that I don’t have to work very hard to maintain (hence my original attempt to have some company that specializes in this stuff do it), but I’ll do what I have to to make this thing right. So how do you make it right? And if I have to run my own server, where should I host it that won’t cost me an arm and a leg?

Thanks for your help!

by David Wheeler ( at February 04, 2008 09:42 PM

February 03, 2008

Joshua Wehner

Configuring a Windows server

I quite enjoyed reading Brent Ashley’s description of his travails when trying to set up a Windows server

When I finally get through a marathon session of setting up a Windows server “just so” to make my application work, it’s like I have created a finely balanced stack of Jenga blocks from which I back away slowly on tiptoe, praying it doesn’t tumble. I’ve get very little confidence that fixing anything will be an excercise in logic and deduction more than having to know some obscure incantation or uninstalling components wholesale and reinstalling and reconfiguring them.


Tagged: ,

by Joshua Wehner ( at February 03, 2008 06:44 PM

February 02, 2008

Planet Perl

OSCON talk

Wondering what talk I should submit to OSCON (and other YAPCs this year too!).

The obvious choice is Web::Scraper since I haven't done this talk other than Europe and Japan, and I can make lots of updates till summer when I give an actual talk (We call it CDD -- Conference Driven Development)

Any suggestions?

by Tatsuhiko Miyagawa at February 02, 2008 09:41 PM

January 30, 2008

Chris Dolan

[Idea Bin] Port bash to Parrot

I'm going to use the "[Idea Bin]" flag to indicate ideas or projects that I would love to develop if I had more time, but realistically admit that I'll never finish. If you choose to use one of these ideas, you have my permission and best wishes.

An implementation of bash on Parrot would be a great test of Parrot's I/O capabilities. The source code for bash is fairly readable considering how arcane are some of its supported operations. Bash has a rather healthy test suite that could be reused during development.

I spent many commutes pondering possible names for such a port, but never came up with a great one. I wanted "posh" to work, but never came up with the right words for the acronym. "bashup" = bash-under-parrot felt too forced.

If such a parrot implementation would enable you to call out to other languages via namespace prefixes on functions, this could let shell be a better glue language than ever. You could incrementally port hairy shell scripts to more expressive programming languages.

Then you could switch all of your /etc/rc scripts to run under parrot by just changing the sharp-bang.

Furthermore, I've been a csh/tcsh user for 15 years and have always envied the power of bash, but never bothered learning more than the rudiments. This would be an excuse to learn it deeply.

by ChrisDolan at January 30, 2008 09:56 PM

January 29, 2008

Yanick Champoux

Greasemonkeying dependencies

Escalation wars... you just have to love'em.

First, David came up with the über-cool CPAN deps page.

Then Andy comes up with a nifty Greasemonkey script to add it to the CPAN distributions main pages.

Then I add a small patch to the script to retrieve some information from the Deps page.

Then David creates an xml interface to CPAN deps, opening the door wide open for Web 2.0 goodiness.

Then (and this is where we are right now) I hack together a new CPAN_Dependencies monkeyscript to take advantage of said xml interface.

This, of course, is nowhere near the end of the story. My new script only scratches the surface of what can be done with the information contained in the xml. As soon as I have some tuits, I'll probably add a way to toggle between showing only the first-level dependencies and all dependencies, and have dependencies color-coded by degree of b0rkage, and whatever bell or whistle I can think of in the meantime.

by Yanick at January 29, 2008 09:55 PM

January 27, 2008

Planet Perl

Tom Limoncelli Interview Transcribed

I’d like to thank Shlomi Fish for taking the time to transcribe the Perlcast interview with Tom Limoncelli about “Time Management For System Administrators”

by Josh McAdam's Perlcast at January 27, 2008 09:42 PM

January 26, 2008

Steffan Müller

perl 5.12, strict by default

So I did it. I proposed to the perl5-porters that we should enable "use strict" by default for some future code. This may be a little less preposterous than it sounds at first, so please wait with hitting the "reply" button until you read the whole of this.

My proposal basically goes as follows:

  • Add a feature called "strict" to
  • Include that feature into the set of default features which are loaded by "use feature ':5.11'" or even just "use 5.11.0;".
  • Add a special case for the -E switch to perl so strictures aren't enabled by default for one-liners.

I'll include my original rationale here:

Personally, I've always wanted perl to have strictures on by default for my code. I would think that 95% of all code bases which were written in this century and which are of non-negligible size import "strict". I don't use strictures for one-liners, of course, but for anything else it's a must. It seems to me like others have similar views on this. Try posting some code without "use strict" to some newsgroup or forum and ask for help. Make sure not to give out your email address, though.

"use 5.10.0;" already auto-imports and loads the 5.10 specific features.

How about having "use 5.11.0;" (or 5.12.0) automatically import strict along with the 5.10+5.11 feature set? Naturally, the -E switch for one-liners should *not* do that.

This would *not* break backwards compatibility. This would not affect one-liners. This would optimize for the common case: If you write enough code to make importing optional features worthwhile, odds are very high you'd be importing "strict" anyway. The 5% who need to disable strictures again can still add a "no strict;" statement.

strictures-correct code has been best-practice for a long time now. Let's make it the default for *new* code.

Just think of strictures as a feature. It just makes sense.

To my surprise, the proposal has been received with very positive feedback. So I wrote the patch.

With some luck, we'll get strictures by default in 5.12! Flame away!


by tsee at January 26, 2008 09:55 PM

Evil PAR tricks, issue 0: Binary including a binary

In my journal entry from December 22, 2006, I said I'd used a few hacks to package parinstallppdgui into an executable binary using PAR::Packer. I'll explore that further here:

parinstallppdgui is mostly a GUI front-end to parinstallppd. It doesn't use PAR::Dist::InstallPPD internally, but uses the system to run parinstallppd so if the child process bombs out, the GUI process can show a friendly warning to the user (comprised of the STDERR and STDOUT of the child process) instead of crashing. That's all very simple if you have perl on your system, of course.

Now, if you want to package parinstallppdgui or any other Perl script that uses another Perl script into an .exe, you'll quickly find out that without a perl on the target system, these two scripts cannot share the same interpreter. The obvious "solution" is to package both of them up into an .exe separately and ship them both. This has several problems. First, you need to ship two executables instead of one. Second, the first executable won't necessarily know where to look for the second if the user doesn't put them in PATH. Adding a couple of FindBin hacks isn't great at solving this, either! Third, these two executables will have a lot in common - starting with all the core Perl modules.

So I took a slightly better, yet more complicated route. The process is as follows:

  1. Add a special case to the parent's source code for execution from inside a PAR binary:

    if (defined $ENV{PAR_TEMP}) {
            require Config;
            require File::Spec;
            $ENV{PATH} .= (defined $ENV{PATH} ? $Config::Config{path_sep} : '')
                                            . File::Spec->catdir($ENV{PAR_TEMP}, 'inc');

    This forces all PAR'd executables that are started by this process to use the same cache area as this process. This might be a dangerous thing to do if both binaries contain different, incompatible versions of some files. But we control everything here, so it should be okay.
  2. Package parinstallppdgui, the parent script:
    pp -o parinstallppdgui.exe parinstallppdgui
  3. Package parinstallppd, the child script:
    pp -o parinstallppd.exe -l expat parinstallppd
    (We include the expat library.)
  4. Remove all files from the child script that are also available from the parent. This makes the child dependent on the parent. Use the pare utility from the PAR::Packer distribution's contrib/ directory for this:
    pare -u parinstallppdgui.exe parinstallppd.exe
  5. Package the parent script again, but this time include the child script as an extra file into the executable:
    pp -o parinstallppdgui.exe -a parinstallppd.exe -l expat parinstallppdgui
  6. Ship the combined binary only.



P.S.: A third and even better solution might be to package both of the scripts into the same binary and symlink or copy that binary to parinstallppd.exe and parinstallppdgui.exe and let PAR figure out what to run. This is cool if you have symlinks and sucks if you don't.

by tsee at January 26, 2008 09:55 PM

CPANTS Distribution Checker (without PAUSE upload)

So CPANTS was down for a couple of weeks. This morning, I noticed it's back, but so far without the cron job that updated the data nightly.

For me, CPANTS has been a way to check my eighty or so CPAN distributions for packaging shortcomings. Unfortunately, that check happens only after I made the release. I installed Module::CPANTS::Analyse which comes with Given a distribution file name, it runs the CPANTS metrics against it.

Since Module::CPANTS::Analyse comes with quite a few prerequisites, I set up a simple web service which you can use to check your distributions before uploading. The interface is a little cumbersome, but I think it's worthwhile. Just upload your distribution at and then visit the result URL given by that script after a few minutes.

The reason for the delay is that I didn't want to install all prerequisites on the hosting account and certainly didn't like running from a CGI process. Thus, my local server fetches distributions-to-scan from there and uploads a result text every three minutes.


by tsee at January 26, 2008 09:55 PM

January 25, 2008

Joshua Wehner, Comments

Comment on 'Massachussets-style health-care reform: results are in'

Parmeter said:


The answer to your question is simple. It is the way these politics are played. See Medicare and -aide as examples. It doesn't matter if the first incarnation was so screwed up that its taken forty some years to try and right it, it was the first to make it through the legal system largely intact. Because it has already survived legal challenges and came out the other side with legislative and judicial approval. Any other state that wants to do the same doesn't have to work to get it going at home. All they have to do is copy and paste.

Simply amazing that the effects of the law can be so far away from what was intended (either through accident or design, it matters not which at this juncture) that I am left wondering if anyone, anywhere will pay politically for the screw up.

by Parmeter at January 25, 2008 11:00 PM

January 24, 2008

Planet Perl

Settling in

Well, I’m here in San Francisco and starting to settle in nicely. Lots of social stuff going on, fun work that doesn’t feel like work, and I found a place to live really quickly and easily.

Me at the Rock Band extravaganza

This photo’s by the lovely yarnivore who took it last weekend at a Rock Band extravaganza where we (I say “we”, though I didn’t do much of it) played right through the full 58-song set list. It took about eight hours.

But the real reason I’m posting today is to assist anyone stalking me. I assume you’re already following my photos on Flickr but you might also like to check out my work blog where I’m, well, posting about work things: Freebase, open data, mashups, that sort of stuff. And if you’re going to be around these parts on Feb 6th, be sure to swing by the Freebase user group meeting for pizza, beer, and of course lots of technical presentations.

No Tags

by Kirrily Robert at January 24, 2008 09:42 PM

January 22, 2008


using POD or something else?

I was curious as to what percentage of Perl'ers use POD for documenting their code. I was curious because I looked at the Template-Toolkit source and while there is POD after the __END__ there is also documentation in the code using normal # type comments. That seems redundant to me but is that the norm?

Also, is there a good "this is how you use POD" with examples (besides perlpod) somewhere?

by sigzero at January 22, 2008 09:57 PM

January 21, 2008

David Golden

CPAN::Reporter::Smoker first alpha release

For a long time, the only easy way to submit CPAN Testers reports was CPANPLUS. The first automated smoke testers for CPAN were built upon it, like CPAN::YACSmoke and POE::Component::CPAN::YACSmoke.

About a year and a half ago, I wrote CPAN::Reporter, to bring CPAN Testers reporting to good-old Since then, some intrepid individuals have built automated smoke testers upon CPAN::Reporter, all writing their own programs to do so. itself added an experimental smoke command to test recent uploads, but it requires XML::LibXML and doesn't test distributions in isolation -- all tested distributions and their dependencies keep getting added to PERL5LIB until things explode.

Yesterday, I released the first, alpha version of CPAN::Reporter::Smoker to provide a better-behaved, more turn-key approach to smoke testing with CPAN::Reporter.

(... configure CPAN and CPAN::Reporter as usual ... )

$ perl -MCPAN::Reporter::Smoker -e start

This initial version still has some limitations (e.g. no developer versions smoked), but I'm ready for anyone interested to try it out and start sending feedback -- compliments, suggestions, or complaints all welcome.

-- dagolden

by dagolden at January 21, 2008 09:56 PM

Chris Laco

My Perl 5.12 Wishlist

It's one thing and one thing only. Unless my memory is wrong, sub attributes can only be on the first line. Please o please, allow them to span multiple lines. When using Catalyst, you could start with this:

sub update : Chained('instance') PathPart Args(0)
The minute you start adding custom attributes, things end up well past 70-80 columns wide:

sub update : Chained('instance') PathPart Args(0) Form('someform.yml') Template('this/page') ActionClass('REST')

by jk2addict at January 21, 2008 09:55 PM

Planet Perl

vim and Perl 5.10

If you use vim and want it to highlight correctly the new keywords in Perl 5.10, you can just drop the following syntax plugin script as ~/.vim/syntax/perl.vim :
so $VIMRUNTIME/syntax/perl.vim
syn keyword perlStatementStorage state
syn keyword perlStatementFiledesc say
if exists("perl_fold") && exists("perl_fold_blocks")
syn match perlConditional "\<given\>"
syn match perlConditional "\<when\>"
syn match perlConditional "\<default\>"
syn match perlRepeat "\<break\>"
syn keyword perlConditional given when default
syn keyword perlRepeat break
if exists("perl_fold")
syn match perlControl "\<BEGIN\|CHECK\|INIT\|END\|UNITCHECK\>" contained
syn keyword perlControl BEGIN END CHECK INIT UNITCHECK

An extension, not implemented here, could be to add a new highlight class for the new regexp verbs (MARK, SKIP, COMMIT, etc.)

by Rafael at January 21, 2008 09:42 PM

January 20, 2008

Planet Perl

Logic Programming with Ovid

Back at the Nordic Perl Workshop 2007, I sat down with Ovid to talk about logic programming. Here is the audio for that interview.

by Josh McAdam's Perlcast at January 20, 2008 09:43 PM

January 19, 2008

Lawrence Watt-Evans

A Word to Hugo Voters

Helix is eligible for nomination in the semiprozine category. A nomination would brighten my summer.

I wouldn’t mind seeing William Sanders up for editor, short form, either.

by lawrence at January 19, 2008 08:01 AM

Lawrence Watt-Evans, Serials

On an unrelated matter…

I would just like to point out to any readers here who happen to be Hugo voters that Helix is eligible for nomination as a semiprozine. If you happen to have your Hugo nominating ballot lying around, and you were thinking, “Gee, what could I nominate, so as not to waste this fine ballot?” — well, there’s one possibility

by Lawrence at January 19, 2008 07:56 AM


At last!

I believe that every book I owed any donor is now on its way, though how I’m defining that gets a bit tricky.

There are seven sitting in a box in the dining room waiting to be taken to the post office. There’s one on my desk waiting for an e-mail confirming how the donor wanted it personalized.

All the others have been mailed.

Most packages included The Vondish Ambassador, a chapbook of “The God in Red,” and an insert map of the Empire of Vond. I signed or personalized The Vondish Ambassador as requested.

However, I know that in at least one case I sent a signed book to someone who hadn’t wanted it signed, and sent an unsigned copy to someone who had requested a signature. I’m fairly sure that I forgot at least one map. It’s possible I also messed up in other ways. My apologies, but packing and mailing hundreds of books is one heck of a job. I got most of them right.

There were also a few people who I could never get a response from, so those books may have gone to incorrect addresses. I tried, honest.

If you did not receive the map (it should be just inside the front cover), let me know, and we’ll see what we can do about it.

Two people who are entitled to a copy of the book declined — one prefers an e-book and the other is waiting for a mass-market edition.

If your copy of the book hasn’t arrived yet at all — especially if you’re outside the U.S. — give it a few days, but if it hasn’t shown up by Candlemas, drop me a line.

As of right now, there’s still nothing definite about a mass-market edition.

Several people have asked me when I’ll be starting the next serial, and what it’s going to be, so let me once again say, “I don’t know.” It depends on when I get other projects done, what sort of offer Tor makes (if any) for the Fall of the Sorcerers, and various other factors, some of them beyond my control.

My best guess is that I’ll start a third serial late this year — maybe as a Christmas present for my readers. Whether it’s Ethshar or science fiction — well, we’ll see.

Thanks to everyone for your continued support!

by Lawrence at January 19, 2008 07:56 AM

January 18, 2008

How to Tell Your Perl Story (at OSCON)

Have you done something stunningly cool or staggeringly useful with Perl in the past year? Conference season will be here soon; it's time to consider giving a talk to your local monger group, a regional conference, or even OSCON. Perl track committee member brian d foy gives several guidelines to help you decide what to talk about and how to present it.

by brian d foy at January 18, 2008 09:57 PM

Planet Perl

Teach-In in Birmingham

I'm going to be presenting the Perl Teach-In in Birmingham on Monday 31st March as part of UKUUG's Spring 2008 Conference. The talk will be (lightly) updated from the one I gave at the BBC last summer.

This tutorial won't be free. As I understand it, the class will only be open to people who are registered at the conference, but I don't currently know how much that will cost or whether you'll be able to buy a ticket for just the tutorial day. I'm sure more information will appear on their web site soon.

I should start looking in to running the Teach-In in London again.

by Dave Cross at January 18, 2008 09:22 PM

Penny Arcade Art

January 17, 2008

Chris Laco

Catalyst + REST

Since we're on the topic of Catalyst and REST, I hereby declare Firefox 2.x broken.

There's this great set of modules under the moniker Catalyst::Action::REST that easily adds REST support to Catalyst. While I have no REST API in Mango (yet), I also use this package to do Content-Type -> View negotiations (text/html-> View::HTML, application/xhtml+xml->View::XHTML, application/atom+xml->View::Atom, etc), and it does it quite well.

Unfortunately, Firefox 2.x throws a kink in the works. The REST controller looks at the Content-Type header, then falls back to the content-type query param, then falls back to the Accept header. It's that last thing that kills. You see, firefox sends this accept header:

text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8, image/png,*/*;q=0.5
So, when I request a regular old web page, really wanting HTML, the REST controller negotiation falls back to text/xml, even though my default type in config is text/html. Grrr.

There are at least two solutions to this [for me in my base class]:

1. Cleanse the Accept header of this madness before calling the REST package into action

2. Map text/xml to my HTML View

Both are evil in their own ways. I started with #2, since people should really be sending application/xml anyhow and as of now, my app doesn't support xml via REST/content negotiation anyways.

#1 is really the better answer since we can't fix Firefox 2.x. For REST clients, they must send a Content-Type header, so those aren't a problem. And you can always override using the content-type param.

Just for giggles, Firefox 3.x beta Accept header is:


by jk2addict at January 17, 2008 09:55 PM

Penny Arcade Art

I'm going to try and draw all our new Wow characters. I started with Kara's hunter.

by Gabriel at January 17, 2008 07:26 PM

January 16, 2008



I have started looking for smaller part-time work in Perl. I really need to push myself and learn as I don't have anyone to "harass" about Perl. I think I am pretty solid in the fundamentals and I have put up a couple commercial sites for friends.

I think I just need to close my eyes and jump.

by sigzero at January 16, 2008 09:57 PM

Planet Perl

Disk usage graphical presentation

I found out by accident about this GNOME tool, the "Disk Usage Analyzer". It has a surprisingly good UI, displaying subdirectories as concentric circular arcs. It makes visually obvious the spots where all the place is wasted. Or spent.

As an illustration, here's a screenshot of it displaying the disk usage taken by a fresh checkout of Perl 5's sources.

I wouldn't have thought that Encode was taking so much space. (This is, of course, due to all the files that describes the various encodings recognized by this module.)

by Rafael at January 16, 2008 09:41 PM

January 13, 2008


Maven for Perl?

I have been reading up on Maven2 for a project at work. It pretty much handles everything about a project (managing dependecies, documentation, tests etc.).

I wonder if something similar would benefit the Perl community or is there something out there that I don't know about or even "it is a bad idea".

by sigzero at January 13, 2008 09:56 PM

Chris Laco


FYI to whomever. Just tried to login to PAUSE. I'm getting https connection errors. Changing the login link to http works just fine.

by jk2addict at January 13, 2008 09:55 PM

January 09, 2008

Penny Arcade Art

Ron has helped us so much on our game. I did this for him just to say congrats on the announcement of DeathSpank.

by Gabriel at January 09, 2008 09:24 PM

January 08, 2008

Planet Perl

Here comes another one, just like the other one

Labor Senator Stephen Conroy’s new Internet censorship policy:

Federal Labor will improve existing government programs in this area by:

Providing a mandatory ‘clean feed’ internet service for all homes, schools and public computers that are used by Australian children, so that ISPs will filter out content identified as prohibited by the Australian Communications and Media Authority (ACMA). The ACMA ‘blacklist’ will also be made more comprehensive to ensure that children are protected from harmful and inappropriate online material.

(emphasis mine)

The previous government’s scare tactics, as seen on a tram shelter in Melbourne.

The difference between this load of steaming horse shit and the rather similar load that got dumped on us in 1999 is that this time the mainstream media actually know what’s going on:

When a Queensland newspaper’s headline reads “Nanny Rudd censors the internet”, you know the times are a-changin’. So, I have some hope that this idiotic proposal will either get ditched entirely, watered down to pointlessness (as 1999’s was), or worked around to a significant degree. I won’t be here for it, but good luck with that.

No Tags

by Kirrily Robert at January 08, 2008 09:42 PM

January 05, 2008

Planet Perl


Happy New Year and welcome back to Perlcast. Though 2007 ended with a very light lineup of shows, we here at Perlcast are excited about what 2008 has to offer. There are plans for more interviews, more presentations, and possibly even some videos and video tutorials about Perl.

Anyway, let’s get back to the podcast. Way back at OSCON 2006, I sat down with Stas Bekman and Philippe M. Chiasson to talk about mod_perl. Though quite a bit of time has passed since the show was recorded, there is still a lot of good mod_perl related information in the show. I hope that you enjoy it.

by Josh McAdam's Perlcast at January 05, 2008 09:21 PM

Planet Perl

California, here I come

I seem to be constitutionally incapble of avoiding that subject line. Sigh. I apologise.

In any case, it’s official. I’m moving to California in less than two weeks’ time.

I put off mentioning it here in some sort of fit of superstition. I didn’t want to jinx it. But back in November I received a job offer from Metaweb, Inc to become the Community Director for Freebase. I accepted, and the visa paperwork began. Yesterday my visa was approved, and now the tickets are booked. I fly out on January 15th.

The job is based in San Francisco in the SOMA district, and I’ll initially be staying with friends in the Mission til I find a share house to move into. Plus I’ll get to travel to conferences, so I’m hoping to get to see a bit of the US and the world.

Right now I’m in the throes of packing everything I own into boxes and saying goodbye to people in Australia. Life is crazy but good.

No Tags

by Kirrily Robert at January 05, 2008 09:21 PM

January 01, 2008

Planet Perl

WoC part two: Database and Domain Design

Part two of the Vienna WoC TODO Manager code is up, in which I design and implement a Catalyst+DBIx::Class+Reaction app from the ground up in public and document the process. The latest article is Database and Domain Design, in which I don my gea...

Read and post comments | Send to a friend

by mst at January 01, 2008 09:41 PM

Lawrence Watt-Evans

Seventh Heaven… I mean, Helix!

Helix No. 7 is now up and open for business — check it out.

There are seven new stories, by Charlie Anders, Maya Bohnhoff, Adam-Troy Castro, David W. Goldman, Selina Rosen, Vaughan Stanger, and Laura J. Underwood, along with poetry by Mike Allen, F. J. Bergmann, Anthony Bernstein, Gene van Troyer, and Jane Yolen, and columns by the regulars — John Barnes, Bud Webster, etc.

The only pay the authors of those seven stories will receive is a share of what readers donate, so if you like what you read, do please show that appreciation in tangible form, either through PayPal or by sending a check.

by lawrence at January 01, 2008 07:54 PM

December 29, 2007

Planet Perl

Vienna WoC TODO Manager series on

I'm going to be building an application to help run the Winter of Code, and since the resulting application is going to be open source and in public subversion as an example of Catalyst+DBIx::Class+Reaction, I've decided to write up the ...

Read and post comments | Send to a friend

by mst at December 29, 2007 09:42 PM

December 27, 2007

Perl Advent Calendar


2007 Perl Advent Calendar: E.L.F.

December 27, 2007 09:56 PM

December 25, 2007

Perl Advent Calendar


2007 Perl Advent Calendar: I can hardly wait

December 25, 2007 09:56 PM


2007 Perl Advent Calendar: Dickens also rates an 8

December 25, 2007 09:56 PM

December 24, 2007

Josh ben Jore

Obstacles to porting SmallTalk debugger in Perl

I've been playing in Squeak recently and it has the best debugger I've ever seen before. Not only can I inspect any part of the running system, I can modify the code for anything, let the absence of methods or other exceptions serve as breakpoints, pop up a level (or many) in the stack and restart a function.

It's sweet. To make this happen in Perl 5 I'd need the following facilities that

"find the source for the thing that is executing"
"project an editor somewhere useful"
"be able to accept the edited code and replace it in the original file (this is difficult. maybe requires PPI)"
"Merge newly compiled block into running program. (trivial? for non-closures. needs rebinding for closures)"
"pop the stack to some arbitrary point. be able to restart the block"

This is just off the top of my head. Maybe it's not worth doing in Perl 5 but it'd be hella nice to have.

by jjore at December 24, 2007 09:59 PM

Catalyst Advent

Using plain classes as Catalyst models

Using plain classes as Catalyst models

A common pitfall when designing models is the tendency to tie application logic to Catalyst. The problem with this approach is that model classes become difficult to reuse outside of Catalyst, which is a common requirement for most applications. A better design approach would be to write and test a plain class outside of your main web application, and then painlessly glue it to Catalyst with a couple lines of code.

A review of Catalyst components

The COMPONENT() method

Catalyst gives you a chance to instantiate all your components (Models, Views and Controllers) during load time by calling the COMPONENT() method on each component class. This means you can implement it and return whatever you want from it. For models this boils down to:

    package MyApp::Model::SomeClass;

    use warnings;
    use strict;
    use base qw/Catalyst::Model/;

    use SomeClass;

    sub COMPONENT {
        my($self, $c, @config) = @_;
        return SomeClass->new(@config);


This particular implementation passes the configuration for this model to the external class on the call to new(). Of course, you could choose to instance the class any way you want to. Later on, $c->model('SomeClass') will get you the SomeClass instance, not MyApp::Model::SomeClass. Notice that the returned object is the very same instance that was created initially when your app was loaded.


Every time $c->model is called, Catalyst gives you a chance to run custom logic by attempting to run ACCEPT_CONTEXT on the model, whatever is returned by this method is what $c->model returns as well. So, if you need a new instance on every call, your model becomes something like:

    package MyApp::Model::SomeClass;

    use warnings;
    use strict;
    use base qw/Catalyst::Model/;

    use SomeClass;

        my($self, $c, @args) = @_;
        return SomeClass->new(@args);


So when you call $c->model('SomeClass'), you'll get a fresh instance of SomeClass not MyApp::Model::SomeClass.

The Catalyst::Model::Adaptor way

Instead of implementing your own glue code, you can use the generic implementation provided by the Catalyst::Model::Adaptor module, which provides several different ways of building your external class instances.

If you need a single application-wide instance of your external class, you can inherit from Catalyst::Model::Adaptor:

    package MyApp::Model::Foo;

    use warnings;
    use strict;
    use base qw/Catalyst::Model::Adaptor/;

        class => 'SomeClass',
        args  => {
            foo => 'bar'


Of course, you can also configure your class via myapp.yaml

        class: SomeClass
            foo: bar

This gives you more flexibility when you decide to change your implementation, just replace SomeClass with whatever class you wish to use, without even touching your code.

Alternate object instancing approaches

For instancing objects on every call to $c->model, just inherit from Catalyst::Model::Factory instead. And for instancing objects on a per-request basis, inherit from Catalyst::Model::Factory::PerRequest. The Catalyst::Model::Adaptor documentation provides information on how to further customize your models to address your specific needs.

For the incredibly lazy

You can easily create glue models by using the helpers provided with Catalyst::Model::Adaptor:

    script/ model SomeClass <type> MyApp::Model::SomeClass

Where <type> can be Adaptor, Factory or Factory::PerRequest.


Jonathan Rockway, for writing Catalyst::Model::Adaptor.


edenc - Eden Cardim -

by edenc ( at December 24, 2007 06:05 AM

Pluggable Modules and Deployable Instances

Pluggable Modules and Deployable Instances

Discussed Concepts :

This article discusses about two catalyst concepts .

1. How chaining can be used to create applications that have a central engine that process core logic and allow independent modules be built on top.(The Application)

2. Par and creating spawns of the application that can span again and integrate to the master site . The individual spawn can be carried around as a separate application.(Instantiating)

The Built Application :

The tutorial is accompanied by a functional and well commented code base which can be checkout using svn from

For demonstrating the above mentioned concepts a quiz application has been taken as example.

The final application must be able to

I). Create quizzes that can be taken on the site or deployed to a trainer's laptop , which the trainer can carry to colleges.The application must make sure that the deployed quiz contains only the required questions in the database as the questions can be proprietary and the trainer must be able to take only what is necessary. It must also allow a deployed quiz to act as master and create smaller quizzes from it . Ideal when a trainer takes 500 questions and has to train 10 batches with different question set in the same college.

II). When creating a quiz it must be possible to choose the modules and the number of questions from each module .Example of questioning modules can be "choose the correct answer" ,"Fill in the blanks " etc.

III). It must be possible to build new modules that can work along with the application and yet can be developed independently without any constraints on its internal logic , look and feel. This tutorial will take you step by step on building such an application .

(The Application) :

This tutorial will take you step by step on building such an application .

Step 1 : The model .

What is needed is a quiz engine that can create quiz containing questions from more than one module . And be able to track who took the quiz and what they scored.

The sql and the schema to create the required tables and models can be seen from the code. Basically there are 4 tables.

QuizMaster::Quizzes stores the generated quizzes. QuizMaster::Modules stores the list of available modules. QuizMaster::QuizModules stores the modules selected for a quiz , and the randomly assigned question numbers from each module. QuizMaster::participants stores who took what quiz and how much they scored.

Step 2 : Creating controller methods for creating the quiz.

Controller methods (index and create ) are written in quiz controller the general way to display the created quiz and to allow to create a new quiz.

Step 3 : Implementing the concept of independent modules.

What is expected is that the application act as a quiz engine that controls modules to ask questions .The modules are designed to ask questions and get answers in whatever manner is best suited for that module and pass back only the result to the engine so that the engine can track the score and the flow.

For example : A quiz might consist of two module "Choose the correct answer " , "Fill in the blanks".

Both the modules may have completely different UI , a module may select more than one value as an answer. A quiz can contain questions (1,2,8) from module 1 and (4,6) from module 2.

The application has to be designed in such a way that the flow , i.e the transition from question 1 to question 2 when in module 1 and the transition from question 8 in module 1 to question 4 in module 2 is handled by the engine.The engine must also handle the score manipulation.

Even when doing the above , the application must still keep it easy to create new modules.

This is possible by combining sessions and chaining in the following way .

We define 3 methods in the quiz controller to do the above.

(start, process and finish)

Each of which are explained below .

start :

  This function does two things 

  1.Initializes the quiz by loading the details of the modules used and their 
    respective question numbers into the session.
  2.Determines the first module and the first question that have to be asked and 
    its corresponding url.

sub start : Local {

  my ($self,$c,$quizid) = @_;

  #Displays a form and gets the participants name.

  if ($c->request->param('name')) {

     #Loads the modules and the questions selected randomly from each module 
     #during create and stores it in session      
    my $quiz = $c->model('QuizMaster::Quizzes')->search({id=>$quizid})->first;
    my $modules = [$quiz->search_related('quizmodules',{quiz=>$quizid})->all];
    my $moduledata;

    foreach my $module (@{$modules}) {


      push @{$moduledata} , { id => $module->id , 
                               questions => [split ' ',$module->questions] };




    #set up counter for the questions and modules

    #set score and total score as 0
    $c->session->{quiz}->{score} = 0;
    $c->session->{quiz}->{tscore} = 0;

    #Sets up the url for the first question of the first module.
    $c->stash->{newurl} = "/quiz/process/$quizid/$moduledata->[0]->{name}/$moduledata->[0]->{questions}->[0]";
    $c->stash->{template} = 'quiz/begin.tt2';



Process :

This method plays the key role of maintaining the flow and scoring

 This controller does two things .
 1.It does scoring for the previously answered question
 2.Set the action path(url) for the next question  that can be used by the module 
   displaying the current question 

sub process : PathPart('quiz/process') Chained('/') CaptureArgs(1) {

  my ($self,$c,$quizid) = @_;


  if ($c->request->method =~ /POST/) {
    $c->log->debug('Entered here');

    # To make sure we don't evaluate a non existing previous answer when displaying the first question
    if ($c->session->{quiz}->{answer}) {
      my $flag= 1;

      # The questioning module has to store the answer for the question in the application's session 
      # Using a hash here allows to have questions with multiple answers

      foreach (keys %{$c->session->{quiz}->{answer}}) {
	if ($c->session->{quiz}->{answer}->{$_} != $c->request->param($_) ) {
	  $flag = 0;


      # The score per question is taken as 10 here . 
      #It can also be set to take a value from the sessions in which case the 
      #questioning modules can assign different marks to each question
      my $spq = 10;

      $c->session->{quiz}->{score} += ($flag * $spq);
      $c->session->{quiz}->{tscore} += $spq;



  #Determine the action path(url for next question)

  my $modindex = $c->session->{quiz}->{modindex};
  my $qindex = $c->session->{quiz}->{qindex};

  #check that the current question is not the last question of the module
  if ( $qindex != $#{$c->session->{quiz}->{modquestions}->[$modindex]->{questions}}) {


    $c->session->{quiz}->{qindex} += 1;
    $qindex ++;

    # generate /quiz/process/quizid/modulename/questionid
    my $modulename = $c->session->{quiz}->{modquestions}->[$modindex]->{name};
    my $questionid = int($c->session->{quiz}->{modquestions}->[$modindex]->{questions}->[$qindex]);


  } else {
    #if it is the last question , check that the current module is not the last module
    if ($modindex != $#{$c->session->{quiz}->{modquestions}}) {
      $qindex = $c->session->{quiz}->{qindex} = 0;
      $c->session->{quiz}->{modindex} += 1;
      $modindex ++;
      my $modulename = $c->session->{quiz}->{modquestions}->[$modindex]->{name};
      my $questionid = int($c->session->{quiz}->{modquestions}->[$modindex]->{questions}->[$qindex]);




    #if the current question is the last question of the last module set action path 
     to the quiz finish controller
    else {




finish :

This method does two things

1. Manipulate the score for the last answer. 2. Save the quiz results to the database.

(Actually this can be re-factored to chain that process method and hence pop point 1 from its responsibility .It will be necessary to do so when complex scoring algorithms are used in the quiz . Say for example each module has a different scoring patter for questions and a that module allows multiple answers and different scores for each answer.In such a case the scoring algorithm will be complex and it will not be a good design to repeat that portion in the controller below for the last question alone)

sub finish : Local {

  my ($self,$c,$quizid) = @_;
  my  $name = $c->session->{quiz}->{participant};
  # Same as in the previous controller , manipulate the score for the last question.  
  my $flag= 1;

      foreach (keys %{$c->session->{quiz}->{answer}}) {
	if ($c->session->{quiz}->{answer}->{$_} != $c->request->param($_) ) {
	  $flag = 0;


  my $spq = 10;

      $c->session->{quiz}->{score} += ($flag * $spq);
      $c->session->{quiz}->{tscore} += $spq;

  my $score = $c->session->{quiz}->{score};
  my $tscore = $c->session->{quiz}->{tscore};

# Save the Quiz results

 my $participant = $c->model('QuizMaster::Participants')->create({
                 name => $name,
		 quiz => $quizid,
		 score => $score,
                 totalscore => $tscore

  $c->stash->{score} = "$score / $tscore";



Step 4: Create a sample module :

Having designed the engine above. There are few things to be kept in mind to create a questioning module .

Model :

1. The module model must have the questions in the namespace modelname::modelname_questions (This can be avoided if the Quiz::Modules table can have the count of the total number of questions available for each module or maybe a field that contains the name of the model that the module uses for storing its questions ).

Controller :

1.There must be a controller with the same name as the module 2.The questionid of the question that is to be challenged will be given to the module's method that is chained with the quiz controller's process method and has PathPart same as the module's name. 3.The form action value(url for the next question) will have to be retrieved from the session. 4.The answer(s) to the current question must be stored in the session as a key/value pair.

When the above points are followed ,

The three methods in the quiz controller (start , process and finish) handle scoring , moving over the questions and moving over to the next module .

With that in mind, the complete controller code for a simple choose the correct answer module is

sub index : PathPart('Ctca') Chained('/quiz/process') Args(1) { my ( $self, $c , $questionid ) = @_;

    my $question = $c->model('Ctca::CtcaQuestions')->search({id=>$questionid})->first;

    $c->stash->{question} = $question;

    $c->stash->{options}= [$question->search_related('options',question=>$questionid)->all];
    # The only extra line by the module that is needed to let the engine handle the flow and scoring 
    $c->session->{quiz}->{answer} = {choice => $question->correct};
    $c->stash->{template} = 'Ctca/index.tt2';


Conclusion :

The above architecture reduces the work involved in designing a new module . When creating a new module one will have to only worry about

 * How the question is displayed and answer taken (drag and drop , jigsaw , draw lines :))
 * Determine the correct answer from the database and store it in the session

Everything else is taken care by the quiz controller .

This makes it easier to develop new modules .

(Instantiating) :

This part of the tutorial outlines the step required in creating spawns of the application that can span again and integrate to the master site . The individual spawn can be carried around as a separate application.

The application is so build from above that

1.If we were to copy the entire folder to a new folder . 2.Delete all the records in the QuizMasterL::Quizzes table except the one selected for deployment. 3.Delete all the records in each quiz module other than the ones used by the quiz 4.Create par and use pp to make a binary with the perl compiler.

We will have a complete spawn of the existing site with a limited number of questions. Hence a trainer can create sub quizzes from the limited number of quizzes and that runs easily with a single click.

We will use a method called deploy in the quiz controller which does the above 4 points. Since it is easier to handle steps (1,4) in a script run locally . The controller script will first do steps (2,3) and save the created databases to a temporary location. Then the system command can be used to invoke a shell script that will do the copy and packaging.

To do step (2,3) [slice an existing db]:

That is to create a slice of the existing database the following procedure is followed.

1.Use deploy() to create the database for the QuizMaster::Quizzes . 2.Insert a record with the quiz id and the name to that database. 3.use deploy() to create the database for each of the module. 4.Read the assigned questions for each module from the QuizMaster::QuizMoules tables and insert those record into the newly created database.

After doing which the control can be passed to the shell script that will do the copy and packaging.

Since we had stated that using the above said convention for the questions table is the only constraint for the module's Model.It is only possible to slice the questions table .It is not possible to know the logic used by the questioning module to store the answers.So we cant slice them. Anyways that is alright as though the questions can make sense without the answers and need to be protected when proprietary , the answers without the questions are just junk and will not make much meaning.


Special thanks to Ma Foi Academy for allowing me to expose part of the code developed for the organization in this article.


Antano Solar John

by Antano Solar John ( at December 24, 2007 06:05 AM





This is part one of a DBIx::Class tutorial I started writing for the folks at work, I hope to turn it into a multi-part releasable document.


See DBIx::Class::Manual::Glossary.

Some terms needed for this doc:


A DBIx::Class::Schema object is created by calling ->connect on our Schema subclass, and passing it the DSN (and other possible values, see DBIx::Class::Schema). Eg: my $schema = Breadcrumbs::Schema->connect('dbi:mysql;dbname=Breadcrumbs', 'user', 'passwd'); Creating this object does not attempt to connect to the database yet.

NB: To make use of an existing mechanism to store credentials for databases, we can do: my $schema = Breadcrumbs::Schema->connect( sub { My::Util('Breadcrumbs') } );.


A DBIx::Class::ResultSet, an object which represents a database query, including all conditions/clauses. Creating one does not run the associated query, it is stored and used when actual data objects are requested. The simplest form of ResultSet represents an entire table, and can be retrieved from the schema object like this: my $rs = $schema->resultset('Path').


A class that describes a table, it's columns and it's relations with other tables.


A DBIx::Class::Row representing an actual row of data resulting from a database query. This could be and entire row, or just certain fields as restricted by a ResultSet.


To create a new set of DBIx::Class DBIx::Class::ResultSource classes, you can either write them by hand, or create from an existing database.

Create ResultSource classes from existing database

DBIx::Class::Schema::Loader's make_schema_at can extract schema definitions from existing databases and create a complete DBIx::Class schema for you, example:

  perl -MDBIx::Class::Schema::Loader=make_schema_at,dump_to_dir:./lib -e 'make_schema_at("Breadcrumbs::Schema", { debug => 1 }, [ "dbi:mysql:dbname=Breadcrumbs","user", "passwd" ])'

This will create a file for each database table (in lib/Breadcrumbs/Schema/), plus the file Breadcrumbs/ which is the DBIx::Class::Schema file.

The table files will contain information about the columns and their types. If the database is innodb, it will also extract relationships based on foreign key references etc. An md5 sum of the contents is added, so that the user can add more relations or other methods to the file, and a later update will not overwrite them.

If the database layout changes

Re-run the make_schema_at command shown above.

Create ResultSource classes from scratch

Setting up relationships

If your databases is mysql and not using innodb, you will have to add the table relationships ourselves. These are the most useful part of DBIx::Class, otherwise we might as well just use DBI..

There are 3 main/useful relationship types, for the rest and a more wordy description, see DBIx::Class::Relationship.

The name of each relationship (the first argument), is important, it is used both as an accessor and as a key to joni across tables.

belongs_to (foreign keys)

Breadcrumbs's Name table has a PathID column which contains an ID from the Path table. To make the Path object simple to retrieve and update, we add the following to the file, after the md5 sum from Loader:

  __PACKAGE__->belongs_to('path', 'Breadcrumbs::Schema::Path', 'PathID');

Read as: The value in the PathID column belongs_to the table represented by Breadcrumbs::Schema::Path.

This creates an accessor path, which we can call on a Name DBIx::Class::Row which will retrieve the appropriate DBIx::Class::Row in the Path table.

  ## Print the path of the current name entry
  print $name->path->path;

We can also set a PathID for a new Name row by calling:


has_many (reverse foreign key)

Going in the opposite direction, each Path row has 0 to many Name entries associated with it, indicated by the PathID column in the Name table. We can make it simple to retrieve all the name values for a particular Path row:

  __PACKAGE__->has_many('names', 'Breadcrumbs::Schema::Name', 'PathID');

Read as: This class has many names in Breadcrumbs::Schema::Name linked via the PathID column.

Creates us an accessor names which can give us a DBIx::Class::ResultSet (of which more later), or an array of Name objects.

  ## find all names for current path entry
  foreach my $name ($path->names)
     print $name->name;

Add a new name for the current path, assuming we have a language object as well:

                        { name => 'Products',
                          lang => $lang }


Whether fetching complete rows, searching for rows, or fetching data from multiple tables, the methods are much the same, all return DBIx::Class::Row objects eventually.

find (single row by unique key)

To fetch a full row using it's Primary Key (they all have PKs, right?), we can retrieve a Row object directly from a ResultSet representing the table:

  ## Just PK:
  my $name1 = $schema->resultset('Name')->find(1);

  ## More meaningful:
  my $name1 = $schema->resultset('Name')->find({ id => 1 });

The Row object contains all the values of all the fields defined in the ResultSource. Not necessarily in the table. Each column has an accessor which is by default the name of the column lower-cased (When using Loader).

  my $namename = $name1->name;   ## Japan
  my $langid   = $name1->langid; ## 1

search (multiple objects, less coluns, conditions)

To fetch a particular Name row and it's Path at the same time, using only one database query:

  my $name_rs = $schema->resultset('Name')->search(
    { '' => 1 },                                ## WHERE
    { prefetch => [ 'path' ] }                       ## JOIN AND SELECT. NB: Rel name!

This creates a DBIx::Class::ResultSet, to retrieve the actual Row object:

  my $namerow = $name_rs->next;

The following SQL is executed:

  SELECT me.ID, me.Name, me.LangID, me.PathID, path.ID, path.Path, path.Parent, path.Position, path.MenuID FROM Name me  JOIN Path path ON ( path.ID = me.PathID ) WHERE ( = ? ): '1'

As with the find, the data is retrieved using the column-name accessors. To retrieve a Row object representing the path:

  my $pathrow = $namerow->path;

  my $actualpath = $pathrow->path;   ## companyinfo/careers/jp
  my $pathparent = $pathrow->parent; ## 36

To fetch just a few columns:

  my $name_rs = $schema->resultset('Name')->search(
    { '' => 1 },                                ## WHERE
      select   => [ qw/id name/ ],                   ## SELECT
      as       => [ qw/id name/ ],

This will only select the ID and Name columns. The as attribute names the columns.

To add more complex conditions:

  ## All names where the patch matches '/support%'
  my $name_search = $schema->resultset('Name')->search(
      'path.path' => { 'like' => '/support/%' },  ## WHERE path.path LIKE '/support/%'
      'join' => [ 'path' ],                       ## JOIN


To insert new rows, call create on a ResultSet object. This will first instantiate a new Row object, then call insert on it. This can be done individually if needed.

  ## INSERT INTO .. 
  my $newname = $schema->resultset('Name')->create(
     name   => 'Support',
     pathid => $pathid,
     langid => $langid,
  print $newname->in_storage();  ## 1 (TRUE)

  my $newpath = $schema->resultset('Path')->new(
     path => 'support',
  print $newpath->in_storage();  ## 0 (FALSE)
  print $newpath->in_storage();  ## 1 (TRUE)


Updating one row

The column-name accessors used to fetch data from a row can also be used to set new values, eg:

  ## Nonsensically change the language of a given Name row
  my $namerow = $schema->resultset('Name')->find({ name => 'Japan' });
  $namerow->update;    ## UPDATE 

Updating many rows with a resultset

Create a resultset containing the condition to select all the rows to update. Calling update on the resultset will run the UPDATE command using the condition in the resultset.

  ## All name rows with value 'Evaluation'
  my $name_rs = $schema->resultset('Name')->search(
    '' => 'Evaluation',
  $name_rs->update({ name => 'Free Trial' });  ## UPDATE .. WHERE

Deleting a row

Just call delete on a Row object.

  ## No more products/es !
  my $pathrow = $schema->resultset('Path')->find({ path => 'products/es' });

This will also delete related rows that would otherwise be inconsistent. It will remove them *after* the main row. This cascading can be turned off on a relationship if necessary.

Delete multiple rows

Call delete on a ResultSet object instead. This will run a DELETE statement with a WHERE clause, and will not cascade the deletes.

  my $path_rs = $schema->resultset('Path')->search(
    'me.path' => 'products/es',
  $path_rs->delete;     ## DELETE .. WHERE 

To delete multiple rows with cascading, call delete_all on the ResultSet, which will delete each row and it's related rows individually.

  $path_rs->delete_all;    ## many DELETE statements


Add some sorta table descriptions to this doc.

Patches and suggestions welcome.


Jess Robinson <>

by Jess Robinson ( at December 24, 2007 06:05 AM

December 21, 2007

Memories of 20 Years of Perl

tile imageThe Perl community just celebrated the 20th anniversary of Perl. Here are some stories from Perl hackers around the world about problems they've solved and memories they've made with the venerable, powerful, and still vital language.

by chromatic at December 21, 2007 09:59 PM

Chris Dolan

Fuse, PDF and PAR

Last week I presented a fun topic to the Madison Perl Mongers: I created a user-mode filesystem that treats PDF files as disk images, and I packaged it with PAR.

For the demonstration, I wrote a quick-and-dirty Mac GUI front end. It probably works only on 10.4 (I didn't test 10.5) and isn't as powerful as the Fuse-PDF command line, but it's more accessible.

by ChrisDolan at December 21, 2007 09:57 PM

Andy Lester, OReilly

Perl 5.10 now available

This is a copy of the official announcement about Perl 5.10.

Today the Perl Foundation announces the release of Perl 5.10, the first major upgrade to the wildly popular dynamic programming language in over five years. This latest version builds on the successful 5.8.x series by adding powerful new language features and improving the Perl interpreter itself. The Perl development team, called the Perl Porters, has taken features and inspiration from the ambitious Perl 6 project, as well as from chiefly academic languages and blended them with Perl’s pragmatic view to practicality and usefulness.

Significant new language features

The most exciting change is the new smart match operator. It implements a new kind of comparison, the specifics of which are contextual based on the inputs to the operator. For example, to find if scalar $needle is in array @haystack, simply use the new ~~ operator:

  if ( $needle ~~ @haystack ) ...

The result is that all comparisons now just Do The Right Thing, a hallmark of Perl programming. Building on the smart-match operator, Perl finally gets a switch statement, and it goes far beyond the kind of traditional switch statement found in languages like C, C++ and Java.

Regular expressions are now far more powerful. Programmers can now use named captures in regular expressions, rather than counting parentheses for positional captures. Perl 5.10 also supports recursive patterns, making many useful constructs, especially in parsing, now possible. Even with these new features, the regular expression engine has been tweaked, tuned and sped up in many cases.

Other improvements include state variables that allow variables to persist between calls to subroutines; user defined pragmata that allow users to write modules to influence the way Perl behaves; a defined-or operator; field hashes for inside-out objects and better error messages.

Interpreter improvements

It’s not just language changes. The Perl interpreter itself is faster with a smaller memory footprint, and has several UTF-8 and threading improvements. The Perl installation is now relocatable, a blessing for systems administrators and operating system packagers. The source code is more portable, and of course many small bugs have been fixed along the way. It all adds up to the best Perl yet.

For a list of all changes in Perl 5.10, see Perl 5.10’s perldelta document included with the source distribution. For a gentler introduction of just the high points, the slides for Ricardo Signes’ Perl 5.10 For People Who Aren’t Totally Insane talk are well worth reading.

Don’t think that the Perl Porters are resting on their laurels. As Rafael Garcia-Suarez, the release manager for Perl 5.10, said: “I would like to thank every one of the Perl Porters for their efforts. I hope we’ll all be proud of what Perl is becoming, and ready to get back to the keyboard for 5.12.”

Where to get Perl

Perl is a standard feature in almost every operating system today except Windows. Users who don’t want to wait for their operating system vendor to release a package can dig into Perl 5.10 by downloading it from CPAN, the Comprehensive Perl Archive Network, at, or from the Perl home page at

Windows users can also take advantage of the power of Perl by compiling a source distribution from CPAN, or downloading one of two easily installed binary distributions. Strawberry Perl is a community-built binary distribution for Windows, and ActiveState’s distribution is free but commercially-maintained. ActiveState’s distribution is available now, and Strawberry Perl’s is imminent.

by Andy Lester at December 21, 2007 07:47 AM

CPAN Watch

CPAN Watch is on hiatus

The Perlbuzz section CPAN Watch is going on an indefinite hiatus. Kirrily Robert, Skud, who has driven CPAN Watch since its start, is moving to San Francisco from Australia, and just doesn't have the time to keep things going.

I'll still be keeping you informed about cool new CPAN releases, but instead of CPAN Watch I'll be putting them in the Mechanix section. So, point your RSS/Atom readers over there for now.

by Andy Lester at December 21, 2007 04:47 AM

December 20, 2007

Lawrence Watt-Evans, Serials

The Books Have Been Ordered

I placed the print order for 400 copies of The Vondish Ambassador this morning. Got the proof copy yesterday, and found it good.

This book is about the same format as the six Wildside Press reprints in the Ethshar series; I’m afraid it doesn’t match The Spriggan Mirror.

Anyway, the books should be here in mid-January. Sorry it couldn’t be in time for Christmas.

by Lawrence at December 20, 2007 07:24 PM

December 19, 2007

Planet Perl

Perl 5.10.0 is out

The news is beginning to propagate on the internet... perl 5.10.0 is out. My informal announcement was posted to perl5-porters yesterday, and it summarizes my views on the subject. Or, more concisely: I'm happy!

I think I deserve a small vacation, and I'll be away in Nice for one week (the week of Christmas).

by Rafael at December 19, 2007 09:42 PM

December 18, 2007

Joshua Wehner, Comments

December 17, 2007

Joshua Wehner, Comments

Comment on 'Safari vs. Safari: label'

Andre Arko said:

I use Multi-Safari, and it's great:

In 10.5.1 the older versions of Safari have problems, but a fixed copy of Safari 2.0.4 can be found here:

by Andre Arko at December 17, 2007 03:11 AM

December 14, 2007

CPAN Watch

CPAN::Dependencies 2.0 is out

David Cantrell writes to the module-authors list about his new CPAN module dependency tracker:
I've just uploaded CPAN::FindDependencies version 2 to the CPAN. This is pretty much a complete re-write which has lots of cool new Stuff:
  • uses Parse::CPAN::Packages instead of, so loads faster and takes a lot less memory;
  • much better core module detection;
  • user can specify which version of perl to use when figuring out what's in core;
  • can cache META.yml files and use a local 02packages file instead of fetching it from a CPAN mirror at startup;
  • add 'maxdepth' parameter to limit how far down the dependency tree it goes;
  • much better tests;
  • 'cpandeps' script is now documented
Why am I telling you this? Cos, for the perl-qa folks, this will be the new brane for soon. For the module-authors list - the bundled 'cpandeps' program is a useful tool for getting an idea of how much extra code gets pulled in when you make your users install a dependency. Re-using code is a Good Thing of course, but taken to extremes it can be a real pain in the arse for those for whom perl is just another environment that they have to support on their machines.

I wrote about David's dependency checker before, and it's pretty slick.

by Andy Lester at December 14, 2007 06:16 PM

December 08, 2007

CPAN Watch

Find::Lib simplifies loading of libraries

Yann Kerherve has released Find::Lib, an alternate way of loading libraries in non-standard locations. Find::Lib lets you specify paths like so:

use base Find::Lib '../bootstrap/lib' => 'My::Bootstrap', %param;

I'd love to hear from anyone who's used it and what they think.

by Andy Lester at December 08, 2007 10:56 PM

Rhesa Rozendaal

Squeezebox, with Perl

Today, my Squeezebox (from arrived in the mail. Its streaming server is written in Perl :-)

I've only glanced at the code, but it looks very well layed out, and uses great modules like TT2 and DBIx::Class. And it's all GPL'ed too, nice!

If you're looking for a good quality, wireless media player, the Squeezebox should be on your list.

by rhesa at December 08, 2007 10:07 PM

December 03, 2007

Chris Dolan

Recommended: code search

I recently had a Solaris failure report from CPAN testers. The failure report had errno.h numbers that I could not interpret, since I lack a Solaris 2.9 box. I knew that Solaris was now open sourced, so I tried to look for errno.h via Google code search. Blech, my google-fu was too weak.

So I instead tried I quickly found the OpenSolaris project, browsed the source code repository and found sys/errno.h. Wow.

It didn't solve my problem (alas, instead I need a new CPAN release with better failure diagnostics) but I was very impressed with the ease of use.

I first learned about Krugle via the 2006 Chicago hackathon. Ken Krugler bought us pizza and talked about getting better Perl/CPAN support into his product.

by ChrisDolan at December 03, 2007 09:58 PM

December 01, 2007

Thomas Tongue

From my iPhone

As I think most who have known me would have predicted, I stepped up to an iPhone several months ago. This post is authored from that device while I wait to get into the Dr.’s office with Ian. Entering text is certainly possible, though this is going to be a short post because its far from pleasant. Still, its a remarkable device that has reshaped the accessibility of information for me on many occasions. If it has one weakness, its the coupling with AT&T, whose service seems positively Neolithic compared to verizon…

More on this topic later. (Told you this would be short)

by ttongue at December 01, 2007 10:19 PM

Doctor Who - The New Series

Peter wrote in and queried me about the new Doctor Who Series. He asked if someone new to the shows should start with Christopher Eccleston’s incarnation, OR just jump in at the beginning of David Tennant’s tenth Doctor. I figured I’d share my opinion here and give another plug for the new series, because it really is outstanding and a great deal of fun.

Definitely start with Christopher Eccleston!

There are a couple of good reasons for this actually, aside from the fact that he’s brilliant in the role and really brings out a very fresh, and somewhat tortured version of the Doctor to the audience. Tortured? Yeah, well you see… there was a war between the Daleks and the Timelords… simply called the Time War. A war so devastating that both sides seem to have been wiped out. So he’s dealing with a ton of survivor guilt, and is now alone in the universe. Which is fertile ground for the character to pick up some serious emotional depth, which Christopher Eccleston portrays very well.

Alot of the history of what happens in that first season also plays out in the 2nd and 3rd season under David Tennant, who is also brilliant, so starting at the new beginning helps make sense of a number of things down the line.

The 4th season starts in April of 2008 I believe, and then there will be at least a 1 year hiatus punctuated by 2 telefilms, and then the 5th season in 2010. On the one hand, that sucks, but it beats having the production crew and writers of the show quit or grow stale.

by Administrator at December 01, 2007 07:26 PM

November 23, 2007

Andy Lester, OReilly

Perl gratitude, 2007

Here in the US, it’s Thanksgiving, a day of eating lots of food, watching football, and sometimes, just sometimes, expressing gratitude and giving thanks for those things that make life wonderful.

Here are the things I’m grateful for in late 2007, in no particular order after the first.

Google Code

Google’s project hosting service has been a godsend. It’s changed the way I do open source projects. It has leapfrogged SourceForge for ease of maintenance, and the bug tracker trumps RT for CPAN that we’ve been using for so long. Add that to the integration with Google Groups which makes it trivial to create mailing lists, and it’s at the tops of my list for 2007. I can’t say enough good about it.

The readers of Perlbuzz

Eleven weeks ago, Skud and I started this little website called Perlbuzz as an alternative to the “more traditional outlets” for news in the Perl world. The response has been tremendous. We get 600 RSS readers every day, and have had over 10,000 unique visitors in that time. It makes me happy that our little venture is used and appreciated by the community.

Test::Harness 3.0

It’s been over a year in the making, but the new version of the crucial Test::Harness 3.0 means more flexibility for module authors, and lots of UI improvements for people who just want to run prove and make test.

Mark Dominus

MJD is so much a fixture in Perl it’s easy to forget that he’s there. For 2007, though, never mind all the things he’s done for Perl in the past, or the hours I’ve spent being enthralled in talks of his. His Universe Of Discourse blog is the single most intelligent blog out there, and sometimes it just happens to be about Perl.

Andy Armstrong

Was Andy Armstrong always around, or did I just not notice? His time and dedication spent on climbing on board with Ovid and Schwern and the rest of the Test::Harness 3.0 crew has been invaluable in getting it out. Plus, he’s a really swell guy anyway.

Dave Hoover

When I finally despaired of the amount of time and frustration it took to organize content for’s Wheaton meetings, Dave Hoover stepped up and volunteered to take it over. I’m thankful, but not as much as I hope the other folks are.


I’m all about having the machine keep an eye out for the stupid things we do, and the goodness of Perl::Critic is always impressive. You won’t like everything Perl::Critic says about your code, but that’s OK. It’s an entire framework for enforcing good Perl coding practices.

The Perl Community in general

The Perl community is populated by some tremendous folks. Some names are more known than others, but these people help make daily Perl life better for me. In no particular order, I want to single out Pete Krawczyk, Kent Cowgill, Elliot Shank, Liz Cortell, Jason Crome, Yaakov Sloman, Michael Schwern, Andy Armstrong, Ricardo Signes, Julian Cash, Jim Thomason, chromatic, Chris Dolan, Adam Kennedy, Josh McAdams and of course Kirrily Robert. If you think you should be on this list, you’re probably right, and I just forgot.

My wife, Amy Lester

Because even if she doesn’t understand this part of my life, she at least understands its importance to me.

I’d love to hear back from any readers about what they’re thankful for. I’m thinking about having a regular “Love Letters to Perl” column on Perlbuzz where people write about what they love in Perl.

by Andy Lester at November 23, 2007 09:55 PM

Pete Prodoehl

Asus Eee PC: First Impressions

Asus Eee PC I am typing this on my Apple keyboard, which is connected to my Asus Eee PC. The Eee PC is also connected to a old Apple VGA monitor running at 1152×864 (though there is a black border all around the screen.) I’m mainly testing the actual OS right now, which happens to be Xandros. It works pretty well.

Xandros is pretty nice. I know Ubuntu is the favorite OS of most desktop Linux people I know, but Xandros seems ok. I still need to customize the system a bit, but for now, it’s pretty functional. I’ve run Firefox, OpenOffice, Skype, ssh’d into a server, played with the webcam, and there is still much more to do.

First, my gripes… On the tiny keyboard there does not seem to be a caps lock indicator, so you don’t know when the caps lock is on. If you’re typing text you can see, it may not be a big deal, but typing a password you see **** and have no idea if it’s uppercase or lowercase. (Note: There is a caps lock indicator, but it’s on screen, I just didn’t notice it at first.) When I plugged in the external monitor it didn’t show immediately (it might be the Mac user in me that expected that) and I had to open a control panel to get it to show up. The trackpad button seemed like it took more pressure to click that it should. Maybe it will loosen up in time. I also need to get used to tapping on the trackpad to click, since I’ve never had a machine that supported that. (I may end up getting a small mouse to use with it.) I noticed the wife had used it to check her email (webmail) and I asked how she like it, her reply was “It was fine, expect for the small screen and hitting four keys when I wanted to hit one.” :)

The kids think it very cool. They’ve already asked for their own, for Xmas, or when they go to high school or college. At some point I’ll let them use it and see what they think. They use Macs and Windows PC’s pretty often, so they might have a different perspective.

Getting the wifi functional was a bit of work, but I will blame that on my network setup at home. (I’ve got a few old Macs connected via USB wifi adapters which complicate things.) I’m pretty sure the wifi is solid now, but we’ll see how it goes. (Update: One thing I noticed was that I wasn’t waiting long enough after booting for it to connect. It just took another minute or so for the connection to be made, then all was good.) When I disconnected the external monitor, I couldn’t use the built in screen because everything was off screen, as it was displaying the LCD display at the resolution I had the external monitor running at, so another note, be sure to set the display back properly for the internal LCD before you disconnect the external monitor.)

Did I mention it’s tiny? You know it’s tiny, but until you see one in person and use it, you don’t appreciate how tiny it is. It seems funny right now to be using such a tiny computer with a full sized keyboard and a 17″ monitor. I’ll be bringing it with me to the next Web414 Meeting so you can see it in person.

by Pete Prodoehl at November 23, 2007 01:02 PM

November 22, 2007

Andy Lester

Perl gratitude, 2007

Here in the US, it's Thanksgiving, a day of eating lots of food, watching football, and sometimes, just sometimes, expressing gratitude and giving thanks for those things that make life wonderful.

Here are the things I'm grateful for in late 2007, in no particular order after the first.

Google Code

Google's project hosting service has been a godsend. It's changed the way I do open source projects. It has leapfrogged SourceForge for ease of maintenance, and the bug tracker trumps RT for CPAN that we've been using for so long. Add that to the integration with Google Groups which makes it trivial to create mailing lists, and it's at the tops of my list for 2007. I can't say enough good about it.

The readers of Perlbuzz

Eleven weeks ago, Skud and I started this little website called Perlbuzz as an alternative to the "more traditional outlets" for news in the Perl world. The response has been tremendous. We get 600 RSS readers every day, and have had over 10,000 unique visitors in that time. It makes me happy that our little venture is used and appreciated by the community.

Test::Harness 3.0

It's been over a year in the making, but the new version of the crucial Test::Harness 3.0 means more flexibility for module authors, and lots of UI improvements for people who just want to run prove and make test.

Mark Dominus

MJD is so much a fixture in Perl it's easy to forget that he's there. For 2007, though, never mind all the things he's done for Perl in the past, or the hours I've spent being enthralled in talks of his. His Universe Of Discourse blog is the single most intelligent blog out there, and sometimes it just happens to be about Perl.

Andy Armstrong

Was Andy Armstrong always around, or did I just not notice? His time and dedication spent on climbing on board with Ovid and Schwern and the rest of the Test::Harness 3.0 crew has been invaluable in getting it out. Plus, he's a really swell guy anyway.

Dave Hoover

When I finally despaired of the amount of time and frustration it took to organize content for's Wheaton meetings, Dave Hoover stepped up and volunteered to take it over. I'm thankful, but not as much as I hope the other folks are.


I'm all about having the machine keep an eye out for the stupid things we do, and the goodness of Perl::Critic is always impressive. You won't like everything Perl::Critic says about your code, but that's OK. It's an entire framework for enforcing good Perl coding practices.

The Perl Community in general

The Perl community is populated by some tremendous folks. Some names are more known than others, but these people help make daily Perl life better for me. In no particular order, I want to single out Pete Krawczyk, Kent Cowgill, Elliot Shank, Liz Cortell, Jason Crome, Yaakov Sloman, Michael Schwern, Andy Armstrong, Ricardo Signes, Julian Cash, Jim Thomason, chromatic, Chris Dolan, Adam Kennedy, Josh McAdams and of course Kirrily Robert. If you think you should be on this list, you're probably right, and I just forgot.

My wife, Amy Lester

Because even if she doesn't understand this part of my life, she at least understands its importance to me.

I'd love to hear back from anyone about what they're thankful for. I'm thinking about having a regular Perlbuzz "Love Letters to Perl" column where people write about what they love in Perl.

by petdance at November 22, 2007 09:56 PM

November 21, 2007

Project Hum

Parrot 0.5.0 is out

The monthly Parrot release is out, version 0.5.0. Included in this version:

  • Implementation
    • PDD15 (OO) branch merged with trunk; this release contains a working, tested implementation of the latest OO model
    • Added pop_eh/push_eh_p/count_eh opcodes
    • Add --runcore command line option
    • Add gcdebug runcore to help track down GC bugs
    • minor improvements to IA-32 JIT
  • Documentation
    • PDD19 (PIR): updates to macros, .pcc* directives
    • PDD25 (Concurrency): updated
    • PDD26 (AST): draft approved
    • PDD23 (Exceptions): draft approved
    • Copyright cleanups
  • Languages/Compilers
    • languages/APL: minor updates, PDD15 conformance
    • languages/dotnet: minor updates
    • languages/lua: minor updates, PDD15 conformance
    • languages/lisp: minor updates
    • languages/perl6: minor updates, PDD15 conformance
    • languages/plumhead: minor updates
    • languages/punie: minor updates, PDD15 conformance
    • languages/nqp: minor updates
    • languages/scheme: many updates, PDD15 conformance, improved tests, use PMCs instead of primitive registers to represent values
    • languages/tcl: bugfixes, PDD15 conformance
    • languages/WMLScript: minor updates
    • compilers/pirc: updates from PDD19, PDD06
    • compilers/pct: minor updates, PDD15 conformance
    • compilers/pge: PDD15 conformance
    • compilers/tge: PDD15 conformance
  • Configuration
    • Improve test coverage
    • Improve reporting when a step fails; allow abort on failure
  • Miscellaneous
    • More coding standard conformance, tests, cleanup, speedups, warnings cleanup
    • Bug cleanup, esp. GC bugs
    • Eliminate .imc extension (use .pir)
    • Simplify some core config steps to not allow interactive prompting
  • Removed
    • clear_eh opcode

by Andy Lester at November 21, 2007 09:37 PM

November 20, 2007

Josh ben Jore

Perl 5 VM @ SPUG Tonight

Tonight at SPUG I'm going to be talking about the Perl 5 Virtual Machine focusing on code aspects.

The original slides can be read directly by KPresenter+Kivio at, as a 8MB Ogg Theora video at , or as a kind of sucky fallback HTML at l.

by jjore at November 20, 2007 09:56 PM

November 18, 2007

David Golden

Can you run Inline::C? I need your help...

If you have or can install Inline::C, I'd greatly appreciate your help testing IO-CaptureOutput-1.05_53.

I've recently adopted IO::CaptureOutput, which is a wonderful tool for capturing program output to STDOUT or STDERR without ties and regardless of whether the output comes from perl, XS or programs in a subprocess.

However, the tests for XS use Inline::C and the C code was found to have portability problems (i.e. segfault on some Win32 platforms). At least one fix for Microsoft Visual C++ (MSVC) then broke on someone else's Linux platform.

(Aside: the fact that it it this hard to portably print the equivalent of "Hello World" to STDOUT and STDERR just astonishes me.)

My latest attempt at updating the C code now uses different code for MSVC and other compilers and now I want to test this as far and as wide as I can.

So if you have installed Inline::C and something that can send test reports (e.g. CPAN::Reporter), please test IO-CaptureOutput-1.05_53. For example, from the CPAN shell:

cpan> test DAGOLDEN/IO-CaptureOutput-1.05_53.tar.gz

Thank you very much,

-- dagolden

by dagolden at November 18, 2007 09:56 PM

November 14, 2007

John Wang

Whither Point Releases?

In the old software days with point releases, major versions would increase from 1 to 2 to 3, etc. Releases in between major versions would point releases along the lines of 1.1, 1.2, 1.3 and smaller releases would be 1.1.1, 1.1.2, 1.1.3, etc. Then came along Windows 95 and the exit of sequential version numbers. With this naming scheme you really can't have Windows 95.1 so we now have Releases, along the lines of Oracle 11g Release 1 and Windows 2003 Server Release 2. You can pretty much guarantee that there isn't going to be an Oracle 11.1g ;)

That's all fine and good from a marketing perspective if the reason is that we are now using a year or abbreviation instead of a simple integer but are there other technical reasons? I recently upgraded from Apache httpd 2.0.x to 2.2.x and the major thing that I encountered was that configuration had changed significantly and that I had to redo my conf files. I've spoken with some people that indicated many organizations are afraid of point releases for enterprise software because they often break things and are not necessarily smooth upgrades. This fit with my Apache httpd experience which got me thinking.

If there exist enough backward compatibility problems with point releases, it would make sense that software publishers would want to avoid point releases (at least from a marketing perspective), when the release is backward compatible, e.g. Releases for former point releases, Service Packs for aggregated patches and the like. Has the single point (vs. double point) release come to mean that backward compatibility has been broken. If so, should it be avoided from a marketing perspective when backward compatibility still exists?

by John Wang at November 14, 2007 09:57 PM

Planet Perl

Automated web screen shots with Perl

I've been looking for a program that will take full screen shots of web pages even when the web page is larger than the window size on my physical screen, requiring scrolling. This morning I found such a program in Petr Šmejkal's Win32::CaptureIE when it was mentioned by Displeaser on DevShed Forums in the "Screenshot of webpage" thread. It uses ImageMagick for image manipulation.

From reading the Win32::CaptureIE POD, the CapturePage function does exactly what I want:

CapturePage ( ) Captures whole page currently loaded in the Internet Explorer window. Only the page content will be captured - no window, no scrollbars. If the page is smaller than the window only the occupied part of the window will be captured. If the page is longer (scrollbars are active) the function will capture the whole page step by step by scrolling the window content (in all directions) and will return a complete image of the page.

After installing ImageMagick, Image::Magick and Win32::CaptureIE on my Windows / ActiveState Perl system, I generated this screen shot with the following short program using no additional processing:

use strict; use warnings;
use Win32::CaptureIE;

StartIE( width => 900 );
Navigate( '' );

my $img = CapturePage();
$img->Write( 'capture.png' );

Perl and CPAN continue to amaze me with their treasure trove of functionality. Are there similar tools for using Firefox, Linux, other image libraries or languages?

UPDATE: ishnid has found two programs with CLIs (posted to the same thread):

  • khtml2png on SourceForge. This is a command-line program that looks like it can be run without a browser. It uses libkhtml (used by Konqueror) and ImageMagick's convertn.
  • Pearl Crescent Page Saver, a commercial app but available in a free version. This is a Firefox extension and requires the browser.

UPDATE 2:: I recently tried Win32::CaptureIE with ImageMagick 6.3.0 and it doesn't work. Apparently there used to be a link to "PerlMagick" in older versions of ImageMagick that may not exist anymore. Unfortunately Win32::CaptureIE relies on PerlMagick.

UPDATE 3:: I just tried the free version of Pearl Crescent with Firefox which it says it should support but I get a "Download error" with pageserverbasic-1.3.xpi.

by John Wang at November 14, 2007 09:42 PM

November 13, 2007

Thomas Tongue, Comments

Comment on iChatAV - Can ya feel the luv? by Dot Product » Blog Archive » WebEx, Skype and SkypeOut…

[…] I’m spending some time trying various tools like iChatAV (which I’ve mentioned previously), WebEx, and Skype (Download Skype For Windows). WebEx is the heavywe […]

by Dot Product » Blog Archive » WebEx, Skype and SkypeOut… at November 13, 2007 09:59 PM

November 09, 2007

Planet Perl

Comparing CPAN Modules with YUI DataTable

There is a lot of choice on the CPAN for open source Perl libraries and sometimes it's difficult to get an idea of how modules compare to each other. CPAN Ratings is a good source of reviews but it's not convenient to compare one module with another. To provide a partial solution, I whipped up a quick CPAN Compare page which will pull the CPAN Ratings from a number of modules and summarize them for you.

CPAN Compare Modules

I decided to use YUI DataTable for this. I've heard good things about YUI so I decided to give it a try. Getting the example code to work off of the Yahoo website almost as straight forward as say using Scriptaculous demos but it was faster than working with Dojo in the early days. The nice thing about the DataTable is that it takes a JavaScript array which can be populated using server-side JSON generated code. I used JSON::XS for this.

YUI DataTable has a nice sorting feature and it can sort on text, numbers, dates, etc. However, it does not seem to be able to sort on visual information only so if you include HTML markup, that will be used for sorting as well. To get around this I used standard text sorting and customized the title fields to assist in the sorting. For example, in a link, I start with <a title=" instead of <a href=" because title is arbitrary and can be used to mirror the InnerHTML. For numbers a text sort will have 25 come before 4 so I added leading zeros to numbers using sprintf and put them in the title attribute as well.

A few Perl modules and the Logo Creator website made this easy to set up. YUI DataTable has a nice default CSS so I just left that as is.

Note: YUI DataTable is convenient if you just drop in a Perl data structure and have it generate the HTML and JS for you. This script uses 3 DataTables (ratings, popular and recent) so I wrote a Perl wrapper for YUI which takes a hashref and generates the client code, extracting the fields from the column definitions. This works because YUI does not require the HTML table to be built beforehand. By not having an underlying table, it's faster to get running but also won't fallback as nicely for people who aren't running JS (8% of users?). As an alternative, jQuery has a couple of add ons which work by enhancing an existing HTML table. jQuery has some nice syntax but I haven't gotten around to using it yet. Perhaps it's worth a look.

by John Wang at November 09, 2007 09:42 PM

November 05, 2007

Andy Lester

ack 1.70 adds context and line-specific matching

ack, my replacement for grep for 95% of the times programmers use grep, just got released to CPAN with version 1.70.

At long last, you can now get contextual lines before and after matched lines, just like GNU grep's -A, -B and -C options. You can also match on a specific line number or range of line numbers with the new --line option. For example, if you want to see the first line of every Perl file in a tree, you'd just do ack --line=1 --perl. Thanks very much to Torsten Biix for putting both these features together for me.

Finally, Elliot Shank pointed out that one of my favorite features, the -1 option, was never documented. Now it is. The -1 option says "stop after the first match of any type." If you find yourself acking for lines, or searching for a specific file with ack -g and then having to Ctrl-C to stop the search process, just add a -1 and Ctrl-C no longer.

ack is available in the ack distribution on CPAN, or by installing the module App::Ack from the CPAN shell. You can also download the single-file version direct from Subversion and drop it right into your ~/bin directory.

by petdance at November 05, 2007 09:56 PM

Josh ben Jore

Glenn Loos-Austin

November 02, 2007

Project Hum

How to debug memory problems in Parrot

chromatic has a couple of cool articles on tracking down segfaults in Parrot that valgrind just can't find. Along the way, he talks about memory management methods and Parrot's pluggable garbage collection system, and shows off his gdb-fu.

by Andy Lester at November 02, 2007 04:27 AM

October 31, 2007

Andrew Moore

How to Sneak Testing Into Your Devlopment Team

There is a growing amount of material available about automated testing in the perl community. I have noticed that often times when an engineer reads an article or listens to a talk on this topic that he or she will respond either by giving a reason that they can't implement it in their workplace, or by asking how they can implement it in their specific workplace given some set of reasons that it's tough.

In the past 10 months, I have transformed my huge mod_perl application from one with no unit tests to having about 50% test coverage. Each of the 7 engineers who have been on the team have used the tests and added to them. The application and the testing environment that I have for it are not perfect, but they're better than they were before, and they'll soon be better than they are now. I did it without issuing an edict requiring unit testing or by having management require it, or even know about it.

Looking back on the progress, I don't really think it was that hard. In fact, I think that there were three main methods that I used to grow this testing system into what it is now. I've essentially tricked my peers (and myself) into becoming better programmers with these methods, and I'll bet that you can too.

Boiling a Frog

They say that you can put a frog in a pan of water, set it on the stove, and bring the water to a boil. This will cook the frog without it jumping out. If you drop the frog in hot water, he'll jump right out. Apparently, it's the sudden change in environment that scares the frog. It's probably not true, but I don't really care to try. Nonetheless, it makes a good analogy.

When I started adding unit tests to my code, I didn't really see that it was necessary to convince all of the other members of my team to fully test their code. I knew that if I tested all of the code that I touched or added eventually we would have dozens and then hundreds of tests that tested parts of the whole application.

As I wandered around the application fixing bugs and adding new features in my normal course of work, I would add unit tests. I knew that each time I checked in a test case the rest of the team would see the new code in the svn commit emails. They knew that unit tests were being added even if they didn't contribute to them. (You do have subversion set to send out emails with patches each time someone commits code, don't you?)

Occasionally, someone checked in a change that broke a few tests when the nightly smokebot was run. I fixed the code or the tests, checked in the patch, and sent a mail to the developer that broke the test cases. I let him know that I made a small change to preserve backwards compatibility, or something like that and moved on. Eventually, the water boiled so to speak and a few other developers running the test suite themselves and adding tests to try out their new code. This meant that I was no longer the only one writing unit tests. The test suite was growing more quickly. That's powerful.

The Ping-Pong Method

The "ping-pong" method is another trick I used to build up our test suite. After I noticed another member of my team check in a new method for an object, I'll try to use it. I write a test case that instantiates the object and tries to call that method. Typically, I find a place where the documentation doesn't really match the behavior. So, I'll send over a mail to the author:

"Hey, Carl. I'm trying to use the new 'bark' method I saw that you just added to the Dog object, and I can't quite figure it out. The docs say that I can optionally pass a volume paramteter, but if I leave it out, the dog doesn't bark. Is it required, or should there be a default?"

Typically, they'll write back and say that there's something missing from the documentation or the code and often even check in a patch or mail one to me. I'll update the test cases that I'm working on and them check them in. Through this back and forth exchange, I can make sure that I understand most of the new code that goes into the application, that the code does what the original author expects it to do, and that there exist test cases to prove it. Knowing that I will be writing test cases for their code eventually started to encourage the other team members to write well-documented, usable code and eventually even their own test cases. After a few weeks of "ping-pong", I'll bet most developers will start writing their own unit tests.

The Ratchet Method

Once the members of the team agreed for the most part that we should be writing test cases for our code and adhering to some kind of coding standard, I checked in a few tests that touch all of the files in the application. These test for violations of POD syntax and POD coverage and for violations tested by Perl::Critic.

When I got started, of course, not all files could pass POD checks or Perl::Critic, so I listed these that failed and made them TODO tests. If a file passed Perl::Critic at level 5, but not severity level 4, I made sure that it was tested at 5 and added a TODO test for it at 4, or whatever level we're shooting for. When files are modified, if the new code causes to file to no longer pass a POD syntax or coverage test or a Perl::Critic test, a developer will know that he needs to clean up his code to match the level of quality that was already there. If a new file is added, since it won't be in the list of current exceptions, it will be required to pass all of the tests at the desired level.

By creating tests like this that test current levels of some measure of code quality, I can ensure that new code added will not be worse than the current level. The tests act as a ratchet that constantly ensures new code is measured as good as or better than the current code.

I think that these three methods are pretty good ways to inject unit testing into your application. At the very least, they're pretty good responses next time someone claims that they can't start writing unit tests for their code since not all members of the team have "drunk the Kool-Aid". Now go start writing better code.

by amoore at October 31, 2007 08:57 PM

Andy Lester

New WWW::Mechanize and Test::WWW::Mechanize spiffiness

For those of you using Mech for your testing of your website:

    $agent->content_contains( qr/\QEnter keyword(s)/ )
        or $agent->dump_all( \*STDERR );

not ok 14 - Content contains '(?-xism:Enter\ keyword\(s\))'
#   Failed test 'Content contains '(?-xism:Enter\ keyword\(s\))''
#   at t/simple-search.t line 31.
#     searched: "<HTML>\x{0a}<HEAD>\x{0a}<TITLE>TitleTales&#153;</TITLE></HEA"...
#   can't find: "(?-xism:Enter\ keyword\(s\))"
POST [simsearch]
  clickval=                      (hidden readonly)
  searchwords=                   (text)
  S=<UNDEF>                      (checkbox) [*<UNDEF>/off|on/Include Out of Print / Please Order Direct Titles]
No longer do you have to do a $mech->save_content() and then run mech-dump on it. How has it taken me so long to put this stuff in there?

by petdance at October 31, 2007 08:56 PM

October 30, 2007

Project Hum

Curses::UI under new ownership

Shawn Boyette has taken over Curses::UI from Marcus Theissen. He tells me that "as of last night, I no longer consider the old CVS repository authoritative." There hasn't been a release since late 2004, so Shawn will be injected new life into the module. There's not yet a new public repository (I highly recommend using Google Code's services at, and any new bugs or changes should get sent to Shawn.

by Andy Lester at October 30, 2007 02:06 PM

October 22, 2007

Planet Perl

Sporting Weekend of Woe

This weekend has been a sporting weekend of woe. England lost in the Rugby World Cup Final, although of course I'm glad that we made it that far. Young Mr. Hamilton failed to capture the drivers world championship in his first season, and Forest only managed a draw at home against Doncaster.

Still, I guess Orient are once again winning, which is good.

And on the bright side, the Montreal Canadiens recorded their first home win of the season. And the New England Patriots continued their unbeaten season with a blow-out at Miami.

Saturday Katrien and I were in Mont Tremblant for much of the day, trying to enjoy what will be our last weekend together for a while – Katrien will back on the European side of the pond for about six weeks, which is going to feel quite strange. Her Visa has not yet come through, and until it does she can only spend six months out of the year here. We want to make sure she can be here at Christmas, and that means spending some time out of the country now. She's looking forward to being in London, but it will seem strange.

by james at October 22, 2007 08:22 PM

October 21, 2007

Planet Perl

Calgary Open Source Systems Festival: The largest free technology event in Calgary

This coming weekend is the Calgary Open Source Systems Festival (COSSFest 2007). For those open source lovers and those curious about open source, this is a must attend event. By the way, I will be giving two talks: one on Machine Learning Development with Perl and another on Open Source Business Analytics. Here is the official [...]

by Lino Ramirez at October 21, 2007 08:41 PM

October 14, 2007

Planet Perl

Help! My Brain Sack is Leaking!

I was on my way to visit a client on Friday morning, just about getting caught in the morning rush hour traffic, and I started to develop a headache.

It kept getting worse and worse, and the next thing I knew I started feeling nauseous. "This isn't good" I thought looking for an exit, somewhere. It kept on getting worse and worse, and just as my vision was starting to blur, I got to an exit. I pulled off the freeway and into a gas station, where I vomited.

"Shit" I thought. I can't visit a client like this. It must be something I ate. I was really feeling terrible at this point. My hands and feet were starting to feel numb, I was an hour from home, and I didn't know what to do.

Nothing else for it, I need to get home.

That's pretty much the last thing I remember from Friday morning.

The next thing I really knew, I woke up in bed at home. Apparently I had called the people I was supposed to be meeting and canceled, called home and said I was on my way, driven back, stumbled into the house, very lucidly told Katrien what was wrong, and then fallen asleep mid-sentence.

This of course, was rather worrying.

It turns out that I'm suffering from a Post-Dural Puncture Headache.

I had an epidural to try to help my back on Thursday, and it didn't go very well. What has happened is that the sack that contains the brain, spinal nerves, and all that goodness (known as the "dura") got punctured by the needle while the epidural procedure was being performed. The Cerebral-Spinal Fluid that surrounds the brain is leaking out of the sack through this hole, and that gives you a headache. When you are upright (either sitting or standing) it gets worse and worse, because of course the fluid that is remaining in the sack goes to the bottom, leaving a nice big air bubble around your brain where liquid is supposed to be…

So I'm stuck lying down. As long as I'm lying down it doesn't hurt too much, but as soon as I stand up it's like I've got the worst hangover ever.

All the pain of getting drunk, but none of the pleasure.

Apparently you can get a "blood patch" to help heal the puncture faster however, this involves taking blood and then injecting it above the puncture so that it forms a clot. I'm not sure that I'm too keen on that to be honest.

Right now I'm fed up of doctors, medicine, and anything to do with my insides.

by james at October 14, 2007 08:42 PM

October 08, 2007

Glenn Loos-Austin

Fun: Test Embed

Here's a new version that's in development (and might have some bugs):


We added the ability to embed stories from on other people's websites. This is a test of some embed code:


Here's some more.

and here's another:


by Glenn at October 08, 2007 08:57 PM

Planet Perl

Battlestar Galactica

I've just finished watching Battlestar Galactica Season 3, and now I need to know what happens in season four. Of course it doesn't air for another 5 weeks or so, but I'm genuinely curious, and will probably make the effort to watch it on TV provided that I know what channel it airs on here!

Does anybody know where to look for BSG in Canada? Help! I can't wait until the DVD release in a years time!

by james at October 08, 2007 08:41 PM

October 06, 2007

Ask Bjørn Hansen atom feed

The use.perl RSS feed is messed up in some particular way that makes Google Reader unable to parse it (at least it was a few days ago).

I setup a Feedburner feed to parse it and output something cleaner:

  - ask

by ask at October 06, 2007 08:56 PM

September 17, 2007

Elliot Shank

Writing configurable Perl::Critic Policies.

As of Perl::Critic 1.07, I would like to discourage the creation of constructors for Policies. Instead, I would encourage the use of P::C::Policy::initialize_if_enabled(). The reasoning is twofold.

One, this allows initialization to be deferred to the point where we know that the policy is going to be used. P::C::PolicyFactory always instantiates every Policy that it can find. It is up to the P::C::Config object to filter that set down. Primarily, this is an issue for Policies which dynamically load other modules.

Two, this method enables the Policy to decide for itself whether it should be enabled. This means that a Policy that depends upon a module that might not be present can remove itself from the set that violates() gets called on, thus speeding things up because it isn't being called on every PPI::Element.

This originated from Chris Dolan's work on the Perl Foundation grant to create the remaining Policies that can be implemented that enforce one of the ideas in PBP. Specifically, for Documentation::PodSpelling, but this change has been made to all the configurable core Policies. In particular, this helps CodeLayout::RequireTidyCode.

Differences from a constructor other than the obvious first parameter:

  1. The configuration is passed in as a hashref and not a hash.
  2. initialize_if_enabled() returns a boolean specifying whether the Policy should be enabled.

This is how the two above policies bow out.

by elliot at September 17, 2007 08:56 PM

Andy Lester


Back on September 5th, I gave a talk to the Chicago Software Process Improvement Network. It was 10 minutes, and it was called "Lessons Learned From Open Source Software Development." I just got my feedback back, and the comments are shown below:
  • Could we get a copy of the slides?
  • interesting and informative
  • Enthusiastic approach to open source
  • Useful background.
  • probably made the evening worth coming to.
  • Enlightening!
  • Lester was upbeat and interesting
  • Excellent - interested in having this speaker again
  • interesting topic, wouldn't mind learning more about it. Great slides.
  • Amazing, friendly presentation of many great ideas
  • interesting and fun but mostly a rant
  • fatuous
  • somewhat disjointed
  • I like more
  • controversial/interesting
  • simple and effective
"Fatuous"? says
  1. foolish or inane, esp. in an unconscious, complacent manner; silly.
  2. unreal; illusory.
I would like to hear what I said that was fatuous. I'm intrigued. Alas, I shall never know.

by Andy Lester at September 17, 2007 02:16 AM

September 11, 2007

Planet Perl

Machine Learning Development with Perl

I just posted in PerlMonks a draft of a 45 minutes-long talk on Machine Learning Development with Perl. Here is an extract of that post: ————————————————– Machine Learning Development with Perl The development of machine learning applications can be seen as a three-phase process involving: preparation, modeling, and implementation (See Fig. 1). As a developer, you have to move [...]

by Lino Ramirez at September 11, 2007 08:22 PM

Presenting AranduCorp

AranduCorp is a consulting firm focused on helping organizations improve their business processes, marketing, and sales. AranduCorp offers training and consulting services on predictive analytics and will soon offer affordable predictive analytics software solutions for small and medium size businesses. For more information visit: AranduCorp’s Website AranduCorp’s Blog

by Lino Ramirez at September 11, 2007 08:22 PM

September 09, 2007

Elliot Shank

Lesson of the day: Readonly, Exporter, and subroutine sigils

They don't get along.

As of the recent 1.07 release, Perl::Critic, has started using Readonly to be more more self-compliant with Perl Best Practices. We had been avoiding use of constant for the reasons described in the book, but had not been willing to add the Readonly dependency until now.

The Perl::Critic coding standard has been to use sigils for subroutines in @EXPORT_OK, etc. and import lists, but Exporter treats them as optional. And, in fact, there's code that strips them off (line 47 in v5.58). I haven't figured out the commonality, but in a few environments, this fails spectacularly. Once we removed the subroutine sigils from everywhere, the problems have gone.

Explicitness: 0, Keyboard laziness: 1.

by elliot at September 09, 2007 08:56 PM

September 05, 2007

John Wang

What is the best digital voice recorder (DVR)?

I just recently picked up a digital voice recorder (aka DVR, not to be confused with digital video recorders) for recording conference calls and meetings. In three short meetings I have become a true believer. I always taken detailed meeting notes but that was because I would write notes during the meeting. With a DVR, I can concentrate on running the call and going back to catch the details later.

For my first DVR I picked up the Olympus DS-30 from FRYs. The benefits that I keyed in on where the large-looking stereo speakers and the noise reduction. Since this is my first DVR I was easily impressed by the utility of it. So far I've recorded and played back on the device, copied the WMA files off using it as a USB storage device on Win XP and converted the WMA to OGG Vorbis using dbPowerAmp. The only thing that doesn't seem to work is the CD that it came with. XP would not recognize it at all but at least I don't need since it doubles as a USB device.

Although it meets my current notetaking requirements easily, I've been thinking about whether it'd be good to use for recording podcasts. My current issue is that it records in WMA and not a FOSS standard. After looking over a number of DVRs, it seems that the higher end ones use WMA, LPEC, DSS, etc. but not common music formats such as MP3 and OGG. What native format do you think is the best for DVRs? Is it fine to record as WMA and convert to OGG Vorbis or are there better options?

I don't know too much about voice recorders at the moment so I'm easy to please. Which ones do you like and what are important features for you?

by John Wang at September 05, 2007 08:57 PM

Database Abstraction - code vs infrastructure

I've worked on a number of database-driven projects and no matter how much people want database abstraction, it was always difficult to code and maintain. I was recently reminded of this when I read this Drupal article on dropping PostgreSQL support. Not only can it be difficult to maintain support for multiple databases, but it may be difficult to find developers.

One solution of modern programming is to move database abstraction from the code to the infrastructure using a ORM (Object-Relational Mapper) or Data Mapper. A ORM and Data Mapper abstracts the database for you so you no longer have to do tie db abstraction to each app. Not only does it let you code once for multiple databases it lets your users migrate their data from one database to another. This blog runs Typo which is based on Ruby on Rails and ActiveRecord. I've been contemplating migrating Typo from MySQL to PostgreSQL and I've been told that it would be as simple as exporting the data with YAML, updating the database.yml file and importing the data. I haven't gotten around to doing it yet but it is a powerful idea. ActiveRecord is a data mapper and isn't as flexible as a full blown ORM but it gets the job done for the most part. For a full-blown ORM, I think of Perl's DBIx::Class which provides a full OO interface to the RDBMS allowing you to code just once for multiple DBs without limiting you when you want to use some esoteric database-specific SQL. DBIx::Class is often used with the Catalyst Framework but is also used by itself.

There are PHP frameworks out there like Symfony and Cake but do any of them have stand-alone ORMs? If so, could Drupal move to something like that and solve their maintainership problems once and for all? Drupal is part of the Go PHP5 effort so there should be no issue using PHP 5 OO. Something to think about for the Drupal folks if a PHP ORM is available.

by John Wang at September 05, 2007 08:21 PM