Tied Variables: One more reason to love Perl

As many of you know, tied variables lend extra magic to an otherwise normal Perl variable.

One of my favorites comes from File::chdir. This provides your Perl script with $CWD and @CWD. When a folder is assigned to $CWD or pushed onto @CWD the working directory is changed, in a platform independent way. The coolest thing about this is if you first local $CWD, then this change in the working directory is done locally to the block, and is undone as the scope ends.

I just released version 0.03 of Tie::Array::CSV. This module allows accessing a CSV file (or other separator parsable by Text::CSV), using a Perl array.

Underneath the hood there is more tie magic! Tie::Array::CSV uses Tie::File which provides random line access to a file as a Perl array. Using this module in mine allows the module to pick the row just like my users will, as an array index.

Version 0.03 adds a new constructor. So that the users don’t even need to be aware of the tie usage, which looks a little strange at first.

As far as I am aware, other languages don’t have anything like tie. Just one more reason to love Perl! Which other Tie classes do you find especially interesting?

Simple config for the perl debugger

I’ve been using a config file ($HOME/.perldb) for some time now. While it’s not the biggest file in the world it automates settings that I’m far too lazy to type every time I fire the beast up.


$DB::deep=1000 ;
sub afterinit { push @DB::typeahead, "{{v" unless $DB::already_curly_curly_v++; } ;
parse_options('dumpDepth=2 NonStop=1') ;

The Explanation


This increases the limit for the recursion limit from 100 - a level that’s so low I seemed to be hitting it all the time

sub afterinit { … }

I like ’v’ as a way of seeing where I’m at in the code, with some context. I hate typing it myself every time the debugger returns to the prompt.

This small piece of voodoo simply pushes the command ’{{v’ onto the list of things to do when the debugger has finished initialising. ’{{’ is “Add to the list of debugger commands to run before each prompt” and ’v’ is “View window around line”.

Until recently the command was just

sub afterinit { push @DB::typeahead, "{{v" } ;

YAPCs, Perl workshops and Monger meetings

As I was trying to buy my flight ticket to the London Perl Workshop I thought I look around if there is some other interesting event on the days before or after. Quickly I landed on Eventbrite and found a couple of interesting talks at The RSA.

As I was already at Eventbrite I checked which Perl events are listed there.
To my surprise there are almost no Perl events listed on Eventbrite.

Maybe if there was a Perl Module for Eventbrite?

Then I checked Grical for Perl, Lanyrd, Joind In, Upcoming of Yahoo and ...


Well almost nothing.

The only place where I saw the London Perl Workshop was the Lanyrd web site and there was only one other Perl event there.

So are we surprised people don't see us?

I don't know how big the impact could be but what if all the YAPC and Perl Workshop organizers started to post their events on these sites? Could that help in getting more attention?

What if each Perl Monger meeting was posted there?

What if someone implemented the modules to access the above web sites?

What if someone wrote a script that could be used by all the organizers to update the various event sites?

Written by Gabor Szabo .

Perl module ideas #1

Below are some of module ideas that I think will be useful someday, but since it's not urgent now, I'm sparing my tuits elsewhere. There will be future posts.

* A module to detect the software of a forum (e.g. vBulletin, phpBB3, etc) and provide some basic API that works for all supported software, e.g.to retrieve threads and posts, open a new topic, reply to a topic, mark topics read, etc.

* Likewise for blog software.

* A module to detect {Yahoo Messenger IDs, Blackberry PIN numbers, street addresses, other contacts} from a text. I have written one for Indonesian phone number, but the others might be useful to extract information from text.

* Something like App::perlmv for MP3 tags.

* App::IniUtils: Command-line utilities to modify INI files, e.g. (ini-add-param, ini-delete-section, ini-sort, ini-comment).

* DOM for Org::Parser.

So many ideas, so little time.

German Perl Workshop day 2

Today, we had more talks than yesterday. Marc Chantreux talked about his module, 'Perlude', an interesting CPAN module porting some of Haskel's ideas to perl.

Gerhard Schwanz presenting Mapweaver was the next speaker, directly followed by Denis Banovic presenting the simplicity of Dancer. For me, this talk was the best of today.

Steffen Ulrich gave an excellent introduction into TLS and explained some recently happening issues and how they could occur.

As a replacement for an omitted talk, Heiner Kuhlmann presented a tool to display some software quality metric values graphically. Nice to see Perl-Critic in colored boxes :-)

Herbert Breunung talked about some features of Perl 6. Whenever I hear him talking, I wish Perl 6 was already production-ready. All the new features are really awesome!

Why and how to promote the Perl Weekly newsletter?

The Ironman blogging contest was created to get more of the Perl mongers write about the stuff they are doing. To raise some awareness to new features of Perl, new CPAN modules or just to new ways of programming in Perl.

We also have blogs.perl.org now that provides an easy way for Perl programmers to start a blog. Right in the middle of the "echo chamber".

Having those blogs is a great way to distribute news about Perl but somehow it feels the number of readers has not grown much.

It is more or less the same "echo chamber".

We need to have a growing number of people reading the items.

This can be done by directing them to the Ironman itself or to the Perlshpere Perl blog aggregator or to Perl Buzz.

Those work for some people but keeping up with all the posts is very time consuming
and not everyone likes to follow Twitter.

DBD::mysql 4.019 and 4.020 are broken on Win32, here's how to downgrade


ActivePerl's Jan Dubois has kindly applied a patch to DBD-mysql 4.020 on their servers, so you can just do this:

Original post:

This a warning to Win32 perl devs using DBD-mysql.

The versions 4.019 and 4.020 are broken in a rather subtle way: All SQL errors are silently ignored and in fact not even triggered, no matter what RaiseError is set to or what kind of error happens. As an example, this code will run without a complaint:

Various messages have been sent to the maintainers of DBD-mysql, including a proposal for a fix. However, implementation of a fix and release of a new version will likely take some time.

In the meantime downgrading is the only viable option, but sadly the ppm client does not make that kind of thing very easy. As such, this is the command you will need to execute to downgrade your DBD-mysql:

Note that is compiled for Perl 5.12. By changing the Perl version part of the url you can also get it for 5.8 and 5.10. For 5.14 there is no ppm available though, so if you're using that you will have to downgrade your entire Perl or try your luck with the 5.12 one.

A Glimpse Of YAPC::Asia Tokyo 2011

tl;dr> YAPC::Asia Tokyo 2011 was a great success. Check out our photos, our videos, and check out the talk slides.

So as I previously announced, YAPC::Asia Tokyo 2011 is now over. Apparently we had more attendees in this single YAPC than all of North American Perl events combined for year 2011:

22:44 r: I just read that 672 attendees number on blogs.perl.
22:46 p: yeah that's easily 30% larger than all of the NA events combined.
22:49 r: yapc 244 + PPW 78 + frozen perl 46 + perl oasis 34 = 402 NA for 2011


About blogs.perl.org

blogs.perl.org is a common blogging platform for the Perl community. Written in Perl and offering the modern features you’ve come to expect in blog platforms, the site is run by Dave Cross and Aaron Crane, with a design donated by Six Apart, Ltd.