What's New in Perl

Ricardo Signes will be giving a talk at YAPC::NA 2012 that he describes as:

There are almost twenty thousand lines of documentation describing what has changed since perl 5.8. Those docs are where you can find out that the // operator is awesome, or that the “r” flag on substitution is going to save you typing and bugs, or that you can stop worrying so much about your exception handling. Unfortunately, they also contain a lot of talk about things like GSVS_mg_SLOPPY or engine derecursivisation or what happens now if you try to reset a glob reference during global destruction. With most common Unix distributions now shipping Perl 5.12, and more and more workplaces moving off 5.8, many programmers are faced with reading these documents. Instead, you can come listen to the forty minute summary.

[From the YAPC::NA Blog.]

Subtle advantage of @_ ?

It eliminates method polymorphism.
Makes it simple for over-riding inherited method, as there is only one method.
Now that makes Liskov Substituion simpler to implement.

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.

.perldb

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

The Explanation

$DB::deep=1000

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.

Building Scalable, Distributed Job Queues with Redis and Redis::Client

Mike Friedman will be giving a talk at YAPC::NA 2012 that he describes as: 

At SocialFlow, we initially built a simple job queue system using a relational database and a daemon for running workers. While this model is sufficient for a relatively small volume of jobs, an increase in scale resulted in problems with concurrency, failover, and efficiency. This presentation examines the process and design that we used to move our jobs system to the Redis structured data store, and the simultaneous development and design philosophy behind the Redis::Client CPAN module.

The presentation will cover the structure of job queues, an analysis of the pros and cons of relational vs. non-relational data-store models for queues, a brief introduction to the Redis platform, and code examples demonstrating a simplified system.

[From the YAPC::NA Blog.]

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 ...

nothing.

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!

Perl, Mobile App. glue.

Robin Darby will be giving a talk at YAPC::NA 2012 described as:

Basics of developing web based services for communication with iPhone and Android apps (including sending ‘alerts’, managing updates).

[From the YAPC::NA Blog.]

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

Edit:

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

Yippeee!

Submit a Talk for YAPC::NA 2012!

Submit a talk for YAPC::NA 2012. We’re especially interested in talks on real-world Perl apps and quintessential Perl 101 talks, but we’re open to any ideas you have. 

[From the YAPC::NA Blog.]

Using XML::Compile to output XSD compliant XML

As part of a recent project I was given an XSD file (xml schema definition) and asked to output compliant XML. CPAN to the rescue. I found XML::Compile::Schema which is a cool module that allowed me to do this with very little fuss. The documentation is really good but I think a tutorial-style post might be helpful.

To do this you’ll need to install XML::Compile and XML::LibXML.

You can use XML::Compile::Schema to read in your xsd file and output a perl hash template. Then you can use that example template to construct a hash of real data and then have XML::Compile::Schema output a valid XML file.

For this tutorial, download a sample .xsd file from here. Then write a perl script like so to dump a perl hash template.

German Perl Workshop day 1

Today, the german perl workshop 2011 started. Today's keynote was done by Heiner Kuhlmann, who talked about software architectures and refactoring. The interesting point was the parallelism between data structures and software structure. All the time I was comparing his talk with Robert C. Martin's book "Clean Code" which mentioned refactoring a couple of times. The common denominator is that refactoring without intensive testing cannot be successful.

Renée Bäcker demonstrated the use of Role::Basic for non-Moose environments. Looks very useful.

Rolf Langsdorf talked about possibilities to extend Perl's syntax using syntactic sugar and function prototypes. He tries to avoid source-filters and parsers in order to avoid breakage of external tools.

Uwe Voelker talked about HTML5::Sanitizer, a module he wrote to clean uploaded HTML code.

Max Maischein demonstrated Web Scraping techniques using FireFox to allow scraping websites that depend on JavaScript.

Looking forward to tomorrow's talks :-)

Asynchronous MySQL Queries in Perl Using DBD::mysql and AnyEvent

A lot of people use MySQL, and these days, asynchronous-style programming has really taken off. If you're involved in both of these camps, you may be wondering
how to send a query to MySQL and have it inform your event loop when it's ready with the results of that query. A common solution is to use a thread or child process
for each connection, and exchange data using IPC. However, if you're using Perl and DBD-mysql 4.019 or better, you have an alternative: the new asynchronous interface.

Using the new async flag that you can provide to the prepare method, along with the new mysql_fd method, it's fairly easy to have MySQL play nice with AnyEvent.
Here's a simple example:

Keep Those Ideas Coming

A while ago we put up the YAPC idea collector. You’ve given us a lot of great feedback so far, but keep those ideas for YAPC::NA 2012 coming, and keep voting on the existing ideas. 

[From the YAPC::NA Blog.]

I'm back

I don't think I've been seen since use Perl; went on indefinite hiatus. I am still programming Java for my day job, but still using Perl to make my life easier. A few months ago I did some investigation into Rose, and these days I am doing some investigation into Moose. DateTime::* modules also continue to hold fascination for me.

I will probably blog about my difficulties and interesting things I see. In the past I've often tended to post about things that don't work the way I would expect them to. I've sometimes been chastised for not filing bug reports, but I don't always want to file a bug report. Sometimes I just want to yak about it.

Anyway, hi, guys!

A free Perl talk Oct. 22nd in Columbus Ohio

The 2011 Code Camp Columbus is nearly upon us. It is all day the 22nd and it is free to all attendees.

I will be giving a talk about building Perl applications to solve everyday problems culminating in a WWW:Mechanize application that shows most of the previous examples working together. At previous conferences and events when I talk about Perl it is the context of using it to automate install tasks and is more about finished applications versus Perl development so this is somewhat new to me.

I plan to put the slides and other material up before the conference for community perusal
and commentary. I usually over plan the amount of material I need for one of these presentations.

Here is the full speaker schedule, there is a wide variety of non-Perl topics as well.

Perl traps for Ruby Programmers

To list in the next Camel the gotchas Ruby programmers might have run into with Perl, I've really had to dust off my Ruby skills, few as they are. I got a lot of good feedback for my Perl traps for Python Programmers, both public and private, so I'm doing it again for Ruby.

I'm only interested in the practical aspects of a person used to Ruby moving to Perl and the things they might try to do based on their Ruby experience. Also, since we already covered some things in the Python section, I'm not going to repeat some of the items.

Several Perl people have good Ruby experience, so please check my work and suggest what I've left out.

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