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Thursday, 29 April, 2010
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Friday, 12 March, 2010

Reading the Modern Perl Book

I’m in the Perl phase of my language obsession rotation. I’ve created a handy language obsession table you can use to simulate the behavior for your favorite GURPS Geek campaign.

Roll 3d6 for the subject.

Roll Result
3-6 Perl
7-9 Python
10-11 Ruby
12-13 Parrot
14 PHP
15-18 Something shiny I found on the Web. You can get plausible results by selecting a random entry from the Wikipedia list of programming languages.

Every week after the first, roll 1d6.

Roll Result
1-3Continue last week's language
4-6Roll on Table 1 for a new language

Alternately, you can set a duration of 1d6 weeks. That’s handy for an ADHD NPC geek, where you don’t want to check every week. Note that this is free time obsession. The language at $work is whatever $work requires.

I don’t know why I felt the need to share this. I’ve already spent more time on that silly table than the actual subject I wanted to write about.

So anyways - I’m messing about with Perl. I have been reading chromatic’s Modern Perl blog for a while - even when I’m not in a Perl cycle. It’s good, you should try it out. He presents a needed perspective on Perl as something more than a musty system administration language.

chromatic is also writing a book and maintaining the draft on github. I finally decided I wanted to read that draft. The README and a tiny bit of Git knowledge provide all I need.

$ git clone git://
$ cd modern_perl_book
$ perl build/tools/

Now there is a handful of POD files in build/chapters which I could read with perldoc.

$ ls build/chapters
chapter_01.pod  chapter_03.pod  chapter_05.pod  chapter_07.pod  chapter_09.pod  chapter_11.pod  chapter_13.pod  chapter_15.pod
chapter_02.pod  chapter_04.pod  chapter_06.pod  chapter_08.pod  chapter_10.pod  chapter_12.pod  chapter_14.pod  chapter_16.pod
$ perldoc build/chapters/chapter_01.pod

I can also generate HTML for those days when perldoc just isn’t making me happy.

$ perl build/tools/
Can't locate Pod/PseudoPod/ in @INC (@INC contains: /usr/local/lib/perl5/5.10.1/darwin-2level /usr/local/lib/perl5/5.10.1 /usr/local/lib/perl5/site_perl/5.10.1/darwin-2level /usr/local/lib/perl5/site_perl/5.10.1 /usr/local/lib/perl5/site_perl .) at build/tools/ line 6.
BEGIN failed--compilation aborted at build/tools/ line 6.

Oops. It looks like there’s a dependency. No problem.

$ sudo cpan Pod::PseudoPod::HTML
$ perl build/tools/
$ ls build/html
chapter_01.html chapter_04.html chapter_07.html chapter_10.html chapter_13.html chapter_16.html
chapter_02.html chapter_05.html chapter_08.html chapter_11.html chapter_14.html style.css
chapter_03.html chapter_06.html chapter_09.html chapter_12.html chapter_15.html

Now I can open the chapters in my favorite Web browser.

$ elinks build/html/chapter_01.html

From here, I can pay attention to chromatic’s tweets — or his dents, since he seems more active on - or watch the modern_perl_book repository on github. Whenever he mentions new content, I will refresh and rebuild.

$ git pull
$ perl build/tools/
$ perl build/tools/

I don’t want to remember three whole commands. Am I taking Laziness too far? Perhaps. Nevertheless, here’s a Perl script to handle the task. It should only rebuild the chapters and HTML if there was an update in the repository.

#!/usr/bin/env perl

use Modern::Perl;

my $git_pull = `git pull`;

if ( $git_pull =~ m{\AAlready up-to-date.} ) {
    say "No changes to book.";
else {
    print $git_pull; # Show what updates were made.

    say "Building chapters.";
    system qw(perl build/tools/;

    say "Building HTML.";
    system qw(perl build/tools/;

    say "All done. Enjoy the update!";