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483 lines
9.0 KiB
483 lines
9.0 KiB
<!DOCTYPE html>
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<html lang=en>
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<head>
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<meta charset="utf-8">
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<title>perl</title>
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<link rel=stylesheet href="slides.css" />
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<link rel="alternate" type="application/atom+xml" title="changes" href="//p1k3.com/userland-book/feed.xml" />
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<script>hljs.initHighlightingOnLoad();</script>
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</head>
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<body>
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<section>
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<p style="font-size: 3em; margin-bottom: 0; text-align: center;">
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All the Perl you need
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</p>
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<p style="font-size: 2em; text-align: center;">
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for slicing and dicing text files
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</p>
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<p style="text-align: center;">
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Brennen Bearnes <bbearnes@wikimedia.org>
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</p>
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<p style="text-align: center;"><small>
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Source:
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<a href="https://code.p1k3.com/gitea/brennen/wmf-engprod-offsite-slides">
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code.p1k3.com/gitea/brennen/wmf-engprod-offsite-slides
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</a><br />
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Slides:
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<a href="https://squiggle.city/~brennen/perl/">
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squiggle.city/~brennen/perl/
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</a>
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</small></p>
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</section>
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<section>
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<h2><a name=Agenda href=#Agenda></a> Agenda</h2>
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<ol>
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<li> A capsule history</li>
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<li> What is Perl actually like?</li>
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<li> Basic syntax and techniques</li>
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<li> Examples</li>
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</ol>
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</section>
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<section>
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<h2><a name=A-capsule-history href=#A-capsule-history></a> A capsule history</h2>
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<ul>
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<li>1987 - Started by Larry Wall</li>
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<li>1991 - <em>Programming Perl</em> - the Camel Book</li>
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<li>1994-95 - Perl 5, CPAN</li>
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<li>late 1990s - Perl CGI unerpins much of the web</li>
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<li>2000ish - Massive derail into Perl 6 development</li>
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</ul>
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</section>
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<section>
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<h2><a name=What-rsquo-s-Perl-actually-like href=#What-rsquo-s-Perl-actually-like></a> What’s Perl actually like?</h2>
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<ul>
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<li>Backronym: “Practical Extraction and Report Language”.</li>
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<li>“There’s more than one way to do it”</li>
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<li>“Executable line-noise”</li>
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<li><a href="https://lobste.rs/s/odi5eu/93_paint_splatters_are_valid_perl">“93% of Paint Splatters are Valid Perl Programs”</a></li>
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</ul>
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</section>
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<section>
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<h2><a name=What-rsquo-s-Perl-actually-like href=#What-rsquo-s-Perl-actually-like></a> What’s Perl actually like?</h2>
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<p>A general-purpose, multi-paradigm programming language.</p>
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<p>That also has a lot in common with the Unix shell.</p>
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</section>
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<section>
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<h2><a name=What-rsquo-s-Perl-actually-like href=#What-rsquo-s-Perl-actually-like></a> What’s Perl actually like?</h2>
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<p>General-purpose, multi-paradigm programming language.</p>
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<p>That also has a lot in common with the Unix shell.</p>
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<p>So: <strong>A widely-installed environment where you can combine small tools to work
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with data.</strong></p>
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</section>
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<section>
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<p>A sample data file, tab-separated names of some authors:</p>
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<!-- exec -->
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<pre><code>$ column -t examples/authors.tsv
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Robinson Eden
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Waring Gwendolyn L.
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Brunner John
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Tolkien John Ronald Reuel
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Walton Jo
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Toews Miriam
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Cadigan Pat
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Le Guin Ursula K.
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Veselka Vanessa
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Wells Martha
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Leckie Ann
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</code></pre>
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<!-- end -->
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</section>
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<section>
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<p>Perl is often described as a superset of <code>grep</code>, <code>sed</code>, and <code>awk</code>.</p>
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<p>Combines filtering, sorting, and transforming strings with stuff that’s hard
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(or missing) in Bash:</p>
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<ul>
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<li>Functions</li>
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<li>Clean basic data structures</li>
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<li>Robust quoting</li>
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<li>Sensible control structures</li>
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<li>Variable scope</li>
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</ul>
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</section>
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<section>
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<p>Like <code>grep</code>:</p>
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<!-- exec -->
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<pre><code>$ perl -ne 'print if m/^T/;' examples/authors.tsv | column -t
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Tolkien John Ronald Reuel
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Toews Miriam
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</code></pre>
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<!-- end -->
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</section>
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<section>
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<p>Like <code>cut</code> or <code>awk</code>:</p>
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<!-- exec -->
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<pre><code>$ perl -anE 'say @F[1];' examples/authors.tsv
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Eden
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Gwendolyn
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John
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John
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Jo
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Miriam
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Pat
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Guin
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Vanessa
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Martha
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Ann
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</code></pre>
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<!-- end -->
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</section>
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<section>
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<p>Like <code>sed</code> or <code>tr</code>:</p>
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<!-- exec -->
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<pre><code>$ perl -pe 'tr/[a-z]/[A-Z]/' examples/authors.tsv | column -t
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ROBINSON EDEN
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WARING GWENDOLYN L.
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BRUNNER JOHN
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TOLKIEN JOHN RONALD REUEL
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WALTON JO
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TOEWS MIRIAM
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CADIGAN PAT
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LE GUIN URSULA K.
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VESELKA VANESSA
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WELLS MARTHA
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LECKIE ANN
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</code></pre>
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<!-- end -->
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</section>
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<section>
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<p>I’m not here to convince you to write large programs in Perl.</p>
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<p>I want to gesture at a portion of the language useful for:</p>
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<ul>
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<li>One-liners</li>
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<li>Short utility scripts</li>
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<li>Exploratory data work & transforms</li>
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</ul>
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<p>Let’s go over some basic syntax and techniques, and then look at a few
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examples from my toolkit.</p>
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</section>
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<section>
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<h2><a name=Basics href=#Basics></a> Basics</h2>
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<ul>
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<li>There’s a <em>lot</em> of syntax</li>
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<li>Much of it recognizable from elsewhere:
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<ul>
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<li>PHP syntax is basically Perl-lite</li>
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<li>Perl regexps: <code>grep</code>, <code>sed</code>, <code>vi</code>, PCRE, etc.</li>
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<li>Idioms from the shell, C, and even BASIC</li>
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</ul>
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</li>
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</ul>
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</section>
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<section>
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<h2><a name=Basics href=#Basics></a> Basics</h2>
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<!-- exec-raw cat examples/hello.pl -->
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<pre><code>#!/usr/bin/env perl
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print "Hello EngProd.\n";
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</code></pre>
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<!-- end -->
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<!-- exec -->
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<pre><code>$ ./examples/hello.pl
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Hello EngProd.
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</code></pre>
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<!-- end -->
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</section>
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<section>
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<h2><a name=Basics-boilerplate-edition href=#Basics-boilerplate-edition></a> Basics - boilerplate edition</h2>
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<!-- exec-raw cat examples/hello_boilerplate.pl -->
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<pre><code>#!/usr/bin/env perl
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use warnings;
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use strict;
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use 5.10.0;
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say greet($ARGV[0]);
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sub greet {
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my ($greetee) = @_;
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return "Hello $greetee.";
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}
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</code></pre>
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<!-- end -->
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<!-- exec -->
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<pre><code>$ ./examples/hello_boilerplate.pl 'EngProd'
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Hello EngProd.
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</code></pre>
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<!-- end -->
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</section>
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<section>
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<h2><a name=A-basic-filter href=#A-basic-filter></a> A basic filter</h2>
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<!-- exec-raw cat examples/filter_authors.pl -->
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<pre><code>#!/usr/bin/env perl
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use warnings;
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use strict;
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use 5.10.0;
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# Extract name where given name matches "John":
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while (<>) {
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say "$2 $1" if m/^(.*)\t(Jo.*?)(\t|$)/i;
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}
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</code></pre>
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<!-- end -->
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<!-- exec -->
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<pre><code>$ ./examples/filter_authors.pl examples/authors.tsv
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John Brunner
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John Tolkien
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Jo Walton
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</code></pre>
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<!-- end -->
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</section>
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<script>
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$(document).ready(function () {
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// ☜ ☝ ☞ ☟ ☆ ✠ ✡ ✢ ✣ ✤ ✥ ✦ ✧ ✩ ✪
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// get all the "slides", hide them
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$sections = $('section');
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$sections.hide();
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var section_number = 0;
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var $cur_section = $( $sections.get(section_number) );
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$cur_section.toggle(); // show first slide
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var transit = function (jump) {
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$('button').hide();
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$cur_section.hide();
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section_number += jump;
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if (section_number > ($sections.length - 1)) {
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section_number = 0;
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}
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$cur_section = $( $sections.get(section_number) );
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$cur_section.toggle({
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duration: 200,
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done: function () { $('button').show(); }
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});
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};
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var $fwd_button = $('<button class=clicker-button>next</button>');
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var $bwd_button = $('<button class=clicker-button>prev</button>');
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$fwd_button.click(function (e) {
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e.preventDefault();
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transit(1);
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});
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$bwd_button.click(function (e) {
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e.preventDefault();
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transit(-1);
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});
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$(document).keydown(function(e) {
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switch(e.which) {
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case 8: // backspace
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case 37: // left
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$bwd_button.click();
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break;
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case 32: // spacebar
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case 39: // right
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$fwd_button.click();
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break;
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case 90:
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toggleFullScreen();
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break;
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default:
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return;
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}
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e.preventDefault();
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});
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$button_group = $('<div class=buttons/>');
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$button_group.append($bwd_button);
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$button_group.append($fwd_button);
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$('body').append($button_group);
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var toggleFullScreen = function () {
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if (!document.fullscreenElement && // alternative standard method
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!document.mozFullScreenElement && !document.webkitFullscreenElement && !document.msFullscreenElement ) { // current working methods
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if (document.documentElement.requestFullscreen) {
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document.documentElement.requestFullscreen();
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} else if (document.documentElement.msRequestFullscreen) {
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document.documentElement.msRequestFullscreen();
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document.documentElement.webkitRequestFullscreen(Element.ALLOW_KEYBOARD_INPUT);
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}
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if (document.exitFullscreen) {
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document.exitFullscreen();
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} else if (document.msExitFullscreen) {
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document.msExitFullscreen();
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