Simon Cozens - Advanced Perl Programming

It was all Nathan Torkington's fault. Our Antipodean programmer, editor, and O'Reilly conference supremo friend asked me to update the original Advanced Perl Programming way back in 2002.

The Perl world had changed drastically in the five years since the publication of the first edition, and it continues to change. Particularly, we've seen a shift away from techniques and toward resourcesfrom doing things yourself with Perl to using what other people have done with Perl. In essence, advanced Perl programming has become more a matter of knowing where to find what you need on the CPAN,[] rather than a matter of knowing what to do.

Perl changed in other ways, too: the announcement of Perl 6 in 2000 ironically caused a renewed interest in Perl 5, with people stretching Perl in new and interesting directions to implement some of the ideas and blue-skies thinking about Perl 6. Contrary to what we all thought back then, far from killing off Perl 5, Perl 6's development has made it stronger and ensured it will be around longer.

So it was in this context that it made sense to update Advanced Perl Programming to reflect the changes in Perl and in the CPAN. We also wanted the new edition to be more in the spirit of Perlto focus on how to achieve practical tasks with a minimum of fuss. This is why we put together chapters on parsing techniques, on dealing with natural language documents, on testing your code, and so on.

But this book is just a beginning; however tempting it was to try to get down everything I ever wanted to say about Perl, it just wasn't possible. First, because Perl usage covers such a wide spreadon the CPAN, there are ready-made modules for folding DNA sequences, paying bills online, checking the weather, and playing poker. And more are being added every day, faster than any author can keep up. Second, as we've mentioned, because Perl is changing. I don't know what the next big advance in Perl will be; I can only take you through some of the more important techniques and resources available at the moment.

Hopefully, though, at the end of this book you'll have a good idea of how to use what's available, how you can save yourself time and effort by using Perl and the Perl resources available to get your job done, and how you can be ready to use and integrate whatever developments come down the line.

In the words of Larry Wall, may you do good magic with Perl!

Contents

, Advanced Techniques, introduces a few common tricks advanced Perl programmers use with examples from popular Perl modules.

, Parsing Techniques, covers parsing irregular or unstructured data with Parse::RecDescent and Parse::Yapp, plus parsing HTML and XML.

, Templating Tools, details some of the most common tools for templating and when to use them, including formats, Text::Template, HTML::Template, HTML::Mason, and the Template Toolkit.

, Objects, Databases, and Applications, explains various ways to efficiently store and retrieve complex data using objectsa concept commonly called object-relational mapping.

, Natural Language Tools, shows some of the ways Perl can manipulate natural language data: inflections, conversions, parsing, extraction, and Bayesian analysis.

, Perl and Unicode, reviews some of the problems and solutions to make the most of Perl's Unicode support.

Chap ter 7, POE, looks at the popular Perl event-based environment for task scheduling, multitasking, and non-blocking I/O code.

, Testing, covers the essentials of testing your code.

, Inline Extensions, talks about how to extend Perl by writing code in other languages, using the Inline::* modules.

, Fun with Perl, closes on a lighter note with a few recreational (and educational) uses of Perl.

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Using Code Examples

This book is here to help you get your job done. In general, you may use the code in this book in your programs and documentation. You do not need to contact us for permission unless you're reproducing a significant portion of the code. For example, writing a program that uses several chunks of code from this book does not require permission. Selling or distributing a CD-ROM of examples from O'Reilly books does require permission. Answering a question by citing this book and quoting example code does not require permission. Incorporating a significant amount of example code from this book into your product's documentation does require permission.

We appreciate, but do not require, attribution. An attribution usually includes the title, author, publisher, and ISBN. For example: " Advanced Perl Programming , Second Edition by Simon Cozens. Copyright 2005 O'Reilly Media, Inc. 0-596-00456-7."

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