This is a modified chapter of Mastering Perl by brian d foy and published by O'Reilly Media. It may differ significantly from that in the book due to corrections, additions of new material, or removal of obsolete material. This material is online for community review in preparation for a second edition.
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Mastering Perl is the third book in the series starting with Learning Perl, which taught you the basics of Perl syntax, progressing to Intermediate Perl, which taught you how to create re-usable Perl software, and finally this book, which pulls everything together to show you how to bend Perl to your will. This isn't a collection of clever tricks, but a way of thinking about Perl programming so you integrate the real-life problems of debugging, maintenance, configuration, and other tasks you'll encounter as a working programmer. This book starts you on your path to becoming the person with the answers, and, failing that, the person who knows how to find the answers or discover the problem.
An introduction to the scope and intent of this book.
More regular expression features, including global matches, lookarounds, readable regexes, and regex debugging.
Avoid some common programing problems with the techniques in this chapter, which covers taint checking and gotchas.
A little bit about the Perl debugger, writing your own debugger, and using the debuggers others wrote.
Before you set out to improve your Perl program, find out where you should concentrate your efforts.
Figure out which implementations do better on time, memory, and other metrics, along with cautions about what your numbers actually mean.
Wrangle Perl code you didn't write (or even code you did write) to make it more presentable and readable by using Perl::Tidy or Perl::Critic.
Learn how Perl keeps track of package variables and how you can use that mechanism for some powerful Perl tricks.
Define subroutines on the fly and turn the tables on normal procedural programming. Iterate through subroutine lists rather than data to make your code more effective and easy to maintain.
Fix code without editing the original source so you can always get back to where you started.
Let your users configure your programs without touching the code.
Learn how Perl reports errors, how you can detect errors Perl doesn't report, and how to tell your users about them.
Let your Perl program talk back to you by using Log4perl, an extremely flexible and powerful logging package.
Store data for later use in other programs, a later run of the same program, or to send as text over a network.
Translate plain ol' documentation into any format that you like, and test it too.
Use bit operations and bit vectors to efficiently store large data.
Implement your own versions of Perl's basic data types to perform fancy operations without getting in the user's way.
Write programs as modules to get all of the benefits of Perl's module distribution, installation, and testing tools.
Explore these resources to continue your Perl education.
My popular step-by-step guide to solving any Perl problem. Follow these steps to improve your troubleshooting skills.
The following typographic conventions are used in this book:
Used for function names, module names, filenames, environment variables, code snippets, and other literal text
Used for emphasis and for new terms where they are defined
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From brian: Many people helped me during the year I took to write this book. The readers of the Mastering Perl mailing
list gave constant feedback on the manuscript and sent patches, which I mostly applied as is, including those from Andy Armstrong,
David H. Adler, Renée Baumlcker, Anthony R. J. Ball, Daniel Bosold, Alessio Bragadini,
Philippe Bruhat, Katharine Farah, Shlomi Fish, David Golden, Bob Goolsby, Ask Bjørn Hansen, Jarkko Hietaniemi, Joseph
Hourcle, Adrian Howard, Offer Kaye, Stefan Lidman, Eric Maki, Josh McAdams, Florian Merges, Jason Messmer, Thomas Nagel, Xavier
Noria, Les Peters, Bill Riker, Yitzchak Scott-Thoennes, Ian Sealy, Sagar R. Shah, Alberto Simões, Derek B. Smith, Kurt
Starsinic, Adam Turoff, David Westbrook, and Evan Zacks. I'm quite re-assured that their constant scrutiny kept me on the right
path.
Tim Bunce provided gracious advice about the profiling chapter, which includes DBI::Profile, and Jeffrey Thalhammer updated me on the current developments with his Perl::Critic module.
Perrin Harkins, Rob Kinyon, and Randal Schwartz gave the manuscript a thorough beating at the end, and I'm glad I chose them as technical reviewers because their advice is always spot on.
Allison Randal provided valuable Perl advice and editorial guidance on the project, even though she probably dreaded my constant queries. Near the end of the year, Andy Oram took over as editor and helped me get the manuscript into shape so we could turn it into a book. The entire O'Reilly Media staff, from editorial, production, marketing, sales, and everyone else, was friendly and helpful, and it's always a pleasure to work with them. It takes much more than an author to create a book, so thank a random O'Reilly employee next time you see one.
Randal Schwartz, my partner at Stonehenge Consulting, warned me that writing a book was a lot of work and still let me mostly take the year off to do it. I started in Perl by reading his Learning Perl and am now quite pleased to be adding another book to the series. As Randal has told me many times "You'll get paid more at Starbucks and get health insurance too." Authors write to share their thoughts with the world, and we write to make other people better programmers.
Finally, I have to thank the Perl community, which has been incredibly kind and supportive over the ten years that I've been part of it. So many great programmers and managers helped me become a better programmer, and I hope this book does the same for people just joining the crowd.