Preface (Learning Perl Objects, References & Modules)

Ten years ago, I wrote the first edition of Learning Perl. In the intervening years, Perl itself has grown substantially from a "cool" scripting language used primarily by Unix system administrators to a robust object-oriented programming language that runs on practically every computing platform known to mankind.

Throughout its three editions, Learning Perl remained the same size (about 300 pages) and continued to cover much of the same material to remain compact and accessible to the beginning programmer. But there is much more to learn about Perl than there was ten years ago.

This book may be entitled Learning Perl Objects, References, and Modules, but I like to think of it as just Learning More Perl.[1] This is the book that picks up where Learning Perl leaves off. It shows how to use Perl to write larger programs.

0.1. Structure of This Book

It's a good idea to read this book from front to back, stopping to do the exercises. Each chapter builds on preceding chapters. You've been warned.

Chapter 1, Introduction: An introduction to the material.
Chapter 2, Building Larger Programs: How to bring code in from separate files so you can have others do some of your work for you.
Chapter 3, Introduction to References: How to allow the same code to operate on different data structures by introducing a level of indirection.
Chapter 4, References and Scoping: How Perl manages to keep track of pointers to data, and an introduction to anonymous data structures and autovivification.
Chapter 5, Manipulating Complex Data Structures: Viewing, searching, and storing nested arrays and hashes.
Chapter 6, Subroutine References: How to capture behavior as a value to be passed around.
Chapter 7, Practical Reference Tricks: Sorting complex operations, the "Schwartzian Transform," and working with recursively defined data.
Chapter 8, Introduction to Objects: Working with classes, method calls, inheritance, and overriding.
Chapter 9, Objects with Data: Adding per-instance data, including constructors, getters, and setters.
Chapter 10, Object Destruction: Adding behavior to an object that is going away, including object persistence.
Chapter 11, Some Advanced Object Topics: Multiple inheritance, automatic methods, and references to filehandles.
Chapter 12, Using Modules: How use works, from the user's and author's perspectives.
Chapter 13, Writing a Distribution: Packaging up a module for sharing, including portable installation instructions.
Chapter 14, Essential Testing: Providing unit and integration tests with your distribution.
Chapter 15, Contributing to CPAN: Submitting your module to the CPAN.
Appendix A, Answers to Exercises: Where to go to get answers.