Dave Thomas - Programming Ruby 1.9 & 2.0: The Pragmatic Programmers Guide

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I wrote forewords to the previous two editions of this book. For the first edition, I wrote about motivation. For the second edition, I wrote about miracles.

For this third edition, Id like to write about courage. I always admire brave people. People around Ruby seem to be brave, like the authors of this book. They were brave to jump in to a relatively unknown language like Ruby. They were brave to try new technology. They could have happily stayed with an old technology, but they didnt. They built their own world using new bricks and mortar. They were adventurers, explorers, and pioneers. By their effort, we have a fruitful resultRuby.

Now, I feel that Ive created my own universe with help from those brave people. At first, I thought it was a miniature universe, like the one in Fessendens Worlds. But now it seems like a real universe. Countless brave people are now working with Ruby. They challenge new things every day, trying to make the world better and bigger. I am very glad I am part of the Ruby world.

I suppose that even the world itself could not contain the books that should be written. But now we have the first book, updated to the most recent. Enjoy.

This book is a new version of the PickAxe, as Programming Ruby is known to Ruby programmers. It is a tutorial and reference for versions 1.9 and 2.0 of the Ruby programming language.

Ruby 1.9 was a significant departure from previous versions. There are major changes in string handling, the scoping of block variables, and the threading model. It has a new virtual machine. The built-in libraries have grown, adding many hundreds of new methods and almost a dozen new classes. The language now supports scores of character encodings, making Ruby one of the only programming languages to live fully in the whole world.

Ruby 2.0 is a (fairly minor) incremental improvement on Ruby 1.9.

When Andy and I wrote the first edition, we had to explain the background and appeal of Ruby. Among other things, we wrote, When we discovered Ruby, we realized that wed found what wed been looking for. More than any other language with which we have worked, Ruby stays out of your way . You can concentrate on solving the problem at hand, instead of struggling with compiler and language issues. Thats how it can help you become a better programmer: by giving you the chance to spend your time creating solutions for your users, not for the compiler.

That belief is even stronger today. More than thirteen years later, Ruby is still my language of choice: I use it for client applications and web applications. I use it to run our publishing business (our online store, http://pragprog.com , is more than 40,000 lines of Rails code), and I use it for all those little programming jobs I do just to get things running smoothly.

In all those years, Ruby has progressed nicely. A large number of methods have been added to the built-in classes and modules, and the size of the standard library (those libraries included in the Ruby distribution) has grown tremendously. The community now has a standard documentation system (RDoc), and RubyGems has become the system of choice for packaging Ruby code for distribution. We have a best-of-breed web application framework, Ruby on Rails, with others waiting in the wings. We are leading the world when it comes to testing, with tools such as RSpec and Cucumber, and were working through the hard problems of packaging and dependency management. Weve matured nicely.

But Ruby is older than that. The first release of this book happened on Rubys 20th birthday (it was created on February 24, 1993). The release of Ruby 2.0 is a celebration of that anniversary.

This version of the PickAxe documents both Ruby 2.0 and Ruby 1.9.3.

Exactly what version of Ruby did I use to write this book? Lets ask Ruby:

This illustrates an important point. Most of the code samples you see in this book are actually executed each time I format the book. When you see some output from a program, that output was produced by running the code and inserting the results into the book.

Throughout the book Ive tried to mark differences between Ruby 1.9 and 2.0 using a small symbol, like the one here 2.0 . If youre reading this as an ebook, youll see little arrows next to this flag. Clicking those will take you to the next or previous 2.0 change. One change I didnt make: I decided to continue to use the word we when talking about the authors in the body of the book. Many of the words come from the first edition, and I certainly dont want to claim any credit for Andys work on that book.

Compared to the major change that occurred between Ruby 1.8 and Ruby 1.9, the update to Ruby 2 is fairly gentle. This book documents all the updated builtin class changes and the new keyword arguments. It spends some time looking at lazy enumerators, and at the updates to the regular expression engine. But, in general, users of Ruby 1.9 will feel right at home, and folks still using Ruby 1.8 should consider skipping straight to Ruby 2.

Visit the Ruby website at ).

And Id certainly appreciate hearing from you. Comments, suggestions, errors in the text, and problems in the examples are all welcome. Email us at rubybook@pragprog.com.

If you find errors in the book, you can add them to the errata page. If youre reading the PDF version of the book, you can also report an erratum by clicking the link in the page footers.

Youll find links to the source code for almost all the books example code at http://www.pragprog.com/titles/ruby4 .