Ruby Cookbook, 2nd Edition

Chapter 1. Ruby 2.1

When the first edition of Ruby Cookbook was published in 2006, Ruby 1.8.4 was the state of the art and Rails had just reached 1.0. Eight years and more than 100 stable releases later, the latest version is now Ruby 2.1.1 and Rails has just reached 4.1.0. Over the last eight years, a lot has changed, both big and small:

• A bytecode interpreter replaced the old Ruby MRI.

• RubyGems and Rake became part of the standard library.

• SOAP and Curses have moved out of the standard library into RubyGems.

• New syntax primitives have been added for hashes, procs, and more.

• New methods like Object#tap and String#prepend have been added.

• New classes like BasicObject, Fiber, and TracePoint have been added.

• The MD5 standard library was renamed Digest::MD5.

• And much more…

The end result is a cleaner language that runs faster and more efficiently than ever before. For example, a simple Rails application is 167–200% faster in Ruby 2.1 than 1.8.

For all that has changed, there is thankfully very little that has been broken in terms of backward compatibility. The vast majority of code written for Ruby 1.8 will work in Ruby 2.1 without any modifications. However, and somewhat obviously, if you write code for Ruby 2.1, it will likely not work in Ruby 1.8 with some of the syntax changes introduced.

In between Ruby 1.8 and 2.1 were two other major releases: 1.9 and 2.0. In this chapter, we will group all the changes from versions 1.9 through 2.1 together instead of pointing ...