Programming Ruby 1.9 The Pragmatic Programmers’ guide

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