The well-grounded Rubyist

"The Well-Grounded Rubyist, Second Edition addresses both newcomers to Ruby as well as Ruby programmers who want to deepen their understanding of the language. This beautifully written and totally revised second edition includes coverage of features that are new in Ruby 2.1, as well as expanded and updated coverage of aspects of the language that have changed."@en
"Elegant and expressive, the Ruby programming language continues to grow in popularity as more programmers discover its strengths and just how useful it can be. Version 1.9.1 of Ruby, covered in this book, includes many new features that no Rubyist, beginning or experienced, will want to do without it. Written in a crystal-clear style, The Well-Grounded Rubyist is a tutorial for all programmers who want to learn to use Ruby effectively. It explains concepts and language features in depth. You'll learn how things work in Ruby and why they work that way. And you'll gain this understanding in the context of Ruby 1.9.1, ensuring that your grasp of the language and its features are up to date."