I've read quite a few Ruby books and this is one of the best. The author very effectively does a number of things in this book:
i) Highlights the conceptual differences between Ruby and other currently popular languages
ii) Shows how those conceptual differences are expressed in programming constructs by walking the reader through a number of small but realistic example problems
iii) Reviews internal details of a number of pieces of real-world software (most notably Rails) to show how the authors of these packages use the techniques he describes to solve their problems
iv) Provides a number of helpful and applicable guidelines on how to 'think in Ruby'
v) Generates a GoF style catalog of implementation patterns
vi) Skewers the notion that 'metaprogramming' is any different than regular programming
After finishing this book I have a real appreciation of the techniques the author describes, and how they can be used to write flexible, powerful, and maintainable software. Before reading this book I was aware of a number of these techniques, but I didn't necessarily understand how they could be effectively used to solve real problems. Now I do. The book truly covers how to think in Ruby - how to naturally solve problems in Ruby, as opposed to adapting techniques commonly used in languages from the C/C++/Java lineage.
The one major criticism I had of Metaprogramming Ruby was the 'fanboy' tone that permeates a lot of the text. Frequently the author seems more interested in getting you to agree with him that Ruby is great than in conveying the concepts being discussed. There are a lot of gratuitous slams of other languages (especially Java) that were frankly unnecessary and distracted from the book. Had the tone of those comparisons been a little more highbrow and a little less schoolyard, this would have been a better book.
Overall rating: 4.5 stars
