Review: Design Patterns in Ruby

Posted by Jonathan

Design Patterns in Ruby by Russ Olsen is an introduction to Design Patterns. It covers 14 out of the 23 patterns of the GoF Design Patters: Elements of Reusable Object-Oriented Software book and adds three Ruby-related patterns. The book examines each pattern in general, shows how it applies to a dynamic language like Ruby and explains when to use or not use the pattern.

The fact that the book is written in an informal style with lots of examples makes it really easy to read and follow. I really liked the format of the pattern examination and find it an excellent overview of and introduction to Design Patterns. The covered GoF patterns (Template Method, Strategy, Observer, Composite, Iterator, Command, Adapter, Proxy, Decorator, Singleton, Factory Method, Abstract Factory Method, Builder, and Interpreter) are the most important ones and are easy to apply in Ruby. Especially the chapter on Interpreter made a very good job of explaining a widely under-utilized pattern. It even showed how to build a parser and didn't stop at the AST.

Apart from those classic patterns, the book introduces Internal Domain-Specific Languages, Meta-Programming, and Convention Over Configuration as newer patterns that are closely related to dynamic languages like Ruby. Those chapters cover nothing new to Rails programmers but are a nice addition to a general Ruby Patterns book. In my opinion the discussion of Meta-Programming could be a bit longer as it only covers class_eval and Ruby has more to offer.

In general, Design Patterns in Ruby is a very good overview of Design Patterns in the modern, dynamic world of Ruby. The book makes sure that the reader understands where a pattern arises and is very good in explaining its usage by example. Further, I cannot praise enough the fact that the author also tells you when NOT to use a pattern and warns about over-usage of inheritance or patterns.

With 338 pages of informal, easy to read examples and explanations, the book is easy to read in two or three afternoons. If you look for an introduction to Design Patterns or want to know how they apply in Ruby, I really recommend Design Patterns in Ruby.

Comments

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  1. Tim – February 05, 2008 @ 01:59 PM

    I have read an article recently that Ruby is “dead”. Any thoughts on this? But they are coming up with a more improved one instead. I think though that people are only starting to get used to Ruby. No need for change now.

  2. Jonathan – February 05, 2008 @ 03:11 PM

    I don’t think that ruby is dead, I think that dynamic languages like Ruby are just starting to become mainstream. What needs to improve in Ruby is the platform and there several projects that try to accomplish this (JRuby, Rubinius, IronRuby, ...).

  3. Markus Jais – February 05, 2008 @ 07:34 PM

    Thanks for this review. I hope I’ll be able to read this book soon. Something like this has been missing for Ruby for a long time.

  4. Estela – February 06, 2008 @ 09:14 AM

    A technical book like this should really be written in an informal and friendly language. Non-technical people or individuals who find it difficult to follow technical instruction appreciate that. They don’t feel alienated. Thanks for sharing this.