Practical Object-Oriented Design in Ruby by Sandi Metz Don't worry about the "in Ruby" part, it's just as good even if you know nothing of Ruby. I enjoyed it a

Practical Object-Oriented Design in Ruby by Sandi Metz Don't worry about the "in Ruby" part, it's just as good even if you know nothing of Ruby. I enjoyed it and have never written a line of Ruby in my life :)