A review by afuerstenau
Practical Object-Oriented Design in Ruby: An Agile Primer by Sandi Metz

5.0

tldr;
Awesome book, read it if you are interested in ruby and/or OOD!

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Great examples, not too complicated but also not too simple. One consistent domain (bicycles) to explain the different concepts. Good distribution between theory and the practical examples.
I learned a lot about when to use classes and when to use modules.