s4u.md

How to Use Mixins and Modules in Your Ruby on Rails Application
Rails Concerns: To Concern Or Not To Concern
The Inherited Hook Method in Ruby - and More Parenting Lessons
Up the Ancestor Chain with method_missing
Unraveling Classes, Instances and Metaclasses in Ruby
Closures in Ruby: Blocks, Procs and Lambdas
Changing the Way Ruby Creates Objects

Ruby's redo, retry and next keywords
Ensuring execution, retrying failures and reraising exceptions in Ruby

Responsible Monkeypatching in Ruby
An Introduction to Pattern Matching in Ruby
Ruby's magical Enumerable module

Inside Enumeration in Ruby
Object Marshalling in Ruby
Diving into Ruby's #dup and #clone
The Magic of Class-level Instance Variables

s4u2.md

Порядок выполнения callback-ов при наследовании
Ghost Methods в Ruby (перевод)