Refactoring in Ruby

Chapter 11. Inheritance

The relationship between a class and its subclass often starts being simple but gets more complicated over time. A subclass often depends on its parent more intimately than does a separate class, but it can go too far.

A key challenge is deciding what a class is (behaves like) versus what a class has or knows. A class structure often starts with inheritance and moves to a more compositional style over time.

In this chapter we’ll cover the following smells:

• Implementation Inheritance, in which subclassing is used purely to reuse code

• Refused Bequest, in which a subclass isn’t substitutable for its superclass

• Inappropriate Intimacy (Subclass Form), in which a subclass is tangled up in its superclass’s implementation ...