POODR Chapter 6

Inheritance and Delegation

  • Compare inheritance and delegation as ways for classes to share behavior. In what way are they closely related?
  • What are the negative consequences of classes that have an instance variable (e.g. @kind_of_bike) to say what variant the class is? How do you spot that pattern. How do you remove it?
  • Can you say what the “Template Method Pattern” is?
Inheritence

  • Lets tour the code for Chapter 6 of POODR

  • Liskoff Substitution Principle (!!)

    • Google it, you will see lots of hits
    • Part of the SOLID principles of OO Design (google that too)
    • Code that works correctly with objects of class P should continue to work correcty with objects of class C (where C < P, C )
    • Or: Code that works correctly with Bicycle should work exactly the same with RoadBike or MountainBike. (Think of the Mechanic doing a “prepare bike”)