Topic 9. Inheritance, polymorphism, abstract classes, and protocols

Goal: learn to create hierarchies with consistent contracts, use super, ABC, and Protocol, process polymorphic collections, check substitutability, and explain a model with a UML diagram.

Lecture contents

1. Inheritance and polymorphism — Inheritance and base classes · Polymorphism and duck typing
2. Abstract classes and methods — Abstract classes and methods
3. super, protocols, and collection abstractions — Extending behavior with super · Protocols and structural typing · Standard collection abstractions
4. Multiple inheritance and composition — Multiple inheritance, MRO, and mixins · Composition and the substitution principle · UML, PyCharm, and testing a hierarchy

Practice and review

• Practice — 3 worked examples with complete code
• Tasks — 30 variants, each with tasks at three difficulty levels
• Summary — conclusions, self-check questions, and useful links