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STARTING OUT WITH Python First Edition by Tony Gaddis

Chapter 10 Inheritance. STARTING OUT WITH Python First Edition by Tony Gaddis. 10.1 Introduction to Inheritance. Concept: Inheritance allows a new class to extend an existing class. The new class inherits the members of the class it extends. 10.1 Introduction to Inheritance.

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STARTING OUT WITH Python First Edition by Tony Gaddis

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  1. Chapter 10Inheritance STARTING OUT WITH PythonFirst Edition by Tony Gaddis

  2. 10.1 Introduction to Inheritance Concept: Inheritance allows a new class to extend an existing class. The new class inherits the members of the class it extends.

  3. 10.1 Introduction to Inheritance • Inheritance and the “Is a” Relationship • An “is a” relationship exists between objects. This means that the specialized object has all of the characteristics of the general object, plus additional characteristics that make it special. • A poodle is a dog • A car is a vehicle • A flower is a plant • A rectangle is a shape • A football player is an athlete

  4. 10.1 Introduction to Inheritance • Inheritance and the “Is a” Relationship • Superclass (base class)– general class • Subclass (derived class) – specialized class • Inherits attributes and methods from the superclass without any of them having to be rewritten

  5. 10.1 Introduction to Inheritance • Inheritance and the “Is a” Relationship Program 10-1 (Lines 1 through 44 of vehicles.py)

  6. 10.1 Introduction to Inheritance • Inheritance and the “Is a” Relationship Program 10-2 (Lines 45 through 72 of vehicles.py)

  7. 10.1 Introduction to Inheritance • Inheritance and the “Is a” Relationship Program 10-3 (car_demo.py)

  8. 10.1 Introduction to Inheritance • Inheritance in UML Diagrams Figure 10-2 UML diagram showing inheritance

  9. 10.2 Polymorphism Concept: Polymorphism allows subclasses to have methods with the same names as methods in their superclasses. It gives the ability for a program to call the correct method depending on the type of object that is used to call it.

  10. 10.2 Polymorphism • Polymorphism refers to an object’s ability to take different forms. • Behaviors: • The ability to define a method in a superclass, and then define a method with the same name in a subclass. When a subclass method has the same name as a superclass method, it is often said that the subclass method overrides the superclass method. • The ability to call the correct version of an overridden method, depending on the type of object that is used to call it. If a subclass object is used to call an overridden method, then the subclass’s version of the method is the one that will execute. If a superclass object is used to call an overridden method, then the superclass’s version of the method is the one that will execute.

  11. 10.2 Polymorphism Program 10-10 (polymorphism_demo.py)

  12. 10.2 Polymorphism • The isinstance Function • Is used to determine whether an object is an instance of a specific class or a subclass of that class • isinstance(object, ClassName)

  13. 10.2 Polymorphism • The isinstance Function Program 10-12 (polymorphism_demo2.py)

  14. Chapter 10Inheritance QUESTIONS ?

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