Inheritance basics

Learn inheritance with class Child(Parent).

Inheritance

Inheritance is when a class takes on the attributes and methods of another class. The child class writes the parent class name in parentheses.

Example: class Dog(Animal): pass. Here Dog is the child, Animal is the parent. Dog inherits all methods of Animal. The parent class must be defined first. Inheritance reduces code duplication.

Parent first

To inherit, the parent class must be defined before the child. Python reads top to bottom; writing an undefined name in parentheses raises a NameError.

Example: first class Animal: pass, then class Dog(Animal): pass. The child can access all public attributes and methods of the parent. You can also add new methods to the child; this gives the child specific behavior.

Exercise Make Dog inherit from Animal

First define the Animal class; add a method def speak(self): and write print("Sound") in the body. Then define the child class with class Dog(Animal): pass. Finally create an instance with d = Dog() and call d.speak().

Show example solution

# Define the Animal and Dog classes
class Animal:
    def speak(self):
        print("Sound")

class Dog(Animal):
    pass

d = Dog()
d.speak()

Test yourself

Which is a valid inheritance definition?
- class Dog -> Animal: pass
- class Dog extends Animal: pass
- class Dog(Animal): pass
- class Dog: Animal: pass
Show answer

class Dog(Animal): pass — In Python inheritance is written as class Child(Parent):.

Complete the inheritance definition

class Dog(____):
    pass

Show answer

class Dog(Animal):
    pass

Match the inheritance parts

Dog

Child class
Animal

Parent class
()

Parentheses

Next lesson: super()

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