Inheritance basics
- Python course
- Intermediate
- Lesson 7/116
- 5 min
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.
Practice 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().
Starter code
# Define the Animal and Dog classesSample solution
# Define the Animal and Dog classes
class Animal:
def speak(self):
print("Sound")
class Dog(Animal):
pass
d = Dog()
d.speak()Expected output
Sound
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Which is a valid inheritance definition?
- class Dog -> Animal: pass
- class Dog extends Animal: pass
- class Dog(Animal): pass Correct answer
- class Dog: Animal: pass
Explanation: In Python inheritance is written as class Child(Parent):.
2 Complete the inheritance definition
class Dog(____):
passclass Dog(Animal):
passExplanation: Dog inherits from Animal.
3 Match the inheritance parts
| Term | Meaning |
|---|---|
Dog |
Child class |
Animal |
Parent class |
() |
Parentheses |