Method overriding

Learn to override methods in derived classes.

Method overriding

Overriding is when a child class redefines a parent method with the same name. When an instance of the child calls the method, the child version runs.

Example: class Animal:\n def speak(self):\n print("Sound") and class Dog(Animal):\n def speak(self):\n print("Woof"). The call d = Dog(); d.speak() prints Woof. The parent version is hidden but can still be called via super().speak().

Child first

When you call a method, Python looks at the child first; if not found, it goes up to the parent. So a same-name method in the child replaces the parent's.

Example: if Dog has speak, d.speak() calls it. A method not in Dog (e.g. sleep) is searched in the parent. This mechanism is called method resolution; the order matters in multiple inheritance.

Exercise Override with Dog.speak

First define the Animal class; add def speak(self): and in the body write print("Sound"). Then define class Dog(Animal):; add def speak(self): and in the body write print("Woof"). Then call d = Dog() and d.speak().

Show example solution

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

class Dog(Animal):
    def speak(self):
        print("Woof")

d = Dog()
d.speak()

Test yourself

Match the override concepts

Animal.speak

Parent method
Dog.speak

Child method
d.speak()

Child version runs
What does overriding mean?
- A child class redefining a parent method
- To call the parent method
- To delete a method
- To merge two methods
Show answer

A child class redefining a parent method — Overriding is the child redefining a method with the same name.

Complete the override body

class Dog(Animal):
    def speak(self):
        print(____)

Show answer

class Dog(Animal):
    def speak(self):
        print("Woof")

Next lesson: Multiple inheritance

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