Introduction to Inheritance

Imagine you’re building a family of classes where some share similar properties or actions. Instead of writing the same code again and again, inheritance allows you to reuse and extend existing classes.

• A parent class (also called a base class) contains common functionality.
• A child class (also called a subclass) inherits this functionality but can also have its own unique features.

It’s like inheriting traits from your parents, but you can still have your own personality!

Why use inheritance?

• Reusability: Avoid rewriting the same code for similar classes.
• Organization: Group related classes together in a logical way.
• Flexibility: Add or override features in the child class without changing the parent class.

How does inheritance work in Python?

Parent class

This is the class that contains the shared functionality.

class Animal:
    def __init__(self, name):
        self.name = name

    def speak(self):
        return "I make a sound"

Child class

This is the class that inherits from the parent class. It can use all the parent’s methods and attributes, and it can also define its own.

class Dog(Animal):  # Inheriting from Animal
    def speak(self):
        return "Woof!"

class Cat(Animal):  # Inheriting from Animal
    def speak(self):
        return "Meow!"

Using the classes

dog = Dog("Buddy")
print(dog.name)        # Output: Buddy (inherited from Animal)
print(dog.speak())     # Output: Woof! (overrides Animal's speak)

cat = Cat("Luna")
print(cat.name)        # Output: Luna (inherited from Animal)
print(cat.speak())     # Output: Meow! (overrides Animal's speak)

What is the super() Function?

The super() function is used to call methods from the parent class. This is helpful when the child class needs to extend the functionality of the parent class rather than completely overriding it. For example:

Let’s say all animals have a name, but dogs also have a breed.

class Animal:
    def __init__(self, name):
        self.name = name

class Dog(Animal):
    def __init__(self, name, breed):
        # Call the parent class's __init__ method
        super().__init__(name)
        self.breed = breed

Here, super().__init__(name) calls the parent’s __init__ method so we don’t have to rewrite the logic for setting name.

Using it:

dog = Dog("Buddy", "Golden Retriever")
print(dog.name)   # Output: Buddy (from parent class)
print(dog.breed)  # Output: Golden Retriever (defined in Dog class)