Python Inheritance

Tutorial on Python Inheritance

Welcome to codeswithpankaj.com! In this tutorial, we will dive deep into the concept of inheritance in Python. We'll explore what inheritance is, its types, and how to implement it in Python with detailed explanations and examples.

Table of Contents

1. Introduction to Inheritance

2. Benefits of Inheritance

3. Types of Inheritance

   • Single Inheritance

   • Multiple Inheritance

   • Multilevel Inheritance

   • Hierarchical Inheritance

   • Hybrid Inheritance

4. Base and Derived Classes

5. Method Overriding

6. The super() Function

7. Inheritance and __init__ Method

8. Practical Examples

9. Summary

1. Introduction to Inheritance

What is Inheritance?

Inheritance is a fundamental concept in object-oriented programming that allows a class to inherit attributes and methods from another class. The class that inherits is called the derived class or child class, while the class being inherited from is called the base class or parent class.

Why Use Inheritance?

• Code Reusability: Inheritance promotes code reuse by allowing new classes to use the properties and methods of existing classes.

• Maintainability: It helps in maintaining the code by minimizing redundancy.

• Extensibility: New functionality can be easily added to an existing class without modifying it.

2. Benefits of Inheritance

• Reusability: You can reuse code from the base class in the derived class.

• Improved Code Organization: It helps in organizing code into a hierarchical structure.

• Polymorphism: Inheritance allows for polymorphic behavior, where a method can have different implementations in different classes.

3. Types of Inheritance

Single Inheritance

Single inheritance involves a single base class and a single derived class.

class Animal:
    def speak(self):
        print("Animal speaks")

class Dog(Animal):
    def bark(self):
        print("Dog barks")

dog = Dog()
dog.speak()
dog.bark()

Multiple Inheritance

Multiple inheritance involves multiple base classes and a single derived class.

class Mammal:
    def has_fur(self):
        print("Has fur")

class Bird:
    def has_feathers(self):
        print("Has feathers")

class Bat(Mammal, Bird):
    def fly(self):
        print("Can fly")

bat = Bat()
bat.has_fur()
bat.has_feathers()
bat.fly()

Multilevel Inheritance

Multilevel inheritance involves a chain of inheritance.

class Animal:
    def speak(self):
        print("Animal speaks")

class Dog(Animal):
    def bark(self):
        print("Dog barks")

class Puppy(Dog):
    def weep(self):
        print("Puppy weeps")

puppy = Puppy()
puppy.speak()
puppy.bark()
puppy.weep()

Hierarchical Inheritance

Hierarchical inheritance involves multiple derived classes inheriting from a single base class.

class Animal:
    def speak(self):
        print("Animal speaks")

class Dog(Animal):
    def bark(self):
        print("Dog barks")

class Cat(Animal):
    def meow(self):
        print("Cat meows")

dog = Dog()
cat = Cat()
dog.speak()
dog.bark()
cat.speak()
cat.meow()

Hybrid Inheritance

Hybrid inheritance is a combination of two or more types of inheritance.

class Engine:
    def start(self):
        print("Engine starts")

class ElectricEngine(Engine):
    def charge(self):
        print("Charging...")

class Car(Engine):
    def drive(self):
        print("Car drives")

class HybridCar(Car, ElectricEngine):
    def eco_mode(self):
        print("Eco mode enabled")

hybrid_car = HybridCar()
hybrid_car.start()
hybrid_car.charge()
hybrid_car.drive()
hybrid_car.eco_mode()

4. Base and Derived Classes

Base Class

The base class is the class being inherited from.

class Base:
    def base_method(self):
        print("Base method")

Derived Class

The derived class inherits from the base class.

class Derived(Base):
    def derived_method(self):
        print("Derived method")

obj = Derived()
obj.base_method()
obj.derived_method()

5. Method Overriding

Method overriding allows a derived class to provide a specific implementation of a method that is already defined in its base class.

class Animal:
    def speak(self):
        print("Animal speaks")

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

dog = Dog()
dog.speak()  # Output: Dog barks

6. The super() Function

The super() function is used to call a method from the base class.

class Animal:
    def speak(self):
        print("Animal speaks")

class Dog(Animal):
    def speak(self):
        super().speak()
        print("Dog barks")

dog = Dog()
dog.speak()

7. Inheritance and __init__ Method

When you initialize an instance of a derived class, the __init__ method of the base class is not called automatically. You must call it explicitly.

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

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

dog = Dog("Buddy", "Golden Retriever")
print(dog.name)
print(dog.breed)

8. Practical Examples

Example 1: Inheritance in Real Life

class Vehicle:
    def __init__(self, make, model):
        self.make = make
        self.model = model

    def display_info(self):
        print(f"Vehicle Make: {self.make}, Model: {self.model}")

class Car(Vehicle):
    def __init__(self, make, model, doors):
        super().__init__(make, model)
        self.doors = doors

    def display_info(self):
        super().display_info()
        print(f"Number of doors: {self.doors}")

car = Car("Toyota", "Corolla", 4)
car.display_info()

Example 2: Polymorphism with Inheritance

class Animal:
    def speak(self):
        pass

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

class Cat(Animal):
    def speak(self):
        print("Cat meows")

def make_animal_speak(animal):
    animal.speak()

dog = Dog()
cat = Cat()

make_animal_speak(dog)
make_animal_speak(cat)

9. Summary

In this tutorial, we covered the concept of inheritance in Python, its benefits, and different types. We also explored method overriding, the super() function, and practical examples to understand inheritance better. With inheritance, you can create more organized, maintainable, and reusable code.

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