Understanding Inheritance in Python

Python is a high-level, general-purpose programming language that makes coding simpler and more intuitive. It provides many features to enable developers to write applications in as few lines of code as possible. One of these features is inheritance, a fundamental concept in object-oriented programming (OOP). In this tutorial, we will dissect the concept of inheritance in Python, touching on topics appropriate for both beginners and experienced Python enthusiasts.

Table of Contents

1. Introduction to Inheritance
2. Types of Inheritance in Python
3. Syntax of Inheritance in Python
4. Use Cases of Inheritance
5. Python super() Function
6. Method Overloading and Overriding
7. Python Inheritance & Examples

1. Introduction to Inheritance

Inheritance is a critical pillar of OOP that facilitates code reusability. Instead of writing new code for each distinct type of object, you can create a general object that can be inherited by other more specialized objects, adding or overwriting as needed.

In Python, inheritance process involves:

• A parent (or base) class
• A child (or derived) class, which inherits from the parent class

This mechanism provides functionally to the child class without rewriting existing code in the parent class. The child class inherits all the features from the parent class, and it can provide additional features or behaviors as needed.

Consider an example of a general class called Bird. This class defines attributes common to all birds, such as the ability to fly and to lay eggs. Now, we can create more specific classes like Penguin and Eagle, which inherit from Bird and add or override attributes as necessary.

2. Types of Inheritance in Python

Python supports multiple forms of inheritance, including:

1. Single Inheritance: One parent class and one child class.
2. Multiple Inheritance: One child class inherits from more than one parent class.
3. Multilevel Inheritance: A child class becomes a parent class for another child class forming a chain of inheritance.
4. Hierarchical Inheritance: One parent class is inherited by multiple child classes.
5. Hybrid Inheritance: A combination of multiple and multilevel inheritance.

3. Syntax of Inheritance in Python

The syntax in Python to implement inheritance is quite straightforward. Here is the basic format:

class ParentClass:
    # body of parent class

class ChildClass(ParentClass):
    # body of child class

In the above syntax, ChildClass is the derived class, which is inheriting from ParentClass, the base class.

4. Use Cases of Inheritance

The most significant benefits of inheritance are code reusability and the ability to improve productivity. Here are a few examples where inheritance comes in handy:

• Organizing code: Inheritance enables you to structure code in a hierarchical manner.
• Extending functionality: Child classes can add functionalities beyond those of the parent class.
• Overwriting functionality: Child classes can override methods in their parent class.

5. Python super() Function

The Python super() function allows us to call a method from the parent class. This can be useful when you want to extend the functionality of a parent method without completely overriding it.

class ParentClass:
    def some_method(self):
        # do something

class ChildClass(ParentClass):
    def some_method(self):
        super().some_method()
        # do something else

6. Method Overloading and Overriding

Python implements method overloading and overriding, concepts related to inheritance.

Method Overloading: In Python, method overloading refers to the ability to define a method in the child class that behaves differently from the one in the parent class, depending on the parameters.

Method Overriding: Method overriding occurs when a child class provides a different implementation of a method already present in its parent class.

7. Python Inheritance & Examples

Now that we grasp the theory behind inheritance, it’s time we put that into practice with a couple of Python examples.

Example 1: Single Inheritance

# Parent class
class Bird:
    def __init__(self):
        print("Bird is ready")

    def whoisThis(self):
        print("Bird")

    def swim(self):
        print("Swim faster")

# Child class
class Penguin(Bird):
    def __init__(self):
        super().__init__()
        print("Penguin is ready")

    def whoisThis(self):
        print("Penguin")

    def run(self):
        print("Run faster")

peggy = Penguin()
peggy.whoisThis()
peggy.swim()
peggy.run()

In the above example, the Penguin class makes use of the super() function to call the __init__() method of the Bird class, instead of overriding entirely.

Example 2: Multiple Inheritance

class Class1:
    def m(self):
        print("In Class1")

class Class2(Class1):
    def m(self):
        print("In Class2")

class Class3(Class1):
    def m(self):
        print("In Class3")

class Class4(Class2, Class3):
    pass

obj = Class4()
obj.m()

In multiple inheritance, Python starts looking for methods from left to right in the parent classes. Therefore, in this case, it executes Class2’s m().

Inheritance makes it possible to create complex real-world objects without rewriting code. Both new and experienced Python developers make use of this powerful feature to increase readability and reduce the amount of code written. Inheritance is an essential tool to have in your Python toolkit, and mastering it will elevate your Python skills to a new level.