With the increasing popularity of Python as a programming language, understanding the basics of inheritance can be an incredibly useful skill to have. Inheritance is an important concept in Python, as it allows users to define a class in terms of another class, thereby creating a hierarchical relationship between the two. This guide will take you through the steps needed to gain a basic understanding of Python inheritance, from understanding the hierarchy of inheritance to implementing inheritance in Python. You’ll learn about the different types of inheritance, and how to use them in the context of Python. By the end of this guide, you’ll have a solid grasp of how inheritance works in Python, and the confidence to use it in your programming projects.

What is Inheritance? #

Inheritance is a process where a subclass (child class) gains the properties of the superclass (parent class). The child class is said to inherit from the parent class. In other words, a class can inherit the properties of another class. This is useful when you want to reuse code from an existing class rather than rewriting it. Inheritance provides a way to extend a class and add more functionality to it without rewriting the original class. Inheriting from a class also allows you to change the behaviour of the inherited class by modifying the inherited class. In other words, when a class inherits from another, it can change and add functionality to the inherited class.

Hierarchy of Inheritance #

Inheritance is a hierarchical relationship between classes. A class inherits properties and methods from another class, forming a hierarchy of classes. Classes at the top of the hierarchy are called superclasses or parent classes, and classes at the bottom of the hierarchy are called subclasses or child classes. The hierarchical relationship between classes is illustrated in the following diagram: The letters represent classes, and the arrows represent the inheritance relationship between them. The Apple class is a superclass, and the Pear class is a subclass. The Apple class is also the superclass of the Orange class, which is a subclass of the Apple superclass. Similarly, the Pear class is both a subclass of the Apple class and a superclass of the Orange class. In a nutshell, the superclass is always above the subclasses, and the subclasses inherit properties and methods from the superclass.

Types of Inheritance #

There are three types ofinheritance in Python: single inheritance, multiple inheritance, and hierarchical inheritance. Each type of inheritance is suitable for a different type of project, and can be used in conjunction with each other in the same project. Single inheritance: In a singleinheritance scenario, a class can inherit from one other class. This is the most common type of inheritance in Python. Multiple inheritance: In a multiple inheritance scenario, a class can inherit from more than one class. This type ofinheritance is rare, and should be avoided where possible. Hierarchicalinheritance: In hierarchical inheritance, a class can inherit from another class and also have other subclasses. This type of inheritance is used when a subclass needs to inherit from multiple superclasses.

Using Inheritance in Python #

A subclass can inherit from its superclass. In this manner, a subclass gains access to the attributes and methods of its superclass. Let’s create a couple of classes to understand this better. Here’s a simple example of a superclass and subclass: The Animal class has a name attribute as well as a method called eat(). The Pet class inherits from the Animal class by including the line super(Pet, self). This line tells the Pet class that it should inherit from the Animal class. The Pet class also has its own name attribute as well as a eat() method. The Pet class can access the name attribute of the Animal class by writing the following line: self.name.

Single Inheritance #

In a single inheritance scenario, a class can inherit from one other class. This is the most common type of inheritance in Python. In a singleinheritance scenario, the superclass is responsible for defining all the attributes and methods that the subclass needs. The subclass simply needs to inherit from the superclass. Let’s understand this with a simple example.

Let’s create a base class called PowerGenerator and a subclass called GasPowerGenerator. The GasPowerGenerator class inherits from the PowerGenerator class. It’s important to understand that the GasPowerGenerator class doesn’t have a separate copy of the name attribute of the base class. The GasPowerGenerator class has access to the name attribute of the PowerGenerator class. The name attribute defined in the PowerGenerator class is available in the GasPowerGenerator class. The GasPowerGenerator class can access the name attribute of the PowerGenerator class by writing the following line: self.base_class.name.

Multiple Inheritance #

In a multiple inheritance scenario, a class can inherit from more than one class. This type ofinheritance is rare, and should be avoided where possible. However, it is possible to implement multiple inheritance in Python. If a class inherits from more than one superclass, the subclass inherits attributes and methods from both superclasses.

Let’s look at a simple example that uses multiple inheritance. The Book class and the ComputerClass class inherit from the PowerGenerator class. The Book class and the ComputerClass class inherit the name attribute from the PowerGenerator class. The name attribute of the PowerGenerator class is “PowerGenerator”. The Book class and the ComputerClass class inherit the name attribute “PowerGenerator” from the PowerGenerator class. The Book class and the ComputerClass class can access the name attribute of the PowerGenerator class by writing the following line: self.base_class.name.

Hierarchical Inheritance #

In hierarchical inheritance, a class can inherit from another class and also have other subclasses. This type ofinheritance is used when a subclass needs to inherit from multiple superclasses.

Let’s look at a simple example that uses hierarchical inheritance. The Book class inherits from the PowerGenerator class and the ComputerClass class inherits from the PowerGenerator class. The Book class and the ComputerClass class inherit the name attribute from the PowerGenerator class. The Book class and the ComputerClass class inherit the name attribute “PowerGenerator” from the PowerGenerator class. The Book class and the ComputerClass class can access the name attribute of the PowerGenerator class by writing the following line: self.base_class.name.

Multilevel Inheritance #

In a scenario where a class inherits from another class that inherits from another class, etc. (a multilevel inheritance scenario), the top-level class is called the root class. The root class can have a name, but it isn’t mandatory. The root class has no parent class, and there can’t be any class above the root class. A multilevelinheritance scenario is useful when a class needs to inherit from multiple root classes.

Let’s look at a simple example that uses multilevel inheritance. In the example above, the Hierarchy class inherits from the Base class and the Base class inherits from the Root class. The Hierarchy class and the Base class inherit the name attribute from the Root class. The Hierarchy class and the Base class can access the name attribute of the Root class by writing the following line: self.root_class.name.

Hybrid Inheritance #

Hybrid inheritance is a combination of the various types ofinheritance. The various types ofinheritance are used to create a hybridinheritance scenario. Hybrid inheritance is rare, and is usually used when a class needs to inherit from multiple root classes.

Let’s look at a simple example that uses hybrid inheritance. In the example above, the Hierarchy class inherits from the Base class, which inherits from the Root class. The Root class doesn’t have any parent class, and there can’t be any class above the Root class. The Base class is the root class of the Base class. The Hierarchy class inherits from the Base class, which inherits from the Root class. The Hierarchy class and the Base class inherit the name attribute from the Root class. The Hierarchy class and the Base class can access the name attribute of the Root class by writing the following line: self.root_class.name.

Implementing Inheritance in Python #

There are two ways in which you can implement inheritance in Python: by using a colon (:) or a dot (.).

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