How To Make a Subclass from a Super Class In Python

In Python, you can create a subclass from a superclass using the class keyword, and by specifying the superclass in parentheses after the subclass name. The subclass inherits attributes and behaviors from the superclass, allowing you to extend or modify its functionality while reusing the existing code. This process is known as inheritance and supports the principles of object-oriented programming. In this article, we are going to learn how to make a Subclass from a Super Class in Python using three approaches.

Make a Subclass from a Super Class In Python

Below are the possible approaches to making a subclass from a superclass in Python

• Using the class keyword and super() method
• Using type.__new__ method
• Using collections.namedtuple

Subclass from a Super Class Using class keyword and super() method

In this approach, a subclass Sub is created from the superclass Base using the class keyword in Python. The subclass inherits attributes from the superclass through the super() function, enabling the reuse and extension of code.

Python3

# super class
class Base:
    # constructor to initialize attributes
    def __init__(self, name, roll, age):
        self.name = name
        self.roll = roll
        self.age = age

# sub class
class Sub(Base):
    # constructor to initialize attributes of both Base and Sub class
    def __init__(self, name, roll, age):
        super().__init__(name, roll, age)

    # method to display information
    def display(self):
        print(f" Name: {self.name}\n Roll: {self.roll}\n Age: {self.age}")

# creating an object of Sub class
obj = Sub("Sonali", 58, 24)
obj.display()

Output

 Name: Sonali
 Roll: 58
 Age: 24

Subclass From a Super Class Using type.__new__ method

In this approach, the type.__new__ method is used to create a subclass Sub from the superclass Base. The third argument, {}, can be used to provide additional attributes or methods to the subclass.

Python3

# Superclass
class Base:
    def __init__(self, name, roll, age):
        self.name = name
        self.roll = roll
        self.age = age

# Create a subclass using type.__new__
Sub = type("Sub", (Base,), {})

# Creating an object of the Subclass with data
obj = Sub("Sonali", 58, 24)

# Displaying information
print(f" Name: {obj.name}\n Roll: {obj.roll}\n Age: {obj.age}")

Output

 Name: Sonali
 Roll: 58
 Age: 24

Subclass from a Super Class Using collections.namedtuple

In this approach, a subclass Sub is created from the superclass Base using a namedtuple. The __new__ method is overridden in the subclass to include an additional attribute and an object obj is instantiated with data.

Python3

from collections import namedtuple

# Superclass using namedtuple
Base = namedtuple('Base', ['name', 'roll', 'age'])

# Subclass with additional attribute
class Sub(Base):
    def __new__(cls, name, roll, age, extra):
        obj = super(Sub, cls).__new__(cls, name, roll, age)
        obj.extra = extra
        return obj

# Creating an object of the Subclass with data
obj = Sub("Sonali", 58, 24, "Additional Info")

# Displaying information
print(f" Name: {obj.name}\n Roll: {obj.roll}\n Age: {obj.age}\n Extra: {obj.extra}")

Output

 Name: Sonali
 Roll: 58
 Age: 24
 Extra: Additional Info