Inheritance vs Instantiation for Python Classes

In Python, inheritance is the capability of one class to derive or inherit the properties from another class. The class that derives properties is called the derived class or child class, and the class from which the properties are being derived is called the base class or parent class.

In other words, inheritance refers to defining a new class with little or no modification to an existing class. Following is the syntax of the inheritance -

class A:  #class A (base class)
   pass
class B(A): #class B (derived class)
   pass

In the following example, we have inherited method1() in the Derived class from the Base class -

class Base:
   def method1(self):
      print("Hello welcome to Python Tutorial")

class Derived(Base):
   def method2(self):
      print("Hello welcome to Tutorialspoint")

obj=Derived()
obj.method2() # method is defined in derived class
obj.method1() #method is defined in base class

Following is the output of the above code -

Hello welcome to Tutorialspoint
Hello welcome to Python Tutorial

Method Overriding

Method overriding is an ability of any object-oriented programming language that allows a subclass or child class to provide a specific implementation of a method that is already provided by one of its super-classes or parent classes.

When a method in a subclass has the same name, same parameters or signature, and same return type(or subtype) as a method in its super-class, then the method in the subclass is said to override the method in the super-class.

Example

In the following example, method1 is defined in both the base class and the derived class. When method1 is called using an instance of the derived class, the version in the derived class overrides the one in the base class -

class Python:      #base class
   def method1(self):
      print("Python is a programming language")
   def method2(self):
      print("Python is an interpreted language")

class Java(Python): #derived classs
   def method1(self):
      print("Java is a programming language")
   def method(self):
      print("Hello, welcome to Java Tutorial")

obj1=Java() 
obj1.method() # calling method defined in the derived class 
obj1.method1() #calling method defined in the base class(method override )

Following is the output of the above code -

Hello, welcome to Java Tutorial
Java is a programming language

Instantiation

Instantiating a class creates a copy of the class, which inherits all class variables and methods. Instantiating a class in Python is simple. To instantiate a class, we simply call the class as if it were a function, passing the arguments that the __init__ method defines. The return value will be the newly created object.

Example

Following is an example of instantiating a class -

class Foo():
   def __init__(self,x,y):
      print(x+y)
f = Foo(45,8) #instantiation

Following is the output of the above code -

53