Method Overriding

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What is Method Overriding?

Method overriding in Python allows a subclass (child class) to provide its own implementation of a method that is already defined in its superclass (parent class).

When a method is overridden:

• The child class version of the method is executed
• The parent class version is ignored for that object

Method overriding occurs when a child class defines a method with the same name and same parameters as a method in the parent class, and the child’s method replaces the parent’s behavior.

Why Method Overriding is Needed

Method overriding enables:

• Customization of inherited behavior
• Polymorphism in object-oriented programming
• Real-world modeling, where subclasses behave differently

Example:

• A generic phone may have a show() method
• Different brands may implement it differently

Basic Example Without Inheritance

class A:
    def show(self):
        print("in A show")

class B:
    def show(self):
        print("in B show")

obj1 = B()
obj1.show()

Output

in B show

Here, class B has its own show() method, so it is executed. However, this is method redefinition, not true overriding, because there is no inheritance.

Method Overriding Using Inheritance

Parent Class

class A:
    def show(self):
        print("in A show")

Child Class (Without Override)

class B(A):
    pass

obj = B()
obj.show()

Output

in A show

• Since B does not define show(), it inherits the method from class A.

Child Class (With Override)

class B(A):
    def show(self):
        print("in B show")

obj = B()
obj.show()

Output

in B show

• The child class method overrides the parent class method.

How Python Decides Which Method to Call?

Python determines method execution based on the actual object type, not the reference or parent class.

“The method called depends on the object created, not the class it inherits from.”

This behavior is known as runtime polymorphism.

Rules for Method Overriding

For method overriding to occur:

• Method name must be same
• Parameters must be same
• Inheritance must exist
• Method resolution happens at runtime
• The child class method takes priority

Real-World Analogy

• A student tells friends he has a Nokia phone
• Later, he gets a Motorola
• When asked again, he no longer says Nokia — he now says Motorola

The new behavior replaces the old one

Similarly:

• Parent class method → Nokia
• Child class method → Motorola
• Child method overrides parent behavior

Overriding Built-in Methods (__str__ Example)

Method overriding is also used to customize built-in methods.

Default Behavior

obj = object()
print(obj)

Shows memory address.

Overriding __str__()

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

    def __str__(self):
        return f"Student name: {self.name}"

s = Student("Navin")
print(s)

Output

Student name: Navin

• The child class overrides object.__str__() to provide meaningful output.

Method Overriding vs Method Overloading

Summary

• Method overriding allows a subclass to modify or enhance the behavior of a method inherited from its parent class.
• When a method is overridden, the child class implementation is executed, replacing the parent class version for that object.
• Python determines which method to invoke based on the actual class of the object at runtime, not the reference type.
• Method overriding is a key mechanism for achieving runtime polymorphism in Python.
• Built-in methods such as __str__(), __init__(), and others are frequently overridden to provide meaningful and customized behavior for objects.