Polymorphism in Python

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Polymorphism in Python

Polymorphism is an important concept in Object-Oriented Programming (OOP) that allows one interface to be used for different data types or objects.

In simple terms: Polymorphism allows different classes to implement the same method name differently.

Why Use Polymorphism?

Basic Example of Polymorphism

class Dog:
    def speak(self):
        print("Woof!")
 
class Cat:
    def speak(self):
        print("Meow!")
 
def animal_sound(animal):
    animal.speak()
 
dog1 = Dog()
cat1 = Cat()
 
animal_sound(dog1)
animal_sound(cat1)

Woof!
Meow!

Explanation: Both Dog and Cat implement speak() method — same interface, different behavior.

Types of Polymorphism in Python

Example 1: Method Overriding

class Vehicle:
    def move(self):
        print("Vehicle is moving.")
 
class Car(Vehicle):
    def move(self):
        print("Car is driving on road.")
 
class Boat(Vehicle):
    def move(self):
        print("Boat is sailing on water.")
 
v1 = Vehicle()
c1 = Car()
b1 = Boat()
 
v1.move()
c1.move()
b1.move()

Vehicle is moving.
Car is driving on road.
Boat is sailing on water.

Example 2: Built-in Polymorphism (len function)

print(len("Hello"))          # String
print(len([1, 2, 3, 4]))     # List
print(len((10, 20, 30)))     # Tuple

5
4
3

Explanation: len() behaves differently based on the data type — built-in polymorphism.

Example 3: Polymorphism with Functions

class Circle:
    def area(self):
        print("Calculating area of circle...")
 
class Square:
    def area(self):
        print("Calculating area of square...")
 
def print_area(shape):
    shape.area()
 
c = Circle()
s = Square()
 
print_area(c)
print_area(s)

Calculating area of circle...
Calculating area of square...

Example 4: Polymorphism with Class Inheritance

class Bird:
    def fly(self):
        print("Bird is flying.")
 
class Sparrow(Bird):
    def fly(self):
        print("Sparrow flies at low altitude.")
 
class Eagle(Bird):
    def fly(self):
        print("Eagle flies high in the sky.")
 
birds = [Bird(), Sparrow(), Eagle()]
for b in birds:
    b.fly()

Bird is flying.
Sparrow flies at low altitude.
Eagle flies high in the sky.

Example 5: Polymorphism in Operator Overloading

print(3 + 5)          # integers
print("Hello " + "World")  # strings
print([1, 2] + [3, 4])    # lists

8
Hello World
[1, 2, 3, 4]

Explanation: The + operator behaves differently based on operand types — operator overloading.

Key Points

Polymorphism enables flexibility — same method name, different behavior Achieved via method overriding and duck typing Built-in functions (len, +, print) are examples of polymorphism Helps write clean, extensible, and maintainable code

Summary

• Polymorphism allows different objects to respond to the same method call in different ways.
• Supports dynamic behavior — actual method called depends on the object.
• Leads to cleaner, more flexible designs.
• Combined with inheritance, it is a key pillar of OOP.

Next, we will explore Dunder Methods (__str__, __repr__) — powerful special methods that allow classes to behave like built-in types.