Python Polymorphism

Polymorphism plays a vital role in OOPS concepts. Based on the different scenario, same entity behaves in different forms.

Class Polymorphism

Different class have same method name which behaves based on the object type. In the below example, Car and Auto are the two different classes having same method name number_of_wheels. Based on the object type, the same function gives the different result in output

#Class Polymorphism
class Car:
    def number_of_wheels(self):
        print("I have four wheels")

class Auto:
    def number_of_wheels(self):
        print("I have three wheels")

#Number of wheels function behaves based on the object type
for vehicle in (Car(), Auto()):
    vehicle.number_of_wheels()

Output

I have four wheels
I have three wheels

Function Polymorphism

Same function which behaves differently for different scenario called as function polymorphism. Below is the simple example in python for function polymorphism

#Function polymorphism
input_list = [10, 20, 30, 40 ,50]
input_string = "Rathna Schools"
input_dict = { 1:"python", 2:"Java", 3:"Javascript" }

#Calling the len function
print(len(input_list))
print(len(input_string))
print(len(input_dict))

Output

5
14
3

Operator Overloading

In python, operator overloading can be achieved like the below example. '+' operator behaves differently for the different input data types

#Operator Overloading
# '+' operator perform addition operation for numbers
num1 = 10
num2 = 20
print(num1+num2)

# '+' operator perform concatenation for strings
word1 = "Rathna "
word2 = "Schools"
print(word1+word2)

Method Overriding

Overriding the parent method definition in their child class is called as method overriding. Below is the simple example for method overriding in python.

class Shape:
    def draw(self):
        pass

class Square(Shape):
    def draw(self):
        print("I am drawing a square")

class Circle(Shape):
    def draw(self):
        print("I am drawing a circle")

#Similar to class polymorphism but here child class methods override the parent method
for shape in (Square(), Circle()):
    shape.draw()

Output

I am drawing a square
I am drawing a circle

Method Overloading

In other programming language, we can achieve method overloading by calling the method with different number of arguments. But, its impossible in python which always consider the last definition of the method.

class Shape:
    def draw(self):
        pass

class Circle(Shape):
    def draw(self):
        print("I am drawing a circe")

    def draw(self, radius):
        print("I am drawing a circle with {}cm".format(radius))

circle = Circle()
#This method works without any issues
circle.draw(10)

#Raises Exception, since second(last) draw method overrides the first(previous) method
circle.draw()

Output

I am drawing a circle with 10cm
Traceback (most recent call last):
File "<string>", line 16, in <module>
TypeError: draw() missing 1 required positional argument: 'radius'