Ways of implementing Polymorphism in Python

In Python programming, Polymorphism is a concept of Object-Oriented Programming in Python. It enables using a single interface with the input of different data types, different classes, or maybe for a different number of inputs.

Example

In this case, the function len() is polymorphic as it is taking a string as input in the first case and is taking a list as input in the second case.

Python3

# length of string
x = len('Geeks')
print(x)

# length of list
y = len([1, 2, 3, 4])
print(y)

Output:

5
4

In Python, Polymorphism is a way of making a function accept objects of different classes if they behave similarly.

Different Ways to Implement Polymorphism in Python

What is Duck Typing in Python

Duck typing is a concept that says that the “type” of the object is a matter of concern only at runtime and you don’t need to explicitly mention the type of the object before you perform any kind of operation on that object, unlike normal typing where the suitability of an object is determined by its type.

In Python, we have the concept of Dynamic typing i.e. we can mention the type of variable/object later. The idea is that you don’t need a type in order to invoke an existing method on an object if a method is defined on it, you can invoke it.

Python3

class GFGCoder:
    def execute(self):
        print("Geeks are working on the code...")

class Geeks:
    def code(self, executor):
        executor.execute()

# Create instances of the classes
executor = GFGCoder()
ide = Geeks()

# Call the code method using the IDE instance
ide.code(executor)

Output:

Geeks are working on the code...

Method Overloading in Python

By default, Python does not support method overloading, but we can achieve it by modifying our methods. Given a single function sum (), the number of parameters can be specified by you. This process of calling the same method in different ways is called method overloading.

Concept of Method Overloading 

Python3

class GFG:
    def sum(self, a = None, b = None, c = None):
        s = 0
        if a != None and b != None and c != None:
            s = a + b + c
        elif a != None and b != None:
            s = a + b
        else:
            s = a
        return s

s = GFG()

# sum of 1 integer
print(s.sum(1))

# sum of 2 integers
print(s.sum(3, 5))

# sum of 3 integers
print(s.sum(1, 2, 3))

Output:

1
8
6

Python Operator Overloading

Operator overloading in Python is the ability of a single operator to perform more than one operation based on the class (type) of operands. So, basically defining methods for operators is known as operator overloading. For e.g: To use the + operator with custom objects you need to define a method called __add__.

 We know the + operator is used for adding numbers and at the same time to concatenate strings. It is possible because the + operator is overloaded by both int class and str class. The operators are actually methods defined in respective classes. 

So if you want to use the + operator to add two objects of some user-defined class then you will have to define that behavior yourself and inform Python about that.

Python3

class Student:
    def __init__(self, m1, m2):
        self.m1 = m1
        self.m2 = m2

S1 = Student (58, 60)
S2 = Student (60, 58)

# this will generate an error
S3 = S1 + S2

Output:

TypeError: unsupported operand type(s) for +: 'Student' and 'Student'

So we can see that the + operator is not supported in a user-defined class. But we can do the same by overloading the + operator for our class.

Python3

class Student:

    # defining init method for class
    def __init__(self, m1, m2):
        self.m1 = m1
        self.m2 = m2

    # overloading the + operator
    def __add__(self, other):
        m1 = self.m1 + other.m1
        m2 = self.m2 + other.m2
        s3 = Student(m1, m2)
        return s3

s1 = Student(58, 59)
s2 = Student(60, 65)
s3 = s1 + s2
print(s3.m1)

Output:

118

Method Overriding in Python

By using method overriding a class may “copy” another class, avoiding duplicated code, and at the same time enhance or customize a part of it. Method overriding is thus a part of the inheritance mechanism.

In Python, method overriding occurs by simply defining the child class in a method with the same name as a method in the parent class.

Python3

# parent class
class Programming:

    # properties
    DataStructures = True
    Algorithms = True

    # function practice
    def practice(self):
        print("Practice makes a man perfect")

    # function consistency
    def consistency(self):
        print("Hard work along with consistency can defeat Talent")

# child class
class Python(Programming):

    # function
    def consistency(self):
        print("Hard work along with consistency can defeat Talent.")

Py = Python()
Py.consistency()
Py.practice()

Output:

Hard work along with consistency can defeat Talent.
Practice makes a man perfect