Polymorphism in Python (With Example)

 Polymorphism 

               Polymorphism refers to having several different forms . It allows programmers to assign different meanings to a variable ,objects or method with the same name . Polymorphism is one of the important features of OOP. In python Polymorphism is simply means defining a number of subclass that have methods of the same name .

Types Of Polymorphism :

In Python there are different ways to provide Polymorphism like Method Overloading and  Operator Overloading also Method Overriding .

Method Overloading : 

      Method Overloading means having a method of same name but different numbers 

arguments. In other programming language like JAVA it support Method overloading 

directly . and compiler overload Method in which number of argument is same as passed

arguments .But python doesn't support Method overloading directly . so to use Method

overloading in python we have to use a concept called as default argument 

EXAMPLE : 

class calculation:    def add(self, a=None ,b=None ,c=None):        if a!=None and b!=None and c!=None :          d= a +b +c          print(d)        elif a!=None and b!=None:            d= a+ b            print(d)        else :            d=a            print(d) obj=calculation() obj.add(5,6,7) obj.add(5,6) obj.add(5) Output : 18 11 5

  In above example we can pass different number of argument for same method  and getting 

expected Output .in this way we can implement Method overloading in Python .

NOTE	None in python is similar to null in c++ and java

Method Overriding :

         Method overriding is Nothing but having two methods with same name and same number

of argument . A same class cannot have two methods of same name and same number of 

argument  so here we have to use a concept of Inheritance .a subclass can have a Method like

 that .

Example :

class greeting:    def show(self):        print("Hello") class greet(greeting):     def show(self):         print("good morning") obj =greet() obj.show() Output : good Morning

 In above example we have two classes in which greet inherits greeting .in both class we 

have method show but compiler is calling subclass method this what method overriding 

means. method of superclass is overridden by subclass method . but if we don't have that

method in subclass  . then the compiler will print super class method .

class greeting:    def show(self):        print("Hello") class greet(greeting):    pass  #no statements obj =greet() obj.show() Output : Hello

Operator Overloading :

   Like Method overloading operator overloading also a form of compile time polymorphism 

In operator overloading different operators have different implementation depending on their 

argument .with operator overloading a programmer is allow to provide his own definition for

an operator by overloading Built in data type .

Example : 

Program to overload + operator on a complex object .

class Complex :

   def __init__(self):

       self.r=0

       self.i=0

   def set(self,r,i):

       self.r=r

       self.i=i

   def __add__(self, C):

       obj = Complex()

       obj.r=self.r+C.r

       obj.i=self.i+C.i

       return obj

   def display (self):

    print("(",self.r,"+",self.i,"i)")

obj1=Complex()

obj1.set(5,9)

obj2=Complex()

obj2.set(2,2)

obj3=Complex()

obj3=obj1+obj2

obj3.display()




Output 7+11i

In above program we use " + " operator to add obj1 and obj 2, we had define __add__()

Method which overload the inbuilt add operator .

We can also overload other operators but for that we must know function name for that 

Operator which are given below 

           

Operator	Function name	Operator	Function name
+            -            *           /          **          %           >>           &            l                      ^           <<	__add__ __sub__ __mul__ __truediv__ __pow__ __mod__ __rshift__ __and__ __or__ __xor__ __lshift__	=+         -=         *=         /=         **=         %=         >>=          &=            l=                      ^=           <<=	__iadd__ __isub__ __imul__ __itruediv__ __ipow__ __imod__ __irshift__ __iand__ __ior__ __ixor__ __ilshift__