Polymorphism

Polymorphism:

• the concept of defining multiple functionalities/logic's to perform one operation is known as a polymorphism.

• poly means -----> many

• morphism means ------> forms ( functionalities/logic's)

Polymorphism can be implemented in two ways,they are

• method overloading ( static polymorphism )

• method overriding ( dynamic polymorphism )

Method Overloading:

• concept of defining multiple methods with same name with different number.of parameters is known as a method overloading or static polymorphism.

• when ever we try to implement method overloading concept in python, by default python interpreter recognize recently defined method only.

• python not support method overloading concept.

class x:

    def m1(self):

        print("i am in single parameter of m1 of class x")

    def m1(self,a):

        print("i am in two parameters of m1 of class x")

x_obj=x( )

x_obj.m1(100)

x_obj.m1( )

i am in two parameters of m1 of class x

Traceback (most recent call last):

  File "E:/python_practice/examples/methodoverloading.py", line 9, in <module>

    x_obj.m1()

TypeError: m1() missing 1 required positional argument: 'a'

• some people tells python support method overloading with example.
• i think it is not correct statement.

class x:

    def add(self,instanceOf,*args):

        if instanceOf == 'int':

            result=0

        if instanceOf=='str':

            result=' '

        for i in args:

            result=result+i

        print(result)

x_obj=x( )

x_obj.add('int',10,20,30)

x_obj.add("str",'siva','krishna')

60

sivakrishna

Note:

• upto my knowledge above example is not a polymorphism.

• polymorphism means  multiple logics to perform single operation.

• but above program single logic to perform multiple operations.

Method Overriding:

• the concept of defining multiple methods with same name with same number.of parameters, one is in super class and another one  is in sub class is known as a method overriding or dynamic polymorphism.

• when ever super class method is overrided in its sub class always sub class method will be executed if sub class object is created. 

class x:

    def m1(self):

        print("i am in m1 of x class")

class y(x):

    def m1(self):

        print("i am in m1 of y class")

y_obj=y( )

y_obj.m1( )

x_obj=x( )

x_obj.m1( )

i am in m1 of y class

i am in m1 of x class

class x:

    def m1(self):

        print("i am in m1 of x class")

class y(x):

    def m1(self):

        print("i am in m1 of y class")

y_obj=y( )

y_obj.m1( )

i am in m1 of y class

Note: 

• my requirement is to display both x class(super class) and y class(sub class) statements.

class x:

    def m1(self):

        print("i am in m1 of x class")

class y(x):

    def m1(self):

        super( ).m1( )

        print("i am in m1 of y class")

y_obj=y( )

y_obj.m1( )

i am in m1 of x class

i am in m1 of y class

super( ):

• super( ) statement is used to call the super class methods or constructor through sub class method or constructor.

Constructor Overriding:

• the concept of defining multiple constructors with same name with same number.of parameters, one is in super class and another one  is in sub class is known as a constructor overriding

class x:

    def __init__(self):

        self.a=100

class y(x):

    def __init__(self):

        self.b=200

y_obj=y()

print(y_obj.b)

print(y_obj.a)

200

Traceback (most recent call last):

  File "E:/python_practice/examples/constructor overriding.py", line 9, in <module>

    print(y_obj.a)

AttributeError: 'y' object has no attribute 'a'

class x:

    def __init__(self):

        self.a=100

class y(x):

    def __init__(self):

        self.b=200

        super().__init__()

y_obj=y()

print(y_obj.b)

print(y_obj.a)

200

100