Polymorphism 2

Python Polymorphism(Abstract Classes)

More common practice of inheritance is the use of Abstract classes and inheritance. Abstract classes are one that never expect to create an instance of it but its expcted to serve as a base class to be over written by the subclasses.

Example:

The Base class

        
class Programming:
    def __init__(self, name):
        self.name = name

    def challenge(self):
        raise NotImplementedError ('
Subclass must 
 implement this abstravt method')

Lets try to create an instance of the Programming class

            
programmer = Programming('HTML')
print(programmer.challenge())

Try it Your self

Lets try creating a subclass of the Programming class and instatiate it

        
class Java(Programming):
    def challenge(self):
        print(self.name + ' Challenged Java')
                            
class Python(Programming):
    def challenge(self):
        print(self.name + ' Challenged Py')

teacher = Java('Teacher')
student = Python('Student')

print(teacher.challenge())
print(student.challenge())

# No error raised

Try it Your self

A real practicable way to use the Abstract class is for example having classes that open files and make a Open method the Base class and other classes open sort of files like pdf,html, py etc.