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Polymorphism

Polymorphism is one of the core principles of object-oriented programming (OOP), along with encapsulation, inheritance, and abstraction. It allows objects of different classes to be treated as objects of a common super class. This is achieved by having methods in different classes with the same name, but potentially different implementations.

 

 

 

Key Concepts of Polymorphism

 

  1. Method Overriding: Subclasses provide specific implementations for methods that are already defined in their super class.
  2. Method Overloading: Not directly supported in Python, but can be achieved by using default parameters.
  3. Duck Typing: Python's dynamic nature allows polymorphism through duck typing, where an object's suitability is determined by the presence of certain methods and properties, rather than the object's actual type.

 

 

Implementing Polymorphism in Python

 

1. Method Overriding

Method overriding occurs when a subclass provides a specific implementation of a method that is already defined in its super class.

Example:

class Animal:
   def speak(self):
       raise NotImplementedError("Subclass must implement abstract method")
class Dog(Animal):
   def speak(self):
       return "Woof!"
class Cat(Animal):
   def speak(self):
       return "Meow!"
# Creating instances of Dog and Cat
dog = Dog()
cat = Cat()
print(dog.speak())  # Output: Woof!
print(cat.speak())  # Output: Meow!
 

 

2. Duck Typing

Duck typing is a concept related to dynamic typing where an object's methods and properties determine the valid semantics, rather than the object's inheritance from a particular class.

Example:

class Bird:
   def fly(self):
       return "Flying high"
class Airplane:
   def fly(self):
       return "Flying with jet engines"
# Polymorphic function
def let_it_fly(obj):
   return obj.fly()
# Using duck typing
bird = Bird()
airplane = Airplane()
print(let_it_fly(bird))       # Output: Flying high
print(let_it_fly(airplane))   # Output: Flying with jet engines
 

 

Polymorphism with Functions and Classes

Polymorphism can also be used with functions and classes to perform a single action in different ways.

Example:

class Shape:
   def area(self):
       raise NotImplementedError("Subclass must implement abstract method")
class Square(Shape):
   def __init__(self, side):
       self.side = side
   def area(self):
       return self.side * self.side
class Circle(Shape):
   def __init__(self, radius):
       self.radius = radius
   def area(self):
       return 3.14 * self.radius * self.radius
# Polymorphic function
def print_area(shape):
   print(f"The area is: {shape.area()}")
# Using polymorphism
square = Square(4)
circle = Circle(3)
print_area(square)  # Output: The area is: 16
print_area(circle)  # Output: The area is: 28.26

 

In this example, the print_area function can handle different types of Shape objects, each providing its own implementation of the area method.

 

 

Benefits of Polymorphism

  • Flexibility: Code can work with objects of different types as long as they follow the same interface.
  • Maintainability: Reduces code duplication and increases maintainability by using a common interface.
  • Extensibility: New classes can be introduced with minimal changes to existing code.

 

 

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