Leverage Polymorphism and Design Patterns in Python for Robust Code

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Design patterns exist to solve recurring problems in software development, helping engineers produce maintainable, testable, and scalable code. Python, a versatile and highly readable programming language, lends itself particularly well to implementing classic design patterns. Central to achieving flexibility and abstraction is polymorphism — the ability for entities to assume multiple forms.

In this article, we will examine four fundamental design patterns — Factory, Template Method, Command, and Observer — and demonstrate how polymorphism plays a crucial role in each case. Along the way, we’ll reinforce best practices in Pythonic idioms and style.

Factory Pattern

Factories encapsulate instantiation of families of related or dependent objects. They promote loose coupling and hide complicated construction logic. Polymorphism helps achieve runtime selection of desired products.

Example: ShapeFactory

from abc import ABC, abstractmethod

class Shape(ABC):
    @abstractmethod
    def draw(self):
        pass

class Rectangle(Shape):
    def draw(self):
        print("Drawing rectangle")

class Square(Shape):
    def draw(self):
        print("Drawing square")

class Circle(Shape):
    def draw(self):
        print("Drawing…