An Introduction to Design Patterns in Python

An Introduction to Design Patterns in Python

Design patterns are reusable solutions to common software design problems. They provide proven solutions and best practices for different scenarios in software development. In this article, we will explore some popular design patterns and learn how to implement them in Python.

1. Singleton Pattern

The Singleton pattern ensures that a class has only one instance and provides a global access point to that instance. It is useful when we want to restrict the instantiation of a class to a single object.

class Singleton:
    _instance = None
    def __new__(cls, *args, **kwargs):
        if not cls._instance:
            cls._instance = super().__new__(cls, *args, **kwargs)
        return cls._instance

2. Factory Pattern

The Factory pattern provides an interface for creating objects but allows subclasses to decide which class to instantiate. It decouples the object creation from the client code.

class ShapeFactory:
    def create_shape(shape_type):
        if shape_type == 'circle':
            return Circle()
        elif shape_type == 'rectangle':
            return Rectangle()
        elif shape_type == 'triangle':
            return Triangle()

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

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

class Triangle:
    def draw(self):
        print("Drawing Triangle")

3. Observer Pattern

The Observer pattern defines a one-to-many dependency between objects. When the state of one object changes, all its dependents are notified and updated automatically.

class Subject:
    def __init__(self):
        self._observers = []

    def attach(self, observer):

    def detach(self, observer):

    def notify(self):
        for observer in self._observers:

class Observer:
    def update(self):
        print("Received update notification")

subject = Subject()
observer1 = Observer()
observer2 = Observer()


Design patterns are an essential part of software development. They provide reusable solutions to common problems and improve code organization and maintainability. In this article, we explored a few popular design patterns, including the Singleton, Factory, and Observer patterns, and learned how to implement them in Python.

By incorporating design patterns into your code, you can write cleaner, more robust, and flexible software.

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