Singleton Pattern Implementation in Python

Design Pattern: Singleton Pattern Implementation

Problem Analysis:

The provided Python code implements the Singleton design pattern. The Singleton pattern ensures that a class has only one instance and provides a global point of access to that instance.

Code Template - Singleton Design Pattern Implementation:

class Singleton:
    _instance = None

    def __new__(cls):
        if not cls._instance:
            cls._instance = super(Singleton, cls).__new__(cls)
        return cls._instance

class MyClass(Singleton):
    pass

# Usage
a = MyClass()
b = MyClass()

print(a is b)  # Output: True - Both a and b refer to the same instance of MyClass

Implementation Details:

1. Singleton Class: Implements the logic to ensure only one instance is created. The _instance attribute holds the reference to the single instance.
2. MyClass: Inherits from Singleton class, ensuring only a single instance of MyClass can be created.
3. Usage: Instantiating MyClass (a and b) demonstrates that both references point to the same instance (a is b = True).

Key Points:

• Implemented Singleton pattern ensures one instance per class.
• Python __new__ method is used for instance creation control.
• Subclasses leverage the Singleton logic by inheriting from the Singleton class.
• Singleton pattern maintains a single instance across the application.

By following this template, you can effectively implement the Singleton design pattern in Python for scenarios requiring only one instance of a class throughout the application.