Singleton Pattern Implementation

Design Pattern Implementation: Singleton Pattern

Problem Analysis

• The provided Python code aims to create a Singleton class that ensures only one instance of the class is created and shared across all instances.

Chosen Design Pattern: Singleton Pattern

• Description: The Singleton pattern ensures a class has only one instance and provides a global point of access to it.
• Key Components: Private static variable _instance to hold the single instance, constructor __new__ to prevent multiple instances creation, and a static method to access the single instance.

Code Template - Singleton Pattern Implementation

class Singleton:
    _instance = None

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

# Usage
singleton1 = Singleton()
singleton2 = Singleton()

print(singleton1 == singleton2)  # Expected output: True

Implementation Details:

• The __new__ method ensures only one instance of the class is created by checking if _instance is None. If it's None, a new instance is created; otherwise, the existing instance is returned.
• The comparison singleton1 == singleton2 should return True since both variables reference the same instance due to the Singleton pattern.

Conclusion

• The Singleton pattern guarantees a single instance of a class and is useful for scenarios where there should be a sole instance available globally.
• Implementing the Singleton pattern ensures that multiple instances of the class are not inadvertently created, maintaining data integrity and control over object creation.