Singleton Pattern Overview

Design Pattern: Singleton Pattern

Problem Analysis:

• The provided code snippet represents the Singleton pattern, which ensures that a class has only one instance and provides a global point of access to that instance.

Code Template - Singleton Pattern Implementation (Python):

class Singleton:
    _instance = None

    def __new__(cls):
        if cls._instance is None:
            cls._instance = super(Singleton, cls).__new__(cls)
            cls._instance.value = None
        return cls._instance

    def set_value(self, value):
        self.value = value

    def get_value(self):
        return self.value

# Usage
s1 = Singleton()
s2 = Singleton()

s1.set_value(10)
print(s2.get_value())  # Output: 10

Implementation Details:

1. The Singleton class is designed with a private variable _instance to store the single instance of the class.
2. The __new__ method is overridden to control the instantiation process and ensure a single instance is created.
3. The set_value and get_value methods allow setting and fetching the value within the singleton instance.
4. s1 and s2 objects are created as singleton instances where setting a value in s1 reflects in s2.

Benefits of Singleton Pattern:

• Ensures a class has only one instance throughout the application.
• Provides a global point of access to the instance.
• Supports lazy initialization for efficient resource utilization.

Conclusion:

The Singleton pattern is useful when a class should have only one instance available globally. The provided code snippet demonstrates a basic implementation of the Singleton pattern in Python, ensuring that only one instance of the Singleton class is created and accessed across multiple objects.