37. Singleton Pattern

The Singleton pattern ensures only one instance of a class exists.

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Example

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

a = Singleton()
b = Singleton()
print(a is b)  # True

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Wrap-Up

Singleton ensures a single shared instance, useful for configurations or logging.