[Design Pattern] Singleton pattern

파이썬 싱글톤 패턴

class SingletonMeta(type):
    _instance = {}

    def __call__(cls, *args, **kwargs):
        if cls not in cls._instance:
            cls._instance[cls] = super().__call__(*args, **kwargs)
            print("make first object")
        else:
            print("return a exist object")

        return cls._instance[cls]


class Singleton(metaclass=SingletonMeta):
    def __init__(self):
        print("\nSingleton Init!")


def test_singleton():
    singletone1 = Singleton()
    singletone2 = Singleton()

    print(f'{id(singletone1)} == {id(singletone2)} -> {id(singletone1) == id(singletone2)}')

 

Singleton Init!
make first object
return a exist object
2608647861000 == 2608647861000 -> True

참고

https://refactoring.guru/design-patterns/singleton/python/example

Design Patterns: Singleton in Python

https://dojang.io/mod/page/view.php?id=2468 

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