装饰器实现单例模式

# 类装饰器 类实现单例模式
def singleton(cls):
    _instance = {}

    def _singleton(*args, **kwargs):
        if cls not in _instance:
            _instance[cls] = cls(*args, **kwargs)
        return _instance[cls]

    return _singleton


@singleton
class A:
    pass


if __name__ == '__main__':
    a = A()
    b = A()
    print(a, b)