Pythonic方式创建具有对象创建限制的工厂

class FactoryMeta(type):
    def __call__(cls, *args, **kwargs):
        if cls._instance is None:
            cls._instance = super().__call__(*args, **kwargs)
        return cls._instance

class Factory(metaclass=FactoryMeta):
    _instance = None

    def __init__(self, name):
        self.name = name

    def create_object(self, value):
        # 创建对象的逻辑
        pass

factory1 = Factory("Factory 1")
factory2 = Factory("Factory 2")

print(factory1 is factory2)  # True，只有一个实例

factory3 = Factory("Factory 3")
print(factory1 is factory3)  # True，仍然是同一个实例