如何在Python中创建自注册工厂？

class FactoryMeta(type):
    factories = {}

    def __new__(cls, name, bases, attrs):
        new_class = super().__new__(cls, name, bases, attrs)
        cls.factories[name] = new_class
        return new_class

class Factory(metaclass=FactoryMeta):
    @staticmethod
    def create(name):
        factory_class = FactoryMeta.factories.get(name)
        if factory_class:
            return factory_class()
        else:
            raise ValueError(f"Unknown product: {name}")

class ProductA(Factory):
    def __init__(self):
        print("Product A created")

class ProductB(Factory):
    def __init__(self):
        print("Product B created")

# 创建产品实例
product_a = Factory.create("ProductA")  # 输出：Product A created
product_b = Factory.create("ProductB")  # 输出：Product B created