Python元类-使类属性可通过类和类实例访问

class MetaClass(type):
    def __init__(cls, name, bases, dct):
        super().__init__(name, bases, dct)
        # 将所有类属性复制到实例的__dict__中
        for key, value in dct.items():
            if not key.startswith('__'):
                setattr(cls, key, property(lambda self, key=key: getattr(self, f'_{key}')))

class MyClass(metaclass=MetaClass):
    class_attribute = "I am a class attribute"

    def __init__(self):
        self._class_attribute = MyClass.class_attribute

# 访问类属性
print(MyClass.class_attribute)  # 输出: I am a class attribute

# 创建实例并访问属性
obj = MyClass()
print(obj.class_attribute)  # 输出: I am a class attribute

class MyClass(metaclass=MetaClass):
    class_attribute = "I am a class attribute"

    def __init__(self):
        self.instance_attribute = "I am an instance attribute"

obj = MyClass()
print(obj.class_attribute)  # 输出: I am a class attribute
print(obj.instance_attribute)  # 输出: I am an instance attribute