数据类中的类属性和元类

class MyClass:
    class_attribute = "I am a class attribute"

print(MyClass.class_attribute)  # 输出: I am a class attribute

obj1 = MyClass()
obj2 = MyClass()
print(obj1.class_attribute)  # 输出: I am a class attribute
print(obj2.class_attribute)  # 输出: I am a class attribute

class MyMeta(type):
    def __new__(cls, name, bases, dct):
        print(f"Creating class {name}")
        return super().__new__(cls, name, bases, dct)

class MyClass(metaclass=MyMeta):
    pass

# 输出: Creating class MyClass

class MyClass:
    _class_attribute = "I am a protected class attribute"

    @property
    def class_attribute(self):
        return self._class_attribute

obj = MyClass()
print(obj.class_attribute)  # 输出: I am a protected class attribute
# obj.class_attribute = "New value"  # 这将引发AttributeError

class OptimizedMeta(type):
    def __new__(cls, name, bases, dct):
        # 简化逻辑，避免复杂操作
        return super().__new__(cls, name, bases, dct)

class MyClass(metaclass=OptimizedMeta):
    pass