class classproperty(property):
    def __get__(self, owner_self, owner_cls):
        return self.fget(owner_cls)
 
class CMeta(type):
    def __setattr__(cls, name, value):
        if isinstance(vars(cls).get(name), classproperty):
            raise AttributeError("can't set attribute")
        super().__setattr__(name, value)
 
class C(metaclass=CMeta):
    @classproperty
    def x(cls):
        return 1
 
print(C.x)
print(C().x)
C.x = 2 # AttributeError: can't set attribute

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