如果使用的旧技巧__slots__不适合您，则此方法或它的某些变体可以做到：只需编写__setattr__您的元类的方法来保护您。在此示例中，我阻止分配新属性，但允许修改现有属性：
def immutable_Meta(name, bases, dct):
class Meta(type):
def __init__(cls, name, bases, dct):
type.__setattr__(cls,"attr",set(dct.keys()))
type.__init__(cls, name, bases, dct)
def __setattr__(cls, attr, value):
if attr not in cls.attr:
raise AttributeError ("Cannot assign attributes to this class")
return type.__setattr__(cls, attr, value)
return Meta(name, bases, dct)
class A:
__Metaclass__ = immutable_Meta
b = "test"
a = A()
a.c = 10 # this works
A.c = 20 # raises valueError
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