class IntField(object):
    def __set_name__(self, owner, name):
        # Python 3.6+ only. On previous versions, you'll need a metaclass or some other workaround to get the name.
        self.name = name
    def __get__(self, instance, owner):
        if instance is None:
            return self
        return instance.__dict__[self.name]
    def __set__(self, instance, value):
        if not isinstance(value, int):
            raise ValueError
        instance.__dict__[self.name] = IntFieldVal(value)

class IntFieldVal(int):
    def make_siren_noises_i_dunno(self):
        print('weeoo weeoo weeoo')

class Foo(object):
    field = IntField()

x = Foo()
y = Foo()
x.field = 3
y.field = 4
print(x.field == 3)
print(y.field == 4)
x.field.make_siren_noises_i_dunno()