python - 何时何地以及如何更改对象的 __class__ attr？

Question

我希望能够做到:

>>> class a(str):
...     pass
...
>>> b = a()
>>> b.__class__ = str
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: __class__ assignment: only for heap types

Answer 1

我是这样解决的:

>>> class C(str):
...     def __getattribute__(self, name):
...         if name == '__class__':
...             return str
...         else:
...             return super(C, self).__getattribute__(name)
...         
>>> c = C()
>>> c.__class__
<type 'str'>