ABCMeta and @abstractmethod suppose to work?

[alanjds]

google#199 opened by @S-YOU on 23 Jan 2017

I don't get OrderedDict working, because I am getting error on

self.__update(*args, **kwds)
TypeError: unbound method update() must be called with MutableMapping instance as first argument (got list instance instead)

self.__update is assigned to MutableMapping.update at class level.

It is not possible to get instance of MutableMapping, because there is abstractmethods on it.

TypeError: Can't instantiate abstract class MutableMapping with abstract methods __delitem__, __getitem__, __iter__, __len__, __setitem__

Is there a way to work-around those?

[alanjds]

Comment by trotterdylan
Monday Jan 23, 2017 at 23:50 GMT

---

I'm surprised that works in CPython. Here's something similar that fails:

>>> class A(object):
...  def foo(self):
...   pass
...
>>> class B(object):
...  bar = A.foo
...
>>> B().bar()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unbound method foo() must be called with A instance as first argument (got nothing instead)

I'm not exactly sure what's going on. Will need to do some more investigation.

[alanjds]

Comment by S-YOU
Tuesday Jan 24, 2017 at 00:30 GMT

---

May be MutableMapping.register(dict) does something monkey patching.