How to declare @staticmethod in zope.interface

I try to create interface with @staticmethod and @classmethod. Declaring class method is simple. But I can't find the correct way to declare static method.

Consider class interface and its implementation:

#!/usr/bin/python3
from zope.interface import Interface, implementer, verify


class ISerializable(Interface):

    def from_dump(slice_id, intex_list, input_stream):
        '''Loads from dump.'''

    def dump(out_stream):
        '''Writes dump.'''

    def load_index_list(input_stream):
        '''staticmethod'''


@implementer(ISerializable)
class MyObject(object):

    def dump(self, out_stream):
        pass

    @classmethod
    def from_dump(cls, slice_id, intex_list, input_stream):
        return cls()

    @staticmethod
    def load_index_list(stream):
        pass

verify.verifyClass(ISerializable, MyObject)
verify.verifyObject(ISerializable, MyObject())
verify.verifyObject(ISerializable, MyObject.from_dump(0, [], 'stream'))

Output:

Traceback (most recent call last):
  File "./test-interface.py", line 31, in <module>
    verify.verifyClass(ISerializable, MyObject)
  File "/usr/local/lib/python3.4/dist-packages/zope/interface/verify.py", line 102, in verifyClass
    return _verify(iface, candidate, tentative, vtype='c')
  File "/usr/local/lib/python3.4/dist-packages/zope/interface/verify.py", line 97, in _verify
    raise BrokenMethodImplementation(name, mess)
zope.interface.exceptions.BrokenMethodImplementation: The implementation of load_index_list violates its contract
        because implementation doesn't allow enough arguments.

How should I correctly declare static method in this interface?

Solution

Obviously the verifyClass does not understand either classmethod or staticmethod properly. The problem is that in Python 3, if you do getattr(MyObject, 'load_index_list') in Python 3, you get a bare function, and verifyClass thinks it is yet another unbound method, and then expects that the implicit self be the first argument.

The easiest fix is to use a classmethod there instead of a staticmethod.

I guess someone could also do a bug report.