“Can't instantiate abstract class … with abstract methods” on class that shouldn't have any abstract method

Question

Take the following minimal example:

import abc

class FooClass(object):
  __metaclass__ = abc.ABCMeta

  @abc.abstractmethod
  def FooMethod(self):
    raise         


        

Answer 1

Jochen is right; the abstract methods are set at class creation and won't me modified just because you reassign an attribute.

You can manually remove it from the list of abstract methods by doing

DerivedType.__abstractmethods__ = frozenset()

or

DerivedType.__abstractmethods__ = frozenset(
        elem for elem in DerivedType.__abstractmethods__ if elem != 'FooMethod')

as well as setattr, so it doesn't still think that FooMethod is abstract.