Marco Sulla wrote at 2021-12-29 11:59 +0100: >On Wed, 29 Dec 2021 at 09:12, Dieter Maurer <die...@handshake.de> wrote: >> `MutableMapping` is a so called abstract base class (--> `abc`). >> >> It uses the `__subclass_check__` (and `__instance_check__`) of >> `abc.ABCMeta` to ensure `issubclass(dict, MutableMapping)`. >> Those can be customized by overriding `MutableMapping.__subclasshook__` >> to ensure that your `frozendict` class (and their subclasses) >> are not considered subclasses of `MutableMapping`. > >It does not work: > ... >>>> issubclass(fd, Mm) >True
There is a cache involved. The `issubclass` above, brings your `fd` in the `Mn`'s subclass cache. > ... >>>> Mm.__subclasshook__ = _my_subclasshook >>>> issubclass(fd, Mm) >True See above. -- https://mail.python.org/mailman/listinfo/python-list
