New classes, __slots__, __dict__

[Tim Peters]

[David Mertz, Ph.D., wonders about __slots__ versus pickling]

[Michael Hudson, points to
    http://mail.python.org/pipermail/python-dev/2002-February/020072.html
    http://mail.python.org/pipermail/python-dev/2002-February/020129.html
]

Another link:

    http://www.python.org/sf/520644

That's bug report "[520644] __slots__ are not pickled".  The short course is
that someclass.__slots__ is unreliable because mutable, and so how to find
all the actual slots in all the classes (direct and base) by magic is
something of a puzzle and/or PITA.  Unless/until that does get done by
magic, you need to define a __getstate__ to spell out which slots do and
don't want to be pickled.