[issue12248] __dir__ semantics changed in Python 2.7.2

[Benjamin Peterson]

Benjamin Peterson <benjamin at python.org> added the comment:

2011/6/4 Soren Hansen <report at bugs.python.org>:
>
> Soren Hansen <soren at linux2go.dk> added the comment:
>
> When I first investigated this problem (I reported the original bug on Launchpad), my first attempt to address this issue in pymox had me quite stumped. The class in question has a __getattr__ method. Up until now, this hasn't affected the use of dir(), but it does now. I really just wanted it return whatever it used to return (since that has worked so far), but realising that this was an old-style class, I couldn't just call super(TheClass, self).__dir__().
>
> So my question is: If this change stays (which seems clear given that the only changes proposed here are ways of relaxing the type requirement of the __dir__ method's return value, not reverting the change altogether), and I have an old-style class with a __getattr__ defined, how do I make that class return whatever it would have usually returned for __dir__()?

Yes, this is a limitation of magic methods on old style classes. The
usual method is something like this:

    def __getattr__(self, name):
        if name == "__dir__":
            return self.__dir__
        # Other stuff

Of course, the best fix is to use new-style classes. :)

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue12248>
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