On Mon, 01 Nov 2010 02:55:35 +0000
Michael Foord <fuzzy...@voidspace.org.uk> wrote:
> Having a more efficient 'slow-path' and moving to that by default would
> fix it. The bug is only a duplicate of the bug in sorted - caused by the
> fact that sets / frozensets can't be sorted in the standard Python way
> (their less than comparison adheres to the set definition). This is
> something that will probably surprise many Python developers:
>
> >>> a = [{2,4}, {1,2}]
> >>> b = a[::-1]
> >>> sorted(a)
> [set([2, 4]), set([1, 2])]
> >>> sorted(b)
> [set([1, 2]), set([2, 4])]
>
> (Fixing the bug in sorted would fix assertItemsEqual ;-)
How is this a bug? The sort algorithm is stable, which means the above
behaviour is a feature.
I see no easy way of eliminating the O(n*n) issue. Custom key functions
can't work in all cases.
Regards
Antoine.
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