[Python-ideas] Disallow orderring comparison to NaN

[Alexander Belopolsky]

On Thu, Apr 28, 2011 at 10:01 AM, Steven D'Aprano <steve at pearwood.info> wrote:
> Alexander Belopolsky wrote:
..
> I think I would like to see a demonstration of this rather than just take
> your word for it.
>
>>>> sorted([4, 5, 1, float('nan'), 3, 2])
> [1, 2, 3, 4, 5, nan]

Hmm, a quick search of the tracker yielded issue7915 which
demonstrates how presence of nans causes sort to leave a list
unsorted.   Using binary search on unsorted data leads to nonsensical
results, but I don't seem to be able to produce infinite loops with
python's bisect.  Maybe I saw nan-caused infinite loops  in some other
libraries.  I learned long ago to rid my data of NaNs before doing any
type of comparison, so my recollection of the associated problems is
admittedly vague.  I'll try to come up with something, though.

http://bugs.python.org/issue7915