> [Neal Norwitz]
> > * AIX sorts numbers and strings in a different order than Linux:
> >
> > >>> 'ick' >= 0 # Linux
> > True
> >
> > >>> 'ick' >= 0 # AIX
> > False
> >
> > This causes failures for test_descrtut and test_random.
>
> It shouldn't. Regardless of platform, this should end up at the tail end of
> default_3way_compare(), resolved by the
>
> c = strcmp(vname, wname);
>
> line with vname "str" and wname "" (an empty string).
>
> But-- ick! --it doesn't, and not on any platform anymore. vname and wname
> are both empty strings now, so it goes on to compare the objects by memory
> address and the outcome is pure accident ... this is because rev 2.197 of
> stringobject.c gave string objects a non-NULL tp_as_number slot for the
> first time. The intent of the emtpy-string gimmick was to make all numeric
> objects "less than" all non-numeric objects (excepting None, which is less
> than every non-None value), in particular so that sorting a list would bring
> all the number-like thingies next to each other. Strings weren't intended
> to take part in this number gimmick too. Then again, comparison is so snaky
> it's hard to predict what it will do. In any case, this is incompatible
> with previous Python releases. Neil(S), was giving strings a tp_as_number
> slot necessary? Or just the least painful way to fix whatever bug it was
> fixing? I suppose the tail end of default_3way_compare could grow more
> special cases to exempt strings from being treated like numbers for the
> purpose of comparison.
I forget what Neil's motivation was; SF bug #615506 doesn't really
mention much for motivation. I suspect it's simply cleanliness.
Maybe PyNumber_Check() could be changed? This has been proposed
before. It could check whether the type implements conversion to int,
for example. Or it could check whether the type derives from a
new-to-introduce abstract base class ("basenumber").
--Guido van Rossum (home page: http://www.python.org/~guido/)
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