[Python-ideas] If I had the time machine for comparisons

[Guido van Rossum]

On Thu, Oct 13, 2011 at 7:06 AM, Jim Jewett <jimjjewett at gmail.com> wrote:
> On Wed, Oct 12, 2011 at 11:18 PM, Guido van Rossum <guido at python.org> wrote:
>
>> (I'm also -1 on adding ordering comparisons; there's little
>> disagreement on that issue.)
>
> If I had a time machine, I would allow comparisons to return
> "unordered" as well.  Right now, objects are comparable or not based
> strictly on the type, even though comparison is inherently about the
> values.
>
> I think that
>
>    range(3) < range(10)
>
> is obviously true, even though it isn't clear whether or not
>
>    range(3, 15, 2) < range(7, -8, -1)
>
> is true.
>
> Here we err by not allowing the first comparison; other objects (like
> dicts) we err by forcing an arbitrary ordering.

Have you used Python3 lately? It doesn't allow dict ordering.

In general Python expresses unordered by raising an exception (often TypeError).

Even though range(1) is "obviously" < range(2), there are so many
unobvious cases that supporting this one special case isn't worth it.

-- 
--Guido van Rossum (python.org/~guido)