[Python-3000] None in Comparisons: None vs. float("inf")

[M.-A. Lemburg]

On 2008-11-12 16:10, Antoine Pitrou wrote:
> M.-A. Lemburg <mal <at> egenix.com> writes:
>> The difference is that None is a singleton, so the set of all
>> None type instances is {None}. You always have an intuitive total order
>> relation on one element sets: the identity relation.
> 
> But it's not what you are asking for. You are asking for None to support ordered
> comparison with objects of other types, which is completely different.
> 
> Having None be comparable with itself for ordered comparisons is certainly
> possible, but it's also completely useless if None doesn't compare with other
> types, which is what we are talking about.

I should have probably made it clearer in my posting:

Having None < None fail is another different (and a lot more
insignificant) problem.

It would be solved by having None added to a consistent Python
object ordering scheme, but is not a consequence of not having
a consistent general object ordering scheme.

So far, I haven't heard a single argument for why not having None
participate in an ordering scheme is a good strategy to use, except
that it's pure. IMHO, practicality beats purity in this special
case.

Anyway, like I said: it's one more thing to add to the list of
surprises in Python 3.0.

-- 
Marc-Andre Lemburg
eGenix.com

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