I think the behavior of NaN in comparisons is more confusing:
>>> sorted([1,nan,2])
[1, nan, 2]
>>> sorted([2,nan,1])
[2, nan, 1]
>>> sorted([2,None,1])
Traceback (most recent call last):
File "<pyshell#28>", line 1, in <module>
sorted([2,None,1])
TypeError: unorderable types: NoneType() < int()
At least the third case is clear that I shouldn't have done that. The way
nan works, the results of sorting where one of the values is nan is
unpredictable and useless.
Yes, I know the rules about how NaN values behave in comparisons.
Notwithstanding that, sorting could use a different comparison rule imposing
a total ordering: -inf, ..., inf, nan as some other systems do.
--- Bruce
On Thu, Nov 13, 2008 at 10:55 AM, Tim Peters <[EMAIL PROTECTED]> wrote:
> [M.-A. Lemburg]
> > ...
> > 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.
>
> I've tracked down plenty of program logic errors that would have been
> discovered more easily if comparing None to (mostly, but among others)
> integers and strings had raised an exception instead of returning a
> meaningless true/false result. Perhaps you haven't. For those who
> have, the attraction to making comparisons with None refuse to return
> nonsense silently is both obvious and visceral.
>
>
> > IMHO, practicality beats purity in this special case.
>
> If hiding program logic errors is practical, sure ;-)
>
> there-is-no-behavior-no-matter-how-bizarre-someone-won't
> come-to-rely-on-ly y'rs - tim
> _______________________________________________
> Python-3000 mailing list
> Python-3000@python.org
> http://mail.python.org/mailman/listinfo/python-3000
> Unsubscribe:
> http://mail.python.org/mailman/options/python-3000/bruce%40leapyear.org
>
_______________________________________________
Python-3000 mailing list
Python-3000@python.org
http://mail.python.org/mailman/listinfo/python-3000
Unsubscribe:
http://mail.python.org/mailman/options/python-3000/archive%40mail-archive.com
