On 2008-11-12 16:10, Antoine Pitrou wrote:
> M.-A. Lemburg 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
On Thu, Nov 13, 2008 at 3:35 AM, M.-A. Lemburg <[EMAIL PROTECTED]> wrote:
> Anyway, like I said: it's one more thing to add to the list of
> surprises in Python 3.0.
I'm happy to do so. I expect that over time it won't be an issue.
--
--Guido van Rossum (home page: http://www.python.org/~guido/)
[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 (mostl
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 "", line 1, in
sorted([2,None,1])
TypeError: unorderable types: NoneType() < int()
At least the th
Be glad you're not programming in C++ then, where trying to sort NaN
can cause segfaults!
More seriously, I think using the following function as the sort key
will make sort do what you want:
def SortNoneFirstAndNanLast(x):
if x is None:
return (1, x)
if isnan(x):
return (3, x)
retu
I agree that that function will fix the problem. You can also use it to fix
sorting any mixed types but that's not my point either. My point is that
when you have None mixed in with numbers, sorting doesn't work in a way that
stops you and makes you fix it. When you have nan mixed in, it just fails
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Something has been baffling me and is still present in py3.0 -rc2.
When initializing a (non-variable) PyTypeObject in Python 2,
PyObject_HEAD_INIT is used. The docs for Python 3 still show that:
http://docs.python.org/dev/3.0/extending/newtypes.ht
