[Python-3000] None in Comparisons

[Daniel Stutzbach]

On Tue, Nov 11, 2008 at 7:06 AM, M.-A. Lemburg <mal at egenix.com> wrote:

> Why was the special case for None being "smaller" than all other
> objects in Python removed from Python 3.0 ? (see object.c in Py2.x)
>

It wasn't true in Python 2.5, either.  Observe:

Cashew:~/pokersleuth/tracker$ python2.5
Python 2.5 (r25:51908, Feb 26 2007, 08:19:26)
[GCC 3.4.4 (cygming special, gdc 0.12, using dmd 0.125)] on cygwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import datetime
>>> now = datetime.datetime.now()
>>> now < None
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: can't compare datetime.datetime to NoneType


Right now to get the desired semantics, I implement a custom AlwaysLeast
and/or AlwaysGreatest singletons for whatever type I'm dealing with.  It's a
bit of  of a pain.  My use cases are all along the following lines:

class TimeSpan:
   def __init__(self):
        self.earliest = AlwaysGreatest
        self.latest = AlwaysLeast

    def update(self, v):
        self.earliest = min(self.earliest, v)
        self.latest = max(self.latest, v)

--
Daniel Stutzbach, Ph.D.
http://www.barsoom.org/~agthorr <http://www.barsoom.org/%7Eagthorr>
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