[Python-Dev] Comparing date+time w/ just time

[Guido van Rossum]

On 10/22/05, skip at pobox.com <skip at pobox.com> wrote:
> With significant input from Fred I made some changes to xmlrpclib a couple
> months ago to better integrate datetime objects into xmlrpclib.  That raised
> some problems because I neglected to add support for comparing datetime
> objects with xmlrpclib.DateTime objects.  (The problem showed up in
> MoinMoin.)  I've been working on that recently (adding rich comparison
> methods to DateTime while retaining __cmp__ for backward compatibility), and
> have second thoughts about one of the original changes.
>
> I tried to support datetime, date and time objects.  My problems are with
> support for time objects.  Marshalling datetimes as xmlrpclib.DateTime
> objects is no problem (though you lose fractions of a second).  Marshalling
> dates is reasonable if you treat the time as 00:00:00.  I decided to marshal
> datetime.time objects by fixing the day portion of the xmlrpclib.DateTime
> object as today's date.  That's the suspect part.
>
> When I went back recently to add better comparison support, I decided to
> compare xmlrpclib.DateTime objects with time objects by simply comparing the
> HH:MM:SS part of the DateTime with the time object.  That's making me a bit
> queazy now.  datetime.time(hour=23) would compare equal to any DateTime with
> its time equal to 11PM.  Under the rule, "in the face of ambiguity, refuse
> the temptation to guess", I'm inclined to dump support for marshalling and
> comparison of time objects altogether.  Do others agree that was a bad idea?

Agreed.

--
--Guido van Rossum (home page: http://www.python.org/~guido/)