On 3/9/07, Collin Winter <[EMAIL PROTECTED]> wrote: > One solution that just occurred to me -- and that skirts the issue of > choosing an interpretation -- is that, when comparing date and > datetime objects, the datetime's .date() method is called and the > result of that call is compared to the original date. That is, > > datetime_obj < date_obj > > is implicitly equivalent to > > datetime_obj.date() < date_obj
Using the .date() is fine when the year/month/day doesn't match. So the following are fine:: datetime.datetime(2005, 1, 1, 0, 0, 0) < datetime.date(2006, 1, 1) datetime.datetime(2007, 1, 1, 0, 0, 0) > datetime.date(2006, 1, 1) It's *not* okay to say that a date() is less than, greater than or equal to a datetime() if the year/month/day *does* match. The correct temporal relation is During, but Python doesn't have a During operator. During is not the same as less-than, greater-than or equal-to, so all of these should be False:: datetime.datetime(2006, 1, 1, 0, 0, 0) < datetime.date(2006, 1, 1) datetime.datetime(2006, 1, 1, 0, 0, 0) > datetime.date(2006, 1, 1) datetime.datetime(2006, 1, 1, 0, 0, 0) == datetime.date(2006, 1, 1) That is, the datetime() is not less than, greater than or equal to the corresponding date(). Some discussion of these kinds of issues is here: http://citeseer.ist.psu.edu/allen94actions.html The essence is that in order to properly compare intervals, you need the Meets, Overlaps, Starts, During and Finishes operators in addition to the Before (<) and Simulaneous (=) operators. So, let's not conflate Before, After or Simultaneous with the other relations -- if it's not strictly Before (<), After (>) or Simultaneous (=), we can just say so by returning False. (I believe these semantics would be just fine for both of the examples offered so far, but let me know if you think that's not true.) STeVe -- I'm not *in*-sane. Indeed, I am so far *out* of sane that you appear a tiny blip on the distant coast of sanity. --- Bucky Katt, Get Fuzzy _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com