[Numpy-discussion] dealing with datetime UTC vs linear time

Mark Wiebe mwwiebe@gmail....
Tue Jun 7 08:09:36 CDT 2011


On Tue, Jun 7, 2011 at 2:29 AM, Mark Dickinson <mdickinson@enthought.com>wrote:

> On Mon, Jun 6, 2011 at 11:12 PM, Mark Wiebe <mwwiebe@gmail.com> wrote:
>


> <snip>
> > On the other hand,
> > with POSIX time, anybody that wants things precise with respect to
> > leap-seconds is automatically excluded. The potential surprises from
> > leap-seconds seem milder than the surprises from time zones and the
> > multitude of possible calendars out there.
>
> Well, except that people are quite used to having to deal with time
> zones / DST / etc. as a matter of course, and that the surprises from
> time zones are likely to bite earlier (i.e., with luck, during
> development rather than after deployment).  I'd argue that the rarity
> of leap seconds (both in terms of ratio of leap seconds to non-leap
> seconds, and in terms of the number of applications that really have
> to care about leap seconds) would make for late-surfacing bugs in
> application code;  so I'd personally prefer to see an 'opt-in' version
> of leap second support, rather than 'opt-out'.  Still, I'm largely
> guessing here, so take with a large pinch of salt.
>

This is what I'm leaning towards now, too. Instead of UTC vs TAI, I think
it's POSIX vs TAI and just for the datetime type, not the timedelta. So I'm
changing my proposal to M8[s:POSIX] and M8[s:TAI] as the dtypes, with POSIX
being the default if nothing is specified.

Thanks,
Mark

(If this were a Python mailing list, I'd trot out 'Practicality Beats
> Purity' from the Zen here.)
>
> > I found it disconcerting that
> > datetime.datetime.now() returns local time with no time zone indication
> on
> > it.
>
> Yes, I agree that that's disturbing.  datetime support for time zones
> isn't the best.
>
> Thanks for the detailed response.  I'll go back to lurking now.
>
> Mark
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