[Python-Dev] Status on PEP-431 Timezones
regebro at gmail.com
Tue Jul 28 08:54:58 CEST 2015
On Tue, Jul 28, 2015 at 8:11 AM, Tim Peters <tim.peters at gmail.com> wrote:
>>> timedelta objects only store days, seconds, and microseconds,
> [Lennart Regebro <regebro at gmail.com>]
>> Except that they don't actually store days. They store 24 hour
> Not really. A timedelta is truly an integer number of microseconds,
> and that's all.
That's what I said. Timedeltas, internally assume that 1 day is 24
hours. Or 86400000 microseconds. That's the assumption internally in
the timedelta object.
The problem with that being that in the real world that's not true.
> 24 hours is 24 hours at any time in _any_ time zone, ignoring leap
> seconds. timedeltas are durations, not points in time. "time zones"
> make no sense applied to durations.
My point exactly.
And should not then adding 86400000 microseconds to a datetime
actually result in a datetime that happens 86400000 microseconds
>> ie, it assumes that one day is always 24 hours.
> That's really not what it's doing
That is really exactly what the timedelta is doing, as you yourself,
just a few lines above say.
> used in explanations. What somedatetime+timedelta really does is
> simpler than that: it adds the number of microseconds represented by
> the timedelta to somedatetime,
No it doesn't.
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