From: Ihor Radchenko <yantar92@posteo.net>
To: Max Nikulin <manikulin@gmail.com>
Cc: emacs-orgmode@gnu.org
Subject: Re: Observation of hysteresis in a GNU libc time conversion function
Date: Thu, 19 Jan 2023 10:31:19 +0000 [thread overview]
Message-ID: <87zgae4xzc.fsf@localhost> (raw)
In-Reply-To: <tq96u9$a76$1@ciao.gmane.io>
Max Nikulin <manikulin@gmail.com> writes:
>> Also, see
>> https://stackoverflow.com/questions/20104531/weird-mktime-logic-with-negative-seconds
>
> My expectation is that ±1 day (or month) should preserve local time
> hours (e.g. 11:00 CET -> 11:00 CEST) if such moment of time exists. ±24
> hours, ±24*60 minutes, ±24*3600 seconds across DST change should cause
> appropriate shift of hours (e.g. 11:00 -> 12:00 is possible).
>
> Moreover "out of range" month day 0 is the only way to specify last
> month day to get
>
> Jan, 31 <- 1 month -> Feb, 28 (or 29) <- 1 month -> Mar, 31
>
> arithmetic.
Can we expect the same to work on Windows? If so, maybe we don't need
all the dancing around rounding off in `org-timestamp-change' and
instead simply use time API?
Re: 11:00 CET -> 11:00 CEST
Note that Org does not exactly offer much of convenience even without
considering TZ.
<2023-01-31 Thu +1m> -> <2023-03-03 Fri +1m>
And nobody really complained so far.
So, maybe we don't even need to care about these subtleties in practice?
--
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>
prev parent reply other threads:[~2023-01-19 10:31 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-17 17:22 Observation of hysteresis in a GNU libc time conversion function Max Nikulin
2023-01-18 9:54 ` Ihor Radchenko
2023-01-18 16:32 ` Max Nikulin
2023-01-18 16:38 ` Max Nikulin
2023-01-19 10:31 ` Ihor Radchenko [this message]
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