emacs-orgmode@gnu.org archives
 help / color / mirror / code / Atom feed
From: Shironeko <shironeko@tesaguri.club>
To: tomas@tuxteam.de
Cc: emacs-orgmode@gnu.org
Subject: Re: Idea for handling timezones
Date: Sat, 03 Apr 2021 17:26:43 +0800	[thread overview]
Message-ID: <bd86bfcf3b3524dc289c2b78549f6594dcca81d6.camel@tesaguri.club> (raw)
In-Reply-To: <20210403083029.GC19516@tuxteam.de>

[-- Attachment #1: Type: text/plain, Size: 1727 bytes --]

tz database and tools using it like the date(1) command can convert between
local times taking into account all the difference like daylight savings time.
An example below, Toronto observes daylight savings whereas Shanghai does not:

$ TZ=Asia/Shanghai date --date='TZ="America/Toronto" 2021-11-07 Sun 00:30'
Sun  7 Nov 12:30:00 CST 2021
$ TZ=Asia/Shanghai date --date='TZ="America/Toronto" 2021-11-07 Sun 01:30'
Sun  7 Nov 13:30:00 CST 2021
$ TZ=Asia/Shanghai date --date='TZ="America/Toronto" 2021-11-07 Sun 02:30'
Sun  7 Nov 15:30:00 CST 2021

$ TZ=America/Toronto date --date='TZ="Asia/Shanghai" 2021-11-07 Sun 12:30'
Sun  7 Nov 00:30:00 EDT 2021
$ TZ=America/Toronto date --date='TZ="Asia/Shanghai" 2021-11-07 Sun 13:30'
Sun  7 Nov 01:30:00 EDT 2021
$ TZ=America/Toronto date --date='TZ="Asia/Shanghai" 2021-11-07 Sun 14:30'
Sun  7 Nov 01:30:00 EST 2021
$ TZ=America/Toronto date --date='TZ="Asia/Shanghai" 2021-11-07 Sun 15:30'
Sun  7 Nov 02:30:00 EST 2021

The ambiguity caused by dialing back is resolved with
$ TZ=Asia/Shanghai date --date='TZ="America/Toronto" 2021-11-07 Sun 01:30 EDT'
Sun  7 Nov 13:30:00 CST 2021
$ TZ=Asia/Shanghai date --date='TZ="America/Toronto" 2021-11-07 Sun 01:30 EST'
Sun  7 Nov 14:30:00 CST 2021

With this, say the user have

#+TIMEZONE: America/Toronto

at the start of their org file, and they moved to Shanghai, all the timestamp in
the org file is converted using something equivalent to

$ TZ=Asia/Shanghai date --date='TZ="America/Toronto" '"$TIMESTAMP"

and the file header changed to

#+TIMEZONE: Asia/Shanghai

when they get back the timestamp is returned with
$ TZ=America/Toronto date --date='TZ="Asia/Shanghai" '"$TIMESTAMP"

shiro

[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 228 bytes --]

  reply	other threads:[~2021-04-03  9:28 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-01  7:40 shironeko
2021-04-02 11:34 ` tomas
2021-04-03  0:36   ` Shironeko
2021-04-03  7:56     ` tomas
2021-04-03  8:03       ` shironeko
2021-04-03  8:30         ` tomas
2021-04-03  9:26           ` Shironeko [this message]
2021-04-03 11:23             ` Greg Minshall
2021-04-03 15:00               ` Russell Adams
2021-04-03 18:51                 ` Greg Minshall
2021-04-03 20:06                   ` Samuel Wales
2021-04-03 22:47                   ` Tim Cross
2021-04-04  0:51                     ` Tom Gillespie
2021-04-04 16:06                       ` Maxim Nikulin
2021-04-23  1:45                         ` Shironeko
2021-04-23  7:54                           ` tomas
2021-04-03 12:43             ` tomas
2021-04-03 12:47               ` Shironeko
2021-04-03 13:20                 ` Shironeko
2021-04-02 23:37 ` Tim Cross
2021-04-03  0:31   ` Samuel Wales
2021-04-03  0:43   ` Shironeko
2021-04-03  0:53     ` Samuel Wales
  -- strict thread matches above, loose matches on Subject: below --
2021-03-31  2:23 Shironeko

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: https://www.orgmode.org/

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=bd86bfcf3b3524dc289c2b78549f6594dcca81d6.camel@tesaguri.club \
    --to=shironeko@tesaguri.club \
    --cc=emacs-orgmode@gnu.org \
    --cc=tomas@tuxteam.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

	https://git.savannah.gnu.org/cgit/emacs/org-mode.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).