From mboxrd@z Thu Jan 1 00:00:00 1970 From: Left Right Subject: Re: Time-zone in dates Date: Thu, 2 Jul 2015 01:17:21 +0300 Message-ID: References: <87zj3moadx.fsf@gmail.com> <87zj3mv9rb.fsf@ucl.ac.uk> <87ioaav72g.fsf@ucl.ac.uk> <87y4j6tgyn.fsf@nicolasgoaziou.fr> <20150626195749.GG5090@fjo-extia-HPdeb> <87zj3iodr4.fsf@ucl.ac.uk> <87egkugfjw.fsf@pierrot.dokosmarshall.org> <878ub1zlzy.fsf@delle7240.chemeng.ucl.ac.uk> <87lhf1i68s.fsf@alphaville.usersys.redhat.com> <87fv581jfv.fsf@ucl.ac.uk> <87d20bj4aq.fsf@alphaville.usersys.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Received: from eggs.gnu.org ([2001:4830:134:3::10]:35688) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZAQJn-0003fS-4O for emacs-orgmode@gnu.org; Wed, 01 Jul 2015 18:17:24 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZAQJl-000392-Vw for emacs-orgmode@gnu.org; Wed, 01 Jul 2015 18:17:23 -0400 Received: from mail-qk0-x233.google.com ([2607:f8b0:400d:c09::233]:36617) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZAQJl-00038q-QA for emacs-orgmode@gnu.org; Wed, 01 Jul 2015 18:17:21 -0400 Received: by qkei195 with SMTP id i195so40141812qke.3 for ; Wed, 01 Jul 2015 15:17:21 -0700 (PDT) In-Reply-To: <87d20bj4aq.fsf@alphaville.usersys.redhat.com> List-Id: "General discussions about Org-mode." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-orgmode-bounces+geo-emacs-orgmode=m.gmane.org@gnu.org Sender: emacs-orgmode-bounces+geo-emacs-orgmode=m.gmane.org@gnu.org To: Nick Dokos Cc: emacs-orgmode@gnu.org My initial case was very similar to the one Michael described in the telepresence example, except that in my case, I need to assign shifts to people living in different timezones. I.e. I need to make sure that a shift assigned to someone in Illinois will end at the same time when the shift of someone from California begins. One way of doing this is to set all times in UTC+0, but some of us (especially myself :) live very close to UTC+0, so I can accidentally confuse my local time with the universal time. It would be also nicer if shifts were in the local time of people assigned to them too. On Wed, Jul 1, 2015 at 6:17 PM, Nick Dokos wrote: > Eric S Fraga writes: > >> On Tuesday, 30 Jun 2015 at 11:08, Nick Dokos wrote: >>> Eric S Fraga writes: >>> >>>> On Monday, 29 Jun 2015 at 21:17, Nick Dokos wrote: >>>>> The only reliable way of doing that is to use UTC as the "internal" >>>>> representation and translate to/from local time on external >>>>> display/input *only*. In the case of org mode, the "internal" >>>>> representation is user-visible, so that can cause confusion and some >>>>> head-scratching. But *any* other method is going to be a nightmare >>>>> (damhikt). >>>> >>>> This may be the correct approach although I worry about losing >>>> information by only storing UTC. Whether this information loss is >>>> important or not is difficult to predict. It may be of ephemeral >>>> importance only. >>> >>> In what way are you losing information? >> >> Sorry, should have been clear: the time zone information itself. By >> reducing to UTC, you lose one bit of information. Whether that matters >> or not in practice is not clear but I'm always uncomfortable when >> considering data representations that lead to information loss. >> >> I've been trying to come up with an example that would illustrate the >> problem but I've failed so far. >> >> Funnily enough, the one example I can think of that would be difficult >> to manage with UTC is the case of not wanting to specify a time >> zone. Somewhat contrived but, for instance, wanting to do something >> every morning such as brushing my teeth. This would be, say, at 7am >> regardless of which time zone I'm in. If this were stored in UTC, it >> would be at a different time depending on where I was at the time. >> > > This is actually a pretty good example. This and Michael Brand's examples > make it clear that storing (just) UTC in the file is untenable. > > Nick > > > > >