From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: W. Greenhouse Newsgroups: gmane.emacs.devel Subject: Re: [PATCH] Make display-time-mode time zone configurable Date: Tue, 16 Feb 2016 14:33:57 +0000 Organization: I need to put my ORGANIZATION here. 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X-Received-From: 80.91.229.3 X-BeenThere: emacs-devel-mXXj517/zsQ@public.gmane.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org-mXXj517/zsQ@public.gmane.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org-mXXj517/zsQ@public.gmane.org Xref: news.gmane.org gmane.emacs.devel:200033 Archived-At: Paul Eggert writes: > Mark Oteiza wrote: >> +(defcustom display-time-zone nil >> + "Variable specifying the time zone used in `display-time-string-forms'. >> +See the function `format-time-string' for an explanation of >> +its ZONE variable." >> + :type '(choice (const :tag "Emacs Local Time" nil) >> + (const :tag "Universal Time" t) >> + (const :tag "System Wall Clock Time" wall) >> + (string "Time Zone Rule")) >> + :link '(function-link format-time-string) >> + :group 'display-time) > > This new defcustom seems to duplicate some or all of the existing > defcustom time-stamp-time-zone. Should there be just custom var? or if > there should be two, how should they differ in operation? The purpose of these seems a bit different. `display-time' is for the user to have a wall clock in the privacy of their own Emacs; the `time-stamp' package, as I understand, is for adding timestamped notes to files, which one is probably sharing with others (and a collaborative project might have some convention about what time zone should be used for recording activity). So they don't really do the same job, and it's a good idea for the user to be able to set them differently. Also, as far as parts of Emacs that deal with time zones, there's also `calendar-time-zone', which uses a totally different format (offset in minutes, instead of zoneinfo-style names)! The calendar also seems to NIH the handling of daylight saving time. Mark submitted this patch after a conversation we had on IRC about how, despite the recent addition of timezone support to `format-time-string', it was still difficult without bad kludges for me to get a local wall clock on an Emacs whose system time had to remain UTC. It might not be desirable for various reasons to alter the "TZ" environment variable for Emacs, which would propagate itself to all subprocesses run by Emacs, and it might also not be right to change the zone with `set-time-zone-rule', which would e.g. result in sending out emails as local time, not UTC. Now that I understand the role of `display-time-string-forms', I can fix the problem for myself there without Mark's proposed defcustom, but the defcustom raises visibility a lot for others who might have the same desired wall-clock configuration as I.