Re: [PATCH] Make display-time-mode time zone configurable

[Mark Oteiza]

On 18/02/16 at 08:57pm, Paul Eggert wrote:
> Mark Oteiza wrote:
> > lots of time-related things are fragmented across Emacs.
> 
> Yes, too fragmented. People have added individual features without knowing
> about the other uses.
> 
> > This patch just conveniently exposes the ZONE feature in
> > display-time-mode in the same way time-stamp-time-zone does in
> > time-stamp.el.  Would it make sense to put a defcustom in (I guess)
> > time.el and have time-stamp.el use it?
> 
> On second thought, probably not. time-stamp.el is about time stamps in
> files, where it makes sense to (for example) standardize on UTC time stamps
> for ease of sharing files with people in other time zones.
> 
> The proposed display-time-zone, on the other hand, is about time stamps in
> the user display. This makes less sense to me, as the user display should
> use consistent time stamps and there are many other ways to display time. I
> suppose the use case would be something like "Although for most purposes
> Emacs should behave as if the time zone is X, the mode line should sometimes
> but not always use time zone Y". Why would the user want that?

My first thought of a use-case is simply keeping time zone in the mode
line the same regardless of what the system time (or local time) may be,
akin to not changing one's watch when travelling.

Alternatively, similar to standardizing on one a particular time zone in
time-stamp.el, it may also be desirable in a privacy sense to
standardize the rest of Emacs' time displays (e.g. time stamps in email
or other network connections) to another time zone but still keep the
"wall clock" (meaning display-time-mode) as local time.

> Does display-time-world address the use case you're interested in? If not,
> what is display-time-world missing?

display-time-world is a one-off popup buffer, whereas display-time-mode lives
in the mode-line, so no.