Re: Impossible to customize world clock

[Eli Zaretskii]

> Date: Tue, 09 Apr 2024 09:46:21 -0400
> From:  Stefan Monnier via Users list for the GNU Emacs text editor 
> <help-gnu-emacs@gnu.org>
> 
> > On MS-Windows, one should customize legacy-style-world-list instead.
> 
> Hmm... it's too bad that in order to automatically make it work on both
> MS-Windows and other systems (by automatically choosing which var to
> use) we end up silently ignoring the user's config when the user isn't
> aware of this mechanism.
> 
> Maybe we should have chosen for `world-clock-list` a format like
> 
>     ("London" "Europe/London" "GMT0BST")

I'm not sure it will work reliably, since the MS-Windows runtime
supports a very small number of zones via those legacy specifiers,
nowhere near the number of zones you will see in the zoneinfo
directory of a typical Posix host.

The more capable modern Windows time zones are arranged differently,
not by city (with a few exceptions), and have different names.  The
conversion between the Posix time zones and Windows time zones is thus
not trivial (but patches for doing that will be most welcome).  As
long as we go only by Posix names, I don't see how we can have a
single structure with both Posix and Windows descriptors.