"Themes" shipping configuration - an unusual convention

[Stefan Kangas]

Stefan Monnier <address@hidden> writes:

> > The pre-configuration could contain just one line:
> >
> >   (require 'shiny-settings)
>
> Nitpick: `require` is *really* not the right job since just loading
> a file should not change Emacs's behavior substantially.
>
> Ideally, it should be a custom-theme, but second best could be
> a minor-mode.

So a theme can be used to change configuration, and indeed this is the
recommended way to do it.  Interesting, and news to me.  But is this a
good convention?  I'm not so sure.

AFAIK, all other applications I have used understand "theme" to mean a
"package containing graphical appearance details".  This definition
from Wikipedia: https://en.wikipedia.org/wiki/Theme_(computing)

I don't think users will expect a "theme" to modify the behavior of
Emacs.  There are usually things called "profiles" where one would
save or load settings from.  This means that if M-x load-theme changes
the behavior of Emacs (significantly or otherwise), they are in for a
surprise.

I would propose to change the convention such that a "theme" is only
meant to modify "graphical appearance details".   Not behavior.  (From
what I can tell, all themes currently shipped with Emacs follow this
convention.[1])

We could introduce a *separate* convention, called e.g. "custom
profiles", which are understood to also change settings.  They could
have their own directory in our tree called "etc/profiles", and
separate commands to load them (say, M-x load-profile).

Of course, a "custom profile" could technically do anything a "theme"
does and vice versa.  Just as a 'require'd package can technically
override any face, enable viper-mode or whatever.  But we should
discourage that.

Best regards,
Stefan Kangas

PS. If anyone can point to an example of a "custom theme" that ships
settings, it would be interesting to see it.

Footnotes:
1. The exception is some variables related to graphical display, which
is not unusual or surprising to my mind.