Re: Dependent colours

[Eli Zaretskii <eliz@gnu.org>]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Thu, 14 Apr 2022 15:00:55 +0200
> 
> In many situations, packages and users need to specify colours to use
> for something.  We generally defer this to the face machinery, because
> which colours to use for something might depend on whether you have a
> light or dark background, or whether it's a GUI Emacs or a terminal one,
> etc.
> 
> This works well as a machinery, but it's pretty cumbersome when the user
> just wants to specify a list of colours.
> 
> So I'm wondering whether we could create something that would make
> things easier for the user here, and if anybody had any thoughts on the
> issue.
> 
> Off the top of my head...  if we had something like
> 
> (make-color "red")
> 
> (make-color ((background light) "blue")
>             ((background dark) "red"))
> 
> Uhm...  Or something...  better...  :-)

I'm not sure I understand: we already have anonymous faces one can get
by specifying just the colors, as in

  '(:foreground "red" :background "blue")

Why is that not enough?