Re: Working with colors in --batch mode

["Kévin Le Gouguec" <kevin.legouguec@gmail.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> Date: Sun, 25 Dec 2022 20:05:59 +0200
>> From: Eli Zaretskii <eliz@gnu.org>
>> 
>> Emacs doesn't (and cannot, I think) load X colors unless it
>> initializes the X display, and that doesn't happen in batch sessions.
>> Basically, batch sessions behave like a colorless TTY session.
>
> Btw, I don't really understand why you need the X machinery for this.
> Doesn't tty-color-standard-values do the job?
>
>  $ emacs -batch --eval "(message \"%s\" (tty-color-standard-values \"#abcdef\"))"
>   => (43947 52685 61423)

Because this message is the latest step in a longer journey that started
with me trying to call modus-themes-contrast in batch mode, as hinted in
the OP.

So I hope to find a solution that will let me keep calling this
high-level function, instead of re-implementing it and its callees
(e.g. color-name-to-rgb).

Thanks for weighing in; it's not obvious to me yet that there's no way
to ask emacs --batch to --eval its way into initializing the X display,
but I may well end up reaching that conclusion after more digging.