Re: Supporting stylistic sets

[Eli Zaretskii]

> From: समीर सिंह Sameer Singh <lumarzeli30@gmail.com>
> Date: Fri, 23 Sep 2022 22:57:41 +0530
> Cc: emacs-devel@gnu.org
> 
>  How did you envision this font property to be used in Emacs?
> 
>  The etc/TODO item for that suggests to implement this as a text
>  property instead.  That is, of course, not carved in stone, but I
>  think we should in any case decide on how this will be used from Lisp
>  before we talk about how to expose it to Lisp.
> 
> I imagined that it would be something like this:
> 
>   (set-fontset-font t 'bengali
>    (font-spec :family "Tiro Bangla"
>       :stylistic-set '("ss03")))
> 
>   (set-face-attribute 'default nil
>      :font "Fira Code"
>      :weight 'regular
>      :height 170
>      :stylistic-set '("cv01" "ss05" "ss03"))
> 
> Just like how weight, foundry, size etc are set and they seem to be font 
> properties.

That means all text that uses the font will use that stylistic-set.
Is that good enough?  What if you want to have the same font with and
without a specific stylistic-set in the same document?.

And if the font is not the default face's font, it means you need to
setup a special face for using it anyway.

So I think a font attribute is not flexible enough for Emacs.  But I'm
interested in what others think.