Re: Changing font weight with buffer-face-mode-invoke

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 27 Jun 2024 10:59:46 +0000
> From: Heime <heimeborgia@protonmail.com>
> Cc: help-gnu-emacs@gnu.org
> 
> > > > Emacs was not designed to support selection of fonts by fine-tuning their
> > > > weight, slant, and other similar attributes, so specifying such fonts works
> > > > in some cases but doesn't work in others.
> > > 
> > > If you do S-<down-mouse-1> to use "Change Buffer Font", one can select those attributes.
> > > I just want to do the same automatically in elisp code.
> > 
> > There's no practical reason for doing so, that's all I'm saying.
> 
> Somehow, the "Change Buffer Font" tool allows selection of that information and
> gets things to work.

No, it doesn't.  It sets things up to use a single font in a single
buffer as the default face's font in that buffer, that's all.  There
are many other situations where fonts are used or passed to various
functions in Emacs, and in quite a few of those using an arbitrary
font with an arbitrary weight or slamt or width will not do what you
expect.

> Could it be that using the :family, :height, :weight is not so rodust, and it is better
> to just use :font ?  How would I call buffer-face-mode-invoke with :font or similar ?

You should use just :family, and perhaps also specify :height.