bug#57693: 29.0.50; Is there a more reliable version of `char-displayable-p'?

[Ihor Radchenko <yantar92@posteo.net>]

Eli Zaretskii <eliz@gnu.org> writes:

> We already have something like that: see glyphless-char-display and
> glyphless-char-display-mode.

Thanks for the pointer! This sounds like a suitable approach when
displaying "fancy" characters.

> The problem is that (a) on GUI displays
> the replacement will be displayed in a box; (b) the replacement must
> be an ASCII character; and (c) the char-table we use for that is
> global, i.e. it affects the entire session.  But if someone wants a
> more flexible feature which lifts some of those restrictions, that's
> the place to start nonetheless.

What about

1. Allowing the char-table to be buffer-local or within text-properties
2. Making (set-char-table-range glyphless-char-display ?A ?B) work on
   GUI as well, not just in terminals
3. Making the rules recursive.
   So that setting something like
   (set-char-table-range glyphless-char-display ?A "1")
   (set-char-table-range glyphless-char-display ?1 "2")
   will display "A" as "2" (A->1->2)

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>