Re: tabulated-list-init-header and glyphless-char-display

[Eli Zaretskii <eliz@gnu.org>]

> From: Chong Yidong <cyd@stupidchicken.com>
> Cc: Stefan Monnier <monnier@iro.umontreal.ca>,  emacs-devel@gnu.org
> Date: Sun, 10 Apr 2011 11:47:58 -0400
> 
> > No, "glyphless" and "without a font" are (and should be) synonyms.
> > Except that on a text terminal, "without a font" means "cannot be
> > encoded for the current terminal encoding".
> 
> That's apparently not how glyphless-char-display works.  The docstring
> is a bit ambiguous, but glyphless-char-display actually *defines* the
> characters that cannot be displayed in an ordinary way.

Yes.

> For instance,
> if you do (aset glyphless-char-display ?a 'empty-box), that tells Emacs
> that "a" is a glyphless character, and causes all "a"'s to be displayed
> as empty boxes.

That's right, but why would you do something like that with a
characters that is perfectly displayable?  You should only do that
with characters that cannot be displayed, like unencodable characters
on a tty.  That's what I was trying to convey; sorry if I failed to
get that across.

> What you are thinking of is a char table that says "how should we
> display character C if it has no font", but AFAICT there is currently no
> such facility.

glyphless-char-display is such a facility, but it is not automatic, it
needs too be filled with appropriate values.  At least the fact that a
character cannot be displayed normally is determined automatically.

Btw, I'm not sure how all this is related to the issue at hand.