Re: display table for eight-bit-graphic

[Kenichi Handa <handa@m17n.org>]

In article <E18coqR-0001T9-00@fencepost.gnu.org>, Richard Stallman <rms@gnu.org> writes:
>     But, I've just found that standard-display-table is setup
>     when we start Emacs with any locale of single byte charset
>     (e.g. iso-8859-1).  It seems that it is done intentionally
>     by set-locale-environment as below.

> The reason for this is probably for the sake of unibyte buffers.
> This way, people who don't like MULE and use Emacs in unibyte
> mode with European character sets get the same behavior as before.

I don't think so.  See this comment again:

	  ;; If default-enable-multibyte-characters is nil,
	  ;; we are using single-byte characters,
	  ;; so the display table and terminal coding system are irrelevant.
	  (when default-enable-multibyte-characters
	    (set-display-table-and-terminal-coding-system language-name))

It seesm that the intention is to use the display table for
multibyte buffers.

> In the past, this code only affected unibyte buffers because those
> character codes 128-255 normally only appeared in them.  But nowadays,
> all those codes are normal in multibyte buffers too.  The display
> table treats each code the same way regardless of whether it comes
> from a unibyte buffer or a multibyte buffer.

Yes.  I don't object to the currently behaviour of display
table itself.  If one really wants to see
eight-bit-control/graphic chars in a multibyte buffer by
some glyph, it's ok to use display table as he wishes.

What I object is to setting up the display table as now by default.

kai.grossjohann@uni-duisburg.de (Kai Großjohann) writes:
> "Ehud Karni" <ehud@unix.mvs.co.il> writes:

>>  I agree. For persons in the ISO-8859-x languages, the 8 bit graphics
>>  is much better than the octal representation.

> I do not agree that displaying the graphics is better.

> It might seem so at first sight, but there are problems later on: for
> instance, you can't search for the 8bit graphics characters by typing
> Latin-1 characters, and people will surely be *very* surprised that
> they can't find their characters!

I agree with that.  Showing different characters by the same
glyph is the source of confusion at least for novice users.
First of all, 8-bit characters should not appear in a
multibyte buffer usually.  It it does, mainly it's because
of a bug of some program, on in a case that it should be
treated as raw bytes, not as characters.  In both cases, it
is better that they are not displayed as graphics.

> Maybe it would be useful to highlight the graphics characters in some
> way so that it is clear that they aren't normal characters.

I'm not sure that is a good idea.  Highlighting means many
things.  Octal displaying is far better to indicate that
they aren't normal characters.

---
Ken'ichi HANDA
handa@m17n.org