Re: [emacs-bidi] Re: improving bidi documents display

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 03 Mar 2011 15:11:06 +0900
> From: "Martin J. Dürst" <duerst@it.aoyama.ac.jp>
> CC: Miles Bader <miles@gnu.org>, eli.osherovich@gmail.com, md5i@md5i.com,
>         emacs-bidi@gnu.org, emacs-devel@gnu.org
> 
> >> But isn't the "changed order" natural for the characters it's attached
> >> to?
> >
> > Only in the context of the kind of text (e.g., TeX) it was copied
> > from.
> 
> The copying may work if the feature is switched on for all buffers.

What feature is that?

> The 
> reason for this is that things have to be reevaluated/fixed anyway every 
> time some buffer changes (e.g. insertion or deletion of a character) 
> happens. So if the text is copied to a buffer that doesn't do any 
> explicit reordering on top of the bidi algorithm, the special 
> overlays/properties/whatever will just be purged out.

This is probably a misunderstanding, prompted by the fact that we are
discussing an imaginary feature.

I was talking about a special text property which tells the display
engine to reorder the characters covered by the property.  By default,
text properties are yanked together with the text.  And since yanking
text (as any other insertion) triggers redisplay, the display engine
_will_ notice this special property and _will_ reorder the text it
covers.

As for a buffer that "doesn't do any explicit reordering", I'm not
sure what you mean.  The current plans are to turn on the bidi
reordering in all buffers by default.  Whether this constitutes
"explicit reordering", I'm not sure, so I don't understand what you
mean, and I also don't see how is that relevant to the effect of
copying the text properties.

If you suggest that this specific property should be stripped off by
yanking, i.e. to add them to yank-excluded-properties, then it's
possible, but not necessarily DWIM-ish, because yanking in the same
buffer would need to leave these properties intact.