Re: Buffer names with R2L characters

[Eli Zaretskii <eliz@gnu.org>]

> Date: Tue, 21 Jun 2011 19:52:18 +0300
> From: "Ehud Karni" <ehud@unix.mvs.co.il>
> Cc: emacs-devel@gnu.org, monnier@iro.umontreal.ca, cloos@jhcloos.com,
>         stephen@xemacs.org, miles@gnu.org
> 
> >   2>FEDCBA>
> >
> > [snip]
> >
> > I can fix this .... by appending a suitable character to the end of
> > the string (after the numeric tail) and making it invisible with text
> > properties.
> 
> The "right" way to fix this is to have the buffer name between 2 zero
> width LRM characters.

First, why do we need the LRM at the beginning?  The mode line is
formatted with L2R "paragraph direction", so the leading LRM is
unneeded (though won't do any harm).  The "*Buffer List*" buffer is
forced to use L2R paragraph direction as well, so the leading LRM is
not needed there as well.

And second, what do you mean by "zero width"?  The current facilities
let me change the LRM display only globally, so I cannot make these
LRM characters zero-width only in the mode line -- they will be
displayed as such in all the buffers and strings.  Moreover, I'm not
sure TTYs support zero-width.

Instead, I propose to make the LRM invisible.  This is supported on
all display types.

> I think Eli is wrong here. An example will help, a file with the
> (logical) name "/abc/def GHIK/LMNO qrst" when uniquified will appear
> as: "def ONML|KIHG qrst" which is clearly wrong.
> 
> My way to solve it is as above, i.e. add zero width LRM on both sides
> of the separator (/ or |) in addition to the enclosing LRMs.

I think this is beginning to become gross.

> The problem is even greater in `dired' with files that have ALL Hebrew
> names. If you have a Hebrew locale, the date has Hebrew in it (the
> month name) then it has some digits and ":" (all neutrals and weak
> L2R ) and then the file name. The bidi algorithm actually exchange
> the month and file name.

Yes, Dired (and other similar modes) will "need work" (TM) to give a
plausible display with bidi.  Patches are welcome.