Re: bidi-display-reordering is now non-nil by default

[David Kastrup]

Stefan Monnier <address@hidden> writes:

>> Emacs should really avoid formatting things with L2R marks that are not
>> actually required.
>
> And then
>
>> Is there a reason nobody responded to my repeated proposal to let
>> `format' deal with inserting L2R marks?
>
> AFAICT these two are contradictory.

If "format" creates a pure L2R string, it will not insert directional
marks.  That is rather simple.

When it puts stuff together that would make cause changes of
directionality from inside a field to outside, it would insert marks to
avoid this.  So format("%sx", v) would not be equivalent to concat(v,
"x").  Something like format("%\\sx", v) might: one would try to make
some modifier for "don't insert directional marks".

> To only insert them when they are really needed, we need additional
> hints that only a human can give.

To get a hit rate of 100%, sure, nothing but human intervention will do.
But if the point is to get behavior that is rather close to optimal
without regressions for L2R texts and without human intervention
everywhere, addressing format is going to give a good start.  Where is
the sense in fields like %-10.10s" if format is going to cut off a
directional mark the user added for proper display?  If format is the
entity inserting the mark in the first place, at least this will go less
wrong.

> But in any case, the bidi support in Emacs-24.1 is just a first step.
> Clearly we'll need more work to make it work well.

Nothing wrong with that.  I'd like to avoid a situation where we'll need
to backpaddle to make it work well.

-- 
David Kastrup