> Cc: Michael Blaustein <[EMAIL PROTECTED]>, [email protected] > From: David Kastrup <[EMAIL PROTECTED]> > Date: Fri, 30 Mar 2007 13:54:09 +0200 > > Eli Zaretskii <[EMAIL PROTECTED]> writes: > > >> Date: Thu, 29 Mar 2007 23:34:49 -0400 > >> From: Michael Blaustein <[EMAIL PROTECTED]> > >> Cc: David Kastrup <[EMAIL PROTECTED]>, [email protected] > >> > >> It's not that bad! (Assuming you mean emacs-bidi-0.9.1 at > >> www.m17n.org.) > > > > No, that's not what I meant. David was asking about the bidi branch > > of the Emacs CVS, which has nothing in common with the m17n version. > > As far as I can tell, m17n provides a Mule based on 20.x, or on a 21 > pretest at most. > > Hard to figure out. That code likely is not of much help, right?
There's some history to the m17n bidi version. A patch to handle bidi display was submitted to Emacs back when v21.1 was in last stages of development. It was rejected (based on negative reaction of Gerd Moellmann, the then head maintainer and the main developer of the v21 display engine) because it used techniques that defeated all the usual display optimizations used by Emacs, such as when you just move the cursor or insert or delete a single character. The patch also used a constant-size buffer to stack characters while they were being reordered -- which doesn't scale well to very long lines. The discussions that followed prompted me to design and implement a bidi reordering engine that was crafted from the ground up to be compatible with the Emacs redisplay requirements. (It wasn't easy, since UAX#9 describes the reordering in a way that assumes batch-style mechanism, i.e. that a string of characters is passed to the engine and is expected to be reordered by the engine en-bloc. By contrast, Emacs wants to reorder characters one by one, as it walks its iterator through buffer text.) I understand that the rejected patch later became the basis for what you now find on the m17n site. In retrospect, perhaps that decision to reject the m17n patch was a bad call, since we could have had a bidi Emacs in v21.x, and gather valuable user experience by now. But Gerd felt very strongly about his opposition, and I at least trusted his judgment, since no one knew the Emacs display engine as well as he did, maybe still don't. _______________________________________________ emacs-bidi mailing list [email protected] http://lists.gnu.org/mailman/listinfo/emacs-bidi
