[XeTeX] additional beginL endL nodes in math

[Khaled Hosny]

On Wed, Apr 15, 2015 at 08:44:12PM +0100, David Carlisle wrote:
> On 15 April 2015 at 20:05, Khaled Hosny <khaledhosny at eglug.org> wrote:
> > On Wed, Apr 15, 2015 at 04:29:47PM +0100, David Carlisle wrote:
> >> Is there no other way that the issues you have could be addressed
> >> without introducing TeX-XeT?
> >
> > I first reported this issue in 2008, 7 years ago, so it seems it is not
> > going to go way magically, much to my surprise. Peter Breitenlohner
> > became aware of this issue 2 years ago and a fix were promised but
> > nothing so far (not that I blame him).
> 
> That was the question really,  is there a pointer to which issue this is fixing
> sorry I don't know my way round the xetex issue control that well:-)

https://sourceforge.net/p/xetex/bugs/11/

(and numerous reports elsewhere)

But basically, eTeX’s TeX--XeT reverses all the nodes between
\beginR/\endR unconditionally, so if you are using specials for e.g.
color or hyperlinks, the “end” whatsit nodes will end up before the
“start” ones, causing all sorts of breakage. The same is true for
\openin/\read or \openout/\write pairs, they will be reversed and
executed in the wrong order.

> > AFAICS, a port from Omega model is unlikely to happen, it is a big
> > invasive change and is as untested as the TeX-XeT model and has its own
> > share of problems, and, more importantly, no one seems to be stepping up
> > to do the required work.
> 
> Yes not surprised, really but still, having two incompatible direction systems
> causes complications for cross-engine format like latex, and having three
> incompatible mechanisms instead isn't exactly an ideal change.

It is either that or live with dysfunctional right-to-left support in
XeTeX, it is obvious which one I’m going to chose, sorry.

Regards,
Khaled