On Tue, Jul 19, 2011 at 11:21:20AM -0600, Idris Samawi Hamid ادريس سماوي حامد wrote: > Salaam, Vafa, all > > On Tue, 19 Jul 2011 02:24:02 -0600, Vafa Khalighi <[email protected]> > wrote: > > >True but at least I think luatex can provides something similar to what > >XeTeX provides by its ICU layout engine and the rest (which obviously is > >much complicated and needs more testing) can be done either by a > >preprocessor or done entirely in lua. > > > > > >Which thereby makes a generic solution impossible. Omega translation > >>processing struggled with this mix of 'pure text', 'macro expansion', > >>'packages content' and it never worked out in complex situations. For me > >>this is a pretty good reason for not adding any hard coded bidi > >>(or foo or > >>bar or whatever) behavior to core luatex but stick to either external > >>libraries (preprocessing or whatever) and/or solutions written > >>in lua that > >>nicely interact with the macro packages concepts. (Well, that's the main > >>reason for having lua as extension language in the first place). > > I am feeling deja vu here ;-) > > We must all remember that luatex has a different philosophy from xetex > etc. luatex provides the most basic, low-level, bi-directionality as > perfectly as possible. > > OTOH, luatex is _not_ interested in deifying any particular paradigm of > rules for processing bidi text. Compare with the Open Type engine: That's > done by lua extensions. Similarly, bidi in mkiv will be done by lua > extensions which can easily be modified and parameterized as needed. > > For example, I may want to use Arabic-numerals in a Persian-typesetting > context or vice versa. Hardcoding the bidi algorithm makes that > inconvenient.
Though I'm generally OK with a lua solution, I don't see how the choice of numerals has any effect on the choice of bidi implementation. > Also, the bidi algorithm is not perfect: it mixes the needs > of an editor or verbatim mode with those of real life typography. These > features should be flexible and capable of being turned on and off. > Consider an Arabic paragraph that's all in Arabic except the first word in > English. It makes no sense to force an LR par in that case. The algorithm actually has a dedicated rule of this use case: http://www.unicode.org/reports/tr9/#Higher-Level_Protocols Regards, Khaled -- Khaled Hosny Egyptian Arab
