[XeTeX] Automatic font switching

[nico]

Hello,

Is there a way with xetex to define several fonts for several ranges of  
unicode characters, so that you don't need to put \fontmain for each part  
of a document handling a language needing a specific font (like CJK  
languages)?

If not, is it planned to add such a feature, and when? I just ask, since  
if it does not exist I'll try to wrap the compilation with some kind of  
python script that would insert the macros according to the characters. Of  
course, I would prefer if it could be done by xetex itself.

Thanks,
BG