[luatex] callbacks in luatex 0.89

[Ulrike Fischer]

Am Thu, 11 Feb 2016 20:04:52 +0100 schrieb Hans Hagen:

> On 2/11/2016 6:00 PM, Ulrike Fischer wrote:
>> Am Thu, 11 Feb 2016 14:53:11 +0100 schrieb Hans Hagen:
>>
>>>> Is there in context code which offers something similar to
>>>> \XeTeXinterchartoks? That means can one declare (unicode)
>>>> blocks/classes of characters and tokens (e.g. font switches,
>>>> language switches etc) which should be inserted between character of
>>>> different blocks?
>>>>
>>>> If yes, where is it?
>>>
>>> No, because it's not the way context does things (or at least I never
>>> needed it so I never bothered to look into writing it). I would probably
>>> look into it when there was demand for some feature not supported yet.
>>> Even then I'd probably not rely interpreting unicode characters but on
>>> proper tagging because one never knows what the intended use/rendering
>>> of some character at some point it.
> 
>> Proper tagging is naturally always more reliable. But I can
>> understand that people who write e.g. a mix of chinese with some
>> english/ascii and need to switch fonts don't want to tag all the
>> time. That can get a bit tiring, also it is error prone.
> 
> (context users are advised to quit reading here)

I'm feeling like the wild girl who spoils the wellbehaved children
;-)

> well, as the latin mixed in chinese text often looks quite horrible i 
> assume basemode will do so you can make a file
> 
>    crapfont.lua

This works fine in context but not with plain or latex in a current
texlive, I get a "metric data not found or bad" error. So it
problably uses either features not present in the generic fontloader
of luaotfload, or features of a newer luatex. How stable is the
code? Will it still work in context in a year?

But beside this I think it doesn't address the real problem. This is
obviously not a replacement for proper tagging as it simply wants to
avoid the need by using a better (fuller) font. But when you switch
from chinese to english, the font is only one of the things that
users probably want to do. Perhaps they want to changes spaces
(around punctuation), fixed names, hyphenations patterns, add some
pdf specials etc ...  


luatexja has the ability to mix fonts (e.g.
http://tex.stackexchange.com/a/68252/2388), but I have no idea how
they do it (most documentation is in japan).


-- 
Ulrike Fischer 
http://www.troubleshooting-tex.de/