[tex-hyphen] versioning hyphenation patterns

[Javier Múgica]

> > > BTW, is LuaTeX able to merge different pattern files on the fly, e.g., a
> > language pattern file with a pattern file for domain specific notions?
>
> Yes, but once merged that becomes a language, and there is no crossover
> between languages. So if you have <common> patterns, as well as <ext_a>,
>   and <ext_b> supplements, then both languages <a> and <b> have to load
> <common> as well as the <ext> file (I hope this makes sense).
>
> Best wishes,
> Taco

Good to have it. I did exactly that for Galician some time ago, where
<ext_a>, <ext_b>... where geology, medicine ... , but due to the
limitation of loading patterns only at format generation I had to
comment lines like

%\input glgeol.tex

in the <common> patterns generating file, and if the user wanted would
have to remove the comments and generate the format again. To be
sincere, I suspect that nobody in Galicia other than me is aware of
that possibility.
Since LuaTeX is able to merge different pattern files on the fly it
will be easier; the <extra> patterns would be easily loaded by a
package, without the user need to know aobut format generation,
patterns... and the like low level features that we don't want the
poor end user to tell he must know.

Regards,
Javier