[lltx] pattern loading in luatex (was: pTeX-compatible hyphenation patterns)

[Stephan Hennig]

[moving to lualatex list]

schrieb Mojca Miklavec:

>> For LuaTeX, are the new German patterns currently held twice in
>> memory, e.g., as language ngerman (via hyph-utf8) and
>> dehyphn-x-2009-06-19 (via dehyph-exptl)?
> 
> They are not held in memory at all (the synonyms are), they are
> loaded on demand. However in XeTeX they are (the same patterns are
> first loaded as ngerman and then as dehyphn-x-2009-06-19; once from
> out package and once from yours).

That is interesting.  With LuaTeX being able to load patterns at
run-time, there are now three different pattern loading strategies
possible (that I can think of):

  1.  Load all patterns in the format.

  2.  Load all patterns unconditionally at start-up, but only
      after loading the format.

  3.  Load requested patterns on demand.

Strategy 2 would already decouple patterns from the format and be a step
into the direction of strategy 3.  My impression was (for whatever
reason), that lualatex uses strategy 2 or at least it did once.  Is it
really true that, now, lualatex loads only requested patterns on demand,
that is, it uses strategy 3?

(Hm, is that what Manuel did before the TL 2010 release?  I'm surely not
following your efforts closely enough.)

Best regards,
Stephan Hennig