[Dev-luatex] A design philosophy question...

Taco Hoekwater taco at elvenkind.com
Tue Apr 3 10:29:55 CEST 2007

David Kastrup wrote:
> (in fact, it is a **** nuisance that [dimexpr] integer 
> division rounds instead of truncating).

I agree, but that is a completely different problem.

>> concerning latex and old docs ... there will always be pdftex vs <
>> 2, so with luatex we have no intention to be 100% downward
>> compatible at all (some internals may also be adapted / extended /
>> opened up, some good old tex code may disappear (lig rebuilding
>> already has), etc
> Interesting.  What do you do instead of ligature rebuilding?

What has happened already is that ligature replacement and kerning
are totally separated inside luatex: at font loading time, the
ligkern information from the tfm metrics is split into ligatures
and kernings. This means there are changes inside main_control()
and reconstitute(). The reconstitution process was not 'perfect'
before, and that now makes it hard to ascertain wether the new
code is 100% identical. I think so, but I am not willing to bet
on it.

What will happen soon is that alternative implementation will become
used for the hyphenation algorithm: one that does not limit words
to 64 characters arbitrarily, and that allows pattern loading and
augmenting at run-time.

And there will likely be more changes along these lines.


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