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

Hans Hagen pragma at wxs.nl
Tue Apr 3 09:03:25 CEST 2007

David Kastrup wrote:
> Anyway, is something like that an area that LuaTeX would actually ever
> consider touching?  After all, it would break document compatibility.
> Which might be, I believe, less of a holy grail for ConTeXt than for
> LaTeX.
in extended mode, when using dimexpr one also gets more precission so a 
switch to etex mode may break backward compatibility anyway

when looking at this aspect, keep in mind that other programs (like 
afm2tfm) also have their special way of truncating/rounding, so as soon 
as one changes tools compatibility

concerning context ... truncating vs rounding is less an issue than 
precission (roundtrip calculations resulting in 1+ sp off comparisons) 
but that is/will be covered with special test stuff

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


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