[XeTeX] [EXT] A LaTeX Unicode initialization desire/question/suggestion

Philip Taylor P.Taylor at Rhul.Ac.Uk
Sat Jan 11 10:05:33 CET 2020

Doug McKenna wrote:
> The solution, I think, is pretty easy.
> "load-unicode-data.tex" already tests for certain compatibility conditions and short-circuits itself accordingly.  Its first executable lines are:
> % The data can only be loaded by Unicode engines. Currently this is limited to
> % XeTeX and LuaTeX, both of which define \Umathcode.
> \ifx\Umathcode\undefined
>    \expandafter\endinput
> \fi
> % Just in case, check for the e-TeX extensions.
> \ifx\eTeXversion\undefined
>    \expandafter\endinput
> \fi
> But the first of these tests is no longer a good test, because JSBox is a Unicode/eTeX engine that does implement \Umathcode but has no need nor desire to execute this file because JSBox's mapping tables have *already* been initialized before any TeX code is ever pushed onto its execution stack, the same as classic TeX does for simple one-byte characters.
How about delaying the definition of \Umathcode until after 
"load-unicode-data.tex" has been processed ?  Is that possible, and 
would it have undesirable side-effects ?

Philip Taylor

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