# [luatex] Logging of font names in box log output

Hans Hagen pragma at wxs.nl
Wed Sep 9 01:28:21 CEST 2015

```Hi,

> you do? interesting:-) I'll dig out the sources and see what's
happening there!

it's a long time ago that i looked into this but i remember that this \a
\b vs \a \a in tex is some kind of side effect (not a feature) ... the
\a getting lost in the process as the message has to use the font id to
get back to the \cs and

\font\a=cmr10
\font\b=cmr10

will (without callbacks) have the same id as the same file is used

i have of course a callback but the latex otf loader also does (maybe
not for tfm files, so maybe you should test what an opentype file reports

so say that \a -> font id 10 and \b -> font id 10 then basically 10
relates to \b (the most recent) but if you get \a \b instead of \b \b
that can be an indication that the latex font loaded forces a different
id (which can be practical in some cases) .. the fontloader can of
course still use the same font resource

you can check it with:

\a \number\fontid\font
\b \number\fontid\font

if they're different then you know it's the fontloader cheating you

Hans

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