[texhax] LaTeX hangs up with $(\ref{label})$ and [spanish]{babel}

[Ian Collier]

philip.ratcliffe at uninsubria.it ("Philip G. Ratcliffe") writes:
[someone asked]
>| I have experienced an annoying behaviour of LaTeX.  When I use a reference
>| inside math mode
>| the TeX program hungs up without any error message.  I have reproduced the
>| problem in the small document below.
>| This happens when using  \usepackage[spanish]{babel} and after using \chapter.

>I suspect it has to do with the way the "spanish" package redefines "."
>although I haven't time to delve any deeper.

It is.

The \ref command temporarily sets \@safe at activestrue while it typesets
the reference ("1.1").

The dot has a 8000 mathcode which makes it active within math mode.
It is defined to be "\es at use@shorthand ." which, when \@safe at actives
is true, expands to "\string .", which expands to just "." and so
the loop starts again.
-- 
---- Ian Collier : imc at comlab.ox.ac.uk : WWW page below
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