Text Formatting ⇒ Xelatex \,

[Laurentius]

I tried running Xelatex from the command line and entering

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\show\,

which returned

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> \,=macro:
->\x@protect \,\protect \,  .

What does this mean? To the uninitiated it looks like the macro is defined in terms of itself.

Thanks.

[Johannes_B]

show can be very helpful, but if i know where a command is comming from, i go to the source and have a look.

Take a look at section 16.6 of source2e.pdf (horizontal space) or take at latex.ltx how \, is defined.

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\DeclareRobustCommand{\,}{%
   \relax\ifmmode\mskip\thinmuskip\else\thinspace\fi
}

[cgnieder]

\show with macros which are robust in the 2e-sense can be a bit frustrating: they usually have definitions like the one you're seeing:

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\show\foo
% > \foo=macro:
% ->\protect \foo  .

What is a bit hidden there is that the name of the internal command \foo includes a trailing space! In such cases a trick can help:

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\begingroup
\let\protect\show \foo
\endgroup

Locally redefine \protect to mean \show and then call the command.

In this very case we also need to disable \x@protect in a way that it eats the following \,:

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\documentclass{article}

\begin{document}

\show\,
% > \,=macro:
% ->\x@protect \,\protect \,  .

\begingroup\makeatletter
\let\x@protect\@gobble\let\protect\show\,
% > \, =\long macro:
% ->\relax \ifmmode \mskip \thinmuskip \else \thinspace \fi .
\endgroup

\end{document}

Regards