[texhax] \emph in

[Wolfgang Lorenz]

Hi list,

While writing some kind of saving mechanism using the \edef macro I
came to a point, at which I do not know further:

Here is a rather minimal example of my problem:

%%% edeftest.tex %%%
\documentclass{book}
\begin{document}
	\edef\e{\emph{text}}
\end{document}
%%% EOF %%%

This short document gives an error message at line 3:
> l.3     \edef\e{\emph{text}
>                         }
> ? 
> ! Undefined control sequence.

As it seems one may not use \emph in a macro-definition using \edef.
The same thing with \def instead of \edef is running smoothly.

I've tried looking this up in the TeX-Book and the LaTeX Companion but
I could not find anything about this.

So, what is it, that I do not know about \emph and \edef, and are there
other macros that are not allowed in an \edef macro definition?


Thank in advanvce,
  Wolfgang Lorenz