Using \printexercise with a macro breaks the index in the .aux file about xsim

[cgnieder]

Please, can you reduce this into one compilable file (maybe with a filecontents environment for a necessary second file) and lets say maximum three exercises, that I can use reproduce the issue in one go?

[N-Coder]

There is one: test1.tex in the linked gist is independently compileable, no need for additional files or filecontents. The other files in the gist are just my attempt of solving the issue in test2.tex and the .aux files generated when compiling the respective tex files. All the code listings above are just excerpts from the files in the gist.

If you need an example that is really as minimal as it can get, use this one and ignore everything said above 😉

\documentclass{article}

\usepackage{xsim}

\DeclareExerciseProperty!{title}
\newcommand{\printexercisewithtitle}[1]{%
	\edef\foundid{\GetExerciseIdForProperty{title}{#1}}%
	\printexercise{exercise}{\foundid}%
}

\DeclareExerciseCollection{foo}

\begin{document}

\collectexercises{foo}
\begin{exercise}[title={Erste},subtitle={Die Erste}]
The first exercise is added to the collection `foo'.
\end{exercise}
\begin{exercise}[title={Zweite},subtitle={Die Zweite}]
The second exercise is also added to the collection `foo'.
\end{exercise}
\collectexercisesstop{foo}

\printexercisewithtitle{Erste}
\printexercisewithtitle{Zweite}

\printexercise{exercise}{1}
\printexercise{exercise}{2}

\end{document}

The output looks like this:

I would expect to see identical exercises 1 and 2 twice, but the first ones are not numbered correctly and don't have a title.

[N-Coder]

The issue seems to be similar to what you explained here on stackexchange.
My understanding was that only the parameter would need expansion (as in \printexercise{exercise}{\XSIMexpandcode{\foundid}}), but actually the whole printexercise thing needs expansion for some reason: \XSIMexpandcode{\printexercise{exercise}{\exid}}.
Maybe putting the code with the correct order of expansion from the stackexchange question as example right next to \printexercise in the XSIM documentation would also prevent others from running into this problem.

[cgnieder]

You are right, this is the same issue. I'll add \xprintexercise as a shortcut for \XSIMexpandcode{\printexercise{}{}} to the next release.