How to use \AtEndDocument with the class exam?

Question

Using \AtEndDocument produces a new page with the class exam, if not put before \documentclass{exam}.

I made a package that modifies some key elements of the class, but the package needs to write something at the end of the document to work properly. To be precise, it uses \glsaddallunused from the glossaries package.

I've read on this very site that using \RequirePackage should work before \documentclass, but even using \RequirePackage to load the packages I use in my package, it yields a bunch of errors (including about some xkeyval package loaded before \documentclass):

Package xkeyval Error: xkeyval loaded before \documentclass. ...keyval loaded before \protect\documentclass}

How can I circumvent this to add stuff on what should have been the last page of my exam file?

Answer 1

You just need to add the text before the class adds the page break to the same hook

\AtEndDocument{bar}
\documentclass{exam}
\begin{document}
foo
\end{document}

Answer 2

Thanks to the advice given by @DavidCarlisle, I was able to find a solution to my problem : loading the etoolbox package and using the \AtEndEnvironment{}{} function.

MWE :

\documentclass{exam}
\usepackage{etoolbox}
\AtEndEnvironment{document}{some text or command}
\begin{document}
foo
\end{document}