Making etoolbox work with the Exam document class

Question

I am trying to use the etoolbox with the document class exam. I have had good luck using etoolbox with the article class, but I can't get it to work inside of the question environment. Here's a minimal example:

\documentclass[12pt]{exam}
\usepackage{etoolbox}

\def\QuizKey{\newpage }

\newcommand{\answer}[2][0 pt]{
\eappto{\QuizKey}{\noexpand\par\arabic{question}.\ \unexpanded{#2}}
\vspace{#1}
}

\begin{document} 
\appto{\QuizKey}{Opening Code}

\begin{questions}
\question When did the Internet first begin?\answer{1985}

\appto{\QuizKey}{Something else to test} 
\end{questions}

\appto{\QuizKey}{Ending Code}

\QuizKey

\end{document}

My end result is that the \QuizKey printout does everything it was told to in the document, except the parts in the questions environment. I'm guessing the \eappto and \appto commands aren't able to reach the hook, or perhaps they are not allowed to be used inside of the environment, but it doesn't seem to cause any errors, either. Is there a way I can fix this?

Answer 1

An environment forms a group, so the change to \QuizKey is lost as soon as the environment ends, unless the change is global. Use \xappto and \gappto.

\documentclass[12pt]{exam}
\usepackage{etoolbox}

\newcommand\QuizKey{\newpage}

\newcommand{\answer}[2][0pt]{% <-- don't forget
  \xappto{\QuizKey}{\arabic{question}.\ \unexpanded{#2\par}}% <-- don't forget
  \vspace{#1}%
}

\begin{document} 
\gappto{\QuizKey}{Opening Code\par}

\begin{questions}
\question When did the Internet first begin?\answer{1985}

\gappto{\QuizKey}{Something else to test\par} 
\end{questions}

\gappto{\QuizKey}{\par Ending Code}

\QuizKey

\end{document}