Compilation fails in beamer class with newenvironment defining nested blocks

Question

I'm failing to understand why this code compiles :

\documentclass{beamer}
\newenvironment{yyy}{\begin{frame} \begin{block}{youpi}  }{\end{block} \end{frame}}
\begin{document}
 { \begin{frame} \begin{block}{youpi}   bonjour \end{block} \end{frame} }
\end{document}

while that one does not :

\documentclass{beamer}
\newenvironment{yyy}{\begin{frame} \begin{block}{youpi}  }{\end{block} \end{frame}}
\begin{document}
  \begin{yyy}    bonjour \end{yyy}
\end{document}

... resulting in

File ended while scanning use of \beamer@collect@@body

If anyone has got an idea, i'd be greatful!

Hi and welcome to TeX.SX. Can you extend your code into a fully compilable minimal working example (MWE)? That would help a lot. — Johannes_B, Sep 13 '14 at 11:23
Oh wow, sorry, the minimal example is so minimal that i thought it was just a snippet. Sorry @skorqa and well done ;-) — Johannes_B, Sep 13 '14 at 11:26
Have a look at Can spaces at the beginning of a line ever cause problems? please. — Johannes_B, Sep 13 '14 at 11:33

score 3 · Accepted Answer · edited Aug 26 '18 at 22:34

This is by-design and it depends on how frames are read by beamer. See this bug on the Beamer github repo, closed as wontfix.

You can however workaround the issue by including your code into a macro (not a new environment):

\documentclass{beamer}

\newcommand{\yyy}[1]{
    \begin{frame}
        \begin{block}{youpi}
        #1
        \end{block}
    \end{frame}
}
\begin{document}
  \yyy{bonjour}
\end{document}

Compilation fails in beamer class with newenvironment defining nested blocks

1 Answers1