Defining a command to close and open environment

Question

While preparing my lectures with beamer, I often find myself having to split a frame into two different ones. For instance, a first version of my slides contains:

\begin{frame}
  \begin{block}{Theorem}
    Blah, blah, blah
  \end{block}
  \begin{block}{Corollary}
    Etc, etc, etc
  \end{block}
\end{frame}

When I complete my slides and add the proofs to these results, I must split it into two different frames

\begin{frame}
  \begin{block}{Theorem}
    Blah, blah, blah
  \end{block}
  \begin{block}{Proof}
    Blah, blah, blah
  \end{block}
\end{frame}

\begin{frame}
  \begin{block}{Corollary}
    Etc, etc, etc
  \end{block}
  \begin{block}{Proof}
    Etc, etc, etc
  \end{block}
\end{frame}

I think that it would be very helpful I if could simply define a command to close and then open the frame environment:

\def\newframe{ \end{frame} \begin{frame} }

\begin{frame}
  \begin{block}{Theorem}
    Blah, blah, blah
  \end{block}
  \begin{block}{Proof}
    Blah, blah, blah
  \end{block}

  \newframe

  \begin{block}{Corollary}
    Etc, etc, etc
  \end{block}
  \begin{block}{Proof}
    Etc, etc, etc
  \end{block}
\end{frame}

However, this approach does not work. Does anyone know if there is any way to define such a command?

Answer 1

There is no way to define a macro that issues \end{frame}\begin{frame} in beamer.

This is because frame is a very peculiar environment: when beamer finds \begin{frame} it looks for the next \end{frame} and stores in memory the entire contents without expanding macros; the macro expansion will take place later, when the frame contents will be processed. Such a way to proceed is necessary, because the contents needs to be processed many times, one for each slide in the frame.

Thus \end{frame} must appear explicitly, not hidden in a macro; if you use \newframe defined as

\def\newframe{ \end{frame} \begin{frame} }

the \end{frame} will appear when LaTeX is already processing a frame, where \end{frame} and \begin{frame} mean nothing: so an error will be raised.