How to use showexpl with an external class?

Question

Showexpl package defines LTXexample environment which allows to define a latex code and shows its result side by side. The problem is that it uses the same documentclass where the latex code is defined and I would like to define which class to use for examples. Do you know if it's possible?

Here you have an examples. It's a beamer presentation with some LTXexamples.

\documentclass{beamer} 
\usepackage{showexpl} 
\lstloadlanguages{[LaTeX]Tex} 
\lstset{% 
    basicstyle=\ttfamily\small, 
    commentstyle=\itshape\ttfamily\small, 
    showspaces=false, 
    showstringspaces=false, 
    breaklines=true, 
    breakautoindent=true, 
    captionpos=t 
} 

\begin{document} 
\frame[containsverbatim]{ 
  \frametitle{First slide} 
  \begin{LTXexample} 
    \begin{itemize} 
       \item a 
       \item b 
       \item c 
    \end{itemize} 
  \end{LTXexample} 

  \begin{LTXexample} 
    \begin{equation} 
       a^2+b^2=\sqrt{\frac{c^2}{1}} 
    \end{equation} 
  \end{LTXexample} 
} 

\frame[containsverbatim]{ 
  \frametitle{Second slide} 
  \begin{LTXexample} 
     \documentclass{article} 
     \begin{document} 
     \section{Section 1} 
        Text for section 1 
     \end{document} 
  \end{LTXexample} 
} 
\end{document}

Second slide doesn't show 'section title' beacuse beamer has its own section behaviour, so it seems that \documentclass{article} inside the example doesn't have any effect. The resulting font is sansserif because beamer uses it.

I know I can use several external documents and insert code and results, but with LTXexample or a similar environment would be easier. Do you know a better solution?

Answer 1

The code must be compiled externally. Loading the code of article.cls and all sorts of packages in the beamer run would lead to chaos. But theoretically if --shell-escape is active it is possible to trigger this external run on-the-fly during the compilation of the beamer run and then to include the resulting pdf with the graphic-option of showexpl. The main problem I see is that you probably don't want to include a complete page but only a part of it (e.g. to show the section). I think it would be difficult to write a good and flexible interface to choose this part.