Create a new environment to display a framed Python interactive session

Question

I want to display an interactive Python session inside a box in BEAMER.

As my presentation has many slides like this I thought it would be convenient to create a new environment, but when I try to compile the following code:

\documentclass{beamer}
\usepackage{pythontex}
\usepackage{tcolorbox}
\newenvironment{boxsession}
  { \begin{tcolorbox}[colframe=blue,colback=blue!5!white,notitle,size=small] \begin{pyconsole} }
  { \end{pyconsole} \end{tcolorbox} }
\begin{document}
\begin{frame}[fragile]
\frametitle{Lists}
\begin{boxsession}
foo = [1, 2, 3]
bar = foo 
baz = foo[:]
foo[-1] = -99
foo
bar
baz
\end{boxsession}
\end{frame}
\end{document}

I get:

Runaway argument?
! File ended while scanning use of \FancyVerbGetLine.
<inserted text> 
                \par 
l.32 \end{frame}
? 

I also tried to use environ to no avail:

\usepackage{environ}
\NewEnviron{boxsession}
  {\begin{tcolorbox}[colframe=blue,colback=blue!5!white,notitle,size=small]
    \begin{pyconsole}
      \BODY
    \end{pyconsole}
  \end{tcolorbox}}

Any ideas how to get around this error?

Answer 1

Since you are processing text, that contains special characters, you need to use \VerbatimEnvironment:

\documentclass{beamer}
\usepackage{pythontex}
\usepackage{tcolorbox}
\newenvironment{boxsession}
  {\VerbatimEnvironment\begin{tcolorbox}[colframe=blue,colback=blue!5!white,notitle,size=small]\begin{pyconsole}}
  {\end{pyconsole}\end{tcolorbox}}
\begin{document}
\begin{frame}[fragile]
\frametitle{Lists}
\begin{boxsession}
foo = [1, 2, 3]
bar = foo 
baz = foo[:]
foo[-1] = -99
foo
bar
baz
\end{boxsession}
\end{frame}
\end{document}

---

Update: Changing the font

pyconsole uses fancyvrb internally (see sec. 10.4.6 of the pythontex manual), so you have to pass through font settings that are understood by fancyvrb:

\documentclass{beamer}
\usepackage{pythontex}
\usepackage{tcolorbox}
\newenvironment{boxsession}[1][fontsize=\normalsize]
{\VerbatimEnvironment\begin{tcolorbox}[colframe=blue,colback=blue!5!white,notitle,size=small]\begin{pyconsole}[][#1]}
{\end{pyconsole}\end{tcolorbox}}
\begin{document}
\begin{frame}[fragile]
\frametitle{Lists}
\begin{boxsession}[fontsize=\tiny]
foo = [1, 2, 3]
bar = foo 
baz = foo[:]
foo[-1] = -99
foo
bar
baz
\end{boxsession}
\end{frame}
\end{document}