newenvironment/newcommand for existing environment in LaTeX-Beamer

Question

I would like to have the solution of highlighting a line in listings-package as a command or environment. To bad I cannot get it working. I tried:

• a simple newenvironment: compile errors
• \newcommand: also compile errors

• the environ-package, see below

  \NewEnviron{listingh}{
    \vspace{-\baselineskip}
    \begin{lstlisting}[backgroundcolor=\color{yellow}]
    \BODY
    \end{lstlisting}
    \vspace{-\baselineskip}
  }
  

Also, same kind of errors. missing {, missing number, threaded a zero etc.

I try to use it with the beamer-package and pdflatex.

Answer 1

In addition to Martin's answer, you need to take special care within the beamer class, because that class also drastically alters LaTeX's expansion habits. See section 2.6 of the beamer manual.

\documentclass{beamer}
\usepackage{listings}

\lstnewenvironment{listingh}[1][]{%
    \vspace{-\baselineskip}%
    \lstset{backgroundcolor=\color{yellow},#1}%
}{%
    \vspace{-\baselineskip}%
}


\begin{document}

\defverbatim[colored]\mycode{%
\begin{listingh}[emph={PRINT,GOTO},emphstyle={\color{blue}}]
10 PRINT "HELLO, WORLD!"
20 GOTO 10
\end{listingh} }


\begin{frame}{BASIC}
\mycode
\end{frame}

% or
\begin{frame}[fragile]{C++}
\begin{listingh}[emph={cout,for},emphstyle={\color{blue}}]
for (;;) {
    cout << "Hello, world!";
}
\end{listingh}

\end{document}

This looks bad but keep in mind you can redefine \mycode over and over again before each frame.

Answer 2

The lstlisting environment is like all verbatim environments special and doesn't work (well) inside another environments. You need to use \lstnewenvironment as described in the listings manual in section 4.16 Environments, p.40:

\lstnewenvironment
    {<name>}[<number>][<opt. default arg.>]
    {<starting code>}
    {<ending code>}

Applied to your code:

\lstnewenvironment{listingh}[1][]{%
    \vspace{-\baselineskip}%
    \lstset{backgroundcolor=\color{yellow},#1}%
}{%
    \vspace{-\baselineskip}%
}

Note the % at the end of lines to avoid spurious spaces.

You need to use the fragile option of the frame environment (or command) if you use listings or any other verbatim code.