Use macros within listing

Question

I would like to use I macro I have defined (including mathematical symbols) within a listing environment. However, the following code prints "\foo{x}" rather than "bar(x)". Is there any way of achieving the latter output?

\documentclass{article}
\usepackage{listings}

\begin{document}
\newcommand{\foo}[1]{$bar(#1)$}

\begin{lstlisting}
\foo{x}
\end{lstlisting}

\end{document}

Answer 1

It's possible to use the escapechar option to the listings environment, for example escapechar=\% would specify, that any LaTeX code after a % character is interpreted as LaTeX and not printed verbatim.

\documentclass{article}
\usepackage{listings}

\begin{document}
\newcommand{\foo}[1]{$bar(#1)$}

\begin{lstlisting}[escapechar=\%]
%\foo{x}%
\end{lstlisting}

\end{document}

This will print a true bar over (x)

\documentclass{article}
\usepackage{mathabx}%
\usepackage{listings}

\begin{document}
\newcommand{\foo}[1]{$\widebar{(#1)}$}

\begin{lstlisting}[escapechar=\%]
%\foo{x}%
Some other stuff
\end{lstlisting}

\end{document}