Using keywords including a dot in the name with the listings package

Question

I am using the listings package which works like charm in most cases.

I tried to define new languages for my needs with the help of morekeywords options in \lstset, but entering special keywords having a dot in the name just do not work. E.g.:

\lstset{morekeywords={read.table}}

I know I could set this keyword in two and set read and table to be also keywords, but I do not want every read to be highlighted in the source code.

Do you have an idea how to set this keyword or how to escape the dot?

Answer 1

After trying to do this by changing the catcode of . to letter and a short look through the listings code I decided to RTFM and found the alsoletter option quite quickly. You also may want to use the alsodigit option instead.

\documentclass{article}

\usepackage{listings}

\lstset{alsoletter={.},morekeywords={read.table}}
\begin{document}

\begin{lstlisting}
   read read.table table read-table
   test
\end{lstlisting}

\end{document}

Answer 2

My answer is a bit later than the other posts, but I decided to put it here to show, how to define a new language (Javascript in the example) and how to emphasize only part of the code as the OP wants. I have also used alsoletter (as the other examples).

\documentclass{article}
\usepackage{xcolor}
\usepackage{listings}

\gdef\emphasis#1{\lstset{emph={write,void,writeln,Hello,#1},
   emphstyle={\ttfamily\textcolor{red}}}}


\begin{document}
\lstdefinelanguage{JavaScript} {
    morekeywords={
        break,const,continue,delete,do,while,export,for,in,function,
        if,else,import,in,instanceOf,label,let,new,return,switch,this,
        throw,try,catch,typeof,var,void,with,yield,
        },
    sensitive=false,
    morecomment=[l]{//},
    morecomment=[s]{/*}{*/},
    morestring=[b]",
    morestring=[d]',
    alsoletter={.}
}


\lstset{
    %frame=tb,
    framesep=5pt,
    basicstyle=\normalsize, %\ttfamily,
    showstringspaces=false,
    keywordstyle=\ttfamily\color{blue},
    identifierstyle=\ttfamily,
    stringstyle=\ttfamily\color{orange},
    commentstyle=\color{orange},
    rulecolor=\color{black},
    xleftmargin=5pt,
    xrightmargin=5pt,
    aboveskip=\bigskipamount,
    belowskip=\bigskipamount,
            backgroundcolor=\color{gray!.50},
     alsoletter={.}
}

\emphasis{document.createElement, headline.appendChild}
\begin{lstlisting}[language=JavaScript]
// some comments
// about your code
var headline = document.createElement(h1);
var text = document.createTextNode(A text node)
// "offline" node manipulation
headline.appendChild(text);
// adding node to DOM
document.getElementsByTagName("body")[0].appendChild(headline);
\end{lstlisting}
\end{document}

It is always preferable to highlight the part of the code under discussion, rather than color code the whole of the script.

Answer 3

You can use

\lstset{alsoletter={.},morekeywords={read.table}}