How to add hyphenation support for custom command?

Question

Given the following custom commands:

\newcommand{\topic}[1]{#1\index{#1}}
\newcommand{\class}[1]{\textsf{\topic{#1}}}

which is used for Java classes with full package name, like:

\class{org.openscience.cdk.layout.StructureDiagramGenerator}

With the current command definition, the class name will not be hyphenated at the periods. How can I change my \newcommand{} to have LaTeX hyphenate the class at periods?

I am using the \class{} inside \caption{} methods which seems to invalidate some solutions.

Answer 1

I would be inclined to use the url package for this task. (It provides flexible options for linebreaking of such things, not only URLs.) Here's an example:

\documentclass[twocolumn]{article}
\usepackage{url}
\DeclareUrlCommand\printtopic{\urlstyle{sf}}
\newcommand{\topic}[1]{\protect\printtopic{#1}\index{#1}}
\DeclareRobustCommand{\class}[1]{\topic{#1}}
\begin{document}
text foo bar baz hello
\class{org.openscience.cdk.layout.StructureDiagramGenerator}
\end{document}

Answer 2

Whatever you do it will be next to impossible to get an acceptable typesetting with all variants of class names. One could use an approach where you can use a semi-manual approach as shown in the example below (last example).

\documentclass[11pt]{article} 
\usepackage[utf8]{inputenc} 

\usepackage{url}
\begin{document}
\overfullrule=0.5pt
\parskip=20pt
Using \textbackslash url, it will remove all spaces the colon will be placed at end of section, whereas a common convention is to move it at the next line

\fbox{\begin{minipage}{1.65in}
\url{org.openscience.cdk.layout.StructureDiagramGenerator}
\end{minipage}}



\gdef\classformatter#1{
    \hyphenpenalty=-200
    \textsf{#1}
}

It is impossible for \TeX to hyphenate the next example, as the fist word of a paragraph is never hyphenated and this is treated as one long word (\TeX\ is probably thinking it is just a long abbreviation).

\begin{minipage}{1.65in}
\classformatter{org.openscience.cdk.organizationlayout.StructureDiagramGenerator}
\end{minipage}


If you type a space at the point you want to allow a break \TeX\ will attempt to hyphenate,

\fbox{\begin{minipage}{1.65in}
\classformatter{org.openscience.cdk .organizationlayout .StructureDiagramGenerator}
\end{minipage}}

You will never avoid a little bit of hand manipulation, allow a break now and then;

\fbox{\begin{minipage}{1.65in}
\classformatter{org.openscience.cdk\\ .organizationlayout .StructureDiagramGenerator}
\end{minipage}}

\end{document}