[Tex/LaTex] Line breaking in \newcommand

Question

I defined a new command for highlighting some text parts:

\newcommand{\keyword}[1]{\colorbox{black!5}{#1}}

Unfortunately, when the text becomes to long it overlaps my margins.
The keyword ignores the margin of the table, as well as the margin of the hole document.

\keyword{exp: c=wordExp \{ if(\$c.matches(``a string'')\{ 
\textbackslash\textbackslash do something \}) \}}

Can I tell my command to make a newline or force it to break after X centimeters?

Thx.

Answer 1

You can use @barbarabeeton's advice. I don't recommend the name \keyword, however, because it is defined elsewhere in some classes. So, the newcommand can look like this:

\newcommand{\KEY}[1]{\colorbox{black!5}{\parbox{\dimexpr\linewidth-2\fboxsep}{#1}}}

Observe this -2\fboxsep, which serves to align the colorbox with the text above and below. Here is a full example:

\documentclass{article}
\usepackage{xcolor}
\begin{document}

\newcommand{\KEY}[1]{\colorbox{black!5}{\parbox{\dimexpr\linewidth-2\fboxsep}{#1}}}

\begin{tabular}{|p{.4\linewidth}|p{.5\linewidth}|}
\hline
Something here to fill half & 
Something here to fill half the line width
\KEY{exp: c=wordExp \{ if(\$c.matches(``a string'')\{ 
\textbackslash\textbackslash do something \}) \}}
\\ \hline
\end{tabular}

\end{document}