🚀 go-pugleaf

In article <1jpnnsINN5el@retriever.cs.umbc.edu>, finin@cs.umbc.edu (Timothy Finin) writes...
>Is there a way to define an environment in LaTeX that takes a single
>optional argument?  
>I would like to have the argument to boxed be optional and default to,
>say \defaultBoxWidth.  Is there a way to do this within LaTeX, or does
>one have to define this directly in TeX?
> 
Yes and no.  All of LaTeX is implemented "directly in TeX", but you can 
look at how LaTeX does it to do the same thing yourself.  Look in the
LaTeX.tex file.

\newsavebox{\mybox}

>  \newenvironment{boxed}[1]%
>      {\beginsbox{\mybox}\begin{minipage}{#1}%
>       }%
>      {\end{minipage}\endsbox
>        \setlength{\fboxsep}{8pt}%
>        \centerline{\fbox{\usebox{\mybox}}}}
> 

becomes:

% in a style file or use \makeatletter
\def\boxed{\@ifnextchar[{\@box@d}{\@box@d[\defaultBoxWidth]}}
\def\@box@d[#1]{\beginsbox{\mybox}\begin{minipage}{#1}}
\def\endboxed{\end{minipage}\endsbox
        \setlength{\fboxsep}{8pt}%
        \centerline{\fbox{\usebox{\mybox}}}

Donald Arseneau        asnd@reg.triumf.ca