How to define a starred version of an environment in LaTeX

Question

I am interested in defining a new environment in LaTeX that has a starred version. How is this done?

Yiannis Lazarides · Accepted Answer · 2012-05-24 10:52:49Z

23

Since the \newenvironment command uses a \csname, you can define it directly.

\documentclass{article}
\newenvironment{test*}
{start}{end}
\begin{document}
\begin{test*}
hello
\end{test*}
\end{document}

You can have any combination of characters (with catcode 11 and 12) as you would in a \csname...\endcsname construct,

\documentclass{article}
\newenvironment{test123*}
{start}{end}
\begin{document}
\begin{test123*}
hello
\end{test123*}
\end{document}

What you do with the starred command is up to you.

answered May 23, 2012 at 18:11

Yiannis Lazarides

116k34 gold badges287 silver badges555 bronze badges

1

I thought it would be much more complicated than this :-) I should have tried it myself before I asked.
– digital-Ink
May 23, 2012 at 18:14
1

@digital-Ink It's a sort of a hidden feature.
– Yiannis Lazarides
May 23, 2012 at 18:15
If you were to define a command, xparse would allow to handle the starred and non-starred case in one definition. For environments, the solution however is less beautiful.
– dgs
May 23, 2012 at 19:01
1

@Yiannis saying "any combination of characters" is perhaps a little misleading as one is only allowed to use characters with catcode 11 and 12, e.g. \newenvironment{foo$} isn't working.
– Frank Mittelbach
May 24, 2012 at 10:40
1

Right, I have a solution for the starred environment business: if it works, it will be in the next xparse update
– Joseph Wright ♦
May 24, 2012 at 12:13

| Show 6 more comments

1 Answer 1