How to expand several arguments in an environment?

Question

I have an environment that I've defined as follows:

\newenvironment{regularEnumerateEx}[2][0em]
  {begin{listSkeleton}[#1]{enumerate}{#2}}
  {\end{listSkeleton}}

The problem is that I need to expand #2 before passing it to listSkeleton. It's okay if #1 is expanded (I think). I know I have to use \expandafter in some way, but not exactly how.

@Martin Scharrer: I'm not familiar enough with LaTeX to comment on that. If expanding it completely is easier and doesn't break anything, then that will suffice. — gablin, Aug 18 '11 at 11:35

Martin Scharrer · Accepted Answer · 2011-08-18T10:42:09.773

12

If it is OK to expand it completely, not just once you can use \edef with a temporary macro:

\newenvironment{regularEnumerateEx}[2][0em]{%
  \edef\temp{%
    \noexpand\begin{listSkeleton}[#1]{enumerate}{#2}%
  }%
  \temp
}{%
  \end{listSkeleton}%
}

If you really only want to expand it once you can do:

\newenvironment{regularEnumerateEx}[2][0em]{%
  \def\temp{\begin{listSkeleton}[#1]{enumerate}}%
  \expandafter\temp\expandafter{#2}%
}{%
  \end{listSkeleton}%
}

Often the macro \@tempa is used for such temparary assignments, but in user documents it requires \makeatletter ... \makatother around the code. So for simplicity I just used \temp. It is anyway just used inside a group.

edited Aug 18 '11 at 10:42

answered Aug 18 '11 at 09:56

Martin Scharrer

262,582

In the first code there is a \noexpand missing, right before \begin. Otherwise the \edef will not work. – Aug 18 '11 at 10:33
@Axel: Yes, indeed. I overlooked that. Fixed now. – Martin Scharrer Aug 18 '11 at 10:42

How to expand several arguments in an environment?

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