Saving a list in a re-usable box

Question

Pardon me if this is a dumb question, but I am a bit rusty about this.

I want to store a list like one generated by the enumerate environment in a re-usable box that I may re-use within a TikZ picture and elsewhere.

In a manner of speaking, fancybox.sty does this with an actual framed box rather than a re-usable box.

Naively, I am looking to do something like:

\documentclass[a4paper,12pt]{article}
\begin{document}
\newsavebox{\enumbox}
\sbox{\enumbox}{%
\begin{enumerate}
    \item Title
    \item Abstract
    \item Keywords
    \item Outline
\end{enumerate}
}
{\centering\usebox{\enumbox}}
\end{document}

Of course, the above does not work because it is neither a parbox nor an lrbox.

Is there any package that does this? Otherwise, what do I have to do to get what I am seeking?

Thanks in advance.

Answer 1

You need to save the enumerate contents in a \vbox:

\setbox\enumbox\vbox{% …

Though, the \centering won’t work because the box is—due to enumerate’s nature— \linewidth wide.
Using it without \centering results in an overfull \hbox because the paragraph indention is inserted as usual.

Solution A

It seems, that in your case you simply could define a macro as

\newcommand*{\enummacro}{\begin{enumerate} … \end{enumerate}}

and use that inside a TikZ node. Advantage: The node would not be \linewidth wide but only as wide as you would have specified.

Solution B

You could measure the width of the list elements (assuming that they all fit on one line width-wise).

Here, I opted for an easier list defining and processing solution, namely

\newcommand*{\mylist}{Title,Abstract,Keywords,Outline}

The \mylist macro only contains the comma-separated elements.

The \getWidthOf macro needs \tikz@textfont and the smuggle macro to be usable inside a tikzpicture (no warranties here).

Solution C

As the enumerate environment introduces vertical and horizontal space which with I do not want to deal and also because the following looks better and is easier to maintain, yet another solution but with a simple tabular.

Code A (enumerate with guessed width)

\documentclass[a4paper,12pt]{article}
\usepackage{tikz}
\newcommand{\enummacro}{%
\begin{enumerate}
    \item Title
    \item Abstract
    \item Keywords
    \item Outline
\end{enumerate}}
\newsavebox\enumbox

\begin{document}
\setbox\enumbox\vbox{\enummacro}
\noindent\usebox\enumbox

\begin{tikzpicture}
    \node[draw, text width=8em, align=center] {\enummacro};
\end{tikzpicture}
\end{document}

Output (enumerate with guessed width)

Solution B (properly measured enumerate)

\documentclass[a4paper,12pt]{article}
\usepackage{tikz}

\newcommand*{\mylist}{Title,Abstract,Keywords,Outline}
\newlength{\widthOfWidestElement}

\makeatletter
\def\qrr@smuggle@length@through@interruptpgfpicture#1\endpgfinterruptpicture{%
    \edef\@tempa{\the#1}%
    \expandafter\endpgfinterruptpicture\expandafter#1\@tempa}
\newcommand*{\getWidthOf}[1]{%
    \pgfinterruptpicture
    \setlength{\widthOfWidestElement}{0pt}%
    \@for\@element:=#1\do{%
        \sbox0{\tikz@textfont\@element}%
        \ifdim\wd0>\widthOfWidestElement\widthOfWidestElement=\wd0\fi
    }%
    \qrr@smuggle@length@through@interruptpgfpicture\widthOfWidestElement
    \endpgfinterruptpicture
    \advance\widthOfWidestElement\itemindent
    \advance\widthOfWidestElement\leftmargin
    \advance\widthOfWidestElement\rightmargin
}
\newcommand*{\makeEnumerate}[1]{%
    \enumerate % maybe better output with
               % \parskip\z@
        \@for\@element:=#1\do{%
            \item \@element
        }
    \endenumerate
}
\makeatother
\begin{document}

\begin{tikzpicture}
    \getWidthOf{\mylist}
    \node[draw, text width=\widthOfWidestElement, align=center] {\makeEnumerate\mylist};
\end{tikzpicture}
\end{document}

Output B (properly measured enumerate)

Code C (tabular)

\documentclass[a4paper,12pt]{article}
\usepackage{tikz,array}

\newcommand*{\mylist}{Title,Abstract,Keywords,Outline}

\makeatletter
\newcommand*{\makeFakeEnumerate}[1]{%
    \begingroup
    \def\@temptabbody{}%
    \setcounter{enumi}{0}%
    \@for\@element:=#1\do{%
        \expandafter\g@addto@macro\expandafter\@temptabbody\expandafter{\expandafter&\@element \\}}%
    \tabular{>{\refstepcounter{enumi}\theenumi.}rl}
        \@temptabbody
    \endtabular
    \endgroup
}
\makeatother
\begin{document}
\begin{tikzpicture}
    \node[draw] {\makeFakeEnumerate\mylist};
\end{tikzpicture}
\end{document}

Output C (tabular)

Answer 2

Unless there is a compelling reason to use a box, it is much simpler to:

\documentclass[a4paper,12pt]{article}
\begin{document}
\newcommand\enumbox{%
\enumerate
    \item test
    \item Abstract
    \item Keywords
    \item Outline
\endenumerate
}
\enumbox
\end{document}

If you want to center do this:

\documentclass[a4paper,12pt]{article}
\usepackage{lipsum}
\begin{document}
\newcommand\enumbox{%
\enumerate
    \item test
    \item Abstract
    \item Keywords
    \item Outline
\endenumerate
}
\lipsum[1]\centering
\fbox{\hbox to 3cm{\vbox{\enumbox}}}
\end{document}