Passing a command as an argument

Question

I got a solution for my quoestion about Smaller roofs for forest but I want to pass a command instead of text to a procedure and this causes an error:

! Argument of \@rsbox has an extra }.
<inserted text> 
                \par 
l.45 \end{forest}

?

This is the code:

\documentclass{minimal}   

\usepackage{forest}



\forestset{
  with translation/.style={
    l sep=0,inner xsep=0,
    append translation/.expanded/.wrap pgfmath arg={\gettranslation{##1}}{content},
    content/.expanded/.wrap pgfmath arg={\gettext{##1}}{content},
  },  
  append translation/.style={append={[#1,no edge,l=0,inner xsep=0,inner ysep=0,outer ysep=0,before
        computing xy={l-=2pt}]}},
  sn edges/.style={for tree={parent anchor=south, child anchor=north,align=center,base=top},
                           where n children=0{tier=word,delay=with translation}{} 
                          }
}


\def\gettext#1{\gettextA#1;;\endget}
\def\gettextA#1;#2;{\removesep#1;}
\def\gettranslation#1{\gettranslationA#1;;\endget}
\def\gettranslationA#1;#2;{\removesep#2;}
\def\removesep#1;#2\endget{#1}





\newcommand{\trace}{\raisebox{0.2ex}{\_}\rule{0cm}{0.7em}}

\begin{document}


\begin{forest}
sn edges
[NP
  [Det [eine;a] ]
  [N$'$
    [A [kluge;smart] ]
    [N$'$
      [N [\trace ] ] ] ] ]
\end{forest}

\end{document}

\end{forest}

Is there a way to allow such commands in translated trees? I do not understand the code, so I am a bit helpless here ...

Answer 1

As mentioned in the comments, you have two simple options that I present below. However, I'm not quite sure what you are after.

\documentclass{minimal}   

\usepackage{forest}



\forestset{
  with translation/.style={
    l sep=0,inner xsep=0,
    append translation/.expanded/.wrap pgfmath arg={\gettranslation{##1}}{content},
    content/.expanded/.wrap pgfmath arg={\gettext{##1}}{content},
  },  
  append translation/.style={append={[#1,no edge,l=0,inner xsep=0,inner ysep=0,outer ysep=0,before
        computing xy={l-=2pt}]}},
  sn edges/.style={for tree={parent anchor=south, child anchor=north,align=center,base=top},
                           where n children=0{tier=word,delay=with translation}{} 
                          }
}


\def\gettext#1{\gettextA#1;;\endget}
\def\gettextA#1;#2;{\removesep#1;}
\def\gettranslation#1{\gettranslationA#1;;\endget}
\def\gettranslationA#1;#2;{\removesep#2;}
\def\removesep#1;#2\endget{#1}

\newcommand\trace{\raisebox{0.2ex}{\_}\rule{0cm}{0.7em}}

\newcommand\traceB{\usebox\tracebox}
\newsavebox\tracebox
\AtBeginDocument{
  \savebox\tracebox{\trace}
}

\begin{document}

\begin{forest}
sn edges
[NP
  [Det [eine;a] ]
  [N$'$
    [A [kluge;smart] ]
    [N$'$
      [N [\noexpand\trace ] ] ] ] ]
\end{forest}


\begin{forest}
sn edges
[NP
  [Det [eine;a] ]
  [N$'$
    [A [kluge;smart] ]
    [N$'$
      [N [\traceB ] ] ] ] ]
\end{forest}

\end{document}