Cfrgtkky

I would like to set the decoration options for an edge by using a macro, like this:

defcurlbl{text along path,text={hi}}

newcommand{myedge}[2]{%

 path (#1) edge[decorate, decoration={curlbl}] (#2);

}

However, this does not work as I intended and I get an error I do not understand:

./minimal.tex:12: Package pgfkeys Error: I do not know the key '/pgf/decoration/pgfkeyscurrentname ' and I am going to ignore it. Perhaps you misspelled it.

Here is my tex file:

documentclass[tikz,border=10pt]{standalone}

usetikzlibrary{positioning,decorations.text}

begin{document}

defcurlbl{text along path,text={hi}}

newcommand{myedge}[2]{%

 path (#1) edge[decorate, decoration={curlbl}] (#2);%

}



begin{tikzpicture}

  node (A) {emph{A}};

  node[below left=10ex and 6ex of A] (B) {emph{B}};

  myedge{A}{B};

end{tikzpicture}



end{document}

Is it possible to use a macro to set the options of a TikZ decoration?

This is a so-called expansion problem: when TikZ parses the path, your macro is not yet expanded. Of course, the problem can of course be solved in various way. An arguably rather elegant way, provided you insist on the overall strategy here to use a macro in this way, is to tell TikZ to expand curlbl. This can be accomplished by using the .expanded key.

documentclass[tikz,border=10pt]{standalone}

usetikzlibrary{positioning,decorations.text}

begin{document}

defcurlbl{text along path,text={hi}}

newcommand{myedge}[2]{%

 path (#1) edge[decorate, decoration/.expanded={curlbl}] (#2);%

}



begin{tikzpicture}

  node (A) {emph{A}};

  node[below left=10ex and 6ex of A] (B) {emph{B}};

  myedge{A}{B};

end{tikzpicture}

end{document}

I strongly suspect that, if you provide us with the full picture, there will be a more TikZy way to achieve that. Without knowing the details, at this point I can only draw your attention to the keys is if and is choice, which are described on p. 889 of the pgfmanual.