Expansion Issues When Passing TikZ Styles to Macro Created by Macro

Question

I'm struggling (again) with expansions. This time I have a generic function \misdirection that creates a TikZ environment subject to a few options. Then, I create a macro \freezeStyle that creates a new macro that has frozen some of the options to \misdirection. So \freezeStyle receives the style that I ultimately want passed to \misdirection.

I tried a few \edefs and couldn't get it working, so I opted to put the code in a state that demonstrates something that compiles but has undesirable behavior. This attempt was inspired by How to submit a set of tikz command with pgfkeys?.

So: How should I modify this so that it works as desired? Please note that my actual misdirection call will involve \csname, so I'd appreciate expandafter solutions that also show how to adapt your solution to that case as well (see code for details).

For cross-references, here is a similar question: Macros that write macros and unexpected side effects, with the same type of undesirable behavior, but the solution there has to do with defining customized \csnames, which doesn't apply to this problem.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows.meta}

\newcommand{\misdirection}[2][]{
\begin{tikzpicture}
    \node (tree) at (0,0) {tree};
    \node (apple) at (3,0) {#2};
    \draw[blue,#1] (tree) -- (apple);
\end{tikzpicture}
}

\pgfkeys{
    /tikz/.cd,
        execute style/.style = {#1},
        execute macro/.style = {execute style/.expand once=#1},
    /demo/.cd,
        name/.store in=\savedname,
        style/.store in=\savedstyle
}

\newcommand{\freezeStyle}[1][]{%
    \pgfqkeys{/demo}{#1}
    \expandafter\def\csname\savedname\endcsname##1{%
        % Incorrect because \savedstyle is not expanded until runtime.
        % I want the value of \savedstyle hardcoded into this macro.
        \misdirection[execute macro = \savedstyle]{##1}

        % This doesn't work either...
        %\expandafter\misdirection\expandafter[\savedstyle]{##1}

        % In my real code, the misdirection call looks more like:
        %\csname someArgumentDependentStuff \endcsname[put style here]{args}
    }
}

\begin{document}
    \freezeStyle[name=helloMom, style={red,thick}]
    \freezeStyle[name=helloDad, style={-{>[length=5mm]},green}]
    \helloMom{4} % Undesirably, this is green with a big arrow.
    \helloDad{5}
\end{document}

Answer 1

I'd just use a "helper" macro so the \savedstyle can be expanded (once):

\documentclass[varwidth,border=5]{standalone}
\usepackage{tikz}
\usetikzlibrary{arrows.meta}

\newcommand{\misdirection}[2][]{%
  \begin{tikzpicture}
    \node (tree) at (0,0) {tree};
    \node (apple) at (3,0) {#2};
    \draw [blue,#1] (tree) -- (apple);
  \end{tikzpicture}\ignorespaces% or \par?
}

\pgfkeys{demo/.cd,
  name/.store in=\savedname,
  style/.store in=\savedstyle
}

\newcommand\freezeStyle[1][]{%
  \pgfqkeys{/demo}{#1}%
  \expandafter\FreezeStyle\expandafter{\savedstyle}{\savedname}}

\def\FreezeStyle#1#2{%
  \expandafter\def\csname#2\endcsname##1{%
     \misdirection[#1]{##1}}}

\begin{document}
    \freezeStyle[name=helloMom, style={red,thick}]
    \freezeStyle[name=helloDad, style={-{>[length=5mm]},green}]
    \helloMom{4} 

    \helloDad{5}
\end{document}

Note, I added an \ignorespaces in the the \misdirection command.

Answer 2

With expl3, just for fun :)

\documentclass{article}
\usepackage{xparse} % automatically loads expl3
\usepackage{tikz}
\usetikzlibrary{arrows.meta}

\newcommand{\misdirection}[2][]{%
  \begin{tikzpicture}
    \node (tree) at (0,0) {tree};
    \node (apple) at (3,0) {#2};
    \draw[blue,#1] (tree) -- (apple);
  \end{tikzpicture}}

\ExplSyntaxOn

% Declare our variables; it's good practice :)
\tl_new:N \l_demo_name_tl
\tl_new:N \l_demo_style_tl

% Set up our keys (`tl` is short for `token list`)
\keys_define:nn { demo } {
  name  .tl_set:N = \l_demo_name_tl,
  style .tl_set:N = \l_demo_style_tl,
}

% Create a macro to behave as if we would call
% \demo_freeze_style:Nn \helloMom { red, thick }...
\cs_new:Nn \demo_freeze_style:Nn {
  \cs_new:Npn #1 ##1 {
    \misdirection[#2]{##1}
  }
}
% ...but then add support for saner syntax in our use case
\cs_generate_variant:Nn \demo_freeze_style:Nn { cV }

% Now, set our keys and use our command :)
\NewDocumentCommand \freezeStyle { O{} } {
  \group_begin:
  \keys_set:nn { demo } { #1 }
  \demo_freeze_style:cV { \tl_use:N \l_demo_name_tl } \l_demo_style_tl
  \group_end:
}

\ExplSyntaxOff


\begin{document}
    \freezeStyle[name=helloMom, style={red,thick}]
    \freezeStyle[name=helloDad, style={-{>[length=5mm]},green}]
    \helloMom{4}
    \helloDad{5}
\end{document}

Answer 3

Here's how to do it without expl3:

\newcommand\freezeStyle[1][]{%
  \pgfqkeys{/demo}{#1}%
  \expandafter\edef\csname\savedname\endcsname##1{%
    \noexpand\misdirection[\savedstyle]{##1}}}

Note that \edef is used here and \noexpand is used to protect macros that should not be expanded.

\typeout{\meaning\helloMom}
macro:#1->\misdirection [execute macro=red,thick]{#1}

---

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows.meta}

\pgfkeys{
    /demo/.cd,
        name/.store in=\savedname,
        style/.store in=\savedstyle
}

\newcommand{\misdirection}[2][]{%
  \begin{tikzpicture}
    \node (tree) at (0,0) {tree};
    \node (apple) at (3,0) {#2};
    \draw[blue,#1] (tree) -- (apple);
  \end{tikzpicture}}

\newcommand\freezeStyle[1][]{%
  \pgfqkeys{/demo}{#1}%
  \expandafter\edef\csname\savedname\endcsname##1{%
    \noexpand\misdirection[\savedstyle]{##1}}}

\begin{document}
    \freezeStyle[name=helloMom, style={red,thick}]
    \freezeStyle[name=helloDad, style={-{>[length=5mm]},green}]
    \helloMom{4}
    \helloDad{5}
\end{document}