Storing options for pgfkeys inside macro

Question

I want to define some options as a list of key-value pairs inside a macro and use that macro inside a command that takes pgfkeys-style options. Here is a MWE:

\documentclass{standalone}
\usepackage{pgfkeys}

\pgfkeys{
    /example/.is family, /example,
    .unknown/.code = {
        (\pgfkeyscurrentkeyRAW,#1)
        \typeout{DEBUG \pgfkeyscurrentkeyRAW}
    }
}

\newcommand{\defvalues}[2][]{
    \pgfkeys{/example, #1}
}

\begin{document}

\def\mylist{c=3,d=4}

\defvalues[a=1,b=2]{}

\expandafter\defvalues\expandafter[\mylist]{}

\expandafter\defvalues\expandafter[f=6,\mylist]{}

\end{document}

In the last line, \mylist is not expanded correctly.

Expected output in the document:

(a,1) (b,2) (c,3) (d,4) (f,6) (c,3) (d,4)

Actual output:

(a,1) (b,2) (c,3) (d,4) (f,6) (c=3,d=4)

Alternatively, when running pdflatex test.tex|grep DEBUG, expected output:

DEBUG a
DEBUG b
DEBUG c
DEBUG d
DEBUG f
DEBUG c
DEBUG d

Actual output:

DEBUG a
DEBUG b
DEBUG c
DEBUG d
DEBUG f
DEBUG c=3,d=4

How do I get \mylist to expand before it is passed to pgfkeys?

Answer 1

Here is a solution using the .style handler to define two lists.

\documentclass{article}
\usepackage{pgfkeys}

\pgfkeys{
  /example/.is family,
  /example,
  .unknown/.code = {
    (\pgfkeyscurrentkeyRAW,#1)
    \typeout{DEBUG \pgfkeyscurrentkeyRAW}
  }
}

\newcommand{\defvalues}[2][]{\pgfkeys{/example,#1}}
\def\mylist{c=3,d=4}
\defvalues[mylist/.style/.expand once={\mylist}]{}
\defvalues[mylist2/.style={g=8,h=45}]{}

\begin{document}
\defvalues[a=1,b=2]{}

\defvalues[mylist]{}

\defvalues[f=6,mylist,mylist2]{}
\end{document}

Output:

(a,1) (b,2)
(c,3) (d,4)
(f,6) (c,3) (d,4) (g,8) (h,45)

Answer 2

I found a solution:

\newcommand{\defvalues}[2][]{
    \edef\opts{/example, #1}
    \expandafter\pgfkeys\expandafter{\opts}
}

This works as expected. I guess it has to do with the fact that \expandafter doesn't work on [] the way it does on {}. Or rather, in the third case, it's only expanding f, not the entire contents of the brackets.