Using macros in \pgfkeys command

Question

Is there a general way to pass a <key list> contained inside a macro to the \pgfkeys command, in order to process it in the usual way? In simple examples, \expandafter helps but I do not really know how to go in more complicated situations. In particular, how should I do, if I want to pass to \pgfkeys some keys explicitly and some through a macro?

\documentclass[varwidth,border=1mm]{standalone}
\usepackage{pgf}
\def\x{g/a=1,g/b=2}
\def\y{a=3,b=4}
\pgfkeys{%
    /g/.is family, /g,
    a/.code={(a is #1)},
    b/.code={(b is #1)},
    c/.code={(c is #1)}
}

\begin{document}
    %\pgfkeys{\x}                                  % CLEARLY FAILING
    \expandafter\pgfkeys\expandafter{\x} \\
    %\pgfkeys{\x,g/c=7}                            % CLEARLY FAILING
    \expandafter\pgfkeys\expandafter{\x,g/c=7} \\
    %\pgfkeys{g,c=5,\y}                            % CLEARLY FAILING
    %\pgfqkeys{/g}{c=5,\y}                         % CLEARLY FAILING
    \pgfkeys{g,c=5,a=3,b=4} \\                 % <-- What I'd like to get from
    \pgfqkeys{/g}{c=5,a=3,b=4}                 % <-- the previous two lines
\end{document}

I stumbled on this aspect applying what described in the 86.6.3 Handlers For Unprocessed Keys section of the pgf manual, trying to process again with \pgfkeys the filtered out keys saved into the \remainingoptions macro.

Answer 1

You can process the keys from a macro with \pgfkeysalsofrom:

\documentclass[varwidth,border=1mm]{standalone}
\usepackage{pgf}
\def\x{g/a=1,g/b=2}
\def\y{a=3,b=4}
\pgfkeys{%
    /g/.is family, /g,
    a/.code={(a is #1)},
    b/.code={(b is #1)},
    c/.code={(c is #1)}
}

\begin{document}
    \pgfkeysalsofrom{\x}    
\end{document}

But you shouldn't try to mix macros and normal keys in one \pgfkeys-argument. That's not a good programming style if you need this. You normally get macros with list of keys from some filtering and the code then should have enough control on the processing to avoid such a mix.

Answer 2

Something like this?

\documentclass[varwidth,border=1mm]{standalone}
\usepackage{pgf}
\def\x{g/a=1,g/b=2}
\def\y{a=3,b=4}
\pgfkeys{%
    /g/.is family, /g,
    a/.code={(a is #1)},
    b/.code={(b is #1)},
    c/.code={(c is #1)}
}

\begin{document}
    %\pgfkeys{\x}                                  % CLEARLY FAILING
    %\expandafter\pgfkeys\expandafter{\x} \\
    %\pgfkeys{\x,g/c=7}                            % CLEARLY FAILING
    \edef\temp{\noexpand\pgfkeys\expandafter{\x,g/c=7}}\temp \\
    %\pgfkeys{g,c=5,\y}                            % CLEARLY FAILING
    %\pgfqkeys{/g}{c=5,\y}                         % CLEARLY FAILING
    \pgfkeys{g,c=5,a=3,b=4} \\                 % <-- What I'd like to get from
    \pgfqkeys{/g}{c=5,a=3,b=4}                 % <-- the previous two lines
\end{document}

Or

\documentclass[varwidth,border=1mm]{standalone}
\usepackage{pgf}
\def\x{g/a=1,g/b=2}
\def\y{a=3,b=4}
\pgfkeys{%
    /g/.is family, /g,
    a/.code={(a is #1)},
    b/.code={(b is #1)},
    c/.code={(c is #1)}
}

\begin{document}
    %\pgfkeys{\x}                                  % CLEARLY FAILING
    %\expandafter\pgfkeys\expandafter{\x} \\
    %\pgfkeys{\x,g/c=7}                            % CLEARLY FAILING
    \edef\temp{\noexpand\pgfkeys\expandafter{\x,g/c=7}}\temp \\
    \edef\temp{\noexpand\pgfkeys{g,c=5,\y} }\temp 
    %\pgfqkeys{/g}{c=5,\y}                         % CLEARLY FAILING
    %\pgfkeys{g,c=5,a=3,b=4} \\                 % <-- What I'd like to get from
    %\pgfqkeys{/g}{c=5,a=3,b=4}                 % <-- the previous two lines
\end{document}