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When passing a comma-separated list the commas are ignored, i.e. the list becomes a single item and I can't seem to find a way to prevent this. What should I do so that TEST C in the attached code will achieve the expected result of "extratcting" the itmes in the list?.

\documentclass{article} \usepackage{pgffor} \newcommand{\setstr}[2]{\expandafter\def\csname#1\endcsname{#2}} \newcommand{\getstr}[1]{\csname#1\endcsname} \newcommand{\PROCESS}[1] { The list items are: \foreach \i in {#1} { (\i) } } \newcommand{\SETC}[2]{\setstr{C#1}{#2}} \newcommand{\RUN}[1]{ \expandafter\PROCESS\expandafter{\getstr{C#1}} } \begin{document} % % The following works % \noindent{TEST A:} \PROCESS{a,b,c,d} \newline % % and the following also works % \noindent{TEST B:} \newcommand{\A}{a,b,c,d} \expandafter\PROCESS\expandafter{\A} \newline % % but this does not work % \noindent{TEST C:} \SETC{1}{a,b,c,d}% \RUN{1}% \newline \end{document}
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    minimal must not be used forever. Commented Oct 16, 2013 at 17:59
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    \expandafter\expandafter\expandafter\expandafter\expandafter\expandafter\expandafter\PROCESS\expandafter\expandafter\expandafter\expandafter\expandafter\expandafter\expandafter{\getstr{C#1}} for \RUN will work. (This is an expansion issue.) But it might be easier to create a slightly different macro that handle a list stored in a macro. (Just like pgffor itself: \foreach \i in {<list>} vs \foreach \i in \listMacro.) Commented Oct 16, 2013 at 18:26
  • @Marienplatz: I don't understand the comment on "minimal" please explain. This is my first attempt at posting here and I thought that is what you did. Commented Oct 16, 2013 at 18:47
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    @DonKreher This is probably meant: Why should the minimal class be avoided? Commented Oct 16, 2013 at 18:48

2 Answers 2

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As Qrrbrbirlbel says in a comment, it's an expansion issue; \getstr requires three expansion steps, not just one.

\documentclass{article} \usepackage{pgffor} \newcommand{\setstr}[2]{\expandafter\def\csname#1\endcsname{#2}} \newcommand{\getstr}[1]{\csname#1\endcsname} \newcommand{\PROCESS}[1]{% The list items are: \foreach \i in {#1} {% (\i) }% } \newcommand{\SETC}[2]{\setstr{C#1}{#2}} \makeatletter \newcommand{\RUN}[1]{% \begingroup\protected@edef\x{\endgroup\protect\PROCESS{\getstr{C#1}}}\x } \makeatother \begin{document} % % The following works % \noindent{TEST A:} \PROCESS{a,b,c,d} % % and the following also works % \newcommand{\A}{a,b,c,d} \noindent{TEST B:} \expandafter\PROCESS\expandafter{\A} % % also this works % \SETC{1}{a,b,c,d} \noindent{TEST C:} \RUN{1} \end{document}

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A slightly different approach, that better preserves the structure of the comma separated list.

\documentclass{article} \usepackage{pgffor} \newcommand{\setstr}[2]{\expandafter\def\csname#1\endcsname{\unexpanded{#2}}} \newcommand{\getstr}[1]{\csname#1\endcsname} \newcommand{\PROCESS}[1]{% The list items are: \foreach \i in {#1} {% (\i) }% } \newcommand{\SETC}[2]{\setstr{C#1}{#2}} \newcommand{\RUN}[1]{% \begingroup\edef\x{\endgroup \noexpand\PROCESS{\getstr{C#1}}}\x } \begin{document} % % The following works % \noindent{TEST A:} \PROCESS{a,b,c,d} % % and the following also works % \newcommand{\A}{a,b,c,d} \noindent{TEST B:} \expandafter\PROCESS\expandafter{\A} % % also this works % \SETC{1}{a,b,c,\textbf{d}} \noindent{TEST C:} \RUN{1} \getstr{C1} \end{document}
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  • This works perfect and now I am finished with the project and can get back to Mathematics ..... I hope. Commented Oct 17, 2013 at 16:27
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Although the OP is probably only interested in LaTeX solutions, here I'll present a ConTeXt solution.

The command \processcommacommand takes two arguments. The first one being the comma separated list, which can be a macro, and a second argument which is the macro to be used to process the list items. Example:

\define[1]\doprocess {(#1)} \define\somelist {foo, bar, baz} \starttext \processcommacommand [alpha, \math{\beta}, gamma] \doprocess \processcommacommand [\somelist] \doprocess \expandafter\processcommacommand\expandafter [\somelist] \doprocess \stoptext

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