Cfrgtkky

I use a macro mychoice{item a, item b, items c,…} that returns one of the items of the comma-separated-list determined by an external counter based on the docsvlist macro from etoolbox. In simple text, this macro works fine, but when I try to use it in a directlua{} from Lua(La)TeX, it raises strange (at least for me) errors.

MWE:

documentclass{article}

usepackage{luacode}

usepackage{etoolbox}

begin{luacode*}

 function dummy(argument)

 end

end{luacode*}



newcounter{choicecounter}

newcounter{argcounter}



newcommand{mychoice}[1]{

    setcounter{argcounter}{0}

    renewcommand*{do}[1]{

        stepcounter{argcounter}

        csedef{argcounterarabic{argcounter}}{##1}}

    docsvlist{#1}

    csuse{argcounterarabic{choicecounter}}

}



newcommand{main}[1]{%

    setcounter{choicecounter}{#1}

    hello world mychoice{one,{two,three}}

    directlua{dummy(luastring{mychoice{foo,bar}})}

}



begin{document}

main{1}



main{2}

end{document}

So this version raises the error. If you comment out the directlua it compiles fine.

What am I doing wrong? Or is there a bug somewhere?

PS: Replacing directlua with luadirect or luaexec from luacode-package or leaving out luastring-command doesn't change anything.

You can use expl3 and clist_item:nn to select an item in a list. This is expandable:

documentclass{article}

usepackage{luacode}

usepackage{expl3}

begin{luacode*}

 function dummy(argument)

  tex.sprint("lua: ".. argument)

 end

end{luacode*}



ExplSyntaxOn

newcommand{main}[1]{%

    hello~world~clist_item:nn{one,{two,three}}{#1}par

    directlua{dummy(luastring{clist_item:nn{foo,bar}{#1}})}

}

ExplSyntaxOff



begin{document}

main{1}



main{2}

end{document}

As egreg suggested in the comments an real expl3 version would use lua_now:e instead of directlua:

 lua_now:e {dummy("lua_escape:e{clist_item:nn{foo,bar}{#1}}")}

The most important thing you need to do is replace luastring with luastringN -- the N stands for "perform NO expansion" -- in the definition of the main macro. In addition, you need to disallow all those gratuitous whitespaces, by placing % at various line ends inside the definitions of the main and mychoice macros.

For the following MWE, I borrowed the form of the dummy function from Ulrike's answer.

documentclass{article}

usepackage{etoolbox}

usepackage{luacode} % for 'luacode' environment and 'luastringN' macro

begin{luacode}

function dummy ( argument )

   tex.sprint ( "lua: " .. argument )

end

end{luacode}



newcounter{choicecounter}

newcounter{argcounter}



newcommand{mychoice}[1]{%

    setcounter{argcounter}{0}%

    renewcommand*{do}[1]{%

        stepcounter{argcounter}%

        csedef{argcounterarabic{argcounter}}{##1}}%

    docsvlist{#1}%

    csuse{argcounterarabic{choicecounter}}%

}



newcommand{main}[1]{%

    setcounter{choicecounter}{#1}%

    mychoice{one,{two,three}}



    directlua{dummy(luastringN{mychoice{one,{two,three}}})}

}



begin{document}

1 --- main{1}



medskip

2 --- main{2}

end{document}