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I'm trying to perform a very simple processing task in LaTeX3, namely, defining a series of functions named in terms of the token lists retrieved from a clist as a stack. Each function will set accordingly a token list variable with a name determined by the stack item, too.

My code is as follows:

\RequirePackage{expl3} \documentclass{memoir} \ExplSyntaxOn \clist_new:N \l_my_clist \clist_gset:Nn \l_my_clist {date,name,phone} \bool_do_while:nn { ! \clist_if_empty_p:N \l_my_clist } { \clist_pop:NN \l_my_clist \l_tmpb_tl \tl_new:c { g_my_ \l_tmpb_tl _tl } \cs_gset:cpn { my_ \l_tmpb_tl :n } #1 { \tl_gset:cn { g_my_ \l_tmpb_tl _tl } {#1} %{ \tl_to_str:n {#1} } } } \my_date:n {the date} \my_name:n {the name} \my_phone:n {the phone} \AtBeginDocument { \g_my_date_tl\par \g_my_name_tl\par \g_my_phone_tl } \ExplSyntaxOff \begin{document} \end{document}

I was expecting to get a three-line (well, three single-line paragraphs) page with thedate thename thephone as text, but I only get the last one. What is it that I'm doing wrong? I've tried also with \tl_use:N \l_tmpb_tl in the code, but to no avail.

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To be honest, I would tackle this in a much less complex way, using a mapping:

\RequirePackage{expl3} \documentclass{memoir} \ExplSyntaxOn \clist_map_inline:nn { date , name , phone } { \tl_new:c { g_my_ #1 _tl } \cs_new:cpx { my_ #1 :n } ##1 { \tl_gset:Nn \exp_not:c { g_my_ #1 _tl } {##1} } } \my_date:n { the~date } \my_name:n { the~name } \my_phone:n { the~phone } \AtBeginDocument { \g_my_date_tl \c_space_tl \g_my_name_tl \c_space_tl \g_my_phone_tl } \ExplSyntaxOff \begin{document} \end{document}

Notice that in the above I've used \cs_new:cpx to expand as far as possible the 'setting' functions: this saves a little complexity later.

Taking the original formulation, your problem is actually expansion. In

\cs_gset:cpn { my_ \l_tmpb_tl :n } #1 { \tl_gset:cn { g_my_ \l_tmpb_tl _tl } {#1} %{ \tl_to_str:n {#1} } }

you set the command to expand exactly to the tokens you've given. Thus while at the point of definition you have \l_tmpb_tl set to date, name and phone sequentially, each definition just contains \l_tmpb_tl (i.e. not the value of the variable). Thus you have to use an x-type approach here (in my alternative you don't actually have to, although I think it's cleaner). Minimal change is therefore

\RequirePackage{expl3} \documentclass{memoir} \ExplSyntaxOn \clist_new:N \l_my_clist \clist_set:Nn \l_my_clist { date , name , phone } \bool_do_while:nn { ! \clist_if_empty_p:N \l_my_clist } { \clist_pop:NN \l_my_clist \l_tmpb_tl \tl_new:c { g_my_ \l_tmpb_tl _tl } \cs_gset:cpx { my_ \l_tmpb_tl :n } #1 { \tl_gset:cn { g_my_ \l_tmpb_tl _tl } {#1} %{ \tl_to_str:n {#1} } } } \my_date:n {the date} \my_name:n {the name} \my_phone:n {the phone} \AtBeginDocument { \g_my_date_tl \g_my_name_tl \g_my_phone_tl } \ExplSyntaxOff \begin{document} \end{document}

although I'd still go with 'pre-converting' the token list name using \exp_not:c.

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  • I had not taken the time yet to read the `ìnterface3`` doc about mappings to token lists. Your answer makes for further motivation to amend this mistake of mine as soon as possible. Commented Sep 6, 2013 at 22:10

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