Hi Wolfgang!
···
Am 07.06.2012 um 14:05 schrieb Philipp Gesang:
Hi all,
my goal is a macro \definestates[foo][...,...] which takes a comma list and creates a monadic macro \foo[n]. \foo[n] should return either the nth item or, if (n > list length), a default. I thought the right tools were \processcommalist to generate the mapping n-><list item>, as well as \processaction to retrieve the items. But naively I didn’t consider expansion ...
My code so far:
··8<···································································· \unprotect
\def\definestates{\dodoubleempty\do_define_states}
\def\do_define_states[#1][#2]{% \expandafter\edef\csname#1_states\endcsname{% \nstates0 %% this is supposed to be expanded so we employ the \raw... variety \rawprocesscommalist[#2]\add_one_state% unknown=>\dummystate,% default=>\dummystate,% }% \do_do_define_states{#1}% }
\let\dummystate\empty
\newcount\nstates \unexpanded\def\add_one_state#1{% \advance\nstates\plusone \the\nstates=>#1,% }
\def\do_do_define_states#1{% \expandafter\def\csname#1\endcsname {\expandafter\dosingleempty\csname do_#1\endcsname}% \expandafter\def\csname do_#1\endcsname[##1]{% \iffirstargument % <[DBG] cmd:#1, state:##1>\par \edef\currentstates{\csname#1_states\endcsname}% %% At this point \currentstates should yield the whole mapping so %% we can use it with \processaction. But ... % \show\currentstates % \currentstates\par %% ... here it still contains %% \nstates 0 \rawprocesscommalist [foo,bar,baz] ... %% and the next directive has an empty result: \rawprocessaction[##1][\currentstates]% \fi }% }
\protect \starttext
\definestates[mystates][foo,bar,baz] %% At this point I’d like \mystates_states to contain (literally) %% “1=>foo,2=>bar,3=>baz,unknown=>,default=>,” %% so the following command \mystates[1] % -> foo %% would be equivalent to %% \processaction[1][1=>foo,2=>bar,3=>baz,unknown=>,default=>,] \mystates[2] % -> bar \mystates[42] % -> dummy
\stoptext ··8<····································································
My question: How can I use \[raw]processcommalist in an expanded definition? How can I get \[raw]processcommalist to operate on the expansion of its second argument? Does this even make sense? If not, what is the proper way?
\unprotect
\unexpanded\def\definestates {\dodoubleargument\definestates_indeed}
\def\definestates_indeed[#1][#2]% {\setuevalue{#1}{\states_entry[#2]}}
\unexpanded\def\states_entry {\dodoubleargument\states_entry_indeed}
\def\states_entry_indeed[#1][#2]% {\getcommalistsize[#1]% \ifnum#2>\commalistsize {\tttf NO ENTRY!}% \else \getfromcommalist[#1][#2]\commalistelement \fi}
Thanks very much. This solves my problem. Very convenient that I can rewrite it to use commacommand. Philipp
\protect
\starttext
\definestates[mystates][foo,bar,baz]
\starttabulate \NC 2 \EQ \mystates [2] \NC\NR \NC 42 \EQ \mystates[42] \NC\NR \stoptabulate
\stoptext
Wolfgang ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki!
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