Am 07.06.2012 um 17:34 schrieb Philipp Gesang: > Hi Wolfgang! > > ···<date: 2012-06-07, Thursday>···<from: Wolfgang Schuster>··· > >> >> 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 comma command.
You can also try to use a Lua variant. \def\states_entry_indeed[#1][#2]% {\startlua local entries = utilities.parsers.settings_to_array("#1") local entry = entries[#2] if entry then context(entry) else context("\\tttf NO ENTRY!") end \stoplua} Wolfgang ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://tex.aanhet.net archive : http://foundry.supelec.fr/projects/contextrev/ wiki : http://contextgarden.net ___________________________________________________________________________________