[NTG-context] how to figure out the number of elements inside \defineconversion?

Hans Hagen pragma at wxs.nl
Thu Aug 10 17:22:38 CEST 2006


Mojca Miklavec wrote:
> Hello,
>
> I would like to \defineconversion and the use that set of symbols
> inside a metapost graphic. But I need to know the number of symbols,
> so that I can define enough "metapost images with symbols" in advance.
> I realise that there might be a problem since conversion can sometimes
> take an arbitrary number (using a command defined elsewhere), but if I
> could have a reasonable guess for conversions defined explicitely,
> that would already help a lot. (As a workaround and/or if there is no
> easy method to figure that out I can still hardcode "25" and wait
> until someone complains that that is not enough to satisfy his/her
> needs.)
>
> Thanks a lot,
>     Mojca
>
>
> \startMPextensions
>   numeric variant; variant = 1;
>   vardef gp_the_symbol(expr n) =
>     picture pict;
>     % using metapost
>     if variant=1:
>       pict := image( fill fullcircle scaled 4pt; ); % TODO
>     % using TeX, variant = 2
>     else: % TODO: limit the number first
>       pict := sometxt(n);
>     fi;
>     pict shifted -center pict
>   enddef ;
>
>   def gp_point(expr x, y, n) =
>     draw (gp_the_symbol(n) scaled 1 shifted (x,y));
>   enddef ;
> \stopMPextensions
>
> \starttext
>
> \defineconversion[abc][$\star$,$\bullet$,$\ast$]
>
> \startTeXtexts
> % TODO: 6 is only a guess: I need a better guess (3 in this case)
> \dostepwiserecurse{1}{6}{1}{\TeXtext{\recurselevel}{{\convertnumber{abc}{\recurselevel}}}}
> \stopTeXtexts
>
> \startMPcode
>   variant := 1;
>   gp_point(1cm,0cm,1);
>   gp_point(2cm,0cm,2);
>   variant := 2;
>   gp_point(1cm,1cm,1);
>   gp_point(2cm,1cm,2);
>   gp_point(3cm,1cm,3);
>   gp_point(4cm,1cm,4);
>   gp_point(5cm,1cm,8);
> \stopMPcode
>
> \stoptext
>   
\unprotect

\def\doifelseconversionnumber#1#2%
  {\doifdefinedelse{\??cv#1#2}}

\protect

\defineconversion[abc][$\star$,$\bullet$,$\ast$]
\defineconversion[def][m,o,j,c,a]

\doloop
  {\doifelseconversionnumber{abc}{\recurselevel}
     {[abc \recurselevel\space defined]}
     {\exitloop}}

\doloop
  {\doifelseconversionnumber{def}{\recurselevel}
     {[def \recurselevel\space defined]}
     {\exitloop}}

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