···<date: 2013-10-10, Thursday>···<from: Thangalin>···

> 
> I noticed something unexpected with the following code:
> 
> \enabletrackers[metapost.showlog]
> 
> \startuseMPgraphic{heading:ThemeTitleStyle}
>   show "HEADING:THEMETITLESTYLE";
>   show \MPstring{heading:title};
> 
>   draw textext( \MPstring{heading:title} ) rotated 5
>     withcolor blue;
> \stopuseMPgraphic
> 
> \defineframed[ThemeTitleStyle][
>   background=\useMPgraphic{ThemeTitleStyle},
> ]
> 
> \def\processword#1{%
>   \setMPtext{heading:title}{#1}%
>   \useMPgraphic{heading:ThemeTitleStyle}
> }
> 
> \define[1]\ThemeChapterTitle{\applytosplitstringword\processword{#1}}
> \setuphead[chapter][deeptextcommand={\ThemeChapterTitle}]
> 
> \starttext
>   \startchapter[title=Why Is heading:ThemeTitleStyle Called Twice?]
>   \input knuth
>   \stopchapter
> \stoptext
> 
> It appears as though heading:ThemeTitleStyle is being called twice:
> 
> metapost        > info:
> >> "HEADING:THEMETITLESTYLE"
> >> "Why"
> metapost        > info:
> >> "HEADING:THEMETITLESTYLE"
> >> "Why"
> 
> I am trying to produce a random number that is not equal to the
> previous random number. However, if the code is called twice, then I'd
> have to add code to ignore one of the calls.
> 
> Any ideas why the code seems to be called twice and what can be done
> to ensure that it is only called once?

Don’t use text ;-) That’s a known issue: as soon as your Metapost
code contains text, it will be processed twice. E.g.:


  \starttext
    \setMPtext{heading:title}{foo}
    \startMPcode
      show "This gets printed twice.";
      draw textext( \MPstring{heading:title} );
    \stopMPcode
  \stoptext

Same for labels, {b,e}tex. See also this thread:

  http://www.ntg.nl/pipermail/ntg-context/2011/056047.html

Best regards,
Philipp