defining and expanding in xml

["Thomas A. Schmitz" <thomas.schmitz@uni-bonn.de>]

Hi gurus,

sorry for this long mail, but this is too difficult for me, and I have
to apologize that I can't provide a minimal example. Here's what I want:

I have one big xml-file which is my lecture course for the semester.
Every single lecture is one section. This xml-file is processed
(needless to say!) with ConTeXt. Every lecture is accompanied by a
presentation, written in and processed by ConTeXt. The TeX files and the
resulting pdfs are named by their dates, such as 07_11_23.pdf for
today's lecture. I have defined a simple counter that will typeset a
number in red at every place in the lecture where I show a new slide
(and then increment the counter); here are the relevant definitions:

\definelabel[SlideNumber][headstyle=normal,way=bytext]
\define\SLN{\color[red]{[\nextSlideNumber]}}
\defineXMLcommand[sln]{\sln}

What I want: I would like to produce a "handout" of the lecture course
which would include the slides at the relevant places. My idea was that
everything is basically in place. I would simply need to define a
"handout" mode which would redefine this \sln command and use the
SlideNumber counter to insert the relevant pages from the presentation
pdf. But I can't get it to work. Here's what I've tried:

1. the value of the \SlideNumber counter should be \currentSlideNumber,
so basically I would like something along these lines:

\define\sln
{\externalfigure[presentations/07_11_23.pdf][page=
\currentSlideNumber]\incrementSlideNumber}

But this throws an error:
! Argument of \pp!doifinstringelse has an extra }.
<inserted text> 
                \par 
<to be read again> 
                   }
\doif #1#2->\edef \!!stringa {#1}
                                 \edef \!!stringb {#2}\ifx \!!stringa
\!!str...

\checkfigureusersettings ...ntedfigurepage \empty 
                                                  {\let
\wantedfigurepage \!...

\calculateexternalfigure ...eckfigureusersettings 

\checkfigurecolorsettings ...
<argument> ...lideNumber },width=.75\textwidth ][]

\calculateexternalscreenfi...
...
l.71       <SLN/>

I assume it is an expansion problem. I tried page=
\expanded{\currentSlideNumber]}, but that doesn't work either. So this
is my first problem: how can I pass the value of SlideNumber on to the
externalfigure command?

2. Next step: I would like to have the name of the corresponding
presentation pdf in another macro so I can include this in the command
definition as well. In TeX, I would simply write someting like 

\let\CurrentPresentation=07_11_23.pdf

into my file and then refer to \CurrentPresentation. But how do I do
this in XML? I was thinking something along the lines

<section Current="07_11_23.pdf">

but am at a loss as to how to pick up this value later.

Sorry for the long post; I'd be very happy if someone could provide some
insights.

Thomas

___________________________________________________________________________________
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  : https://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________