[NTG-context] conditional not working in \setuphead

[Wolfgang Schuster]

Pablo Rodriguez schrieb am 20.04.2020 um 18:55:
> Dear list,
> 
> I have the following sample:
> 
>    \startbuffer[demo]
>    <doc>
>      <section id="section-i1">
>        <text>first</text>
>      </section>
>      <section id="section-i2">
>        <text>second</text>
>      </section>
> 
>    </doc>
>    \stopbuffer
> 
>    \startxmlsetups xml:initialize
>       \xmlsetsetup{#1}{doc|section}{xml:*}
>    \stopxmlsetups
> 
>    \xmlregistersetup{xml:initialize}
> 
>    \startxmlsetups xml:doc
>       \xmlflush{#1}
>    \stopxmlsetups
> 
>    \startxmlsetups xml:section
>       \startsection[title={\xmlatt{#1}{id}},
>          beforesection={\doif{\xmlatt{#1}{id}}{\selectedtopic}
>              {conditional}}]
>          \xmlflush{#1}
>          \doif{\xmlatt{#1}{id}}{\selectedtopic}{conditional}
>       \stopsection
>    \stopxmlsetups
> 
>    \def\selectedtopic{section-i1}
> 
>    \starttext
>       \xmlprocessbuffer{main}{demo}{}
>    \stoptext
> 
> How can I make the conditional in the beforesection option work?

The argument of the beforesection-key is placed before ConTeXt stores 
the values of \startsection which means you can do it this way.

What you can do here is to put whatever something in a macro before you 
call \startsection and access the value of this macro with the 
beforesection-key. You should ensure the content if this temporary macro 
is cleared when your conditional is false.

\setuphead
   [section]
   [beforesection=\getvariable{xml}{beforesection}]

\startxmlsetups xml:section

     \doifelse{\xmlatt{#1}{id}}{\selectedtopic}
         {\setvariable{xml}{beforesection}{conditional}}
         {\setvariable{xml}{beforesection}{}}

     \startsection[title={\xmlatt{#1}{id}}]
         \xmlflush{#1}
     \stopsection

\stopxmlsetups

Wolfgang