denis.maier@unibe.ch schrieb am 12.09.2023 um 21:38:
>
> *Von:*Wolfgang Schuster <wolfgang.schuster.lists@gmail.com>
> *Gesendet:* Dienstag, 12. September 2023 21:30
> *An:* Maier, Denis Christian (UB) <denis.maier@unibe.ch>
> *Cc:* ntg-context@ntg.nl
> *Betreff:* Re: [NTG-context] Using structureuservariables before the 
> heading
>
> denis.maier@unibe.ch <mailto:denis.maier@unibe.ch> schrieb am 
> 12.09.2023 um 21:24:
>
>     *Von:*Wolfgang Schuster <wolfgang.schuster.lists@gmail.com>
>     <mailto:wolfgang.schuster.lists@gmail.com>
>     *Gesendet:* Dienstag, 12. September 2023 20:41
>     *An:* mailing list for ConTeXt users <ntg-context@ntg.nl>
>     <mailto:ntg-context@ntg.nl>; Maier, Denis Christian (UB)
>     <denis.maier@unibe.ch> <mailto:denis.maier@unibe.ch>
>     *Betreff:* Re: [NTG-context] Using structureuservariables before
>     the heading
>
>     denis.maier@unibe.ch <mailto:denis.maier@unibe.ch> schrieb am
>     12.09.2023 um 17:47:
>
>
>         Hi,
>
>         is it possible to access a structureuservariable before the
>         heading’s title ?
>
>         Using the «before» key does not seem to work.
>
>
>     There are ways but not in a general way because you try to access
>     the values
>     before they are known to ConTeXt. To provide a proper solution you
>     have
>     to tell what you're trying to achieve.
>
>     I’m just trying to output the author’s name above a chapter
>     heading. Do you need more information?
>
>
> You can create a custom header for the chapter page and show the value 
> of the author key
> which works without problems because the header is added after to the 
> finished page
> after the value is available.
>
> Another option when the name should appear in the same space as the 
> chapter title
> is a custom layout for the title.
>
> Yes, I’ve tried that in the original MWE:
>
> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>
> \setuphead[chapter][
>
>     before={Before: \structureuservariable{author}\blank},
>
>     beforesection={Beforesection: \structureuservariable{author}\blank},
>
>     insidesection={Insidesection: \structureuservariable{author}\blank},
>
>     after={After: \structureuservariable{author}\blank},
>
>     ]
>
> \def\myChapterCommand#1#2{\structureuservariable{author}\space\blank}
>
> \define[2]\myChapterCommand{\structureuservariable{author}\blank 
> #1\space#2}
>
> %\def\myChapterCommand#1#2{\structureuservariable{author}\blank 
> #1\space#2} % does not work
>
> % \starttexdefinition myChapterCommand #1 #2 % doesn't work either, 
> but at least blanks should work
>
> %   \structureuservariable{author}
>
> %   Test
>
> %   \blank
>
> %   #1\space#2
>
> % \stoptexdefinition
>
> \starttext
>
> \myChapterCommand{1}{asdf}
>
> \startchapter[title=First][author=First Author]
>
> \input knuth
>
> \stopchapter
>
> \startchapter[title=Second][author=Second Author]
>
> \input knuth
>
> \stopchapter
>
> \setuphead[chapter]
>
>     [
>
>     before=,after=,beforesection=,insidesection=,
>
>     command=\myChapterCommand,
>
> ]
>
> \startchapter[title=Third][author={Third Author}]
>
> \input knuth
>
> \stopchapter
>
> \stoptext
>
> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>
> Here, I’m getting «Third author» just before «3 Third». So I guess 
> this goes in the right direction, but \define doesn’t allow for blanks 
> etc. \starttexdefinition and \def on the other hand gave me erros.
>

You need a box to get the author on a separate line.

% \define[2]\ChapterCommand
%   {\vbox
%      {\structureuservariable{author}
%      \blank
%      #1\space#2}}

\starttexdefinition protected ChapterCommand #1#2
   \vbox\bgroup
     \structureuservariable{author}
     \blank
     #1\space#2
   \egroup
\stoptexdefinition

\setuphead
   [chapter]
   [command=\ChapterCommand]

\starttext

\startchapter[title=First][author=First Author]
\input knuth
\stopchapter

\startchapter[title=Second][author=Second Author]
\input knuth
\stopchapter

\startchapter[title=Third][author={Third Author}]
\input knuth
\stopchapter

\stoptext

Wolfgang