denis.maier@unibe.ch schrieb am 12.09.2023 um 21:24:

*Von:*Wolfgang Schuster *Gesendet:* Dienstag, 12. September 2023 20:41 *An:* mailing list for ConTeXt users ; Maier, Denis Christian (UB) *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. Wolfgang

denis.maier@unibe.ch schrieb am 12.09.2023 um 21:38:

*Von:*Wolfgang Schuster *Gesendet:* Dienstag, 12. September 2023 21:30 *An:* Maier, Denis Christian (UB) *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 mailto:wolfgang.schuster.lists@gmail.com *Gesendet:* Dienstag, 12. September 2023 20:41 *An:* mailing list for ConTeXt users mailto:ntg-context@ntg.nl; Maier, Denis Christian (UB) 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

denis.maier@unibe.ch schrieb am 12.09.2023 um 23:32:

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

Thank you so much, Wolfgang!

Why do you need protected here? I’ve realized that \protected\def also helps a bit, but, of course, paragraph breaks are ignored there as well…

You probably haven't noticed it yet but unlike the other predefined layouts for sections you don't have to write "alternative=command" to use the layout which is passed to the command key. To make this work ConTeXt has to check whether the argument of the command key is empty or not but this is problematic when you pass commands with arguments. When you try to example below you can see that the first definition of \Mycommand fails because \edef\CheckMycommand tries to expand its argument which causes problems because \Mycommand tries to read the following argument. To solve this problem you can use the \protected modifier when you create \Mycommand. \starttext \def\Mycommand#1{#1}% fails %\protected\def\Mycommand#1{#1}% works \edef\CheckMycommand{\Mycommand} \ifempty\CheckMycommand \tex{Mycommand} is empty \else \tex{Mycommand} has content \fi \stoptext

If just found the following in the lowlevel-macros manual:

«Traditional TEX has three prefixes that can be used with macros: \global, \outer and \long. The last two are no-op's in LuaMetaTEX and if you want to know what they do (did) you can look it up in the TEXbook.»

So, \long is gone, but why is that? Is there a new mechanism that serves the same purpose? Other than using a vbox, I mean…

The purpose of the \long modifier is to specify whether the argument of a command can or cannot contain multiple paragraph (either by an empty line or with \par). This was needed by TeX in the early days where memory was limited but not on the current machines. For a very long time ConTeXt made each command definition long by default (i.e. \def\...{...} behaved the same way as \long\def\...{...}) and as a result \long was dropped. \def\CommandA#1{#1} \long\def\CommandB#1{#1} \starttext \CommandA{xxx}% works \CommandA{xxx yyy}% fails because you have a empty line in the argument \CommandA{xxx\par yyy}%fails because you have \par in the argument \CommandB{xxx\par yyy}% works because \CommandB is \long \stoptext Wolfgang