[NTG-context] Re: expanded doif's

[Wolfgang Schuster <wolfgang.schuster.lists@gmail.com>]

Hans van der Meer schrieb am 17.06.2024 um 09:01:
> I want to show an errormessage when the macro is undefined. It requires 
> expansion of \xmlatt{#1}{name}.
> \ifdefined\xmlatt{#1}{name} didn't worked nor \expandafter\ifdefined
> I thought of the expanding \doif's.
> 
> See the attached output of this xmlsetup attached.
> 
> \startxmlsetups hvdm:system:macrocall
> %
> \doifelsedefined{\xmlatt{#1}{name}}
> {
> %
> %macro without argument
> %
> \ifxmlattempty{#1}{arg}
> \begincsname\xmlatt{#1}{name}\endcsname
> %
> %macro with argument
> %
> \else
> \begincsname\xmlatt{#1}{name}\endcsname{\xmlatt{#1}{arg}}
> \fi
> }
> {
> \ERROR{macro \xmlatt{#1}{name} is not defined}
> }
> \stopxmlsetups

I have no idea what's wrong in your code without a proper minimal 
example. As the example below shows you can use \doifelsedefined in 
combination with \xmlatt.

\startbuffer[ifdefined]
<document>
   <macro name="bold" arg="text"/>
   <macro name="hvdm" arg="text"/>
</document>
\stopbuffer

\startxmlsetups xml:document
   \xmlflush{#1}
\stopxmlsetups

\startxmlsetups xml:macro

   \doifelsedefined{\xmlatt{#1}{name}}
     {\texdefinition{\xmlatt{#1}{name}}{\xmlatt{#1}{arg}}}
     {{\tttf macro \tex{\xmlatt{#1}{name}} not defined}}

% \ifcsname\xmlatt{#1}{name}\endcsname
%   \lastnamedcs{\xmlatt{#1}{arg}}
% \else
%   %
% \fi

\stopxmlsetups

\startxmlsetups xml:hvdm
\xmlsetsetup{\xmldocument}{document|macro}{xml:*}
\stopxmlsetups

\xmlregistersetup{xml:hvdm}

\starttext
\xmlprocessbuffer{hvdm}{ifdefined}{}
\stoptext

Wolfgang
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