[NTG-context] how to define an environment with key=value arguments

[Henning Hraban Ramm <texml@fiee.net>]

Hi,
for an involved image placement (full page image starting each chapter, 
several stacked elements), I’d like an environment that accepts 
key-value arguments, like

\startMyFigure[page=left,title={My caption}]
\externalfigure[dummy]…
\stopMyFigure

I don’t think that a real float makes sense, even if the interface looks 
similar, since it’s always a full page in a fixed place, I need no 
numbering and can place the caption myself.

Does it make sense to use \definestartstop?
How would I “plugin“ the argument handling?


Or should I better define start and stop separately?

\def\startMyFigure[#1]{
% e.g. use utilities.parsers.settings_to_hash(#1)
}
\def\stopMyFigure{}


Probably I’ll need to catch the content (\externalfigure, might become 
more) and use it in a \setlayer – so perhaps something like

\definebuffer[MyFigure]
\define\stopMyFigure{%
  \setlayer[page]{\getMyFigure}}}
}

?
But then I don’t know how to handle the arguments.

Probably it makes most sense to do it in Lua, like

\startluacode
      interfaces.implement {
          name      = "startMyFigure",
          public    = true,
          arguments = {"hash",},
          actions   = function(h, a)
		-- …
		end, }
\stopluacode

But I didn’t find how to do environments.


Hraban

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