[NTG-context] Can I share METAPOST vardefs over multiple pages?

[Aditya Mahajan]

On Mon, 16 Mar 2020, Gerben Wierda wrote:

> This worked when I was just doing METAPOST. Now, I am using my lua code to produce the METAPOST code that produces the pictures. And the picture itself is put in a file for METAPOST as follows:
>
> File test4-mplib-run-001.mp:
>
> % begin graphic: n=0
>
> ; beginfig(1) ; defaultfont:="name:dejavuserif*default"; CurrentLayout:="article"; def OverlayLineColor=black enddef; def OverlayColor =black enddef; ;picture pic; x:=80.000; y:=200.000; w:=133.000; h:=53.000;pic := ApplicationComponentLogo( w, h, typeString) shifted (x, -y); draw pic;picture pic; x:=273.000; y:=253.000; w:=133.000; h:=53.000;pic := Function( w, h, typeString) shifted (x, -y); draw pic;picture pic; x:=380.000; y:=133.000; w:=133.000; h:=53.000;pic := Service( w, h, typeString) shifted (x, -y); draw pic;path p; p := (200.000,-227.000)--(333.000,-227.000)--(333.000,-273.000); draw p;path p; p := (393.000,-253.000)--(393.000,-180.000); draw p;;; endfig ;
> % end graphic
>
> This apparently is tried to get run through METAPOST separately and that clearly doesn’t work, because ApplicationComponentLogo isn’t defined. This is the result of the following setup:
>
> \starttext
> \startMPdefinitions (or inclusions, no difference)
> % ApplicationComponentLogo is defined here with a vardef
> \stopMPdefinitions
> \ctxlua{foo(“filename”)} 	% produces a series of
> 				%    context.startMPpage { instance = "doublefun” }
> 				%    several of:
> 				%	context( METAPOST statements in a string)
> 				%    context.stopMPpage()
> \stoptext
>
> How do I get my MPdefinitions available in those METAPOST runs?

Since you are using \startMPpage[instace=doublefun], you need to do the 
definitions for doublefun instance: so use

\startMPdefinitions{doublefun}
...
\stopMPdefinitions

Aditya