Re: [NTG-context] troubles with \MPinclusions

21 Feb 2019

...
On 21 Feb 2019, at 10:03, Damien Thiriet  wrote:
Hi,
Why does (1) compile, whereas (2) doesn’t?
For me, both compile. However (2) does not work.

1. Variable names x and y are special and cleared before
   every graphic. This is related to the fact that “z" is 
   defined as a shortcut for "(x,y)”. Both of these are
   traditional. 

   Every metapost graphic does at least this at its start:

   save x,y;
   currentpicture := nullpicture;
   currentpen:=defaultpen;

   so pair xx[]; would have worked just fine.

   In general, I would advice to stay away from single-letter
   variable names inside MPinclusions, and use CamelCase
   to avoid clashes with metafun internals.

2. You need a bigger pen to actually see the dots even if
   you change the variable name. :)

Best wishes,
Taco
...
I can't understand why can MPinclusions store path and not pairs.
%%%%%%%%%%%% (1) %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\setuppapersize[A4,landscape]
\startMPinclusions
u:=1mm ;
%fond
path p ;
p:= (0,0) -- (150u,0) -- (150u,95u) -- (0,95u) -- cycle ;
pair x[] ;
x[0]:= (20u,90u) ;
x[1]:= (40u,90u) ;
x[2]:= (90u,90u) ;
x[3]:= (140u,90u) ;
\stopMPinclusions
\startreusableMPgraphic{test}
draw p ;
\stopreusableMPgraphic
\starttext 
   \reuseMPgraphic{test}
\stoptext
%%%%%%%%%%%% (1) %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\setuppapersize[A4,landscape]
\startMPinclusions
u:=1mm ;
%fond
path p ;
p:= (0,0) -- (150u,0) -- (150u,95u) -- (0,95u) -- cycle ;
pair x[] ;
x[0]:= (20u,90u) ;
x[1]:= (40u,90u) ;
x[2]:= (90u,90u) ;
x[3]:= (140u,90u) ;
\stopMPinclusions
\startreusableMPgraphic{test}
draw p ;
for i=0 step 1 until 3 :
   drawdot x[i] ;
endfor ;
\stopreusableMPgraphic
\starttext 
   \reuseMPgraphic{test}
More generaly, which kind of variables cannot be stored in
\startMPinclusions ?
Thanks,
Damien Thiriet
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Taco Hoekwater
Elvenkind BV