[metapost] metapost 1.999 Semicolon Weirdness

[Hans Hagen]

On 5/13/2014 11:00 PM, Hartmut Henkel wrote:
> Hi,
>
> the following program runs fine with MetaPost Version 1.999:
>
> prologues:=3;
>    beginfig(1);
>    path p;
>    z1 = (0.000000,0.000000);
> z2 = (10.000000,0.000000);
> z3 = (10.000000,10.000000);
> z4 = (0.000000,0.000000);
> p := z1 .. controls z2 and z3 .. z4;
>    message(decimal(arclength(p)));
>    pickup pencircle scaled 0.050000;  drawdot z1 withcolor red;
>    drawdot z2 withcolor red;
>    drawdot z3 withcolor red;
>    drawdot z4 withcolor red;
>    pickup pencircle scaled 0.010000   draw (z1--z2--z3--z4) withcolor red;
>    draw p;
>    currentpicture := currentpicture scaled 10;
>    endfig;
>    end;
>
> Now i wonder why, since by accident there is no semicolon in line 14
> between "pickup pencircle scaled 0.010000" and "draw (z1--z2...".
> Shouldn't this give an error?

pickup is a macro:

def pickup secondary q =
     if numeric q :
         numeric_pickup_
     else :
         pen_pickup_
     fi q
enddef ;

that one calls:

def numeric_pickup_ primary q =
     if unknown pen_[q] :
        ...
     else :
        ...
     fi ;
enddef ;

def pen_pickup_ primary q =
     currentpen := q ;
     ...
     path currentpen_path ;
enddef ;

and there are ;'s embedded .. however:

     pickup pencircle scaled 0.010000

     ;

     numeric n ; n := savepen ;

     pickup n ;

     fill fullcircle scaled 1cm withcolor red;

needs the ; so you can best play safe and always add the ;

Hans

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                                           Hans Hagen | PRAGMA ADE
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