Another Question

Hello All,

I have a metapost program that begins as below ---

mpost -numbersystem=double displayMP.mp
This is MetaPost, version 1.9991 (TeX Live 2016) (kpathsea version 6.2.2)
(/usr/local/texlive/2016/texmf-dist/metapost/base/mpost.mp
(/usr/local/texlive/2016/texmf-dist/metapost/base/plain.mp
Preloading the plain mem file, version 1.005) ) (./displayMP.mp (./SCHEMA0)
(./SCHEMA1)
data file: fourObjects
>> left
>> pen
! Not implemented: penoffset(unknown numeric)of(pen).
<to be read again>
                   ;
pen_pickup_->...part.penoffset.left.of.currentpen;

pen_bot:=ypart.penoffset.r...
<to be read again>
                   ;
drawVisible->...ckup.pencircle.scaled.mpLineWidth;

for.i=0upto(numberObjects-...
l.702 ^^IdrawVisible
                     ;
The mpLineWidth variable is properly set before the pickup pencircle
statement is interpreted.

Then if an r is typed ...  I end up with the following ...

! Internal quantity `pen_bot' must receive a known numeric value.
<to be read again>
                   ;
pen_pickup_->...art.penoffset.right.of.currentpen;
                                                  path.currentpen_path;
<to be read again>
                   ;
drawVisible->...ckup.pencircle.scaled.mpLineWidth;

for.i=0upto(numberObjects-...
l.722 ^^IdrawVisible
                     ;
[4] )
(see the transcript file for additional information)
4 output files written: fourObjects.1 .. fourObjects.4
Transcript written on displayMP.log.


But now if I use the four files   fourObjects.1 ... fourObjects.4  the line
width drawn is what I asked for.

Why is there all these extra statements by metapost?   I  do not have a
small example of this behavior.



Many thanks in advance for your comments.

--
http://tug.org/metapost/