[metapost] Problem with showing paths

[Laurence Finston]

For a particular application, I'm calling MP from within a program via a pipe and I want to read the output and use it for setting variables in my application.  The intention is to use "point x of <path>" to take a path of length n and convert it into an equivalent path of length n*m where m is some whole number > 1 (within reason).

The problem is the way the lines in the output of "show" are broken:  The lines are fairly short (max. 80 characters, including the newline) and the x- and y-coordinates of the points can be broken across two lines, which makes parsing unnecessarily difficult.

This is how I'm calling MP:

mpost -interaction=nonstopmode -numbersystem "double" ftemp.mp

This is the contents of ftemp.mp:

tracingonline := 1;
path q;
q = (0cm, 0cm) ..  (1cm, -1cm) ..  (2cm, -2cm) ..  (1cm, -2cm) ..  (0cm, -2cm) ..  cycle;

path r;

n = (length q) / 10;

r = point 0 of q;

pair m;

for i = n step n until length q:
  m := point i of q;
  r := r .. m;
endfor;

r := r .. cycle;

show r;

end

This is the output of `show r':

>> Path at line 22:
(0,0)..controls (5.1033274754586504,-4.02658918875927) and (10.206654950917301,
-8.0531783775185382)
 ..(15.309982426375951,-12.079767566277809)..controls (20.836084424375677,-16.4
39931139579933) and (25.294686318678266,-22.003298723890239)
 ..(28.346450000000001,-28.346450000000001)..controls (32.480291212340902,-36.9
3872086349576) and (41.608988021726468,-41.963264226932786)
 ..(51.079824151240217,-40.859169680064937)..controls (60.177536433158913,-39.7
98573299547179) and (64.427271503927471,-51.786503064755529)
 ..(56.692900000000002,-56.692900000000002)..controls (52.969536959567222,-59.0
54862701313922) and (48.735413750965591,-60.492376958047501)
 ..(44.343636589685651,-60.885560755932076)..controls (38.685824079616481,-61.3
92089236029079) and (33.028509373892845,-59.909378434497384)
 ..(28.346450000000001,-56.692900000000002)..controls (24.097340827760725,-53.7
73849444054306) and (18.504358165205602,-53.716232375214233)
 ..(14.196014949203713,-56.547126869699198)..controls (9.9003101788908374,-59.3
69716987182123) and (4.3527609114952526,-59.426682524700915)
 ..(0,-56.692900000000002)..controls (-12.410724714480779,-48.898255857308889)
and (-22.071879582360939,-37.416127407829819)
 ..(-27.62972345019935,-23.855414418073572)..controls (-34.633713352935132,-6.7
662159604187089) and (-15.885082241839086,9.4212918781208899)
 ..(0,0)..controls (0,0) and (0,0)
 ..cycle

Is there anyway to fix this?  It would also be nice to limit the number of decimal places for the coordinates, by rounding or even by truncating.

As a workaround, I've written a macro to write the data I need to a file (see attachment), but it would be nicer if "show" could be used instead.

Thanks,

Laurence
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