[metapost] uinsg z1, z2, ... in more than one macros caused 'Inconsistent equation'

[Steven Woody]

hi,

in my mp file, i defined two macros, say foo, bar,  using def ...
enddef;   then in the main figure, i call foo followed by bar.  And, i
used z1, z2 in both foo and bar as temporarily.  but the metapost
reported "Inconsistent equation" when it processed in calling of bar.
i think i need to make z1, z2 local in foo and bar respectively, but i
failed, because "save z1, z2" will cause another errors.  what's the
clue?

thanks in advance.

-- 
woody

then sun rose thinly from the sea and the old man could see the other
boats, low on the water and well in toward the shore, spread out
across the current.