[Rd] external pointers

[Ross Boylan]

I have some C data I want to pass back to R opaquely, and then back to
C.  I understand external pointers are the way to do so.

I'm trying to find how they interact with garbage collection and object
lifetime, and what I need to do so that the memory lives until the
calling R process ends.

Could anyone give me some pointers?  I haven't found much documentation.
An earlier message suggested looking at simpleref.nw, but I can't find
that file.

So the overall pattern, from R, would look like
opaque <- setup(arg1, arg2, ....)  # setup calls a C fn
docompute(arg1, argb, opaque)  # many times. docompute also calls C
# and then when I return opaque and  the memory it's wrapping get
#cleaned up.  If necessary I could do
teardown(opaque)  # at the end

"C" is actually C++ via a C interface, if that matters.  In particular,
the memory allocated will likely be from the C++ run-time, and needs C++
destructors.

-- 
Ross Boylan                                      wk:  (415) 514-8146
185 Berry St #5700                               ross at biostat.ucsf.edu
Dept of Epidemiology and Biostatistics           fax: (415) 514-8150
University of California, San Francisco
San Francisco, CA 94107-1739                     hm:  (415) 550-1062