Passing lists from R to C, extracting elements, and sending lists back again

Dear Michael,

I had to tackle a similar issue while programming the AMORE package.
I recommend you to have a look at the source code of its "copynet.c" file. You
may find useful the reading of the "copynet_RC" function ( Copies the SEXP net
to the *ptnet) and the "copynet_CR" function (Copies *ptnet to SEXP net).

Of course, I do not pretend to establish what best practices should be, just to
show you how I solved a similar issue following my personal understanding of
what was appropriated in that situation.

Best wishes and Merry Christmas!
Manuel