[Rd] capturing value of C or Fortran function
Harris A. Jaffee
hjaffee at jhmi.edu
Wed Dec 13 17:56:13 CET 2006
The value, if there is one, of a function called by .C or .Fortran is not
captured, so one needs a wrapper. To avoid that, the user would have to
declare that there is a value, specify its type, and supply an R variable
to hold the value. Presumably, all of these could be combined in a new
"VALUE=var" parameter. Then do_dotCode could arrange the correct type of
C variable to receive the value (for every one of the 66 possible instances
of the call), and then transfer that value to 'var'. It seems doable with
a strong enough macro, if a bit complicated. Or one could say VALUE=<type>
and get the value as a new, (n+1)_th element of the current list value.
Of course, existing code naming an argument with "VALUE" would break, so a
completely new interface, perhaps .C.function(), .Fortran.function(), would
be required to avoid that.
Has this facility been ruled out?
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