capturing value of C or Fortran function
Well, fortran subroutines don't really have return values (versus fortran functions, which do - as far as I know that's the only difference between fortran subroutines and functions). There is also a somewhat sticky matter, of C routines that returns fairly complex types, like pointers, strings... and likewise, fortran functions can return rather complex things, like matrices, etc. It is going to be difficult to do a one-size-fit-all solution. So all you are trying to cater for, is a rather small subset of C/fortran functions which returns a single int or a single double? (anything to do with arrays you'll need to "smuggle" the array size out the old-fashion way via argument pointers).
Harris A. Jaffee wrote:
Re: src/main/dotcode.c:do_dotCode() 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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