On Jan 7, 2010, at 3:24 PM, Solt, David George wrote:

Thanks for the suggestions. I'm reworking the last proposals a bit. My goal is to come up with something that allows for most interfaces (all but f77) to have a way to do large counts, leave f77 alone, and still have some consistency across languages and across what we already do.

1) Function overloading as available in Fortran90 and newer right?

I'd vote for the F2003 MPI bindings and later. I don't really want to touch either the F77 or F90 bindings.

2) One concern I have with going to MPI_Count is that I think that MPI_Send(buf, 10, ....) should always be legal. If we introduce a type that is up to the implementation, then that may not be legal any longer? Do we specify in the standard that MPI_Count MUST be defined by the implementation to be something that can be cast to/from an integer constant?

Can you give an example where it won't be legal?

3) Another concern with introducing MPI_Count TYPE in Fortran90/newer is that it is inconsistent with the way other types are handled (MPI_Comm, MPI_Request, MPI_Info, etc.) It seems a bit strange to me that we are going to pick out this one thing and make it a TYPE in all newer Fortrans even though everything else is declared as an INTEGER.

In the F2003 bindings, we have opaque types for all the MPI handles -- they're no longer integers. :-) That being said, there were some technical issues raised at the Portland meeting -- I can't remember many of them now, but one sticks out: what about functions that take a count as an OUT argument? Those can't just seamlessly be recompiled (unless MPI_Count === int). -- Jeff Squyres jsquyres_at_[hidden]