[MPI3 Fortran] fortran types

Jeff Squyres jsquyres at cisco.com
Wed May 6 16:25:51 CDT 2009

(changing the subject because this is a different topic than the ASYNC  

On May 6, 2009, at 5:21 PM, Craig Rasmussen wrote:

> > Question: Is MPI_Request actually a Fortran derived TYPE, or is it
> > just a KIND value for an INTEGER?  I had thought that all of these
> > flag and handle-like arguments were treated as integers in the
> > Fortran interface.  Making it an actual defined type would have some
> > advantages, but would that cause a problem with existing codes?
> Right, user code would have to change in the MPI-3 interfaces.  This
> does create a problem regarding the naming of the MPI module.  We had
> discussed leaving the module name alone.  So both MPI-2 and MPI-3
> would use the same module name, ie,
> use MPI
> I don't see how the module name can be the same and just a "quality of
> implementation" issue.  I think we have to say,
> use MPI3
> I don't want to give up using derived types for things like
> TYPE(MPI_Comm), unless the implementers are happy using integers.

Nope!  Using "something better" would certainly be nice.  Indeed,  
having a lack of translation between Fortran and C handles would be  
great.  I don't really care if it's a Fortran derived type or whether  
it maps directly back to the C handle (e.g., in OMPI's case, using the  
equivalent of (void*) so that the Fortran handle value would be  
identical to the C handle value).

Jeff Squyres
Cisco Systems

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