[Mpi-22] Another MPI-2.2 attribute ambiguity?

[Jeff Squyres]

So then you're in favor of #1 from my original post, right?

     http://lists.mpi-forum.org/mpi-22/2009/05/0407.php

On May 19, 2009, at 4:39 PM, William Gropp wrote:

> Silly me, I missed that.
>
> In Fortran (particularly thinking in terms of Fortran 77, since that
> was the original design), the Fortran callback should be able to do
> things like increment the "extra data" - i.e., if the extra data is a
> counter, the Fortran callback should be able to increment it.  Since
> Fortran 77 has no pointers (and pointers in Fortran 90 aren't the same
> as addresses), having an address is worthless in a Fortran 77
> program.  So if the MPI implementation stores the address of the extra
> data and passes that to the call back (by value, so Fortran sees the
> address of the extra data), users should get what they expect in
> Fortran.
>
> Bill
>
> On May 19, 2009, at 12:22 PM, Iain Bason wrote:
>
> >
> > On May 19, 2009, at 1:16 PM, William Gropp wrote:
> >
> >> MPICH2 passes the value of the extra_state that was saved in the
> >> internal storage to the callback routine, which is case 2 (the copy
> >> is implicit as the value is passed to the routine and C semantics
> >> ensures that the value isn't changed).
> >
> > But this is the Fortran interface, not the C interface.
> >
> > Iain
> >
>
> William Gropp
> Deputy Director for Research
> Institute for Advanced Computing Applications and Technologies
> Paul and Cynthia Saylor Professor of Computer Science
> University of Illinois Urbana-Champaign
>
>
>
>
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-- 
Jeff Squyres
Cisco Systems