[MPI3 Fortran] Agenda for MPI3 Fortran Working group next week

N.M. Maclaren nmm1 at cam.ac.uk
Thu Jun 4 12:07:49 CDT 2009

On Jun 4 2009, Iain Bason wrote:
>Nick seems to want them to be more than a pointer to an opaque type,  
>but I'm not sure exactly what he wants, nor why he wants it.

No, that's NOT what I am saying!

What I am saying is that the opaque type isn't a simple one, and it isn't
a clean specification for it to be specified as something that doesn't
correspond to how it behaves.  If you are still lost, consider two aspects
of the copying issue.

    When an object A is copied to B:
        a) Do all components of A get copied, or do some get cleared,
    reset or whatever?
        b) when components of B are changed, do they also change in A,
    or are they now independent?

Those questions are deep ones in programming language theory, and their
answers in MPI terms are not simple.  It is a serious mistake to use a
Fortran facility which necessarily answers those questions, without first
checking if the answers are compatible with MPI's answers.

Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
Email:  nmm1 at cam.ac.uk
Tel.:  +44 1223 334761    Fax:  +44 1223 334679

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