Begin forwarded message:
From: Aleksandar Donev <ado...@math.princeton.edu>
Date: November 21, 2005 9:30:18 AM MST
To: J3 <j...@j3-fortran.org>
Subject: (j3.2005) Re: Derived types according to MPI2
Hello,
Malcolm Cohen wrote:
Which just goes to show that the authors of MPI2 didn't understand
Fortran, since that is completely and utterly false in every sense
that matters.
Yes, but the interesting thing is neither me nor Van were aware of
what
the standard actually allows in terms of derived types and the storage
for the components, and presumably we know Fortran better. Can storage
for the components be separated from the scalar derived type itself?
This probably makes no visible difference for scalars, but for arrays
it does. Again, I am asking about what STORAGE_SIZE for derived types
should mean.
Dan Nagle wrote:
Please be aware that the "external world" of the MPI standard
is really the virtual machine of the C standard.
Yes, of course, I am certainly not proposing binding to hardware.
When defining a programming language, the "needless abstraction"
I should have qualified with "some needless abstractions". Of course
abstractions are good, especially when it does not matter to the user
how something is done as long as it is done well. But if you want to
pass an array of derived types to a parallel IO routine that is not
compiled by your super-smart Fortran compiler that chooses to scatter
the components across virtual-address space (yes, I mean virtual),
then
you do NOT want that abstraction.
It is about choice. Leave preaching to the preachers. Programming is a
profession for a reason---programmers are experienced and educated and
understand the issues and don't need lectures on abstractions.
Aleks
