on Thu Dec 25 2008, Adam Merz <adammerz-AT-hotmail.com> wrote:
Vladimir Batov writes:
1. Boost.MPI efficiency does not seem to rely on PODness. Rather it seem to be due to serialization (or rather ability to bypass it).
This isn't technically correct, I think; in MPI's case (though not Interprocess'), the type must be serializable regardless, but the ideal efficiency scenario comes from specializing both boost::mpi::is_mpi_datatype and boost::serialization::is_bitwise_serializable. Note that the documentation for these traits ([1] and [2], respectively) both specifically mention POD types -- this is no coincidence.
[1] http://www.boost.org/doc/libs/1_37_0/doc/html/boost/mpi/is_mpi_datatype.html [2] http://www.boost.org/doc/libs/1_37_0/libs/serialization/doc/traits.html
Vladimir is technically correct in fact. It just so happens that PODs are *guaranteed* to satisfy both the necessary qualifications. In practice, many non-PODs will also do that, but of course that's not guaranteed to be true, portably, for most non-POD types. -- Dave Abrahams BoostPro Computing http://www.boostpro.com