Why not just free the object?
Consider this library routine:
void MakeDatatype( nx, ny, ly, lz, MPI_Datatype *new )
{
MPI_Datatype newx1;
MPI_Type_vector( ly, 1, nx, MPI_DOUBLE, &newx1 );
MPI_Type_hvector( lz, 1, nx*ny*sizeof(double), newx1,
new );
MPI_Type_free( &newx1 );
MPI_Type_commit( new );
}
Without the MPI_Type_free( &newx1 ), it would be very awkward
to later free newx1 when new was freed.