NAME

       MPI_Comm_set_attr - Stores attribute value associated with a key.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Comm_set_attr(MPI_Comm comm, int comm_keyval, void *attribute_val)

Fortran Syntax (see FORTRAN 77 NOTES)

       USE MPI
       ! or the older form: INCLUDE 'mpif.h'
       MPI_COMM_SET_ATTR(COMM, COMM_KEYVAL, ATTRIBUTE_VAL, IERROR)
            INTEGER   COMM, COMM_KEYVAL, IERROR
            INTEGER(KIND=MPI_ADDRESS_KIND) ATTRIBUTE_VAL

Fortran 2008 Syntax

       USE mpi_f08
       MPI_Comm_set_attr(comm, comm_keyval, attribute_val, ierror)
            TYPE(MPI_Comm), INTENT(IN) :: comm
            INTEGER, INTENT(IN) :: comm_keyval
            INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(IN) :: attribute_val
            INTEGER, OPTIONAL, INTENT(OUT) :: ierror

C++ Syntax

       #include <mpi.h>
       void MPI::Comm::Set_attr(int comm_keyval, const void* attribute_val) const

INPUT/OUTPUT PARAMETER

       comm      Communicator from which attribute will be attached (handle).

INPUT PARAMETERS

       comm_keyval
                 Key value (integer).

       attribute_val
                 Attribute value.

OUTPUT PARAMETER

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       MPI_Comm_set_attr  stores  the  stipulated  attribute  value  attribute_val  for  subsequent retrieval by
       MPI_Comm_get_attr. If the value is already present, then the outcome is as  if  MPI_Comm_delete_attr  was
       first  called  to delete the previous value (and the callback function delete_fn was executed), and a new
       value was next stored. The call is erroneous if there is no key with  value  comm_keyval;  in  particular
       MPI_KEYVAL_INVALID  is  an  erroneous key value. The call will fail if the delete_fn function returned an
       error code other than MPI_SUCCESS.

       This function replaces MPI_Attr_put, the use of which is deprecated. The  C  binding  is  identical.  The
       Fortran binding differs in that attribute_val is an address-sized integer.

FORTRAN 77 NOTES

       The  MPI  standard prescribes portable Fortran syntax for the ATTRIBUTE_VAL argument only for Fortran 90.
       Sun FORTRAN 77 users may use the non-portable syntax

            INTEGER*MPI_ADDRESS_KIND ATTRIBUTE_VAL

       where MPI_ADDRESS_KIND is a constant defined in mpif.h and gives the length of the  declared  integer  in
       bytes.

NOTES

       Values  of  the  permanent  attributes  MPI_TAG_UB,  MPI_HOST, MPI_IO, and MPI_WTIME_IS_GLOBAL may not be
       changed.

       The type of the attribute value depends on whether C or Fortran is being used. In C, an  attribute  value
       is  a  pointer (void *); in Fortran, it is a single, address-size integer system for which a pointer does
       not fit in an integer.

       If an attribute is already present, the delete function (specified  when  the  corresponding  keyval  was
       created) will be called.

ERRORS

       Almost  all  MPI  routines  return  an  error  value; C routines as the value of the function and Fortran
       routines in the last argument. C++ functions do not return errors. If the default error handler is set to
       MPI::ERRORS_THROW_EXCEPTIONS,  then  on  error  the  C++  exception  mechanism  will  be used to throw an
       MPI::Exception object.

       Before the error value is returned, the current MPI error handler  is  called.  By  default,  this  error
       handler  aborts  the  MPI  job,  except  for  I/O  function errors. The error handler may be changed with
       MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values
       to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.