# MPI_Type_set_attr

Stores attribute value associated with a key

## Synopsis

    int MPI_Type_set_attr(MPI_Datatype datatype, int type_keyval, void *attribute_val)

## Input Parameters

datatype
  MPI Datatype to which attribute will be attached (handle)
type_keyval
  key value, as returned by `MPI_Type_create_keyval` (integer)
attribute_val
  attribute value

## Notes

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 an address-sized integer.

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

## Notes for Fortran

All MPI routines in Fortran (except for `MPI_WTIME` and `MPI_WTICK`) have an additional argument `ierr` at the end of the argument list. `ierr` is an integer and has the same meaning as the return value of the routine in C. In Fortran, MPI routines are subroutines, and are invoked with the `call` statement.

All MPI objects (e.g., `MPI_Datatype`, `MPI_Comm`) are of type `INTEGER` in Fortran.

## Errors

All MPI routines (except `MPI_Wtime` and `MPI_Wtick`) return an error value; C routines as the value of the function and Fortran routines in the last argument. Before the value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job. The error handler may be changed with `MPI_Comm_set_errhandler` (for communicators), `MPI_File_set_errhandler` (for files), and `MPI_Win_set_errhandler` (for RMA windows). The MPI-1 routine `MPI_Errhandler_set` may be used but its use is deprecated. 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; however, MPI implementations will attempt to continue whenever possible.

MPI_SUCCESS
  No error; MPI routine completed successfully.

MPI_ERR_TYPE
  Invalid datatype argument. Additionally, this error can occur if an uncommitted MPI_Datatype (see `MPI_Type_commit`) is used in a communication call.

MPI_ERR_KEYVAL
  Invalid keyval