Copy callback function for \fIwin_keyval\fP (function).
.TP 1i
win_delete_attr_fn
Delete callback function for \fIwin_keyval\fP (function).
.TP 1i
extra_state
Extra state for callback functions.
.SH OUTPUT PARAMETERS
.ft R
.TP 1i
win_keyval
Key value for future access (integer).
.TP 1i
IERROR
Fortran only: Error status (integer).
.SH DESCRIPTION
.ft R
The argument \fIwin_copy_attr_fn\fP may be specified as MPI_WIN_NULL_COPY_FN or MPI_WIN_DUP_FN from either C, C++, or Fortran. MPI_WIN_NULL_COPY_FN is a function that serves only to return \fIflag\fP = 0 and MPI_SUCCESS. MPI_WIN_DUP_FN is a simple-minded copy function that sets \fIflag\fP = 1, returns the value of \fIattribute_val_in\fP in \fIattribute_val_out\fP, and returns MPI_SUCCESS.
.sp
The argument \fIwin_delete_attr_fn\fP may be specified as MPI_WIN_NULL_DELETE_FN from either C, C++, or Fortran. MPI_WIN_NULL_DELETE_FN is a function that serves only to return MPI_SUCCESS.
.sp
The C callback functions are:
.sp
.nf
typedef int MPI_Win_copy_attr_function(MPI_Win \fIoldwin\fP, int \fIwin_keyval\fP,
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.