.\"Copyright 2006-2008 Sun Microsystems, Inc.
.\"Copyright (c) 1996 Thinking Machines
.TH MPI_Comm_delete_attr 3 "Dec 08, 2009" "1.4" "Open MPI"
.SH NAME
\fBMPI_Comm_delete_attr\fP \- Deletes attribute value associated with a key. 

.SH SYNTAX
.ft R
.SH C Syntax
.nf
#include <mpi.h>
int MPI_Comm_delete_attr(MPI_Comm \fIcomm\fP, int \fIcomm_keyval\fP)

.SH Fortran Syntax
.nf
INCLUDE 'mpif.h'
MPI_Comm_delete_attr(\fICOMM, COMM_KEYVAL, IERROR\fP)
	INTEGER	\fICOMM, COMM_KEYVAL, IERROR \fP

.SH C++ Syntax
.nf
#include <mpi.h>
void MPI::Comm::Delete_attr(int \fIcomm_keyval\fP)

.SH INPUT/OUTPUT PARAMETER
.ft R
.TP 1i
comm
Communicator from which the attribute is deleted (handle). 

.SH INPUT PARAMETER
.ft R
.TP 1i
comm_keyval
Key value (integer).

.SH OUTPUT PARAMETER
.ft R
.TP 1i
IERROR
Fortran only: Error status (integer). 

.SH DESCRIPTION
.ft R
MPI_Comm_delete_attr deletes an attribute from cache by key. This function invokes the attribute delete function delete_fn specified when the \fIcomm_keyval\fP was created. The call will fail if the delete_fn function returns an error code other than MPI_SUCCESS.  

Whenever a communicator is replicated using the function MPI_Comm_dup, all callback copy functions for attributes that are currently set are invoked (in arbitrary order). Whenever a communicator is deleted using the function MPI_Comm_free, all callback delete functions for attributes that are currently set are invoked. 
.sp
This function is the same as MPI_Attr_delete but is needed to match the communicator-specific functions introduced in the MPI-2 standard. The use of MPI_Attr_delete is deprecated. 


.SH 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.
.sp
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.