'\"
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
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'\"
'\" RCS: @(#) $Id: CrtCloseHdlr.3,v 1.2 1998/09/14 18:39:47 stanton Exp $
'\" The definitions below are for supplemental macros used in Tcl/Tk
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.TH Tcl_CreateCloseHandler 3 7.5 Tcl "Tcl Library Procedures"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
Tcl_CreateCloseHandler, Tcl_DeleteCloseHandler \- arrange for callbacks when channels are closed
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
void
\fBTcl_CreateCloseHandler\fR(\fIchannel, proc, clientData\fR)
.sp
void
\fBTcl_DeleteCloseHandler\fR(\fIchannel, proc, clientData\fR)
.sp
.SH ARGUMENTS
.AS Tcl_CloseProc callbackData in
.AP Tcl_Channel channel in
The channel for which to create or delete a close callback.
.AP Tcl_CloseProc *proc in
The procedure to call as the callback.
.AP ClientData clientData in
Arbitrary one-word value to pass to \fIproc\fR.
.BE

.SH DESCRIPTION
.PP
\fBTcl_CreateCloseHandler\fR arranges for \fIproc\fR to be called when
\fIchannel\fR is closed with \fBTcl_Close\fR or
\fBTcl_UnregisterChannel\fR, or using the Tcl \fBclose\fR command.
\fIProc\fR should match the following prototype:
.PP
.CS
typedef void Tcl_CloseProc(
	ClientData \fIclientData\fR);
.CE
.PP
The \fIclientData\fR is the same as the value provided in the call to
\fBTcl_CreateCloseHandler\fR.
.PP
\fBTcl_DeleteCloseHandler\fR removes a close callback for \fIchannel\fR.
The \fIproc\fR and \fIclientData\fR identify which close callback to
remove; \fBTcl_DeleteCloseHandler\fR does nothing if its \fIproc\fR and
\fIclientData\fR arguments do not match the \fIproc\fR and \fIclientData\fR
for a  close handler for \fIchannel\fR.

.SH "SEE ALSO"
close(n), Tcl_Close(3), Tcl_UnregisterChannel(3)

.SH KEYWORDS
callback, channel closing