141 lines
5.8 KiB
Groff
141 lines
5.8 KiB
Groff
'\"
|
|
'\" Copyright (c) 1995-1996 Sun Microsystems, Inc.
|
|
'\"
|
|
'\" See the file "license.terms" for information on usage and redistribution
|
|
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
|
|
'\"
|
|
.TH Tcl_Exit 3 8.5 Tcl "Tcl Library Procedures"
|
|
.so man.macros
|
|
.BS
|
|
.SH NAME
|
|
Tcl_Exit, Tcl_Finalize, Tcl_CreateExitHandler, Tcl_DeleteExitHandler, Tcl_ExitThread, Tcl_FinalizeThread, Tcl_CreateThreadExitHandler, Tcl_DeleteThreadExitHandler, Tcl_SetExitProc \- end the application or thread (and invoke exit handlers)
|
|
.SH SYNOPSIS
|
|
.nf
|
|
\fB#include <tcl.h>\fR
|
|
.sp
|
|
\fBTcl_Exit\fR(\fIstatus\fR)
|
|
.sp
|
|
\fBTcl_Finalize\fR()
|
|
.sp
|
|
\fBTcl_CreateExitHandler\fR(\fIproc, clientData\fR)
|
|
.sp
|
|
\fBTcl_DeleteExitHandler\fR(\fIproc, clientData\fR)
|
|
.sp
|
|
\fBTcl_ExitThread\fR(\fIstatus\fR)
|
|
.sp
|
|
\fBTcl_FinalizeThread\fR()
|
|
.sp
|
|
\fBTcl_CreateThreadExitHandler\fR(\fIproc, clientData\fR)
|
|
.sp
|
|
\fBTcl_DeleteThreadExitHandler\fR(\fIproc, clientData\fR)
|
|
.sp
|
|
Tcl_ExitProc *
|
|
\fBTcl_SetExitProc\fR(\fIproc\fR)
|
|
.SH ARGUMENTS
|
|
.AS Tcl_ExitProc clientData
|
|
.AP int status in
|
|
Provides information about why the application or thread exited.
|
|
Exact meaning may
|
|
be platform-specific. 0 usually means a normal exit, any nonzero value
|
|
usually means that an error occurred.
|
|
.AP Tcl_ExitProc *proc in
|
|
Procedure to invoke before exiting application, or (for
|
|
\fBTcl_SetExitProc\fR) NULL to uninstall the current application exit
|
|
procedure.
|
|
.AP ClientData clientData in
|
|
Arbitrary one-word value to pass to \fIproc\fR.
|
|
.BE
|
|
|
|
.SH DESCRIPTION
|
|
.PP
|
|
The procedures described here provide a graceful mechanism to end the
|
|
execution of a \fBTcl\fR application. Exit handlers are invoked to cleanup the
|
|
application's state before ending the execution of \fBTcl\fR code.
|
|
.PP
|
|
Invoke \fBTcl_Exit\fR to end a \fBTcl\fR application and to exit from this
|
|
process. This procedure is invoked by the \fBexit\fR command, and can be
|
|
invoked anyplace else to terminate the application.
|
|
No-one should ever invoke the \fBexit\fR system procedure directly; always
|
|
invoke \fBTcl_Exit\fR instead, so that it can invoke exit handlers.
|
|
Note that if other code invokes \fBexit\fR system procedure directly, or
|
|
otherwise causes the application to terminate without calling
|
|
\fBTcl_Exit\fR, the exit handlers will not be run.
|
|
\fBTcl_Exit\fR internally invokes the \fBexit\fR system call, thus it never
|
|
returns control to its caller.
|
|
If an application exit handler has been installed (see
|
|
\fBTcl_SetExitProc\fR), that handler is invoked with an argument
|
|
consisting of the exit status (cast to ClientData); the application
|
|
exit handler should not return control to Tcl.
|
|
.PP
|
|
\fBTcl_Finalize\fR is similar to \fBTcl_Exit\fR except that it does not
|
|
exit from the current process.
|
|
It is useful for cleaning up when a process is finished using \fBTcl\fR but
|
|
wishes to continue executing, and when \fBTcl\fR is used in a dynamically
|
|
loaded extension that is about to be unloaded.
|
|
Your code should always invoke \fBTcl_Finalize\fR when \fBTcl\fR is being
|
|
unloaded, to ensure proper cleanup. \fBTcl_Finalize\fR can be safely called
|
|
more than once.
|
|
.PP
|
|
\fBTcl_ExitThread\fR is used to terminate the current thread and invoke
|
|
per-thread exit handlers. This finalization is done by
|
|
\fBTcl_FinalizeThread\fR, which you can call if you just want to clean
|
|
up per-thread state and invoke the thread exit handlers.
|
|
\fBTcl_Finalize\fR calls \fBTcl_FinalizeThread\fR for the current
|
|
thread automatically.
|
|
.PP
|
|
\fBTcl_CreateExitHandler\fR arranges for \fIproc\fR to be invoked
|
|
by \fBTcl_Finalize\fR and \fBTcl_Exit\fR.
|
|
\fBTcl_CreateThreadExitHandler\fR arranges for \fIproc\fR to be invoked
|
|
by \fBTcl_FinalizeThread\fR and \fBTcl_ExitThread\fR.
|
|
This provides a hook for cleanup operations such as flushing buffers
|
|
and freeing global memory.
|
|
\fIProc\fR should match the type \fBTcl_ExitProc\fR:
|
|
.PP
|
|
.CS
|
|
typedef void \fBTcl_ExitProc\fR(
|
|
ClientData \fIclientData\fR);
|
|
.CE
|
|
.PP
|
|
The \fIclientData\fR parameter to \fIproc\fR is a
|
|
copy of the \fIclientData\fR argument given to
|
|
\fBTcl_CreateExitHandler\fR or \fBTcl_CreateThreadExitHandler\fR when
|
|
the callback
|
|
was created. Typically, \fIclientData\fR points to a data
|
|
structure containing application-specific information about
|
|
what to do in \fIproc\fR.
|
|
.PP
|
|
\fBTcl_DeleteExitHandler\fR and \fBTcl_DeleteThreadExitHandler\fR may be
|
|
called to delete a
|
|
previously-created exit handler. It removes the handler
|
|
indicated by \fIproc\fR and \fIclientData\fR so that no call
|
|
to \fIproc\fR will be made. If no such handler exists then
|
|
\fBTcl_DeleteExitHandler\fR or \fBTcl_DeleteThreadExitHandler\fR does nothing.
|
|
.PP
|
|
\fBTcl_Finalize\fR and \fBTcl_Exit\fR execute all registered exit handlers,
|
|
in reverse order from the order in which they were registered.
|
|
This matches the natural order in which extensions are loaded and unloaded;
|
|
if extension \fBA\fR loads extension \fBB\fR, it usually
|
|
unloads \fBB\fR before it itself is unloaded.
|
|
If extension \fBA\fR registers its exit handlers before loading extension
|
|
\fBB\fR, this ensures that any exit handlers for \fBB\fR will be executed
|
|
before the exit handlers for \fBA\fR.
|
|
.PP
|
|
\fBTcl_Finalize\fR and \fBTcl_Exit\fR call \fBTcl_FinalizeThread\fR
|
|
and the thread exit handlers \fIafter\fR
|
|
the process-wide exit handlers. This is because thread finalization shuts
|
|
down the I/O channel system, so any attempt at I/O by the global exit
|
|
handlers will vanish into the bitbucket.
|
|
.PP
|
|
\fBTcl_SetExitProc\fR installs an application exit handler, returning
|
|
the previously-installed application exit handler or NULL if no
|
|
application handler was installed. If an application exit handler is
|
|
installed, that exit handler takes over complete responsibility for
|
|
finalization of Tcl's subsystems via \fBTcl_Finalize\fR at an
|
|
appropriate time. The argument passed to \fIproc\fR when it is
|
|
invoked will be the exit status code (as passed to \fBTcl_Exit\fR)
|
|
cast to a ClientData value.
|
|
.SH "SEE ALSO"
|
|
exit(n)
|
|
.SH KEYWORDS
|
|
abort, callback, cleanup, dynamic loading, end application, exit, unloading, thread
|