[25] | 1 | '\" |
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| 2 | '\" Copyright (c) 1995-1996 Sun Microsystems, Inc. |
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| 3 | '\" |
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| 4 | '\" See the file "license.terms" for information on usage and redistribution |
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| 5 | '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. |
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| 6 | '\" |
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| 7 | '\" RCS: @(#) $Id: Exit.3,v 1.6 2003/09/29 21:47:38 dkf Exp $ |
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| 8 | '\" |
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| 9 | .so man.macros |
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| 10 | .TH Tcl_Exit 3 8.5 Tcl "Tcl Library Procedures" |
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| 11 | .BS |
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| 12 | .SH NAME |
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| 13 | 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) |
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| 14 | .SH SYNOPSIS |
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| 15 | .nf |
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| 16 | \fB#include <tcl.h>\fR |
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| 17 | .sp |
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| 18 | \fBTcl_Exit\fR(\fIstatus\fR) |
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| 19 | .sp |
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| 20 | \fBTcl_Finalize\fR() |
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| 21 | .sp |
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| 22 | \fBTcl_CreateExitHandler\fR(\fIproc, clientData\fR) |
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| 23 | .sp |
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| 24 | \fBTcl_DeleteExitHandler\fR(\fIproc, clientData\fR) |
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| 25 | .sp |
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| 26 | \fBTcl_ExitThread\fR(\fIstatus\fR) |
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| 27 | .sp |
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| 28 | \fBTcl_FinalizeThread\fR() |
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| 29 | .sp |
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| 30 | \fBTcl_CreateThreadExitHandler\fR(\fIproc, clientData\fR) |
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| 31 | .sp |
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| 32 | \fBTcl_DeleteThreadExitHandler\fR(\fIproc, clientData\fR) |
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| 33 | .sp |
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| 34 | .VS 8.5 |
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| 35 | Tcl_ExitProc * |
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| 36 | \fBTcl_SetExitProc\fR(\fIproc\fR) |
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| 37 | .VE 8.5 |
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| 38 | .SH ARGUMENTS |
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| 39 | .AS Tcl_ExitProc clientData |
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| 40 | .AP int status in |
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| 41 | Provides information about why the application or thread exited. |
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| 42 | Exact meaning may |
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| 43 | be platform-specific. 0 usually means a normal exit, any nonzero value |
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| 44 | usually means that an error occurred. |
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| 45 | .AP Tcl_ExitProc *proc in |
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| 46 | Procedure to invoke before exiting application, or (for |
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| 47 | \fBTcl_SetExitProc\fR) NULL to uninstall the current application exit |
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| 48 | procedure. |
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| 49 | .AP ClientData clientData in |
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| 50 | Arbitrary one-word value to pass to \fIproc\fR. |
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| 51 | .BE |
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| 52 | |
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| 53 | .SH DESCRIPTION |
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| 54 | .PP |
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| 55 | The procedures described here provide a graceful mechanism to end the |
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| 56 | execution of a \fBTcl\fR application. Exit handlers are invoked to cleanup the |
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| 57 | application's state before ending the execution of \fBTcl\fR code. |
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| 58 | .PP |
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| 59 | Invoke \fBTcl_Exit\fR to end a \fBTcl\fR application and to exit from this |
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| 60 | process. This procedure is invoked by the \fBexit\fR command, and can be |
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| 61 | invoked anyplace else to terminate the application. |
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| 62 | No-one should ever invoke the \fBexit\fR system procedure directly; always |
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| 63 | invoke \fBTcl_Exit\fR instead, so that it can invoke exit handlers. |
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| 64 | Note that if other code invokes \fBexit\fR system procedure directly, or |
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| 65 | otherwise causes the application to terminate without calling |
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| 66 | \fBTcl_Exit\fR, the exit handlers will not be run. |
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| 67 | \fBTcl_Exit\fR internally invokes the \fBexit\fR system call, thus it never |
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| 68 | returns control to its caller. |
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| 69 | .VS 8.5 |
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| 70 | If an application exit handler has been installed (see |
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| 71 | \fBTcl_SetExitProc\fR), that handler is invoked with an argument |
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| 72 | consisting of the exit status (cast to ClientData); the application |
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| 73 | exit handler should not return control to Tcl. |
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| 74 | .VE 8.5 |
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| 75 | .PP |
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| 76 | \fBTcl_Finalize\fR is similar to \fBTcl_Exit\fR except that it does not |
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| 77 | exit from the current process. |
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| 78 | It is useful for cleaning up when a process is finished using \fBTcl\fR but |
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| 79 | wishes to continue executing, and when \fBTcl\fR is used in a dynamically |
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| 80 | loaded extension that is about to be unloaded. |
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| 81 | On some systems \fBTcl\fR is automatically notified when it is being |
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| 82 | unloaded, and it calls \fBTcl_Finalize\fR internally; on these systems it |
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| 83 | not necessary for the caller to explicitly call \fBTcl_Finalize\fR. |
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| 84 | However, to ensure portability, your code should always invoke |
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| 85 | \fBTcl_Finalize\fR when \fBTcl\fR is being unloaded, to ensure that the |
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| 86 | code will work on all platforms. \fBTcl_Finalize\fR can be safely called |
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| 87 | more than once. |
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| 88 | .PP |
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| 89 | \fBTcl_ExitThread\fR is used to terminate the current thread and invoke |
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| 90 | per-thread exit handlers. This finalization is done by |
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| 91 | \fBTcl_FinalizeThread\fR, which you can call if you just want to clean |
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| 92 | up per-thread state and invoke the thread exit handlers. |
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| 93 | \fBTcl_Finalize\fR calls \fBTcl_FinalizeThread\fR for the current |
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| 94 | thread automatically. |
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| 95 | .PP |
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| 96 | \fBTcl_CreateExitHandler\fR arranges for \fIproc\fR to be invoked |
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| 97 | by \fBTcl_Finalize\fR and \fBTcl_Exit\fR. |
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| 98 | \fBTcl_CreateThreadExitHandler\fR arranges for \fIproc\fR to be invoked |
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| 99 | by \fBTcl_FinalizeThread\fR and \fBTcl_ExitThread\fR. |
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| 100 | This provides a hook for cleanup operations such as flushing buffers |
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| 101 | and freeing global memory. |
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| 102 | \fIProc\fR should match the type \fBTcl_ExitProc\fR: |
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| 103 | .CS |
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| 104 | typedef void Tcl_ExitProc(ClientData \fIclientData\fR); |
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| 105 | .CE |
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| 106 | The \fIclientData\fR parameter to \fIproc\fR is a |
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| 107 | copy of the \fIclientData\fR argument given to |
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| 108 | \fBTcl_CreateExitHandler\fR or \fBTcl_CreateThreadExitHandler\fR when |
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| 109 | the callback |
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| 110 | was created. Typically, \fIclientData\fR points to a data |
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| 111 | structure containing application-specific information about |
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| 112 | what to do in \fIproc\fR. |
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| 113 | .PP |
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| 114 | \fBTcl_DeleteExitHandler\fR and \fBTcl_DeleteThreadExitHandler\fR may be |
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| 115 | called to delete a |
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| 116 | previously-created exit handler. It removes the handler |
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| 117 | indicated by \fIproc\fR and \fIclientData\fR so that no call |
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| 118 | to \fIproc\fR will be made. If no such handler exists then |
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| 119 | \fBTcl_DeleteExitHandler\fR or \fBTcl_DeleteThreadExitHandler\fR does nothing. |
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| 120 | .PP |
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| 121 | .PP |
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| 122 | \fBTcl_Finalize\fR and \fBTcl_Exit\fR execute all registered exit handlers, |
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| 123 | in reverse order from the order in which they were registered. |
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| 124 | This matches the natural order in which extensions are loaded and unloaded; |
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| 125 | if extension \fBA\fR loads extension \fBB\fR, it usually |
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| 126 | unloads \fBB\fR before it itself is unloaded. |
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| 127 | If extension \fBA\fR registers its exit handlers before loading extension |
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| 128 | \fBB\fR, this ensures that any exit handlers for \fBB\fR will be executed |
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| 129 | before the exit handlers for \fBA\fR. |
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| 130 | .PP |
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| 131 | \fBTcl_Finalize\fR and \fBTcl_Exit\fR call \fBTcl_FinalizeThread\fR |
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| 132 | and the thread exit handlers \fIafter\fR |
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| 133 | the process-wide exit handlers. This is because thread finalization shuts |
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| 134 | down the I/O channel system, so any attempt at I/O by the global exit |
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| 135 | handlers will vanish into the bitbucket. |
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| 136 | .PP |
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| 137 | .VS 8.5 |
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| 138 | \fBTcl_SetExitProc\fR installs an application exit handler, returning |
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| 139 | the previously-installed application exit handler or NULL if no |
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| 140 | application handler was installed. If an application exit handler is |
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| 141 | installed, that exit handler takes over complete responsibility for |
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| 142 | finalization of Tcl's subsystems via \fBTcl_Finalize\fR at an |
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| 143 | appropriate time. The argument passed to \fIproc\fR when it is |
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| 144 | invoked will be the exit status code (as passed to \fBTcl_Exit\fR) |
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| 145 | cast to a ClientData value. |
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| 146 | .VE 8.5 |
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| 147 | |
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| 148 | .SH KEYWORDS |
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| 149 | callback, cleanup, dynamic loading, end application, exit, unloading, thread |
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