| '\" |
| '\" Copyright (c) 2002 Donal K. Fellows |
| '\" |
| '\" See the file "license.terms" for information on usage and redistribution |
| '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. |
| '\" |
| '\" CVS: @(#) $Id: TraceCmd.3,v 1.3 2003/01/21 19:39:59 hunt Exp $ |
| '\" |
| '\" The definitions below are for supplemental macros used in Tcl/Tk |
| '\" manual entries. |
| '\" |
| '\" .AP type name in/out ?indent? |
| '\" Start paragraph describing an argument to a library procedure. |
| '\" type is type of argument (int, etc.), in/out is either "in", "out", |
| '\" or "in/out" to describe whether procedure reads or modifies arg, |
| '\" and indent is equivalent to second arg of .IP (shouldn't ever be |
| '\" needed; use .AS below instead) |
| '\" |
| '\" .AS ?type? ?name? |
| '\" Give maximum sizes of arguments for setting tab stops. Type and |
| '\" name are examples of largest possible arguments that will be passed |
| '\" to .AP later. If args are omitted, default tab stops are used. |
| '\" |
| '\" .BS |
| '\" Start box enclosure. From here until next .BE, everything will be |
| '\" enclosed in one large box. |
| '\" |
| '\" .BE |
| '\" End of box enclosure. |
| '\" |
| '\" .CS |
| '\" Begin code excerpt. |
| '\" |
| '\" .CE |
| '\" End code excerpt. |
| '\" |
| '\" .VS ?version? ?br? |
| '\" Begin vertical sidebar, for use in marking newly-changed parts |
| '\" of man pages. The first argument is ignored and used for recording |
| '\" the version when the .VS was added, so that the sidebars can be |
| '\" found and removed when they reach a certain age. If another argument |
| '\" is present, then a line break is forced before starting the sidebar. |
| '\" |
| '\" .VE |
| '\" End of vertical sidebar. |
| '\" |
| '\" .DS |
| '\" Begin an indented unfilled display. |
| '\" |
| '\" .DE |
| '\" End of indented unfilled display. |
| '\" |
| '\" .SO |
| '\" Start of list of standard options for a Tk widget. The |
| '\" options follow on successive lines, in four columns separated |
| '\" by tabs. |
| '\" |
| '\" .SE |
| '\" End of list of standard options for a Tk widget. |
| '\" |
| '\" .OP cmdName dbName dbClass |
| '\" Start of description of a specific option. cmdName gives the |
| '\" option's name as specified in the class command, dbName gives |
| '\" the option's name in the option database, and dbClass gives |
| '\" the option's class in the option database. |
| '\" |
| '\" .UL arg1 arg2 |
| '\" Print arg1 underlined, then print arg2 normally. |
| '\" |
| '\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $ |
| '\" |
| '\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages. |
| .if t .wh -1.3i ^B |
| .nr ^l \n(.l |
| .ad b |
| '\" # Start an argument description |
| .de AP |
| .ie !"\\$4"" .TP \\$4 |
| .el \{\ |
| . ie !"\\$2"" .TP \\n()Cu |
| . el .TP 15 |
| .\} |
| .ta \\n()Au \\n()Bu |
| .ie !"\\$3"" \{\ |
| \&\\$1 \\fI\\$2\\fP (\\$3) |
| .\".b |
| .\} |
| .el \{\ |
| .br |
| .ie !"\\$2"" \{\ |
| \&\\$1 \\fI\\$2\\fP |
| .\} |
| .el \{\ |
| \&\\fI\\$1\\fP |
| .\} |
| .\} |
| .. |
| '\" # define tabbing values for .AP |
| .de AS |
| .nr )A 10n |
| .if !"\\$1"" .nr )A \\w'\\$1'u+3n |
| .nr )B \\n()Au+15n |
| .\" |
| .if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n |
| .nr )C \\n()Bu+\\w'(in/out)'u+2n |
| .. |
| .AS Tcl_Interp Tcl_CreateInterp in/out |
| '\" # BS - start boxed text |
| '\" # ^y = starting y location |
| '\" # ^b = 1 |
| .de BS |
| .br |
| .mk ^y |
| .nr ^b 1u |
| .if n .nf |
| .if n .ti 0 |
| .if n \l'\\n(.lu\(ul' |
| .if n .fi |
| .. |
| '\" # BE - end boxed text (draw box now) |
| .de BE |
| .nf |
| .ti 0 |
| .mk ^t |
| .ie n \l'\\n(^lu\(ul' |
| .el \{\ |
| .\" Draw four-sided box normally, but don't draw top of |
| .\" box if the box started on an earlier page. |
| .ie !\\n(^b-1 \{\ |
| \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' |
| .\} |
| .el \}\ |
| \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' |
| .\} |
| .\} |
| .fi |
| .br |
| .nr ^b 0 |
| .. |
| '\" # VS - start vertical sidebar |
| '\" # ^Y = starting y location |
| '\" # ^v = 1 (for troff; for nroff this doesn't matter) |
| .de VS |
| .if !"\\$2"" .br |
| .mk ^Y |
| .ie n 'mc \s12\(br\s0 |
| .el .nr ^v 1u |
| .. |
| '\" # VE - end of vertical sidebar |
| .de VE |
| .ie n 'mc |
| .el \{\ |
| .ev 2 |
| .nf |
| .ti 0 |
| .mk ^t |
| \h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n' |
| .sp -1 |
| .fi |
| .ev |
| .\} |
| .nr ^v 0 |
| .. |
| '\" # Special macro to handle page bottom: finish off current |
| '\" # box/sidebar if in box/sidebar mode, then invoked standard |
| '\" # page bottom macro. |
| .de ^B |
| .ev 2 |
| 'ti 0 |
| 'nf |
| .mk ^t |
| .if \\n(^b \{\ |
| .\" Draw three-sided box if this is the box's first page, |
| .\" draw two sides but no top otherwise. |
| .ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c |
| .el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c |
| .\} |
| .if \\n(^v \{\ |
| .nr ^x \\n(^tu+1v-\\n(^Yu |
| \kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c |
| .\} |
| .bp |
| 'fi |
| .ev |
| .if \\n(^b \{\ |
| .mk ^y |
| .nr ^b 2 |
| .\} |
| .if \\n(^v \{\ |
| .mk ^Y |
| .\} |
| .. |
| '\" # DS - begin display |
| .de DS |
| .RS |
| .nf |
| .sp |
| .. |
| '\" # DE - end display |
| .de DE |
| .fi |
| .RE |
| .sp |
| .. |
| '\" # SO - start of list of standard options |
| .de SO |
| .SH "STANDARD OPTIONS" |
| .LP |
| .nf |
| .ta 5.5c 11c |
| .ft B |
| .. |
| '\" # SE - end of list of standard options |
| .de SE |
| .fi |
| .ft R |
| .LP |
| See the \\fBoptions\\fR manual entry for details on the standard options. |
| .. |
| '\" # OP - start of full description for a single option |
| .de OP |
| .LP |
| .nf |
| .ta 4c |
| Command-Line Name: \\fB\\$1\\fR |
| Database Name: \\fB\\$2\\fR |
| Database Class: \\fB\\$3\\fR |
| .fi |
| .IP |
| .. |
| '\" # CS - begin code excerpt |
| .de CS |
| .RS |
| .nf |
| .ta .25i .5i .75i 1i |
| .. |
| '\" # CE - end code excerpt |
| .de CE |
| .fi |
| .RE |
| .. |
| .de UL |
| \\$1\l'|0\(ul'\\$2 |
| .. |
| .TH Tcl_TraceCommand 3 7.4 Tcl "Tcl Library Procedures" |
| .BS |
| .SH NAME |
| Tcl_CommandTraceInfo, Tcl_TraceCommand, Tcl_UntraceCommand \- monitor renames and deletes of a command |
| .SH SYNOPSIS |
| .nf |
| \fB#include <tcl.h>\fR |
| .sp |
| ClientData |
| \fBTcl_CommandTraceInfo(\fIinterp, cmdName, flags, proc, prevClientData\fB)\fR |
| .sp |
| int |
| \fBTcl_TraceCommand(\fIinterp, cmdName, flags, proc, clientData\fB)\fR |
| .sp |
| void |
| \fBTcl_UntraceCommand(\fIinterp, cmdName, flags, proc, clientData\fB)\fR |
| .SH ARGUMENTS |
| .AS Tcl_CommandTraceProc prevClientData |
| .AP Tcl_Interp *interp in |
| Interpreter containing the command. |
| .AP "CONST char" *cmdName in |
| Name of command. |
| .AP int flags in |
| OR-ed collection of the value TCL_TRACE_RENAME and TCL_TRACE_DELETE. |
| .AP Tcl_CommandTraceProc *proc in |
| Procedure to call when specified operations occur to \fIcmdName\fR. |
| .AP ClientData clientData in |
| Arbitrary argument to pass to \fIproc\fR. |
| .AP ClientData prevClientData in |
| If non-NULL, gives last value returned by \fBTcl_CommandTraceInfo\fR, |
| so this call will return information about next trace. If NULL, this |
| call will return information about first trace. |
| .BE |
| |
| .SH DESCRIPTION |
| .PP |
| \fBTcl_TraceCommand\fR allows a C procedure to monitor operations |
| performed on a Tcl command, so that the C procedure is invoked |
| whenever the command is renamed or deleted. If the trace is created |
| successfully then \fBTcl_TraceCommand\fR returns TCL_OK. If an error |
| occurred (e.g. \fIcmdName\fR specifies a non-existent command) then |
| TCL_ERROR is returned and an error message is left in the |
| interpreter's result. |
| .PP |
| The \fIflags\fR argument to \fBTcl_TraceCommand\fR indicates when the |
| trace procedure is to be invoked. It consists of an OR-ed combination |
| of any of the following values: |
| .TP |
| \fBTCL_TRACE_RENAME\fR |
| Invoke \fIproc\fR whenever the command is renamed. |
| .TP |
| \fBTCL_TRACE_DELETE\fR |
| Invoke \fIproc\fR when the command is deleted. |
| .PP |
| Whenever one of the specified operations occurs to the command, |
| \fIproc\fR will be invoked. It should have arguments and result that |
| match the type \fBTcl_CommandTraceProc\fR: |
| .CS |
| typedef void Tcl_CommandTraceProc( |
| ClientData \fIclientData\fR, |
| Tcl_Interp *\fIinterp\fR, |
| CONST char *\fIoldName\fR, |
| CONST char *\fInewName\fR, |
| int \fIflags\fR); |
| .CE |
| The \fIclientData\fR and \fIinterp\fR parameters will have the same |
| values as those passed to \fBTcl_TraceCommand\fR when the trace was |
| created. \fIClientData\fR typically points to an application-specific |
| data structure that describes what to do when \fIproc\fR is invoked. |
| \fIOldName\fR gives the name of the command being renamed, and |
| \fInewName\fR gives the name that the command is being renamed to (or |
| an empty string or NULL when the command is being deleted.) |
| \fIFlags\fR is an OR-ed combination of bits potentially providing |
| several pieces of information. One of the bits TCL_TRACE_RENAME and |
| TCL_TRACE_DELETE will be set in \fIflags\fR to indicate which |
| operation is being performed on the command. The bit |
| TCL_TRACE_DESTROYED will be set in \fIflags\fR if the trace is about |
| to be destroyed; this information may be useful to \fIproc\fR so that |
| it can clean up its own internal data structures (see the section |
| TCL_TRACE_DESTROYED below for more details). Lastly, the bit |
| TCL_INTERP_DESTROYED will be set if the entire interpreter is being |
| destroyed. When this bit is set, \fIproc\fR must be especially |
| careful in the things it does (see the section TCL_INTERP_DESTROYED |
| below). |
| .PP |
| \fBTcl_UntraceCommand\fR may be used to remove a trace. If the |
| command specified by \fIinterp\fR, \fIcmdName\fR, and \fIflags\fR has |
| a trace set with \fIflags\fR, \fIproc\fR, and \fIclientData\fR, then |
| the corresponding trace is removed. If no such trace exists, then the |
| call to \fBTcl_UntraceCommand\fR has no effect. The same bits are |
| valid for \fIflags\fR as for calls to \fBTcl_TraceCommand\fR. |
| .PP |
| \fBTcl_CommandTraceInfo\fR may be used to retrieve information about |
| traces set on a given command. |
| The return value from \fBTcl_CommandTraceInfo\fR is the \fIclientData\fR |
| associated with a particular trace. |
| The trace must be on the command specified by the \fIinterp\fR, |
| \fIcmdName\fR, and \fIflags\fR arguments (note that currently the |
| flags are ignored; \fIflags\fR should be set to 0 for future |
| compatibility) and its trace procedure must the same as the \fIproc\fR |
| argument. |
| If the \fIprevClientData\fR argument is NULL then the return |
| value corresponds to the first (most recently created) matching |
| trace, or NULL if there are no matching traces. |
| If the \fIprevClientData\fR argument isn't NULL, then it should |
| be the return value from a previous call to \fBTcl_CommandTraceInfo\fR. |
| In this case, the new return value will correspond to the next |
| matching trace after the one whose \fIclientData\fR matches |
| \fIprevClientData\fR, or NULL if no trace matches \fIprevClientData\fR |
| or if there are no more matching traces after it. |
| This mechanism makes it possible to step through all of the |
| traces for a given command that have the same \fIproc\fR. |
| |
| .SH "CALLING COMMANDS DURING TRACES" |
| .PP |
| During rename traces, the command being renamed is visible with both |
| names simultaneously, and the command still exists during delete |
| traces (if TCL_INTERP_DESTROYED is not set). However, there is no |
| mechanism for signaling that an error occurred in a trace procedure, |
| so great care should be taken that errors do not get silently lost. |
| |
| .SH "MULTIPLE TRACES" |
| .PP |
| It is possible for multiple traces to exist on the same command. |
| When this happens, all of the trace procedures will be invoked on each |
| access, in order from most-recently-created to least-recently-created. |
| Attempts to delete the command during a delete trace will fail |
| silently, since the command is already scheduled for deletion anyway. |
| If the command being renamed is renamed by one of its rename traces, |
| that renaming takes precedence over the one that triggered the trace |
| and the collection of traces will not be reexecuted; if several traces |
| rename the command, the last renaming takes precedence. |
| |
| .SH "TCL_TRACE_DESTROYED FLAG" |
| .PP |
| In a delete callback to \fIproc\fR, the TCL_TRACE_DESTROYED bit |
| is set in \fIflags\fR. |
| |
| '\" Perhaps need some more comments here? - DKF |
| |
| .SH "TCL_INTERP_DESTROYED" |
| .PP |
| When an interpreter is destroyed, unset traces are called for |
| all of its commands. |
| The TCL_INTERP_DESTROYED bit will be set in the \fIflags\fR |
| argument passed to the trace procedures. |
| Trace procedures must be extremely careful in what they do if |
| the TCL_INTERP_DESTROYED bit is set. |
| It is not safe for the procedures to invoke any Tcl procedures |
| on the interpreter, since its state is partially deleted. |
| All that trace procedures should do under these circumstances is |
| to clean up and free their own internal data structures. |
| |
| .SH BUGS |
| .PP |
| Tcl doesn't do any error checking to prevent trace procedures |
| from misusing the interpreter during traces with TCL_INTERP_DESTROYED |
| set. |
| |
| .SH KEYWORDS |
| clientData, trace, command |