| 1 | '\" |
| 2 | '\" Copyright (c) 2002 Donal K. Fellows |
| 3 | '\" |
| 4 | '\" See the file "license.terms" for information on usage and redistribution |
| 5 | '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. |
| 6 | '\" |
| 7 | '\" CVS: @(#) $Id: TraceCmd.3,v 1.5 2002/07/01 18:24:39 jenglish Exp $ |
| 8 | '\" |
| 9 | '\" The definitions below are for supplemental macros used in Tcl/Tk |
| 10 | '\" manual entries. |
| 11 | '\" |
| 12 | '\" .AP type name in/out ?indent? |
| 13 | '\" Start paragraph describing an argument to a library procedure. |
| 14 | '\" type is type of argument (int, etc.), in/out is either "in", "out", |
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| 17 | '\" needed; use .AS below instead) |
| 18 | '\" |
| 19 | '\" .AS ?type? ?name? |
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| 31 | '\" .CS |
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| 37 | '\" .VS ?version? ?br? |
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| 39 | '\" of man pages. The first argument is ignored and used for recording |
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| 54 | '\" Start of list of standard options for a Tk widget. The |
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| 58 | '\" .SE |
| 59 | '\" End of list of standard options for a Tk widget. |
| 60 | '\" |
| 61 | '\" .OP cmdName dbName dbClass |
| 62 | '\" Start of description of a specific option. cmdName gives the |
| 63 | '\" option's name as specified in the class command, dbName gives |
| 64 | '\" the option's name in the option database, and dbClass gives |
| 65 | '\" the option's class in the option database. |
| 66 | '\" |
| 67 | '\" .UL arg1 arg2 |
| 68 | '\" Print arg1 underlined, then print arg2 normally. |
| 69 | '\" |
| 70 | '\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $ |
| 71 | '\" |
| 72 | '\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages. |
| 73 | .if t .wh -1.3i ^B |
| 74 | .nr ^l \n(.l |
| 75 | .ad b |
| 76 | '\" # Start an argument description |
| 77 | .de AP |
| 78 | .ie !"\\$4"" .TP \\$4 |
| 79 | .el \{\ |
| 80 | . ie !"\\$2"" .TP \\n()Cu |
| 81 | . el .TP 15 |
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| 83 | .ta \\n()Au \\n()Bu |
| 84 | .ie !"\\$3"" \{\ |
| 85 | \&\\$1 \\fI\\$2\\fP (\\$3) |
| 86 | .\".b |
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| 90 | .ie !"\\$2"" \{\ |
| 91 | \&\\$1 \\fI\\$2\\fP |
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| 106 | .. |
| 107 | .AS Tcl_Interp Tcl_CreateInterp in/out |
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| 133 | \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' |
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| 176 | .el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c |
| 177 | .\} |
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| 180 | \kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c |
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| 202 | .RE |
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| 204 | .. |
| 205 | '\" # SO - start of list of standard options |
| 206 | .de SO |
| 207 | .SH "STANDARD OPTIONS" |
| 208 | .LP |
| 209 | .nf |
| 210 | .ta 5.5c 11c |
| 211 | .ft B |
| 212 | .. |
| 213 | '\" # SE - end of list of standard options |
| 214 | .de SE |
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| 216 | .ft R |
| 217 | .LP |
| 218 | See the \\fBoptions\\fR manual entry for details on the standard options. |
| 219 | .. |
| 220 | '\" # OP - start of full description for a single option |
| 221 | .de OP |
| 222 | .LP |
| 223 | .nf |
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| 225 | Command-Line Name: \\fB\\$1\\fR |
| 226 | Database Name: \\fB\\$2\\fR |
| 227 | Database Class: \\fB\\$3\\fR |
| 228 | .fi |
| 229 | .IP |
| 230 | .. |
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| 241 | .. |
| 242 | .de UL |
| 243 | \\$1\l'|0\(ul'\\$2 |
| 244 | .. |
| 245 | .TH Tcl_TraceCommand 3 7.4 Tcl "Tcl Library Procedures" |
| 246 | .BS |
| 247 | .SH NAME |
| 248 | Tcl_CommandTraceInfo, Tcl_TraceCommand, Tcl_UntraceCommand \- monitor renames and deletes of a command |
| 249 | .SH SYNOPSIS |
| 250 | .nf |
| 251 | \fB#include <tcl.h>\fR |
| 252 | .sp |
| 253 | ClientData |
| 254 | \fBTcl_CommandTraceInfo(\fIinterp, cmdName, flags, proc, prevClientData\fB)\fR |
| 255 | .sp |
| 256 | int |
| 257 | \fBTcl_TraceCommand(\fIinterp, cmdName, flags, proc, clientData\fB)\fR |
| 258 | .sp |
| 259 | void |
| 260 | \fBTcl_UntraceCommand(\fIinterp, cmdName, flags, proc, clientData\fB)\fR |
| 261 | .SH ARGUMENTS |
| 262 | .AS Tcl_CommandTraceProc prevClientData |
| 263 | .AP Tcl_Interp *interp in |
| 264 | Interpreter containing the command. |
| 265 | .AP "CONST char" *cmdName in |
| 266 | Name of command. |
| 267 | .AP int flags in |
| 268 | OR-ed collection of the value TCL_TRACE_RENAME and TCL_TRACE_DELETE. |
| 269 | .AP Tcl_CommandTraceProc *proc in |
| 270 | Procedure to call when specified operations occur to \fIcmdName\fR. |
| 271 | .AP ClientData clientData in |
| 272 | Arbitrary argument to pass to \fIproc\fR. |
| 273 | .AP ClientData prevClientData in |
| 274 | If non-NULL, gives last value returned by \fBTcl_CommandTraceInfo\fR, |
| 275 | so this call will return information about next trace. If NULL, this |
| 276 | call will return information about first trace. |
| 277 | .BE |
| 278 | |
| 279 | .SH DESCRIPTION |
| 280 | .PP |
| 281 | \fBTcl_TraceCommand\fR allows a C procedure to monitor operations |
| 282 | performed on a Tcl command, so that the C procedure is invoked |
| 283 | whenever the command is renamed or deleted. If the trace is created |
| 284 | successfully then \fBTcl_TraceCommand\fR returns TCL_OK. If an error |
| 285 | occurred (e.g. \fIcmdName\fR specifies a non-existent command) then |
| 286 | TCL_ERROR is returned and an error message is left in the |
| 287 | interpreter's result. |
| 288 | .PP |
| 289 | The \fIflags\fR argument to \fBTcl_TraceCommand\fR indicates when the |
| 290 | trace procedure is to be invoked. It consists of an OR-ed combination |
| 291 | of any of the following values: |
| 292 | .TP |
| 293 | \fBTCL_TRACE_RENAME\fR |
| 294 | Invoke \fIproc\fR whenever the command is renamed. |
| 295 | .TP |
| 296 | \fBTCL_TRACE_DELETE\fR |
| 297 | Invoke \fIproc\fR when the command is deleted. |
| 298 | .PP |
| 299 | Whenever one of the specified operations occurs to the command, |
| 300 | \fIproc\fR will be invoked. It should have arguments and result that |
| 301 | match the type \fBTcl_CommandTraceProc\fR: |
| 302 | .CS |
| 303 | typedef void Tcl_CommandTraceProc( |
| 304 | ClientData \fIclientData\fR, |
| 305 | Tcl_Interp *\fIinterp\fR, |
| 306 | CONST char *\fIoldName\fR, |
| 307 | CONST char *\fInewName\fR, |
| 308 | int \fIflags\fR); |
| 309 | .CE |
| 310 | The \fIclientData\fR and \fIinterp\fR parameters will have the same |
| 311 | values as those passed to \fBTcl_TraceCommand\fR when the trace was |
| 312 | created. \fIClientData\fR typically points to an application-specific |
| 313 | data structure that describes what to do when \fIproc\fR is invoked. |
| 314 | \fIOldName\fR gives the name of the command being renamed, and |
| 315 | \fInewName\fR gives the name that the command is being renamed to (or |
| 316 | an empty string or NULL when the command is being deleted.) |
| 317 | \fIFlags\fR is an OR-ed combination of bits potentially providing |
| 318 | several pieces of information. One of the bits TCL_TRACE_RENAME and |
| 319 | TCL_TRACE_DELETE will be set in \fIflags\fR to indicate which |
| 320 | operation is being performed on the command. The bit |
| 321 | TCL_TRACE_DESTROYED will be set in \fIflags\fR if the trace is about |
| 322 | to be destroyed; this information may be useful to \fIproc\fR so that |
| 323 | it can clean up its own internal data structures (see the section |
| 324 | TCL_TRACE_DESTROYED below for more details). Lastly, the bit |
| 325 | TCL_INTERP_DESTROYED will be set if the entire interpreter is being |
| 326 | destroyed. When this bit is set, \fIproc\fR must be especially |
| 327 | careful in the things it does (see the section TCL_INTERP_DESTROYED |
| 328 | below). |
| 329 | .PP |
| 330 | \fBTcl_UntraceCommand\fR may be used to remove a trace. If the |
| 331 | command specified by \fIinterp\fR, \fIcmdName\fR, and \fIflags\fR has |
| 332 | a trace set with \fIflags\fR, \fIproc\fR, and \fIclientData\fR, then |
| 333 | the corresponding trace is removed. If no such trace exists, then the |
| 334 | call to \fBTcl_UntraceCommand\fR has no effect. The same bits are |
| 335 | valid for \fIflags\fR as for calls to \fBTcl_TraceCommand\fR. |
| 336 | .PP |
| 337 | \fBTcl_CommandTraceInfo\fR may be used to retrieve information about |
| 338 | traces set on a given command. |
| 339 | The return value from \fBTcl_CommandTraceInfo\fR is the \fIclientData\fR |
| 340 | associated with a particular trace. |
| 341 | The trace must be on the command specified by the \fIinterp\fR, |
| 342 | \fIcmdName\fR, and \fIflags\fR arguments (note that currently the |
| 343 | flags are ignored; \fIflags\fR should be set to 0 for future |
| 344 | compatibility) and its trace procedure must the same as the \fIproc\fR |
| 345 | argument. |
| 346 | If the \fIprevClientData\fR argument is NULL then the return |
| 347 | value corresponds to the first (most recently created) matching |
| 348 | trace, or NULL if there are no matching traces. |
| 349 | If the \fIprevClientData\fR argument isn't NULL, then it should |
| 350 | be the return value from a previous call to \fBTcl_CommandTraceInfo\fR. |
| 351 | In this case, the new return value will correspond to the next |
| 352 | matching trace after the one whose \fIclientData\fR matches |
| 353 | \fIprevClientData\fR, or NULL if no trace matches \fIprevClientData\fR |
| 354 | or if there are no more matching traces after it. |
| 355 | This mechanism makes it possible to step through all of the |
| 356 | traces for a given command that have the same \fIproc\fR. |
| 357 | |
| 358 | .SH "CALLING COMMANDS DURING TRACES" |
| 359 | .PP |
| 360 | During rename traces, the command being renamed is visible with both |
| 361 | names simultaneously, and the command still exists during delete |
| 362 | traces (if TCL_INTERP_DESTROYED is not set). However, there is no |
| 363 | mechanism for signaling that an error occurred in a trace procedure, |
| 364 | so great care should be taken that errors do not get silently lost. |
| 365 | |
| 366 | .SH "MULTIPLE TRACES" |
| 367 | .PP |
| 368 | It is possible for multiple traces to exist on the same command. |
| 369 | When this happens, all of the trace procedures will be invoked on each |
| 370 | access, in order from most-recently-created to least-recently-created. |
| 371 | Attempts to delete the command during a delete trace will fail |
| 372 | silently, since the command is already scheduled for deletion anyway. |
| 373 | If the command being renamed is renamed by one of its rename traces, |
| 374 | that renaming takes precedence over the one that triggered the trace |
| 375 | and the collection of traces will not be reexecuted; if several traces |
| 376 | rename the command, the last renaming takes precedence. |
| 377 | |
| 378 | .SH "TCL_TRACE_DESTROYED FLAG" |
| 379 | .PP |
| 380 | In a delete callback to \fIproc\fR, the TCL_TRACE_DESTROYED bit |
| 381 | is set in \fIflags\fR. |
| 382 | |
| 383 | '\" Perhaps need some more comments here? - DKF |
| 384 | |
| 385 | .SH "TCL_INTERP_DESTROYED" |
| 386 | .PP |
| 387 | When an interpreter is destroyed, unset traces are called for |
| 388 | all of its commands. |
| 389 | The TCL_INTERP_DESTROYED bit will be set in the \fIflags\fR |
| 390 | argument passed to the trace procedures. |
| 391 | Trace procedures must be extremely careful in what they do if |
| 392 | the TCL_INTERP_DESTROYED bit is set. |
| 393 | It is not safe for the procedures to invoke any Tcl procedures |
| 394 | on the interpreter, since its state is partially deleted. |
| 395 | All that trace procedures should do under these circumstances is |
| 396 | to clean up and free their own internal data structures. |
| 397 | |
| 398 | .SH BUGS |
| 399 | .PP |
| 400 | Tcl doesn't do any error checking to prevent trace procedures |
| 401 | from misusing the interpreter during traces with TCL_INTERP_DESTROYED |
| 402 | set. |
| 403 | |
| 404 | .SH KEYWORDS |
| 405 | clientData, trace, command |