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| 72 | '\" |
| 73 | '\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages. |
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| 77 | '\" # Start an argument description |
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| 208 | .SH "STANDARD OPTIONS" |
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| 219 | See the \\fBoptions\\fR manual entry for details on the standard options. |
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| 226 | Command-Line Name: \\fB\\$1\\fR |
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| 245 | .. |
| 246 | .TH Tcl_SetResult 3 8.0 Tcl "Tcl Library Procedures" |
| 247 | .BS |
| 248 | .SH NAME |
| 249 | Tcl_SetObjResult, Tcl_GetObjResult, Tcl_SetResult, Tcl_GetStringResult, Tcl_AppendResult, Tcl_AppendResultVA, Tcl_AppendElement, Tcl_ResetResult, Tcl_FreeResult \- manipulate Tcl result |
| 250 | .SH SYNOPSIS |
| 251 | .nf |
| 252 | \fB#include <tcl.h>\fR |
| 253 | .sp |
| 254 | \fBTcl_SetObjResult\fR(\fIinterp, objPtr\fR) |
| 255 | .sp |
| 256 | Tcl_Obj * |
| 257 | \fBTcl_GetObjResult\fR(\fIinterp\fR) |
| 258 | .sp |
| 259 | \fBTcl_SetResult\fR(\fIinterp, string, freeProc\fR) |
| 260 | .sp |
| 261 | CONST char * |
| 262 | \fBTcl_GetStringResult\fR(\fIinterp\fR) |
| 263 | .sp |
| 264 | \fBTcl_AppendResult\fR(\fIinterp, string, string, ... , \fB(char *) NULL\fR) |
| 265 | .sp |
| 266 | \fBTcl_AppendResultVA\fR(\fIinterp, argList\fR) |
| 267 | .sp |
| 268 | \fBTcl_AppendElement\fR(\fIinterp, string\fR) |
| 269 | .sp |
| 270 | \fBTcl_ResetResult\fR(\fIinterp\fR) |
| 271 | .sp |
| 272 | \fBTcl_FreeResult\fR(\fIinterp\fR) |
| 273 | .SH ARGUMENTS |
| 274 | .AS Tcl_FreeProc freeProc |
| 275 | .AP Tcl_Interp *interp out |
| 276 | Interpreter whose result is to be modified or read. |
| 277 | .AP Tcl_Obj *objPtr in |
| 278 | Object value to become result for \fIinterp\fR. |
| 279 | .AP char *string in |
| 280 | String value to become result for \fIinterp\fR or to be |
| 281 | appended to the existing result. |
| 282 | .AP Tcl_FreeProc *freeProc in |
| 283 | Address of procedure to call to release storage at |
| 284 | \fIstring\fR, or \fBTCL_STATIC\fR, \fBTCL_DYNAMIC\fR, or |
| 285 | \fBTCL_VOLATILE\fR. |
| 286 | .AP va_list argList in |
| 287 | An argument list which must have been initialised using |
| 288 | \fBTCL_VARARGS_START\fR, and cleared using \fBva_end\fR. |
| 289 | .BE |
| 290 | |
| 291 | .SH DESCRIPTION |
| 292 | .PP |
| 293 | The procedures described here are utilities for manipulating the |
| 294 | result value in a Tcl interpreter. |
| 295 | The interpreter result may be either a Tcl object or a string. |
| 296 | For example, \fBTcl_SetObjResult\fR and \fBTcl_SetResult\fR |
| 297 | set the interpreter result to, respectively, an object and a string. |
| 298 | Similarly, \fBTcl_GetObjResult\fR and \fBTcl_GetStringResult\fR |
| 299 | return the interpreter result as an object and as a string. |
| 300 | The procedures always keep the string and object forms |
| 301 | of the interpreter result consistent. |
| 302 | For example, if \fBTcl_SetObjResult\fR is called to set |
| 303 | the result to an object, |
| 304 | then \fBTcl_GetStringResult\fR is called, |
| 305 | it will return the object's string value. |
| 306 | .PP |
| 307 | \fBTcl_SetObjResult\fR |
| 308 | arranges for \fIobjPtr\fR to be the result for \fIinterp\fR, |
| 309 | replacing any existing result. |
| 310 | The result is left pointing to the object |
| 311 | referenced by \fIobjPtr\fR. |
| 312 | \fIobjPtr\fR's reference count is incremented |
| 313 | since there is now a new reference to it from \fIinterp\fR. |
| 314 | The reference count for any old result object |
| 315 | is decremented and the old result object is freed if no |
| 316 | references to it remain. |
| 317 | .PP |
| 318 | \fBTcl_GetObjResult\fR returns the result for \fIinterp\fR as an object. |
| 319 | The object's reference count is not incremented; |
| 320 | if the caller needs to retain a long-term pointer to the object |
| 321 | they should use \fBTcl_IncrRefCount\fR to increment its reference count |
| 322 | in order to keep it from being freed too early or accidently changed. |
| 323 | .PP |
| 324 | \fBTcl_SetResult\fR |
| 325 | arranges for \fIstring\fR to be the result for the current Tcl |
| 326 | command in \fIinterp\fR, replacing any existing result. |
| 327 | The \fIfreeProc\fR argument specifies how to manage the storage |
| 328 | for the \fIstring\fR argument; |
| 329 | it is discussed in the section |
| 330 | \fBTHE TCL_FREEPROC ARGUMENT TO TCL_SETRESULT\fR below. |
| 331 | If \fIstring\fR is \fBNULL\fR, then \fIfreeProc\fR is ignored |
| 332 | and \fBTcl_SetResult\fR |
| 333 | re-initializes \fIinterp\fR's result to point to an empty string. |
| 334 | .PP |
| 335 | \fBTcl_GetStringResult\fR returns the result for \fIinterp\fR as an string. |
| 336 | If the result was set to an object by a \fBTcl_SetObjResult\fR call, |
| 337 | the object form will be converted to a string and returned. |
| 338 | If the object's string representation contains null bytes, |
| 339 | this conversion will lose information. |
| 340 | For this reason, programmers are encouraged to |
| 341 | write their code to use the new object API procedures |
| 342 | and to call \fBTcl_GetObjResult\fR instead. |
| 343 | .PP |
| 344 | \fBTcl_ResetResult\fR clears the result for \fIinterp\fR |
| 345 | and leaves the result in its normal empty initialized state. |
| 346 | If the result is an object, |
| 347 | its reference count is decremented and the result is left |
| 348 | pointing to an unshared object representing an empty string. |
| 349 | If the result is a dynamically allocated string, its memory is free*d |
| 350 | and the result is left as a empty string. |
| 351 | \fBTcl_ResetResult\fR also clears the error state managed by |
| 352 | \fBTcl_AddErrorInfo\fR, \fBTcl_AddObjErrorInfo\fR, |
| 353 | and \fBTcl_SetErrorCode\fR. |
| 354 | |
| 355 | .SH "OLD STRING PROCEDURES" |
| 356 | .PP |
| 357 | Use of the following procedures is deprecated |
| 358 | since they manipulate the Tcl result as a string. |
| 359 | Procedures such as \fBTcl_SetObjResult\fR |
| 360 | that manipulate the result as an object |
| 361 | can be significantly more efficient. |
| 362 | .PP |
| 363 | \fBTcl_AppendResult\fR makes it easy to build up Tcl results in pieces. |
| 364 | It takes each of its \fIstring\fR arguments and appends them in order |
| 365 | to the current result associated with \fIinterp\fR. |
| 366 | If the result is in its initialized empty state (e.g. a command procedure |
| 367 | was just invoked or \fBTcl_ResetResult\fR was just called), |
| 368 | then \fBTcl_AppendResult\fR sets the result to the concatenation of |
| 369 | its \fIstring\fR arguments. |
| 370 | \fBTcl_AppendResult\fR may be called repeatedly as additional pieces |
| 371 | of the result are produced. |
| 372 | \fBTcl_AppendResult\fR takes care of all the |
| 373 | storage management issues associated with managing \fIinterp\fR's |
| 374 | result, such as allocating a larger result area if necessary. |
| 375 | It also converts the current interpreter result from an object |
| 376 | to a string, if necessary, before appending the argument strings. |
| 377 | Any number of \fIstring\fR arguments may be passed in a single |
| 378 | call; the last argument in the list must be a NULL pointer. |
| 379 | .PP |
| 380 | \fBTcl_AppendResultVA\fR is the same as \fBTcl_AppendResult\fR except that |
| 381 | instead of taking a variable number of arguments it takes an argument list. |
| 382 | .PP |
| 383 | \fBTcl_AppendElement\fR is similar to \fBTcl_AppendResult\fR in |
| 384 | that it allows results to be built up in pieces. |
| 385 | However, \fBTcl_AppendElement\fR takes only a single \fIstring\fR |
| 386 | argument and it appends that argument to the current result |
| 387 | as a proper Tcl list element. |
| 388 | \fBTcl_AppendElement\fR adds backslashes or braces if necessary |
| 389 | to ensure that \fIinterp\fR's result can be parsed as a list and that |
| 390 | \fIstring\fR will be extracted as a single element. |
| 391 | Under normal conditions, \fBTcl_AppendElement\fR will add a space |
| 392 | character to \fIinterp\fR's result just before adding the new |
| 393 | list element, so that the list elements in the result are properly |
| 394 | separated. |
| 395 | However if the new list element is the first in a list or sub-list |
| 396 | (i.e. \fIinterp\fR's current result is empty, or consists of the |
| 397 | single character ``{'', or ends in the characters `` {'') then no |
| 398 | space is added. |
| 399 | .PP |
| 400 | \fBTcl_FreeResult\fR performs part of the work |
| 401 | of \fBTcl_ResetResult\fR. |
| 402 | It frees up the memory associated with \fIinterp\fR's result. |
| 403 | It also sets \fIinterp->freeProc\fR to zero, but doesn't |
| 404 | change \fIinterp->result\fR or clear error state. |
| 405 | \fBTcl_FreeResult\fR is most commonly used when a procedure |
| 406 | is about to replace one result value with another. |
| 407 | |
| 408 | .SH "DIRECT ACCESS TO INTERP->RESULT IS DEPRECATED" |
| 409 | .PP |
| 410 | It used to be legal for programs to |
| 411 | directly read and write \fIinterp->result\fR |
| 412 | to manipulate the interpreter result. |
| 413 | Direct access to \fIinterp->result\fR is now strongly deprecated |
| 414 | because it can make the result's string and object forms inconsistent. |
| 415 | Programs should always read the result |
| 416 | using the procedures \fBTcl_GetObjResult\fR or \fBTcl_GetStringResult\fR, |
| 417 | and write the result using \fBTcl_SetObjResult\fR or \fBTcl_SetResult\fR. |
| 418 | |
| 419 | .SH "THE TCL_FREEPROC ARGUMENT TO TCL_SETRESULT" |
| 420 | .PP |
| 421 | \fBTcl_SetResult\fR's \fIfreeProc\fR argument specifies how |
| 422 | the Tcl system is to manage the storage for the \fIstring\fR argument. |
| 423 | If \fBTcl_SetResult\fR or \fBTcl_SetObjResult\fR are called |
| 424 | at a time when \fIinterp\fR holds a string result, |
| 425 | they do whatever is necessary to dispose of the old string result |
| 426 | (see the \fBTcl_Interp\fR manual entry for details on this). |
| 427 | .PP |
| 428 | If \fIfreeProc\fR is \fBTCL_STATIC\fR it means that \fIstring\fR |
| 429 | refers to an area of static storage that is guaranteed not to be |
| 430 | modified until at least the next call to \fBTcl_Eval\fR. |
| 431 | If \fIfreeProc\fR |
| 432 | is \fBTCL_DYNAMIC\fR it means that \fIstring\fR was allocated with a call |
| 433 | to \fBTcl_Alloc\fR and is now the property of the Tcl system. |
| 434 | \fBTcl_SetResult\fR will arrange for the string's storage to be |
| 435 | released by calling \fBTcl_Free\fR when it is no longer needed. |
| 436 | If \fIfreeProc\fR is \fBTCL_VOLATILE\fR it means that \fIstring\fR |
| 437 | points to an area of memory that is likely to be overwritten when |
| 438 | \fBTcl_SetResult\fR returns (e.g. it points to something in a stack frame). |
| 439 | In this case \fBTcl_SetResult\fR will make a copy of the string in |
| 440 | dynamically allocated storage and arrange for the copy to be the |
| 441 | result for the current Tcl command. |
| 442 | .PP |
| 443 | If \fIfreeProc\fR isn't one of the values \fBTCL_STATIC\fR, |
| 444 | \fBTCL_DYNAMIC\fR, and \fBTCL_VOLATILE\fR, then it is the address |
| 445 | of a procedure that Tcl should call to free the string. |
| 446 | This allows applications to use non-standard storage allocators. |
| 447 | When Tcl no longer needs the storage for the string, it will |
| 448 | call \fIfreeProc\fR. \fIFreeProc\fR should have arguments and |
| 449 | result that match the type \fBTcl_FreeProc\fR: |
| 450 | .CS |
| 451 | typedef void Tcl_FreeProc(char *\fIblockPtr\fR); |
| 452 | .CE |
| 453 | When \fIfreeProc\fR is called, its \fIblockPtr\fR will be set to |
| 454 | the value of \fIstring\fR passed to \fBTcl_SetResult\fR. |
| 455 | |
| 456 | .SH "SEE ALSO" |
| 457 | Tcl_AddErrorInfo, Tcl_CreateObjCommand, Tcl_SetErrorCode, Tcl_Interp |
| 458 | |
| 459 | .SH KEYWORDS |
| 460 | append, command, element, list, object, result, return value, interpreter |