| 1 | '\" |
| 2 | '\" Copyright (c) 1993 The Regents of the University of California. |
| 3 | '\" Copyright (c) 1994-1996 Sun Microsystems, Inc. |
| 4 | '\" |
| 5 | '\" See the file "license.terms" for information on usage and redistribution |
| 6 | '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. |
| 7 | '\" |
| 8 | '\" RCS: @(#) $Id: return.n,v 1.3.18.1 2004/10/27 14:23:58 dkf Exp $ |
| 9 | '\" |
| 10 | '\" The definitions below are for supplemental macros used in Tcl/Tk |
| 11 | '\" manual entries. |
| 12 | '\" |
| 13 | '\" .AP type name in/out ?indent? |
| 14 | '\" Start paragraph describing an argument to a library procedure. |
| 15 | '\" type is type of argument (int, etc.), in/out is either "in", "out", |
| 16 | '\" or "in/out" to describe whether procedure reads or modifies arg, |
| 17 | '\" and indent is equivalent to second arg of .IP (shouldn't ever be |
| 18 | '\" needed; use .AS below instead) |
| 19 | '\" |
| 20 | '\" .AS ?type? ?name? |
| 21 | '\" Give maximum sizes of arguments for setting tab stops. Type and |
| 22 | '\" name are examples of largest possible arguments that will be passed |
| 23 | '\" to .AP later. If args are omitted, default tab stops are used. |
| 24 | '\" |
| 25 | '\" .BS |
| 26 | '\" Start box enclosure. From here until next .BE, everything will be |
| 27 | '\" enclosed in one large box. |
| 28 | '\" |
| 29 | '\" .BE |
| 30 | '\" End of box enclosure. |
| 31 | '\" |
| 32 | '\" .CS |
| 33 | '\" Begin code excerpt. |
| 34 | '\" |
| 35 | '\" .CE |
| 36 | '\" End code excerpt. |
| 37 | '\" |
| 38 | '\" .VS ?version? ?br? |
| 39 | '\" Begin vertical sidebar, for use in marking newly-changed parts |
| 40 | '\" of man pages. The first argument is ignored and used for recording |
| 41 | '\" the version when the .VS was added, so that the sidebars can be |
| 42 | '\" found and removed when they reach a certain age. If another argument |
| 43 | '\" is present, then a line break is forced before starting the sidebar. |
| 44 | '\" |
| 45 | '\" .VE |
| 46 | '\" End of vertical sidebar. |
| 47 | '\" |
| 48 | '\" .DS |
| 49 | '\" Begin an indented unfilled display. |
| 50 | '\" |
| 51 | '\" .DE |
| 52 | '\" End of indented unfilled display. |
| 53 | '\" |
| 54 | '\" .SO |
| 55 | '\" Start of list of standard options for a Tk widget. The |
| 56 | '\" options follow on successive lines, in four columns separated |
| 57 | '\" by tabs. |
| 58 | '\" |
| 59 | '\" .SE |
| 60 | '\" End of list of standard options for a Tk widget. |
| 61 | '\" |
| 62 | '\" .OP cmdName dbName dbClass |
| 63 | '\" Start of description of a specific option. cmdName gives the |
| 64 | '\" option's name as specified in the class command, dbName gives |
| 65 | '\" the option's name in the option database, and dbClass gives |
| 66 | '\" the option's class in the option database. |
| 67 | '\" |
| 68 | '\" .UL arg1 arg2 |
| 69 | '\" Print arg1 underlined, then print arg2 normally. |
| 70 | '\" |
| 71 | '\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $ |
| 72 | '\" |
| 73 | '\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages. |
| 74 | .if t .wh -1.3i ^B |
| 75 | .nr ^l \n(.l |
| 76 | .ad b |
| 77 | '\" # Start an argument description |
| 78 | .de AP |
| 79 | .ie !"\\$4"" .TP \\$4 |
| 80 | .el \{\ |
| 81 | . ie !"\\$2"" .TP \\n()Cu |
| 82 | . el .TP 15 |
| 83 | .\} |
| 84 | .ta \\n()Au \\n()Bu |
| 85 | .ie !"\\$3"" \{\ |
| 86 | \&\\$1 \\fI\\$2\\fP (\\$3) |
| 87 | .\".b |
| 88 | .\} |
| 89 | .el \{\ |
| 90 | .br |
| 91 | .ie !"\\$2"" \{\ |
| 92 | \&\\$1 \\fI\\$2\\fP |
| 93 | .\} |
| 94 | .el \{\ |
| 95 | \&\\fI\\$1\\fP |
| 96 | .\} |
| 97 | .\} |
| 98 | .. |
| 99 | '\" # define tabbing values for .AP |
| 100 | .de AS |
| 101 | .nr )A 10n |
| 102 | .if !"\\$1"" .nr )A \\w'\\$1'u+3n |
| 103 | .nr )B \\n()Au+15n |
| 104 | .\" |
| 105 | .if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n |
| 106 | .nr )C \\n()Bu+\\w'(in/out)'u+2n |
| 107 | .. |
| 108 | .AS Tcl_Interp Tcl_CreateInterp in/out |
| 109 | '\" # BS - start boxed text |
| 110 | '\" # ^y = starting y location |
| 111 | '\" # ^b = 1 |
| 112 | .de BS |
| 113 | .br |
| 114 | .mk ^y |
| 115 | .nr ^b 1u |
| 116 | .if n .nf |
| 117 | .if n .ti 0 |
| 118 | .if n \l'\\n(.lu\(ul' |
| 119 | .if n .fi |
| 120 | .. |
| 121 | '\" # BE - end boxed text (draw box now) |
| 122 | .de BE |
| 123 | .nf |
| 124 | .ti 0 |
| 125 | .mk ^t |
| 126 | .ie n \l'\\n(^lu\(ul' |
| 127 | .el \{\ |
| 128 | .\" Draw four-sided box normally, but don't draw top of |
| 129 | .\" box if the box started on an earlier page. |
| 130 | .ie !\\n(^b-1 \{\ |
| 131 | \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' |
| 132 | .\} |
| 133 | .el \}\ |
| 134 | \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' |
| 135 | .\} |
| 136 | .\} |
| 137 | .fi |
| 138 | .br |
| 139 | .nr ^b 0 |
| 140 | .. |
| 141 | '\" # VS - start vertical sidebar |
| 142 | '\" # ^Y = starting y location |
| 143 | '\" # ^v = 1 (for troff; for nroff this doesn't matter) |
| 144 | .de VS |
| 145 | .if !"\\$2"" .br |
| 146 | .mk ^Y |
| 147 | .ie n 'mc \s12\(br\s0 |
| 148 | .el .nr ^v 1u |
| 149 | .. |
| 150 | '\" # VE - end of vertical sidebar |
| 151 | .de VE |
| 152 | .ie n 'mc |
| 153 | .el \{\ |
| 154 | .ev 2 |
| 155 | .nf |
| 156 | .ti 0 |
| 157 | .mk ^t |
| 158 | \h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n' |
| 159 | .sp -1 |
| 160 | .fi |
| 161 | .ev |
| 162 | .\} |
| 163 | .nr ^v 0 |
| 164 | .. |
| 165 | '\" # Special macro to handle page bottom: finish off current |
| 166 | '\" # box/sidebar if in box/sidebar mode, then invoked standard |
| 167 | '\" # page bottom macro. |
| 168 | .de ^B |
| 169 | .ev 2 |
| 170 | 'ti 0 |
| 171 | 'nf |
| 172 | .mk ^t |
| 173 | .if \\n(^b \{\ |
| 174 | .\" Draw three-sided box if this is the box's first page, |
| 175 | .\" draw two sides but no top otherwise. |
| 176 | .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 |
| 177 | .el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c |
| 178 | .\} |
| 179 | .if \\n(^v \{\ |
| 180 | .nr ^x \\n(^tu+1v-\\n(^Yu |
| 181 | \kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c |
| 182 | .\} |
| 183 | .bp |
| 184 | 'fi |
| 185 | .ev |
| 186 | .if \\n(^b \{\ |
| 187 | .mk ^y |
| 188 | .nr ^b 2 |
| 189 | .\} |
| 190 | .if \\n(^v \{\ |
| 191 | .mk ^Y |
| 192 | .\} |
| 193 | .. |
| 194 | '\" # DS - begin display |
| 195 | .de DS |
| 196 | .RS |
| 197 | .nf |
| 198 | .sp |
| 199 | .. |
| 200 | '\" # DE - end display |
| 201 | .de DE |
| 202 | .fi |
| 203 | .RE |
| 204 | .sp |
| 205 | .. |
| 206 | '\" # SO - start of list of standard options |
| 207 | .de SO |
| 208 | .SH "STANDARD OPTIONS" |
| 209 | .LP |
| 210 | .nf |
| 211 | .ta 5.5c 11c |
| 212 | .ft B |
| 213 | .. |
| 214 | '\" # SE - end of list of standard options |
| 215 | .de SE |
| 216 | .fi |
| 217 | .ft R |
| 218 | .LP |
| 219 | See the \\fBoptions\\fR manual entry for details on the standard options. |
| 220 | .. |
| 221 | '\" # OP - start of full description for a single option |
| 222 | .de OP |
| 223 | .LP |
| 224 | .nf |
| 225 | .ta 4c |
| 226 | Command-Line Name: \\fB\\$1\\fR |
| 227 | Database Name: \\fB\\$2\\fR |
| 228 | Database Class: \\fB\\$3\\fR |
| 229 | .fi |
| 230 | .IP |
| 231 | .. |
| 232 | '\" # CS - begin code excerpt |
| 233 | .de CS |
| 234 | .RS |
| 235 | .nf |
| 236 | .ta .25i .5i .75i 1i |
| 237 | .. |
| 238 | '\" # CE - end code excerpt |
| 239 | .de CE |
| 240 | .fi |
| 241 | .RE |
| 242 | .. |
| 243 | .de UL |
| 244 | \\$1\l'|0\(ul'\\$2 |
| 245 | .. |
| 246 | .TH return n 7.0 Tcl "Tcl Built-In Commands" |
| 247 | .BS |
| 248 | '\" Note: do not modify the .SH NAME line immediately below! |
| 249 | .SH NAME |
| 250 | return \- Return from a procedure |
| 251 | .SH SYNOPSIS |
| 252 | \fBreturn \fR?\fB\-code \fIcode\fR? ?\fB\-errorinfo \fIinfo\fR? ?\fB\-errorcode\fI code\fR? ?\fIstring\fR? |
| 253 | .BE |
| 254 | |
| 255 | .SH DESCRIPTION |
| 256 | .PP |
| 257 | Return immediately from the current procedure |
| 258 | (or top-level command or \fBsource\fR command), |
| 259 | with \fIstring\fR as the return value. If \fIstring\fR is not specified then |
| 260 | an empty string will be returned as result. |
| 261 | .SH "EXCEPTIONAL RETURN CODES" |
| 262 | .PP |
| 263 | In addition to the result of a procedure, the return |
| 264 | code of a procedure may also be set by \fBreturn\fR |
| 265 | through use of the \fB-code\fR option. |
| 266 | In the usual case where the \fB\-code\fR option isn't |
| 267 | specified the procedure will return normally. |
| 268 | However, the \fB\-code\fR option may be used to generate an |
| 269 | exceptional return from the procedure. |
| 270 | \fICode\fR may have any of the following values: |
| 271 | .TP 13 |
| 272 | \fBok (or 0)\fR |
| 273 | Normal return: same as if the option is omitted. The return code |
| 274 | of the procedure is 0 (\fBTCL_OK\fR). |
| 275 | .TP 13 |
| 276 | \fBerror (1)\fR |
| 277 | Error return: the return code of the procedure is 1 (\fBTCL_ERROR\fR). |
| 278 | The procedure command behaves in its calling context as if it |
| 279 | were the command \fBerror \fIresult\fR. See below for additional |
| 280 | options. |
| 281 | .TP 13 |
| 282 | \fBreturn (2)\fR |
| 283 | The return code of the procedure is 2 (\fBTCL_RETURN\fR). The |
| 284 | procedure command behaves in its calling context as if it |
| 285 | were the command \fBreturn\fR (with no arguments). |
| 286 | .TP 13 |
| 287 | \fBbreak (3)\fR |
| 288 | The return code of the procedure is 3 (\fBTCL_BREAK\fR). The |
| 289 | procedure command behaves in its calling context as if it |
| 290 | were the command \fBbreak\fR. |
| 291 | .TP 13 |
| 292 | \fBcontinue (4)\fR |
| 293 | The return code of the procedure is 4 (\fBTCL_CONTINUE\fR). The |
| 294 | procedure command behaves in its calling context as if it |
| 295 | were the command \fBcontinue\fR. |
| 296 | .TP 13 |
| 297 | \fIvalue\fR |
| 298 | \fIValue\fR must be an integer; it will be returned as the |
| 299 | return code for the current procedure. |
| 300 | .LP |
| 301 | The \fB\-code\fR option is rarely used. |
| 302 | It is provided so that procedures that implement |
| 303 | new control structures can reflect exceptional conditions back to |
| 304 | their callers. |
| 305 | .PP |
| 306 | Two additional options, \fB\-errorinfo\fR and \fB\-errorcode\fR, |
| 307 | may be used to provide additional information during error |
| 308 | returns. |
| 309 | These options are ignored unless \fIcode\fR is \fBerror\fR. |
| 310 | .PP |
| 311 | The \fB\-errorinfo\fR option specifies an initial stack |
| 312 | trace for the \fBerrorInfo\fR variable; if it is not specified then |
| 313 | the stack trace left in \fBerrorInfo\fR will include the call to |
| 314 | the procedure and higher levels on the stack but it will not include |
| 315 | any information about the context of the error within the procedure. |
| 316 | Typically the \fIinfo\fR value is supplied from the value left |
| 317 | in \fBerrorInfo\fR after a \fBcatch\fR command trapped an error within |
| 318 | the procedure. |
| 319 | .PP |
| 320 | If the \fB\-errorcode\fR option is specified then \fIcode\fR provides |
| 321 | a value for the \fBerrorCode\fR variable. |
| 322 | If the option is not specified then \fBerrorCode\fR will |
| 323 | default to \fBNONE\fR. |
| 324 | .SH EXAMPLES |
| 325 | First, a simple example of using \fBreturn\fR to return from a |
| 326 | procedure, interrupting the procedure body. |
| 327 | .CS |
| 328 | proc printOneLine {} { |
| 329 | puts "line 1" ;# This line will be printed. |
| 330 | \fBreturn\fR |
| 331 | puts "line 2" ;# This line will not be printed. |
| 332 | } |
| 333 | .CE |
| 334 | .PP |
| 335 | Next, an example of using \fBreturn\fR to set the value |
| 336 | returned by the procedure. |
| 337 | .CS |
| 338 | proc returnX {} {\fBreturn\fR X} |
| 339 | puts [returnX] ;# prints "X" |
| 340 | .CE |
| 341 | .PP |
| 342 | Next, a more complete example, using \fBreturn -code error\fR |
| 343 | to report invalid arguments. |
| 344 | .CS |
| 345 | proc factorial {n} { |
| 346 | if {![string is integer $n] || ($n < 0)} { |
| 347 | \fBreturn\fR -code error \\ |
| 348 | "expected non-negative integer,\\ |
| 349 | but got \\"$n\\"" |
| 350 | } |
| 351 | if {$n < 2} { |
| 352 | \fBreturn\fR 1 |
| 353 | } |
| 354 | set m [expr {$n - 1}] |
| 355 | set code [catch {factorial $m} factor] |
| 356 | if {$code != 0} { |
| 357 | \fBreturn\fR -code $code $factor |
| 358 | } |
| 359 | set product [expr {$n * $factor}] |
| 360 | if {$product < 0} { |
| 361 | \fBreturn\fR -code error \\ |
| 362 | "overflow computing factorial of $n" |
| 363 | } |
| 364 | \fBreturn\fR $product |
| 365 | } |
| 366 | .CE |
| 367 | .PP |
| 368 | Next, a procedure replacement for \fBbreak\fR. |
| 369 | .CS |
| 370 | proc myBreak {} { |
| 371 | \fBreturn\fR -code break |
| 372 | } |
| 373 | .CE |
| 374 | |
| 375 | .SH "SEE ALSO" |
| 376 | break(n), catch(n), continue(n), error(n), proc(n), source(n), tclvars(n) |
| 377 | |
| 378 | .SH KEYWORDS |
| 379 | break, catch, continue, error, procedure, return |