Initial commit of OpenSPARC T2 design and verification files.
[OpenSPARC-T2-DV] / tools / src / nas,5.n2.os.2 / lib / python / man / mann / return.n
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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.
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178.\}
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181\kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c
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208.SH "STANDARD OPTIONS"
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219See the \\fBoptions\\fR manual entry for details on the standard options.
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226Command-Line Name: \\fB\\$1\\fR
227Database Name: \\fB\\$2\\fR
228Database Class: \\fB\\$3\\fR
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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
250return \- 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
257Return immediately from the current procedure
258(or top-level command or \fBsource\fR command),
259with \fIstring\fR as the return value. If \fIstring\fR is not specified then
260an empty string will be returned as result.
261.SH "EXCEPTIONAL RETURN CODES"
262.PP
263In addition to the result of a procedure, the return
264code of a procedure may also be set by \fBreturn\fR
265through use of the \fB-code\fR option.
266In the usual case where the \fB\-code\fR option isn't
267specified the procedure will return normally.
268However, the \fB\-code\fR option may be used to generate an
269exceptional return from the procedure.
270\fICode\fR may have any of the following values:
271.TP 13
272\fBok (or 0)\fR
273Normal return: same as if the option is omitted. The return code
274of the procedure is 0 (\fBTCL_OK\fR).
275.TP 13
276\fBerror (1)\fR
277Error return: the return code of the procedure is 1 (\fBTCL_ERROR\fR).
278The procedure command behaves in its calling context as if it
279were the command \fBerror \fIresult\fR. See below for additional
280options.
281.TP 13
282\fBreturn (2)\fR
283The return code of the procedure is 2 (\fBTCL_RETURN\fR). The
284procedure command behaves in its calling context as if it
285were the command \fBreturn\fR (with no arguments).
286.TP 13
287\fBbreak (3)\fR
288The return code of the procedure is 3 (\fBTCL_BREAK\fR). The
289procedure command behaves in its calling context as if it
290were the command \fBbreak\fR.
291.TP 13
292\fBcontinue (4)\fR
293The return code of the procedure is 4 (\fBTCL_CONTINUE\fR). The
294procedure command behaves in its calling context as if it
295were the command \fBcontinue\fR.
296.TP 13
297\fIvalue\fR
298\fIValue\fR must be an integer; it will be returned as the
299return code for the current procedure.
300.LP
301The \fB\-code\fR option is rarely used.
302It is provided so that procedures that implement
303new control structures can reflect exceptional conditions back to
304their callers.
305.PP
306Two additional options, \fB\-errorinfo\fR and \fB\-errorcode\fR,
307may be used to provide additional information during error
308returns.
309These options are ignored unless \fIcode\fR is \fBerror\fR.
310.PP
311The \fB\-errorinfo\fR option specifies an initial stack
312trace for the \fBerrorInfo\fR variable; if it is not specified then
313the stack trace left in \fBerrorInfo\fR will include the call to
314the procedure and higher levels on the stack but it will not include
315any information about the context of the error within the procedure.
316Typically the \fIinfo\fR value is supplied from the value left
317in \fBerrorInfo\fR after a \fBcatch\fR command trapped an error within
318the procedure.
319.PP
320If the \fB\-errorcode\fR option is specified then \fIcode\fR provides
321a value for the \fBerrorCode\fR variable.
322If the option is not specified then \fBerrorCode\fR will
323default to \fBNONE\fR.
324.SH EXAMPLES
325First, a simple example of using \fBreturn\fR to return from a
326procedure, interrupting the procedure body.
327.CS
328proc 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
335Next, an example of using \fBreturn\fR to set the value
336returned by the procedure.
337.CS
338proc returnX {} {\fBreturn\fR X}
339puts [returnX] ;# prints "X"
340.CE
341.PP
342Next, a more complete example, using \fBreturn -code error\fR
343to report invalid arguments.
344.CS
345proc 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
368Next, a procedure replacement for \fBbreak\fR.
369.CS
370proc myBreak {} {
371 \fBreturn\fR -code break
372}
373.CE
374
375.SH "SEE ALSO"
376break(n), catch(n), continue(n), error(n), proc(n), source(n), tclvars(n)
377
378.SH KEYWORDS
379break, catch, continue, error, procedure, return