'\"
'\" Copyright (c) 1993 The Regents of the University of California.
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
+'\" Contributions from Don Porter, NIST, 2003. (not subject to US copyright)
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
-'\" RCS: @(#) $Id: return.n,v 1.3 2000/09/07 14:27:51 poenitz 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.
+.TH return n 8.5 Tcl "Tcl Built-In Commands"
+.\" The -*- nroff -*- 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 ?manpage?
+.\" Start of list of standard options for a Tk widget. The manpage
+.\" argument defines where to look up the standard options; if
+.\" omitted, defaults to "options". The options follow on successive
+.\" lines, in three 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.
+.\"
+.\" .QW arg1 ?arg2?
+.\" Print arg1 in quotes, then arg2 normally (for trailing punctuation).
+.\"
+.\" .PQ arg1 ?arg2?
+.\" Print an open parenthesis, arg1 in quotes, then arg2 normally
+.\" (for trailing punctuation) and then a closing parenthesis.
+.\"
+.\" # 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
+.\" # Start an argument description
.de AP
.ie !"\\$4"" .TP \\$4
.el \{\
.\}
.ta \\n()Au \\n()Bu
.ie !"\\$3"" \{\
-\&\\$1 \\fI\\$2\\fP (\\$3)
+\&\\$1 \\fI\\$2\\fP (\\$3)
.\".b
.\}
.el \{\
.\}
.\}
..
-'\" # define tabbing values for .AP
+.\" # define tabbing values for .AP
.de AS
.nr )A 10n
.if !"\\$1"" .nr )A \\w'\\$1'u+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
+.\" # BS - start boxed text
+.\" # ^y = starting y location
+.\" # ^b = 1
.de BS
.br
.mk ^y
.if n \l'\\n(.lu\(ul'
.if n .fi
..
-'\" # BE - end boxed text (draw box now)
+.\" # BE - end boxed text (draw box now)
.de BE
.nf
.ti 0
.br
.nr ^b 0
..
-'\" # VS - start vertical sidebar
-'\" # ^Y = starting y location
-'\" # ^v = 1 (for troff; for nroff this doesn't matter)
+.\" # 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
+.\" # VE - end of vertical sidebar
.de VE
.ie n 'mc
.el \{\
.\}
.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.
+.\" # 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
.mk ^Y
.\}
..
-'\" # DS - begin display
+.\" # DS - begin display
.de DS
.RS
.nf
.sp
..
-'\" # DE - end display
+.\" # DE - end display
.de DE
.fi
.RE
.sp
..
-'\" # SO - start of list of standard options
+.\" # SO - start of list of standard options
.de SO
+'ie '\\$1'' .ds So \\fBoptions\\fR
+'el .ds So \\fB\\$1\\fR
.SH "STANDARD OPTIONS"
.LP
.nf
.ta 5.5c 11c
.ft B
..
-'\" # SE - end of list of standard options
+.\" # 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.
+See the \\*(So manual entry for details on the standard options.
..
-'\" # OP - start of full description for a single option
+.\" # OP - start of full description for a single option
.de OP
.LP
.nf
.fi
.IP
..
-'\" # CS - begin code excerpt
+.\" # CS - begin code excerpt
.de CS
.RS
.nf
.ta .25i .5i .75i 1i
..
-'\" # CE - end code excerpt
+.\" # CE - end code excerpt
.de CE
.fi
.RE
..
+.\" # UL - underline word
.de UL
\\$1\l'|0\(ul'\\$2
..
-.TH return n 7.0 Tcl "Tcl Built-In Commands"
+.\" # QW - apply quotation marks to word
+.de QW
+.ie '\\*(lq'"' ``\\$1''\\$2
+.\"" fix emacs highlighting
+.el \\*(lq\\$1\\*(rq\\$2
+..
+.\" # PQ - apply parens and quotation marks to word
+.de PQ
+.ie '\\*(lq'"' (``\\$1''\\$2)\\$3
+.\"" fix emacs highlighting
+.el (\\*(lq\\$1\\*(rq\\$2)\\$3
+..
+.\" # QR - quoted range
+.de QR
+.ie '\\*(lq'"' ``\\$1''\\-``\\$2''\\$3
+.\"" fix emacs highlighting
+.el \\*(lq\\$1\\*(rq\\-\\*(lq\\$2\\*(rq\\$3
+..
+.\" # MT - "empty" string
+.de MT
+.QW ""
+..
.BS
'\" Note: do not modify the .SH NAME line immediately below!
.SH NAME
-return \- Return from a procedure
+return \- Return from a procedure, or set return code of a script
.SH SYNOPSIS
-\fBreturn \fR?\fB\-code \fIcode\fR? ?\fB\-errorinfo \fIinfo\fR? ?\fB\-errorcode\fI code\fR? ?\fIstring\fR?
+\fBreturn \fR?\fIresult\fR?
+.sp
+\fBreturn \fR?\fB\-code \fIcode\fR? ?\fIresult\fR?
+.sp
+\fBreturn \fR?\fIoption value \fR...? ?\fIresult\fR?
.BE
-
.SH DESCRIPTION
.PP
-Return immediately from the current procedure
-(or top-level command or \fBsource\fR command),
-with \fIstring\fR as the return value. If \fIstring\fR is not specified then
-an empty string will be returned as result.
-
-.SH "EXCEPTIONAL RETURNS"
+In its simplest usage, the \fBreturn\fR command is used without options
+in the body of a procedure to immediately return control to the caller
+of the procedure. If a \fIresult\fR argument is provided, its value
+becomes the result of the procedure passed back to the caller.
+If \fIresult\fR is not specified then an empty string will be returned
+to the caller as the result of the procedure.
.PP
-In the usual case where the \fB\-code\fR option isn't
-specified the procedure will return normally (its completion
-code will be TCL_OK).
+The \fBreturn\fR command serves a similar function within script
+files that are evaluated by the \fBsource\fR command. When \fBsource\fR
+evaluates the contents of a file as a script, an invocation of
+the \fBreturn\fR command will cause script evaluation
+to immediately cease, and the value \fIresult\fR (or an empty string)
+will be returned as the result of the \fBsource\fR command.
+.SH "EXCEPTIONAL RETURN CODES"
+.PP
+In addition to the result of a procedure, the return
+code of a procedure may also be set by \fBreturn\fR
+through use of the \fB\-code\fR option.
+In the usual case where the \fB\-code\fR option is not
+specified the procedure will return normally.
However, the \fB\-code\fR option may be used to generate an
exceptional return from the procedure.
\fICode\fR may have any of the following values:
-.TP 10
-\fBok\fR
-Normal return: same as if the option is omitted.
-.TP 10
-\fBerror\fR
-Error return: same as if the \fBerror\fR command were used to
-terminate the procedure, except for handling of \fBerrorInfo\fR
-and \fBerrorCode\fR variables (see below).
-.TP 10
-\fBreturn\fR
-The current procedure will return with a completion code of
-TCL_RETURN, so that the procedure that invoked it will return
-also.
-.TP 10
-\fBbreak\fR
-The current procedure will return with a completion code of
-TCL_BREAK, which will terminate the innermost nested loop in
-the code that invoked the current procedure.
-.TP 10
-\fBcontinue\fR
-The current procedure will return with a completion code of
-TCL_CONTINUE, which will terminate the current iteration of
-the innermost nested loop in the code that invoked the current
-procedure.
-.TP 10
+.TP 13
+\fBok\fR (or \fB0\fR)
+.
+Normal return: same as if the option is omitted. The return code
+of the procedure is 0 (\fBTCL_OK\fR).
+.TP 13
+\fBerror\fR (or \fB1\fR)
+.
+Error return: the return code of the procedure is 1 (\fBTCL_ERROR\fR).
+The procedure command behaves in its calling context as if it
+were the command \fBerror\fR \fIresult\fR. See below for additional
+options.
+.TP 13
+\fBreturn\fR (or \fB2\fR)
+.
+The return code of the procedure is 2 (\fBTCL_RETURN\fR). The
+procedure command behaves in its calling context as if it
+were the command \fBreturn\fR (with no arguments).
+.TP 13
+\fBbreak\fR (or \fB3\fR)
+.
+The return code of the procedure is 3 (\fBTCL_BREAK\fR). The
+procedure command behaves in its calling context as if it
+were the command \fBbreak\fR.
+.TP 13
+\fBcontinue\fR (or \fB4\fR)
+.
+The return code of the procedure is 4 (\fBTCL_CONTINUE\fR). The
+procedure command behaves in its calling context as if it
+were the command \fBcontinue\fR.
+.TP 13
\fIvalue\fR
+.
\fIValue\fR must be an integer; it will be returned as the
-completion code for the current procedure.
+return code for the current procedure.
.LP
-The \fB\-code\fR option is rarely used.
-It is provided so that procedures that implement
-new control structures can reflect exceptional conditions back to
-their callers.
+When a procedure wants to signal that it has received invalid
+arguments from its caller, it may use \fBreturn -code error\fR
+with \fIresult\fR set to a suitable error message. Otherwise
+usage of the \fBreturn -code\fR option is mostly limited to
+procedures that implement a new control structure.
+.PP
+The \fBreturn \-code\fR command acts similarly within script
+files that are evaluated by the \fBsource\fR command. During the
+evaluation of the contents of a file as a script by \fBsource\fR,
+an invocation of the \fBreturn \-code \fIcode\fR command will cause
+the return code of \fBsource\fR to be \fIcode\fR.
+.SH "RETURN OPTIONS"
+.PP
+In addition to a result and a return code, evaluation of a command
+in Tcl also produces a dictionary of return options. In general
+usage, all \fIoption value\fR pairs given as arguments to \fBreturn\fR
+become entries in the return options dictionary, and any values at all
+are acceptable except as noted below. The \fBcatch\fR command may be
+used to capture all of this information \(em the return code, the result,
+and the return options dictionary \(em that arise from evaluation of a
+script.
+.PP
+As documented above, the \fB\-code\fR entry in the return options dictionary
+receives special treatment by Tcl. There are other return options also
+recognized and treated specially by Tcl. They are:
+.TP
+\fB\-errorcode \fIlist\fR
+.
+The \fB\-errorcode\fR option receives special treatment only when the value
+of the \fB\-code\fR option is \fBTCL_ERROR\fR. Then the \fIlist\fR value
+is meant to be additional information about the error,
+presented as a Tcl list for further processing by programs.
+If no \fB\-errorcode\fR option is provided to \fBreturn\fR when
+the \fB\-code error\fR option is provided, Tcl will set the value
+of the \fB\-errorcode\fR entry in the return options dictionary
+to the default value of \fBNONE\fR. The \fB\-errorcode\fR return
+option will also be stored in the global variable \fBerrorCode\fR.
+.TP
+\fB\-errorinfo \fIinfo\fR
+.
+The \fB\-errorinfo\fR option receives special treatment only when the value
+of the \fB\-code\fR option is \fBTCL_ERROR\fR. Then \fIinfo\fR is the initial
+stack trace, meant to provide to a human reader additional information
+about the context in which the error occurred. The stack trace will
+also be stored in the global variable \fBerrorInfo\fR.
+If no \fB\-errorinfo\fR option is provided to \fBreturn\fR when
+the \fB\-code error\fR option is provided, Tcl will provide its own
+initial stack trace value in the entry for \fB\-errorinfo\fR. Tcl's
+initial stack trace will include only the call to the procedure, and
+stack unwinding will append information about higher stack levels, but
+there will be no information about the context of the error within
+the procedure. Typically the \fIinfo\fR value is supplied from
+the value of \fB\-errorinfo\fR in a return options dictionary captured
+by the \fBcatch\fR command (or from the copy of that information
+stored in the global variable \fBerrorInfo\fR).
+.TP
+\fB\-errorstack \fIlist\fR
+.VS 8.6
+The \fB\-errorstack\fR option receives special treatment only when the value
+of the \fB\-code\fR option is \fBTCL_ERROR\fR. Then \fIlist\fR is the initial
+error stack, recording actual argument values passed to each proc level. The error stack will
+also be reachable through \fBinfo errorstack\fR.
+If no \fB\-errorstack\fR option is provided to \fBreturn\fR when
+the \fB\-code error\fR option is provided, Tcl will provide its own
+initial error stack in the entry for \fB\-errorstack\fR. Tcl's
+initial error stack will include only the call to the procedure, and
+stack unwinding will append information about higher stack levels, but
+there will be no information about the context of the error within
+the procedure. Typically the \fIlist\fR value is supplied from
+the value of \fB\-errorstack\fR in a return options dictionary captured
+by the \fBcatch\fR command (or from the copy of that information from
+\fBinfo errorstack\fR).
+.VE 8.6
+.TP
+\fB\-level \fIlevel\fR
+.
+The \fB\-level\fR and \fB\-code\fR options work together to set the return
+code to be returned by one of the commands currently being evaluated.
+The \fIlevel\fR value must be a non-negative integer representing a number
+of levels on the call stack. It defines the number of levels up the stack
+at which the return code of a command currently being evaluated should
+be \fIcode\fR. If no \fB\-level\fR option is provided, the default value
+of \fIlevel\fR is 1, so that \fBreturn\fR sets the return code that the
+current procedure returns to its caller, 1 level up the call stack. The
+mechanism by which these options work is described in more detail below.
+.TP
+\fB\-options \fIoptions\fR
+.
+The value \fIoptions\fR must be a valid dictionary. The entries of that
+dictionary are treated as additional \fIoption value\fR pairs for the
+\fBreturn\fR command.
+.SH "RETURN CODE HANDLING MECHANISMS"
+.PP
+Return codes are used in Tcl to control program flow. A Tcl script
+is a sequence of Tcl commands. So long as each command evaluation
+returns a return code of \fBTCL_OK\fR, evaluation will continue to the next
+command in the script. Any exceptional return code (non-\fBTCL_OK\fR)
+returned by a command evaluation causes the flow on to the next
+command to be interrupted. Script evaluation ceases, and the
+exceptional return code from the command becomes the return code
+of the full script evaluation. This is the mechanism by which
+errors during script evaluation cause an interruption and unwinding
+of the call stack. It is also the mechanism by which commands
+like \fBbreak\fR, \fBcontinue\fR, and \fBreturn\fR cause script
+evaluation to terminate without evaluating all commands in sequence.
+.PP
+Some of Tcl's built-in commands evaluate scripts as part of their
+functioning. These commands can make use of exceptional return
+codes to enable special features. For example, the built-in
+Tcl commands that provide loops \(em such as \fBwhile\fR, \fBfor\fR,
+and \fBforeach\fR \(em evaluate a script that is the body of the
+loop. If evaluation of the loop body returns the return code
+of \fBTCL_BREAK\fR or \fBTCL_CONTINUE\fR, the loop command can react in such
+a way as to give the \fBbreak\fR and \fBcontinue\fR commands
+their documented interpretation in loops.
+.PP
+Procedure invocation also involves evaluation of a script, the body
+of the procedure. Procedure invocation provides special treatment
+when evaluation of the procedure body returns the return code
+\fBTCL_RETURN\fR. In that circumstance, the \fB\-level\fR entry in the
+return options dictionary is decremented. If after decrementing,
+the value of the \fB\-level\fR entry is 0, then the value of
+the \fB\-code\fR entry becomes the return code of the procedure.
+If after decrementing, the value of the \fB\-level\fR entry is
+greater than zero, then the return code of the procedure is
+\fBTCL_RETURN\fR. If the procedure invocation occurred during the
+evaluation of the body of another procedure, the process will
+repeat itself up the call stack, decrementing the value of the
+\fB\-level\fR entry at each level, so that the \fIcode\fR will
+be the return code of the current command \fIlevel\fR levels
+up the call stack. The \fBsource\fR command performs the
+same handling of the \fBTCL_RETURN\fR return code, which explains
+the similarity of \fBreturn\fR invocation during a \fBsource\fR
+to \fBreturn\fR invocation within a procedure.
+.PP
+The return code of the \fBreturn\fR command itself triggers this
+special handling by procedure invocation. If \fBreturn\fR
+is provided the option \fB\-level 0\fR, then the return code
+of the \fBreturn\fR command itself will be the value \fIcode\fR
+of the \fB\-code\fR option (or \fBTCL_OK\fR by default). Any other value
+for the \fB\-level\fR option (including the default value of 1)
+will cause the return code of the \fBreturn\fR command itself
+to be \fBTCL_RETURN\fR, triggering a return from the enclosing procedure.
+.SH EXAMPLES
+.PP
+First, a simple example of using \fBreturn\fR to return from a
+procedure, interrupting the procedure body.
+.PP
+.CS
+proc printOneLine {} {
+ puts "line 1" ;# This line will be printed.
+ \fBreturn\fR
+ puts "line 2" ;# This line will not be printed.
+}
+.CE
+.PP
+Next, an example of using \fBreturn\fR to set the value
+returned by the procedure.
+.PP
+.CS
+proc returnX {} {\fBreturn\fR X}
+puts [returnX] ;# prints "X"
+.CE
+.PP
+Next, a more complete example, using \fBreturn -code error\fR
+to report invalid arguments.
+.PP
+.CS
+proc factorial {n} {
+ if {![string is integer $n] || ($n < 0)} {
+ \fBreturn\fR -code error \e
+ "expected non-negative integer,\e
+ but got \e"$n\e""
+ }
+ if {$n < 2} {
+ \fBreturn\fR 1
+ }
+ set m [expr {$n - 1}]
+ set code [catch {factorial $m} factor]
+ if {$code != 0} {
+ \fBreturn\fR -code $code $factor
+ }
+ set product [expr {$n * $factor}]
+ if {$product < 0} {
+ \fBreturn\fR -code error \e
+ "overflow computing factorial of $n"
+ }
+ \fBreturn\fR $product
+}
+.CE
+.PP
+Next, a procedure replacement for \fBbreak\fR.
+.PP
+.CS
+proc myBreak {} {
+ \fBreturn\fR -code break
+}
+.CE
+.PP
+With the \fB\-level 0\fR option, \fBreturn\fR itself can serve
+as a replacement for \fBbreak\fR, with the help of \fBinterp alias\fR.
+.PP
+.CS
+interp alias {} Break {} \fBreturn\fR -level 0 -code break
+.CE
+.PP
+An example of using \fBcatch\fR and \fBreturn -options\fR to
+re-raise a caught error:
.PP
-Two additional options, \fB\-errorinfo\fR and \fB\-errorcode\fR,
-may be used to provide additional information during error
-returns.
-These options are ignored unless \fIcode\fR is \fBerror\fR.
+.CS
+proc doSomething {} {
+ set resource [allocate]
+ catch {
+ # Long script of operations
+ # that might raise an error
+ } result options
+ deallocate $resource
+ \fBreturn\fR -options $options $result
+}
+.CE
.PP
-The \fB\-errorinfo\fR option specifies an initial stack
-trace for the \fBerrorInfo\fR variable; if it is not specified then
-the stack trace left in \fBerrorInfo\fR will include the call to
-the procedure and higher levels on the stack but it will not include
-any information about the context of the error within the procedure.
-Typically the \fIinfo\fR value is supplied from the value left
-in \fBerrorInfo\fR after a \fBcatch\fR command trapped an error within
-the procedure.
+Finally an example of advanced use of the \fBreturn\fR options
+to create a procedure replacement for \fBreturn\fR itself:
.PP
-If the \fB\-errorcode\fR option is specified then \fIcode\fR provides
-a value for the \fBerrorCode\fR variable.
-If the option is not specified then \fBerrorCode\fR will
-default to \fBNONE\fR.
-
+.CS
+proc myReturn {args} {
+ set result ""
+ if {[llength $args] % 2} {
+ set result [lindex $args end]
+ set args [lrange $args 0 end-1]
+ }
+ set options [dict merge {-level 1} $args]
+ dict incr options -level
+ \fBreturn\fR -options $options $result
+}
+.CE
.SH "SEE ALSO"
-break(n), continue(n), error(n), proc(n)
-
+break(n), catch(n), continue(n), dict(n), error(n), errorCode(n),
+errorInfo(n), proc(n), source(n), throw(n), try(n)
.SH KEYWORDS
-break, continue, error, procedure, return
+break, catch, continue, error, exception, procedure, result, return
+.\" Local Variables:
+.\" mode: nroff
+.\" End:
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