Provided by: tcl8.4-doc_8.4.19-4ubuntu3_all bug

NAME

       return - Return from a procedure

SYNOPSIS

       return ?-code code? ?-errorinfo info? ?-errorcode code? ?string?
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DESCRIPTION

       Return  immediately  from  the current procedure (or top-level command or source command),
       with string as the return value.  If string is not specified then an empty string will  be
       returned as result.

EXCEPTIONAL RETURN CODES

       In  addition  to the result of a procedure, the return code of a procedure may also be set
       by return through use of the -code option.  In the usual case where the -code option isn't
       specified  the  procedure  will return normally.  However, the -code option may be used to
       generate an exceptional return from the procedure.  Code may have  any  of  the  following
       values:

       ok (or 0)    Normal  return:   same  as  if the option is omitted.  The return code of the
                    procedure is 0 (TCL_OK).

       error (1)    Error return: the return  code  of  the  procedure  is  1  (TCL_ERROR).   The
                    procedure  command  behaves  in its calling context as if it were the command
                    error result.  See below for additional options.

       return (2)   The return code of the procedure is 2 (TCL_RETURN).   The  procedure  command
                    behaves  in  its  calling  context  as if it were the command return (with no
                    arguments).

       break (3)    The return code of the procedure is 3  (TCL_BREAK).   The  procedure  command
                    behaves in its calling context as if it were the command break.

       continue (4) The  return code of the procedure is 4 (TCL_CONTINUE).  The procedure command
                    behaves in its calling context as if it were the command continue.

       value        Value must be an integer;  it will be returned as the  return  code  for  the
                    current procedure.

       The  -code  option  is  rarely used.  It is provided so that procedures that implement new
       control structures can reflect exceptional conditions back to their callers.

       Two additional options, -errorinfo and -errorcode,  may  be  used  to  provide  additional
       information during error returns.  These options are ignored unless code is error.

       The  -errorinfo option specifies an initial stack trace for the errorInfo variable;  if it
       is not specified then the stack trace left in errorInfo  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 info value is supplied from  the
       value left in errorInfo after a catch command trapped an error within the procedure.

       If  the  -errorcode  option  is  specified  then  code  provides a value for the errorCode
       variable.  If the option is not specified then errorCode will default to NONE.

EXAMPLES

       First, a simple example of using return to  return  from  a  procedure,  interrupting  the
       procedure body.
              proc printOneLine {} {
                 puts "line 1"    ;# This line will be printed.
                 return
                 puts "line 2"    ;# This line will not be printed.
              }

       Next, an example of using return to set the value returned by the procedure.
              proc returnX {} {return X}
              puts [returnX]    ;# prints "X"

       Next, a more complete example, using return -code error to report invalid arguments.
              proc factorial {n} {
                 if {![string is integer $n] || ($n < 0)} {
                    return -code error \
                          "expected non-negative integer,\
                           but got \"$n\""
                 }
                 if {$n < 2} {
                    return 1
                 }
                 set m [expr {$n - 1}]
                 set code [catch {factorial $m} factor]
                 if {$code != 0} {
                    return -code $code $factor
                 }
                 set product [expr {$n * $factor}]
                 if {$product < 0} {
                    return -code error \
                          "overflow computing factorial of $n"
                 }
                 return $product
              }

       Next, a procedure replacement for break.
              proc myBreak {} {
                 return -code break
              }

SEE ALSO

       break(3tcl),   catch(3tcl),   continue(3tcl),   error(3tcl),   proc(3tcl),   source(3tcl),
       tclvars(3tcl)

KEYWORDS

       break, catch, continue, error, procedure, return