[Tcl-bugs] [Bug #119191] return in after script causes bogus bgerror

[<no...@so...>]

Bug #119191, was updated on 2000-Oct-25 22:03
Here is a current snapshot of the bug.

Project: Tcl
Category: Commands
Status: Open
Resolution: None
Bug Group: 8.0.5
Priority: 5
Summary: return in after script causes bogus bgerror

Details: OriginalBugID: 2577 Bug
Version: 8.0.5
SubmitDate: '1999-08-18'
LastModified: '2000-04-03'
Severity: SER
Status: Assigned
Submitter: techsupp
ChangedBy: hobbs
RelatedBugIDs: 3998 750
OS: Solaris
OSVersion: 2.5.1
Machine: Other
FixedDate: '2000-10-25'
ClosedDate: '2000-10-25'


Name: Tedd Hadley

Comments:
The reason for the error seems to be code in tclTimer.c AfterProc:
    
        result =  afterPtr->command);
        if (result != TCL_OK) {
            Tcl_AddErrorInfo(interp, "\n    (\"after\" script)");
            Tcl_BackgroundError(interp);
        }
    
    Tcl_GlobalEval can, of course, return a value other than TCL_OK without
    it being TCL_ERROR -- TCL_RETURN in this case.  I patched my version
    by changing the condition to if(result == TCL_ERROR).  This may or may
    not be the right fix...

ReproducibleScript:
after 0 {
       return
    }
    update

ObservedBehavior:
return in an after script causes a fake error.

DesiredBehavior:
No error expected



wish4.2 didn't complain, but 8.0+ does. 
-- 04/03/2000 hobbs

Follow-Ups:

Date: 2000-Nov-13 05:50
By: dkf

Comment:
Return at the global level (which is where after scripts are executed) should always cause an error.
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Date: 2000-Nov-13 13:53
By: dgp

Comment:
I disagree that [return] should throw an error at
level #0.  That's not what the docs say.  From return(n):
...
DESCRIPTION
     Return immediately from the current procedure (or  top-level
     command or source command), with string as the return value.
...

[return] has behaved this way at least as long as I've
used Tcl (since Tcl 7.4), and I've seen plenty of code
that depends on this behavior.  Notably the use of
[return] to exit a pkgIndex.tcl file before the end
of file is quite useful.

-------------------------------------------------------

Date: 2000-Nov-24 05:24
By: dkf

Comment:
And if the [return] *is* the current top-level command?  In that case, I read the description as being functionally equivalent to something that just has a result of the given string (like [format %s $string] for example.)

IMHO, what [return] does is make the current context terminate with the given message/code/errorInfo/errorCode.  But what this means at the top-level is a little unclear to me.
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For detailed info, follow this link:
http://sourceforge.net/bugs/?func=detailbug&bug_id=119191&group_id=10894