[Tcl-bugs] [ tktoolkit-Bugs-220802 ] trace on a textvariable does not report errors

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

Bugs item #220802, was opened at 2000-10-31 19:54
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=112997&aid=220802&group_id=12997

Category: 07. [entry]
Group: : 8.0.5
Status: Open
Resolution: None
Priority: 5
Submitted By: Brent B. Welch (welch)
>Assigned to: Jeffrey Hobbs (hobbs)
Summary: trace on a textvariable does not report errors

Initial Comment:
OriginalBugID: 1745 Bug
Version: 8.0.5
SubmitDate: '1999-04-07'
LastModified: '1999-11-16'
Severity: MED
Status: Assigned
Submitter: pat
ChangedBy: hobbs
OS: Windows NT
OSVersion: 4 sp4
Machine: X86


Name: Wiebe Wiersema

ReproducibleScript:
1. start wish80.exe
2. enter following script in console
  proc showit args {
    error "aargh"
  }
  entry .e -textvariable foo
  trace variable foo w showit

3. try to set the variable foo directly (this fails as expected)
set foo 1
->can't set "foo": aargh

3. try to set the variable foo indirectly through the widget (this does
not fail)
.e insert end 123
-> widget contains 123 and variable foo contains 123

ObservedBehavior:
the traced procedure clearly raises an error. 
If you activate the trace by entering data into the entrywidget the
raised error is ignored. The smae happens when enterimng data by hand in
the entry widget. This is contrary to the behaviour specified in the
manual pages.
-Quoted rom manual page for trace-
"The return value from command is ignored except that if it returns an
error of any sort then the traced operation also returns an error with
the same error message returned by the trace command (this mechanism can
be used to implement read-only variables, for example)."

DesiredBehavior:
I expect to see an error as specified in the manual page for trace.

The Tcl_SetVar used by the entry widget doesn't use
TCL_LEAVE_ERROR_MSG, but doesn't handle any error case either... 
-- 11/16/1999 hobbs

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