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Re: NSComboBoxCell bug


From: Quentin Mathé
Subject: Re: NSComboBoxCell bug
Date: Fri, 12 May 2006 02:33:17 +0200

Le 7 mai 06 à 21:58, Fred Kiefer a écrit :

Wolfgang Lux wrote:

While this may fix your problem, I'd strongly advise against it.

Sorry, I already had hat fix applied, but if you are able to convince me
it does harm, I will take it out again.

Hi Fred,

I'm not sure about this one, I have to make some tests, but I think Wolgang is right on the fact this fix isn't correct.

Calling textDidChange: in validateSelection *is* the right thing to do because the contents of the combo box did change after a user induced change (which is when textDidChange: should be called according to the docs). Other objects watching the contents of the combo box may in fact
rely on the NSTextDidChangeNotification being  sent.

Did you inspect the code that was changed? It is not about any code
directly on NSComboBoxCell, the validateSelection method is on the
GSComboWindow, this is a fairly internal class. Everything that goes no here should only be of interest for the internal interaction of GNUstep.
Specificall the code where the textDidChange: call on the text object
(again not on the NSComboBoxCell) was removed has a FIXME around it, as
it should not be needed at all. At least Quentin thought so, when he
wrote the code.

I added the following lines :

// FIXME: Because NSCell doesn't behave correctly the line just over has
      // no effect, to correct this fact, the code below is needed.
      [textObject setString: [_cell _stringValueAtIndex:
        [_cell indexOfSelectedItem]]];

      /*
* Dispatch the text notifications and by side effect update the cell * object value with the -textDidChange: method of NSTextField which is
       * the editor delegate
       */
      [(NSTextView *)textObject didChangeText];
      // End of the code to remove

to workaround the fact [_cell setStringValue: blabla] wasn't triggering textDidChange: notification as it should. When this method is entered, the cell is normally being edited with the field editor. In this precise case, the first problem was the field editor wasn't updated on -setStringValue: and by the way the textDidChange: notification wasn't sent on GNUstep (this doesn't match Cocoa behavior). Do you know whether this bug has been fixed ? I haven't fixed this bug when I worked on NSComboBoxCell and related, because it was tricky to implement and no core developers had a precise idea on how to do it iirc.

The interaction between the text object and the cell is again totally
internal, no other object should be watching for any notifications here. All the notifications send by the NSComboBoxCell are hopefully unaffected.

That's not true. Even if no objects are watching most of the time, any objects can be potentially interested by field editor or cell notifications. _cell is the combobox cell precisely here. If the previous bug hasn't been fixed, NSComboBoxCell notifications are going to be affected, because in this precise case the textDidChange: notification is sent by the field editor (taking care of the combobox cell duty).

The problem really is that NSComboBox's textDidChange: method should
not perform text completion. Instead, text completion should only be
performed when the user has entered text, so I think it would be more
appropriate to override insertText: in NSComboBox and attempt text
completion there.

The textDidChange: method is not on the control NSComboBox, but on the
cell class NSComboBoxCell.

Wolfgang was probably referring to NSComboBoxCell here. Otherwise, I think what he suggests is probably the right solution (I'm unable to think of a bad side effect of -insertText: right now).

Please, don't get me wrong, I am not saying that the current code, or
more specifically the last change is fully correct.

Noted :-).

If you see a
problem, please explain it or better, show it with some example code.

Will know more on the issue after some tests.

Cheers,
Quentin.

--
Quentin Mathé
address@hidden





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