Re: [Pyobjc-dev] UI bindings no longer work for me

[Mani G. <ma...@tu...>]

On Tue, Sep 1, 2009 at 2:26 AM, Ronald Oussoren<ron...@ma...> wrote:
>
> On 1 Sep, 2009, at 6:23, Jason Foreman wrote:
>
>> On Aug 31, 2009, at 10:12 PM, Mani Ghasemlou wrote:
>>>
>>> I have an NSImageView, whose Hidden state is bound to a variable of my
>>> app delegate. Clicking the "Show" button sets this value to False, and
>>> "Hide" sets this value to True.
>>>
>>> Using Snow Leopard, the NSImageView's Hidden state does not change
>>> when clicking these buttons. Using Leopard, the image shows and hides
>>> itself depending on the button pressed.
>>>
>>> Can someone help me understand what I might be doing wrong?
>>
>>
>> I'm sure someone with more PyObjC experience can give you a better answer,
>> but here's my findings:
>>
>> There seems to be an issue with the way you initialize your app delegate
>> and KVC/KVO.  If you change your calls like "self.hideComputer = False" to
>> "self.setValue_forKey_(False, 'hideComputer')" it starts working.
>>  Similarly, you can override the app delegate's init method, and this seems
>> to setup KVC correctly for the hideComputer field:
>>
>> class BindingsUITestAppDelegate(NSObject):
>>   # hideComputer = ivar('hideComputer')
>>   def init(self):
>>       self.hideComputer = False
>>       return self
>>   .... etc
>>
>>
>> I don't have any idea why this is, and am anxious myself to hear an
>> explanation from the gurus.  But in the meantime this might be a suitable
>> workaround for you.
>
> This will be fixed in the next release of PyObjC. A collegue ran into the
> same issue a while back, and it turns out that the machinery that should
> ensure that the right KVO methods are called didn't work properly anymore.
>
> There are two workarounds for this:
> 1) Use setValue_forKey_ (or self._.hideComputer = False)
> 2) Explicitly call willChangeValueForKey_ and didChangeValueForKey_
>
> I haven't committed the proper fix because the fix is in my SL tree and I
> haven't had time after the SL release to actually commit the code. The
> commit, and the next PyObjC 2.2 beta release, will happen sometime this week
> (the release will probably be done in the weekend).
>
> Ronald
>>
>>
>> Jason
>>
>>
>>


Gentlemen, thank you for the quick replies. I will go ahead and
implement the workaround.

Regards,
Mani