[Openmcl-devel] NSSlider not responsive

Osei Poku osei.poku at gmail.com
Sat Feb 2 17:04:25 PST 2008

On Feb 2, 2008, at 6:16 PM, Gary Byers wrote:
> On Sat, 2 Feb 2008, Osei Poku wrote:
>>> On Sat, 2 Feb 2008, Osei Poku wrote:
>>>> On thing to note is that when I set the target of the slider's  
>>>> action
>>>> to be a simple text label using takeFloatValueFrom:, the slider  
>>>> moves
>>>> as expected and can be dragged up and down.  Could this be a lisp
>>>> callback issue?
>> On Feb 2, 2008, at 5:34 PM, Gary Byers wrote:
>>> What was the slider's target before you made this change ?
>> The slider's target was the window-controller/WindowController  
>> class using the #/slide: message.
> It was the class, or an instance of it ?

To an instance of it.  Sorry for my imprecise terminology.

I have some update on this problem and the solution was very silly.   
Maybe you can explain it.

When my slide: method was defined without a specified return type (ie  
(objc:defmethod #/slide ((self window-controller) sender) ...)), the  
slider movement was not smooth.  When the slide: method was defined  
with a :void return type (ie (objc:defmethod (#/slide: :void) ((self  
window-controller) sender) ....)) then the slider motion was smooth  
and continuously updated the target control as I expect.

> You defined a #/slide method that would be applicable to any - 
> instance-
> of your window-controller class.
> The class itself (which in ObjC is an instance of its metaclass;  
> that's
> a little different from CLOS, where most classes are instances of
> STANDARD-CLASS) doesn't likely respond to #/slide.
> If you want the -class- WINDOW-CONTROLLER to respond to #/slide, you
> need to define the method on that classe's metaclasss (which in the
> bridge would be named +WINDOW-CONTROLLER)
> (objc:defmethod (#/slide :void) ((self +window-controller) sender)
>  ..)
> That method will be applicable to any instance of the metaclass
> +WINDOW-CONTROLLER.  There will typically only ever be one
> such instance (the class WINDOW-CONTROLLER), and if that class
> object is indeed the target if the slider's action, the class
> will receive the message.
> If having the class wind up as the slider's target was unintentional,
> I'd be tempted to blame IB 3.0 (with the caveats that I haven't done
> much Cocoa stuff in several months and was never -that- comfortable
> with IB 3.0 to begin with.)

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