[MacRuby-devel] Bindings only working one-way

[Michael Winterstein]

>
> for example:
> attr_accessor :billy # will create setter and getter for billy with
> all the appropritate KVO methods
>
> def updateMyValue(sender) #called from a button perhaps
> 	setBilly(4)
> end
>
> #or setValue:4 forKey:billy
>
> #@billy = 4 will not work, because it bypasses the accessor methods
>
>
> So you don't need to override the accessors unless you are doing some
> additional work.
>
> If you do override the accessors then you will have to put the whole
> willChangeValueForKey, and didChangeValueForKey  calls in your
> overwritten method.
> In your code below you do override the accessor, and therefore lose
> the KVO.
>
>

This turned out to be the key.  The way to make it work automatically  
is just to use attr_accessor, but "setX(value)" within the program to  
modify it (even though that method isn't one you wrote). I had  
tried  .=  and self.X =, neither of which work, but that one does.

It even works with the Matrix binding to selectedTags.  I get the  
sense it may be trickier with something more complex or dynamic -  
which I may eventually want to do, but I'm happy with this for now.

The trickier one was actually the Booleans.  When you bind to a  
Boolean variable, it's now being set in a non-Ruby way.  What that  
means is:
something if X
no longer works the way you'd expect - this is always true.
Instead you need to do:
something if X == true

I know some people prefer the more explicit style anyways, and maybe  
that's one reason why.  Or it could be considered a bug.  As I  
understand it, the NS YES and NO are integer values which is sort of  
troublesome with the way Ruby treats 'false'.

Thanks,

Michael