Re: Key Value Observation is over reacting

[Richard Frith-Macdonald]

On 2007-12-13 17:34:34 +0000 Fred Kiefer <address@hidden> wrote:

> While testing key value binding I found a problem with the current KVO
> code. When an object is starting to get watched a new class gets 
> cooked
> up to handle the set calls on the object. Here all setter methods get
> overridden, which is fine, as we don't want to change the class when
> another key on the same object gets watched and this also allows to
> reuse the new class for other objects.
> But some of the replaced methods just don't are setters, even if the
> look like. This later leads to a problem when the corresponding getter
> is called and none exists. Here we should at least check, if a getter
> exists and only then treat the method as a setter. 
>
> Is it OK, to change that code or is there something I overlooked?

I'm not sure ... while it does not sound unreasonable that every 
setter must have a corresponding getter, neither does it sound 
obviously true to me.  I would suggest writing a testcase to determine 
what methods are overridden, and running it on MacOS-X before going 
any further ... best to try to make sure that our implementation has 
the same behavior as Apple's.

It may be that Apple check for the presence of a getter immediately 
before using it rather than at the point when the subclass is created.