Re: Dynamically subclassing an observed object
Re: Dynamically subclassing an observed object
- Subject: Re: Dynamically subclassing an observed object
- From: Dave DeLong <email@hidden>
- Date: Wed, 13 Oct 2010 15:02:29 -0600
Good questions.
I know that this swizzling will only be happening on NSViews (since that's what my code operates on). As I mentioned in the original email, my current implementation exchanges -dealloc with a new one, which then invokes the original dealloc method. This appears to work well, but it doesn't feel as clean to me (though I have no quantitative evidence as to why that may be).
As for associated objects, my code was originally implemented this way, but I ended up switching to an NSMapTable held by a singleton so that the code would be Leopard-compatible.
As for the rationale behind why I need to do this, I'll just refer to my blog post on the matter: http://davedelong.com/blog/2010/10/07/fun-objective-c-dynamic-subclassing
Cheers,
Dave
On Oct 13, 2010, at 2:54 PM, Ken Thomases wrote:
> On Oct 13, 2010, at 2:44 PM, Dave DeLong wrote:
>
>> I maintain some code that does dynamic subclassing to override an object's -dealloc method to do some extra cleanup prior to deallocation. (And for the curious, this cleanup is not necessary when using Garbage Collection)
>
> As mentioned, it's not safe to do isa-swizzling because KVO also does it.
>
> Have you considered doing method swizzling on -[NSObject dealloc]? (And maybe -[NSProxy dealloc], too, I guess.)
>
> Also, have you considered whether you really need to be doing these sorts of hacks at all? ;) For example, could you get away with objc_setAssociatedObject()?
>
> Regards,
> Ken
>
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