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 15:52:17 -0600
Yeah, thanks for this. I've been over Mike's code, and he gets around this issue by using class_setSuperclass(), which the documentation says should not be used.
How would using a CFDictionary with custom callbacks make things any better? In order to find things in the dictionary, things are binned by their hash. Presumably when a CFDictionary needs to grow, it's going to rehash all of the keys (using CFHash() or -hash), but if some of those keys point to deallocated memory (ie, the user is not using Garbage Collection), then I'm liable to crash. This is what necessitated the auto-cleanup subclassing in the first place. Would a CFMutableDictionaryRef allow me to get around this issue?
Dave
On Oct 13, 2010, at 3:47 PM, Kyle Sluder wrote:
> On Wed, Oct 13, 2010 at 2:02 PM, Dave DeLong <email@hidden> wrote:
>> 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
>
> Funny enough, it sounds like the blog post I linked you to (and the
> ones following it) that talks about MAZeroingWeakRef does precisely
> what you need: http://www.mikeash.com/pyblog/introducing-mazeroingweakref.html
>
> You can find Mike's code on github.
>
> Alternatively, you could go back to the NSMapTable approach, but
> instead of using an NSMapTable use a CFDictionary with custom
> callbacks.
>
> --Kyle Sluder
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