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 15:57:37 -0600
Ah, I think I see what you're saying. I could create a custom CFDictionaryHashCallBack to simply return the pointer value or something, thereby skirting the -hash problem.
Intriguing. I'll play with this and report back. The thing I have against this approach is that it potentially allows for a whole bunch of unused memory to be strongly referenced (the associated value for the no-longer-used key), whereas the dynamic subclass (or dealloc swizzling) approach allowed me to always keep things cleaned up.
Dave
On Oct 13, 2010, at 3:52 PM, Dave DeLong wrote:
> 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:
>
>> Alternatively, you could go back to the NSMapTable approach, but
>> instead of using an NSMapTable use a CFDictionary with custom
>> callbacks.
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