Re: mutableArrayValueForKey: truth or dare
Re: mutableArrayValueForKey: truth or dare
- Subject: Re: mutableArrayValueForKey: truth or dare
- From: Ken Thomases <email@hidden>
- Date: Thu, 17 Jun 2010 21:23:13 -0500
On Jun 17, 2010, at 8:41 PM, Charles Srstka wrote:
> On Jun 17, 2010, at 8:19 PM, Matt Neuburg wrote:
>
>> On or about 6/17/10 5:56 PM, thus spake "Roland King" <email@hidden>:
>>
>>> if ... you just have a class variable called <key> or _<key> then the
>>> whole array is not replaced, the method you call on NSMutableArrayValueForKey:
>>> is passed through to that underlying variable which does what you might expect
>>> and operates on the array variable directly.
>>>
>>> That's not such a rare case.
>>
>> In fact it is exactly the case I had in mind. :) That's really just what I
>> wanted to hear. Someone asked "how do you think the proxy object works";
>> that *is* how I was thinking it might work. Thx - m.
>
> The problem with things like this is the way it destroys encapsulation.
Exactly.
Matt, if you have a to-many relationship property, do you make the return type of the getter NSMutableArray*? I should hope not, or you're asking for problems.
Therefore, why did you "want[...] to hear" that KVC would do the rough equivalent? It's a terrible idea to let KVC access instance variables directly. My firm belief is that Apple only maintains that "feature" for backwards compatibility.
I never subclass NSObject directly. Instead, I have a custom subclass of NSObject one of whose main purposes is to override +accessInstanceVariablesDirectly to return NO. Likewise, whenever I subclass other framework classes, I install such an override, too. Because of that, I mentally excise the direct-ivar-access steps from the KVC accessor search patterns.
Regards,
Ken
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