Re: overriding a method with NSObject's version
Re: overriding a method with NSObject's version
- Subject: Re: overriding a method with NSObject's version
- From: "email@hidden" <email@hidden>
- Date: Sat, 24 Nov 2012 14:23:33 +0000
On 24 Nov 2012, at 09:55, Roland King <email@hidden> wrote:
> I have a fairly well-used and oft-subclassed class which overrides valueForKey: and setValue:ForKey: to behave like the NSDictionary versions, because this class looks much like an NSDictionary. I have a subclass of that which wants to do 'normal' KVO, and so I need valueForKey: and setValueForKey: to return to the default NSObject version.
>
> I could use composition but that's a lot of boilerplate to re-expose the properties of the composed class and I really did want it to be a subclass. I could code up a custom valueForKey: which does the right thing, but that's fragile if I add more properties or subclass again. So I want to actually make the implementation of those two methods in my subclass use the NSObject implementation.
>
>
Would something like the following be worth considering:
Class A uses custom valueForKey.
SubClass A1 needs the super implementation.
A:
+ (BOOL)useCustomKVO
{
return YES;
}
- (id)valueForKey:(NSString *)key
{
if (!self.class.useCustomKVO) {
return [super valueForKey:key];
}
// do custom KVO
}
A1 : A:
+ (BOOL)useCustomKVO
{
return NO;
}
Regards
Jonathan Mitchell
Mugginsoft LLP
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