Re: KVO and the observeValueForKeyPath bottleneck

FROM : Jim Correia
DATE : Tue Jul 18 18:11:27 2006

On Jul 17, 2006, at 9:00 PM, Chris Kane wrote:

> If you assume that @"" string constants are NOT globally uniqued in 
> a binary, but only to a given compilation unit, then 
> ThisClassUniqueObservationContext could be a constant string:
>
> static NSString * ThisClassUniqueObservationContext = @"MyContext";


Even if the strings are globally uniqued across the entire binary, 
assuming a FBFroobazle class, something like this is probably good 
enough:

static NSString * FBFroobazzleValueObservationContext = 
@"FBFroobazzleValueObservationContext";

Certainly better than

static void * FBFroobazzleValueObservationContext = (void *)2192;

There is the chance that someone else will use the string 
@"FBFroobazzleValueObservationContext" as an observation context 
elsewhere in the inheritance tree, but I think that a) it would be a 
programmer error b) is probably not worth losing any sleep over.

And there is certainly a smaller chance of a collision than with an 
arbitrarily picked number.

Jim