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Re: When do I need to override hash?
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Re: When do I need to override hash?


  • Subject: Re: When do I need to override hash?
  • From: "Adam R. Maxwell" <email@hidden>
  • Date: Wed, 19 Aug 2009 18:34:47 -0700


On Aug 19, 2009, at 6:19 PM, Seth Willits wrote:

On Aug 19, 2009, at 4:28 PM, Gideon King wrote:

So do I need to override hash too? If so, are there any recommendations as to how to determine the hash easily?

I probably shouldn't admit this, but I've yet to override hash and have yet to notice any problems. The docs say I should, so I realize I likely should, but I would really like a concrete reason to do so. I've never called hash, nor seen it ever called by anyone else's code. I assume the frameworks call it from somewhere, but where?

NSDictionary, NSSet, NSHashTable, NSMapTable, and possibly other classes all use hash. So if you ever put your objects in an NSSet or use them as dictionary keys, -hash should be called at some point.



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References: 
 >When do I need to override hash? (From: Gideon King <email@hidden>)
 >Re: When do I need to override hash? (From: Nathan Vander Wilt <email@hidden>)
 >Re: When do I need to override hash? (From: Seth Willits <email@hidden>)

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