Re: When do I need to override hash?
Re: When do I need to override hash?
- Subject: Re: When do I need to override hash?
- From: Bryan Henry <email@hidden>
- Date: Thu, 20 Aug 2009 16:40:21 -0400
Yes, but the problem with a hash based on the pointer is that it
limits your isEqual implemenation from being based on anything more
than the pointer, or you violate the "If objects are equal, they must
have the same hash" rule.
(Earlier email was a brain fart on my part.)
- Bryan
Sent from my iPhone
On Aug 20, 2009, at 4:37 PM, Kyle Sluder <email@hidden> wrote:
On Thu, Aug 20, 2009 at 1:33 PM, Clark Cox<email@hidden> wrote:
-isEqual: is how Cocoa collections define equality. Saying that two
objects are "equal" means, by definition, that -[obj1 isEqual: obj2]
returns true.
This has nothing to do with -hash.
P: Two objects are equal.
Q: They have the same hash.
P -> Q.
Note that Q does not imply P.
--Kyle Sluder
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