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: Shawn Erickson <email@hidden>
- Date: Thu, 20 Aug 2009 13:47:54 -0700
On Thu, Aug 20, 2009 at 1:37 PM, Kyle Sluder<email@hidden> wrote:
> P: Two objects are equal.
> Q: They have the same hash.
>
> P -> Q.
>
> Note that Q does not imply P.
Or said another way...
If the hash of ObjectA is equal to the hash of ObjectB then ObjectA
_could_ be equal to ObjectB. If their hash differ they cannot be
equal. The use of a hash to do a quick reject of equality is common
for stl collections, java collections, Cocoa collections, etc.
-Shawn
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