Re: Struct hash issues with string fields

[Ali Çehreli]

On 05/27/2012 04:22 AM, Andrej Mitrovic wrote:
On 5/27/12, Ali Çehreli<acehr...@yahoo.com>  wrote:
On 05/26/2012 05:13 PM, Ali Çehreli wrote:
  >  once you define toHash(), you
  >  must also define opCmp() and opEquals() that are all consistent with
  >  each other.

Correction: opEquals() is only for potential optimizations. What is
needed alongside toHash() is just opCmp(), and the reason is to be able
to resolve hash collisions.

Thanks! Is this documented somewhere on dlang.org?

Yes. It is under the "Using Structs or Unions as the KeyType" section of 
the As­so­cia­tive Ar­rays documentation:

  http://dlang.org/hash-map.html

It actually says "The implementation may use either opEquals or opCmp or 
both". So I guess opEquals() is still necessary for portability.

Ali

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