From: Andrew Walrond <andrew@...>
Date: 2005-05-05T22:33:29+09:00
Subject: Re: Whats so different about a Hash?

On Thursday 05 May 2005 14:19, Adriano Ferreira wrote:
>
> > irb(main):040:0> a.eql?(b)
> > => true
>
> When I do this, I get:
>
> irb(main):003:0> {1=>2}.eql?({1=>2})
> => false

I've been discussing this on ruby-core aswell. It turns out that this was 
'fixed' in then latest stable snapshot.

>
> For numbers, strings and arrays you will find .hash and .eql? methods
> which are consistent, meaning they play fair as hash keys.
>
> This is not the same with Hash objects. Probably for performance
> reasons and because in some ocasions one expects hashes to be equal
> only if they are the same objects, .hash and .eql? are not defined
> such that hashes are equal if they have the same pairs. I think they
> actually inherit Object methods such that
>      hash1.eql?(hash2)    is the same as    hash1===hash2
> and
>      hash1.hash      calls     Object.hash    which is based on object ID
>

Understood. See my forwarded message...

Andrew Walrond