From: Rick DeNatale <rick.denatale@...>
Date: 2006-09-21T09:34:17+09:00
Subject: Re: Bug in Hash#hash? (Ruby 1.8.4)

On 9/20/06, Yukihiro Matsumoto <matz@ruby-lang.org> wrote:
> Hi,
>
> In message "Re: Bug in Hash#hash? (Ruby 1.8.4)"
>     on Wed, 20 Sep 2006 23:40:11 +0900, "Eyal Oren" <eyal.oren@gmail.com> writes:
>
> |say one = {:a=>:b}
> |then one.hash != one.clone.hash
> |is that a bug or correct?
> |
> |(using ruby 1.8.4 (2005-12-24) [i486-linux])
>
> Currently it's an intended behavior.  Hash is not designed to be hash
> key (two hashes are considered to be a same key if they are exactly
> the same object).  It's not likely to change in 1.8 series.  In 1.9,
> maybe.

And I think more precisely, it's that hash needs to be implemented so
that a.eql?(b) implies a.hash == b.hash

one = {:a => :b}
two = one.clone

one == two #=> true
one.eql?(two) #=> false

Smalltalkers might recall that Smalltalk has both a Hash which uses
Smalltalks equivalents to Ruby's hash and ==, and IdentityHash which
uses Smalltalks equivalents to Ruby's object_id for the hash, and
equal?



-- 
Rick DeNatale

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