From: Robert Dober <robert.dober@...>
Date: 2006-06-26T21:01:55+09:00
Subject: Re: Ruby and Java equality usage

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On 6/26/06, Alexandru Popescu <the.mindstorm.mailinglist@gmail.com> wrote:
>
> Hi!
>
> I have posted a quick (reminder like) entry about how equality is
> handled by Ruby and Java:
>
>
> http://themindstorms.blogspot.com/2006/06/parallel-of-equality-in-2-world=
s-ruby.html
>
> However, I feel I have missed to explain correctly why eql? and =3D=3D
> are both needed (and I've been reading through Ruby books and searched
> the ruby mailing list). Maybe somebody can clarify it and give a
> better example. I will be happy to update the entry to reflect the
> "new" knowledge.


I am surprised you did not find this reference, possibly I missed a point i=
n
your mail
http://www.ruby-doc.org/core/classes/Object.html#M001416
if I interpret it correctly

=3D=3D is supposed to be redefined in classes in order to reflect identity =
on an
"application" level.
equal? shall not be redefined in order to be available for object identity,
something like
          a.equal?(b) iff a.object_id =3D=3D b.object_id
eql? is used for Hash entry comparison and is not redefined most of the tim=
e

Just citing ruby doc for those who do not want to follow the link ;)

Cheers
Robert

./alex
> --
> .w( the_mindstorm )p.
> ---
> (http://themindstorms.blogspot.com)
>
>


--=20
Deux choses sont infinies : l'univers et la b=EAtise humaine ; en ce qui
concerne l'univers, je n'en ai pas acquis la certitude absolue.

- Albert Einstein

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