From: Alexandru Popescu <the.mindstorm.mailinglist@...>
Date: 2006-06-27T01:18:04+09:00
Subject: Re: Ruby and Java equality usage

Oops... it looks like I've touched a nice one :-) (but somehow I am
happy that my confusion has basis)

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


On 6/26/06, Molitor, Stephen L <Stephen.L.Molitor@erac.com> wrote:
> On Jun 26, 2006 Matthew Smillie wrote:
>
> > Coming from C, I tend to think of Ruby variables as pointers to
> values,
> > so I tend to think of the difference between eql? and == as akin to
> the
> > following:
>
> > Ruby eql? - i.e., are they at the same spot in memory?
> >    int* a; int* b;
> >    a == b;
>
> > Ruby ==  - i.e., do they contain the same value?
> >    int* a; int* b;
> >    *a == *b;
>
> The equals? method checks identity.  As it says here,
> http://www.ruby-doc.org/core/classes/Object.html#M001416, the eql?
> method can be and usually is overridden to be synonymous with ==.  If
> you put your objects in a hash you're going to want to override hash and
> eql? to have equivalent semantics.
>
> Having three separate equality methods leads to this kind of confusion.
> You need two (identity and value equality) but not 3 IHMO.
>
> Steve
>
>
>
>
>