From: Robert Klemme <shortcutter@...>
Date: 2010-06-07T05:55:10+09:00
Subject: Re: comparing objects

On 05.06.2010 16:41, Robert Dober wrote:
> On Sat, Jun 5, 2010 at 2:35 PM, Robert Klemme
> <shortcutter@googlemail.com> wrote:
>> On 05.06.2010 00:35, Anderson Leite wrote:
>>>  Before
>>>> we can provide solutions we have to know what problem must be solved.
>>> I have a list of objects that came from database and another list of
>>> objects extracted from a xml. I need the elements who are in both lists.
>>>
>>>
>>> Then...I thought to compare objects overriding the == method like Marcin
>>> Wolski wrote. There is another solution ?
>> If all objects you are dealing with implement #eql? and #hash in a way to be
>> suitable for that comparison then using #eql? is the most straightforward
>> approach.
> Not #eql?, #== please.

Why?  Array#& uses #eql? - as Hash lookup methods do, too.

$ ruby19 -e 'class C;def eql?(x)printf "eq %p\n",x;false;end;def 
hash;0;end;end;[C.new] & [C.new]'
eq #<C:0x10028284>

Kind regards

	robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/