From: Elliot Temple <curi@...>
Date: 2006-06-27T02:37:30+09:00
Subject: Re: Ruby and Java equality usage


On Jun 26, 2006, at 10:20 AM, Robert Klemme wrote:

> 2006/6/26, Robert Dober <robert.dober@gmail.com>:
>
>> Personally I find this situation a bit odd.  I'd prefer a single
>> > equivalence relation per class not two.
>>
>> Although I do not feel the same that seems a normal concern, as I  
>> pointed
>> out to the OP.
>> Honestly I think it depends on the programming culture we are  
>> coming from
>> and when
>> in our mind these are synonyms we are likely to get bitten by that  
>> kind of
>> code.
>
> At the moment I'm not so sure whether culture is the background.  I
> tend to think that there's a more fundamental issue: having a single
> equivalence relation defined on instances of a class seems to make
> things easier in several areas and I believe that it rather reduces
> programming errors.

Perhaps the issue is not so much having more than one, but having  
unhelpful names for them. We don't get confused by the variety of  
each-like methods available. And no one forgets the difference  
between times, upto, and downto, despite their similarities. If we  
had ==, same_place_in_memory, same_in_hash, and same_object_id (or  
whatever they are) people wouldn't get confused even with lots of them.

-- Elliot Temple
http://www.curi.us/blog/