From: Jacek Olszak <jacekolszak@...2.pl>
Date: 2005-11-09T17:56:20+09:00
Subject: Re: Question about symbols


Thanks everyone for replies. I've got it :D Now I know why should I use  
symbols.

Regards
Jacek

On Wed, 09 Nov 2005 09:32:12 +0100, Robert Klemme <bob.news@gmx.net> wrote:

> mental@rydia.net wrote:
>> Quoting Robert Klemme <bob.news@gmx.net>:
>>
>>> Because they are immutable, fast and less memory consuming.  They
>>> are typically used for a limited and known set of keys.
>>
>> Well, they consume memory differently -- not necessarily less.
>
> There are two reasons why I wrote about higher memory consumption for
> strings:
>
> 1. If you have a string constant in your code like "foo" or 'bar' then  
> the
> constant takes up memory and each evaluation creates a new String object.
> Although they share the internal char buffer there is some memory
> overhead.  You can easily try it:
>
>>> 5.times { puts "foo".object_id }
> 135178740
> 135178716
> 135178620
> 135178488
> 135178464
> => 5
>
> 2. If stored in multiple places then there's still only one symbol but
> multiple strings.  Even worse, if those strings stem from different
> sources they won't even share their char buffer.
>
>> Symbols are never garbage-collected, so you should not use them for
>> situations where you could have an unbounded number of unique
>> symbol values.
>
> That's why I recommended to use them with a limited set of values only.
>
> Hope that makes things a bit clearer.
>
> Kind regards
>
>     robert
>
>
>
>



-- 
Using Opera's revolutionary e-mail client: http://www.opera.com/mail/