From: rolo <rohitlodha@...>
Date: 2004-04-10T03:39:57+09:00
Subject: Re: Cache of objects



-----Original Message-----
From: Joel VanderWerf [mailto:vjoel@PATH.Berkeley.EDU]
Sent: Friday, April 09, 2004 11:58 PM
To: ruby-talk ML
Subject: Re: Cache of objects


rolo wrote:
> class Thing
>    @cache = {}
>    def self.instance(name)
>      @cache[name] ||= new(name)
>    end
>    def initialize(name)
>      @name = name
>    end
> end
> 
> t1 = Thing.instance "t"
> t2 = Thing.instance "t"
> 
> p t1.id
> p t2.id
> 
> 
> [rolo] mysterious. it works! but since cache is an instance level variable how is it shared amongst all the class instances?

@cache is an instance variable of the class Object called Thing. It's 
just a regular instance variable, but it happens to be stored in a class 
object instead of in instances of the class. Instances of Thing can't 
access it directly.

[rolo] should it not be @@cache ?