From: rolo <rohitlodha@...>
Date: 2004-04-10T05:13:17+09:00
Subject: Re: Cache of objects


> > 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 ?

No, that's a class variable, which is different from an instance
variable of a Class object.  In spite of the shared use of '@',
they're separate and different things.

[rolo] There are 2 things here. one Thing object and other t1 object.
@cache is a variable that belongs to Thing or t1?

rolo