From: Rick DeNatale <rick.denatale@...>
Date: 2008-07-14T23:47:16+09:00
Subject: Re: Help with class instance variables

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On Mon, Jul 14, 2008 at 7:58 AM, Ittay Dror <ittay.dror@gmail.com> wrote:

> Hi,
>
> Rick Denatale wrote:
>
> > You haven't used an class variables on this thread.  Your initial code
> > created class instance variables, i.e. instance variables belonging to
> > the
> > object which represents the class.  Class variables in Ruby use a double
> > @
> > prefix, are visible/shared between the class, any subclasses, and
> > instances
> > of the same, have some interesting quirks in their semantics and are
> > avoided
> > or at least used sparingly by many experienced Rubyists.
> >
> >
>
> Let me rephrase, trying to to use any terminology. Let's say I have a
> class Person whose instances have variables like name and age. Now, the
> Person class also has a cache for all persons, loaded from a file. So
> this is a single variable shared by all instances and is initialized
> once. How do I initialize it in Ruby?
>

Well, it depends on just what you are doing with the cache.

class Person

   def self.setup_cache
        @cache = #... whatever you do to initialize the cache
   end

   setup_cache

   # Now assuming we've got some kind of key to access the cache we probably
want a class method to get
   # cached people

   def self.person(cache_key)
       @cache[cache_key]
   end
end
-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/

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