From: gotoken@... (GOTO Kentaro)
Date: 2001-01-16T20:56:45+09:00
Subject: [ruby-talk:9374] Re: attr_accessor in base class

In message "[ruby-talk:9373] attr_accessor in base class"
    on 01/01/16, DaVinci <bombadil@wanadoo.es> writes:
> I have a rpoblem with object orientation. Intention is to define
> instances usable from all classes. For example:
>
> 	class Configuration
>		attr_reader :size
>	
>		def initialize(size)
>			@size = size
>		end
>	end
>
>	class Foo
>		def initialize
>			puts @conf.size
>		end
>	end
>
>	attr_reader :conf

attr_reader is a private method of Class but you are using it in a
Object cotext, i.e. the top-level self.

>	@conf = Configuration.new(100)

And here, you are substituting to @conf which is an instance variable
of the top-level self.  So, @conf is never shared between the
top-level self object and a Foo object; An instance variable is belong
to a object.

> Why I can not use attr_reader form base class?. Might I use a global
> variable to define instance?.

That is a way.  You can solve this problem gloval variable if you
really want to use that object everywhare.  Otherwise I recommend
a class varible @@conf of Foo.

-- Gotoken

  P.S.,  Conrad, thanks for your kind explanation on Rocks :-)