From: Rick DeNatale <rick.denatale@...>
Date: 2009-10-12T07:25:48+09:00
Subject: Re: Class Level inheritable attributes - are we there yet?

On Sun, Oct 11, 2009 at 3:34 PM, dreamcat four <dreamcat4@gmail.com> wrote:
.
> 2) Not having an accessor definition will break other code.
>
> puts A.instance_variables.inspect
> => ["@foo"]
> puts B.instance_variables.inspect
> => []
> puts C.instance_variables.inspect
> => ["@foo"]
>

attribute accessors don't cause instance variables to exist until the
setter (or some other method) initializes the instance variable:

class A
  attr_accessor :bar
  class << self
    attr_accessor :foo
  end
end

A.instance_variables # => []
a = A.new
a.instance_variables # => []

A.foo = 42
a.bar = 39

A.instance_variables # => ["@foo"]
a.instance_variables # => ["@bar"]





-- 
Rick DeNatale

Blog: http://talklikeaduck.denhaven2.com/
Twitter: http://twitter.com/RickDeNatale
WWR: http://www.workingwithrails.com/person/9021-rick-denatale
LinkedIn: http://www.linkedin.com/in/rickdenatale