From: ara.t.howard@...
Date: 2006-10-26T14:33:53+09:00
Subject: Re: Popularity Contest: Initializing Class-Level Instance Variables

On Thu, 26 Oct 2006, Phrogz wrote:

> Subclassing a class that uses class-level instance variables requires that
> you initialize them for subclasses. Which of the following three techniques
> do you prefer?

   harp:~ > cat a.rb
   require 'rubygems'
   require 'attributes'

   class A
     class << self
       attribute 'a' => 42
       attribute(:b){ "__#{ self.name }__" }  # deferred initialization!
     end
   end

   class B < A
   end

   p A.a
   p A.b
   p B.a
   p B.b


   harp:~ > ruby a.rb
   42
   "__A__"
   42
   "__B__"


one can use traits too - but it's pretty heavy if you don't need all it's
features.  btw, traits was writtern to solve __exactly__ this common problem.

regards.

-a
-- 
my religion is very simple.  my religion is kindness. -- the dalai lama