From: Stephen Bannasch <stephen.bannasch@...>
Date: 2006-04-11T07:36:26+09:00
Subject: Re: class variables and inheritance (ActiveRecord problem)

I realized after working more that cattr_accessor was defined in the 
core extensions in ActiveSupport as an extension of the class Class. 
I now working on understanding how this works:

# Extends the class object with class and instance accessors for 
class attributes,
# just like the native attr* accessors for instance attributes.
class Class # :nodoc:
   def cattr_reader(*syms)
     syms.flatten.each do |sym|
       class_eval(<<-EOS, __FILE__, __LINE__)
         unless defined? @@#{sym}
           @@#{sym} = nil
         end

         def self.#{sym}
           @@#{sym}
         end

         def #{sym}
           @@#{sym}
         end
       EOS
     end
   end

   def cattr_writer(*syms)
     syms.flatten.each do |sym|
       class_eval(<<-EOS, __FILE__, __LINE__)
         unless defined? @@#{sym}
           @@#{sym} = nil
         end

         def self.#{sym}=(obj)
           @@#{sym} = obj
         end

         def #{sym}=(obj)
           @@#{sym} = obj
         end
       EOS
     end
   end


-- 
- Stephen Bannasch
   Concord Consortium, http://www.concord.org