1  module InheritableClassAttributes
   2    def self.included(base)
   3      base.extend ClassMethods
   4      base.module_eval do
   5        class << self
   6          alias inherited_without_inheritable_class_attributes inherited
   7          alias inherited inherited_with_inheritable_class_attributes
   8        end
   9      end
  10    end
  11    
  12    module ClassMethods
  13      def inheritable_cattr_readers
  14        @inheritable_class_readers ||= []
  15      end
  16      
  17      def inheritable_cattr_writers
  18        @inheritable_class_writers ||= []
  19      end
  20      
  21      def cattr_inheritable_reader(*symbols)
  22        symbols.each do |symbol|
  23          self.inheritable_cattr_readers << symbol
  24          self.module_eval %{
  25            def self.#{symbol}
  26              @#{symbol}
  27            end 
  28          }
  29        end
  30        self.inheritable_cattr_readers.uniq!
  31      end
  32      
  33      def cattr_inheritable_writer(*symbols)
  34        symbols.each do |symbol|
  35          self.inheritable_cattr_writers << symbol
  36          self.module_eval %{
  37            def self.#{symbol}=(value)
  38              @#{symbol} = value
  39            end 
  40          }
  41        end
  42        self.inheritable_cattr_writers.uniq!
  43      end
  44      
  45      def cattr_inheritable_accessor(*symbols)
  46        cattr_inheritable_writer(*symbols)
  47        cattr_inheritable_reader(*symbols)
  48      end
  49      
  50      def inherited_with_inheritable_class_attributes(klass)
  51        inherited_without_inheritable_class_attributes(klass) if respond_to?(:inherited_without_inheritable_class_attributes)
  52        
  53        readers = inheritable_cattr_readers.dup
  54        writers = inheritable_cattr_writers.dup
  55        inheritables = [:inheritable_cattr_readers, :inheritable_cattr_writers]
  56        
  57        (readers + writers + inheritables).uniq.each do |attr|
  58          var = "@#{attr}"
  59          old_value = self.module_eval(var)
  60          new_value = (old_value.dup rescue old_value)
  61          klass.module_eval("#{var} = new_value")
  62        end
  63      end
  64    end
  65  en