lib/inheritable_class_attributes.rb

   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 end