lib/industrialist/manufacturable.rb in industrialist-0.2.0 vs lib/industrialist/manufacturable.rb in industrialist-0.2.1

@@ -1,21 +1,31 @@
 require 'industrialist/factory'
+require 'industrialist/warning_helper'
 
 module Industrialist
   module Manufacturable
+    extend WarningHelper
+
+    ALREADY_INCLUDED_WARNING_MESSAGE = 'warning: a factory is already defined on this class hierarchy'.freeze
+
     def self.included(base)
+      warning(ALREADY_INCLUDED_WARNING_MESSAGE) if base.class_variable_defined?(:@@factory)
+
       base.extend ClassMethods
+      base.class_variable_set(:@@factory, Industrialist::Factory.new)
     end
 
     module ClassMethods
-      @@factory = Industrialist::Factory.new
-
       def create_factory(identifier)
-        Object.const_set(identifier, @@factory)
+        Object.const_set(identifier, factory)
       end
 
       def corresponds_to(key)
-        @@factory.register(key, self)
+        factory.register(key, self)
+      end
+
+      def factory
+        class_variable_get(:@@factory)
       end
     end
   end
 end