1 files changed, 49 insertions, 0 deletions
diff --git a/actionpack/lib/action_controller/dependencies.rb b/actionpack/lib/action_controller/dependencies.rb
new file mode 100644
index 0000000000..6f092500d1
--- /dev/null
+++ b/actionpack/lib/action_controller/dependencies.rb
@@ -0,0 +1,49 @@
+module ActionController #:nodoc:
+  module Dependencies #:nodoc:
+    def self.append_features(base)
+      super
+      base.extend(ClassMethods)
+    end
+
+    module ClassMethods
+      def model(*models)
+        require_dependencies(:model, models)
+        depend_on(:model, models)
+      end
+
+      def service(*services)
+        require_dependencies(:service, services)
+        depend_on(:service, services)
+      end
+      
+      def observer(*observers)
+        require_dependencies(:observer, observers)
+        depend_on(:observer, observers)
+        instantiate_observers(observers)
+      end
+
+      def dependencies_on(layer) # :nodoc:
+        read_inheritable_attribute("#{layer}_dependencies")
+      end
+    
+      def depend_on(layer, dependencies)
+        write_inheritable_array("#{layer}_dependencies", dependencies)
+      end
+
+      private
+        def instantiate_observers(observers)
+          observers.flatten.each { |observer| Object.const_get(Inflector.classify(observer.to_s)).instance }
+        end
+        
+        def require_dependencies(layer, dependencies)
+          dependencies.flatten.each do |dependency|
+            begin
+              require_or_load(dependency.to_s)
+            rescue LoadError
+              raise LoadError, "Missing #{layer} #{dependency}.rb"
+            end
+          end
+        end
+    end
+  end
+end