1 files changed, 4 insertions, 91 deletions

diff --git a/activerecord/lib/active_record/observer.rb b/activerecord/lib/active_record/observer.rb
index 89ec0962bf..a34ff4a47a 100644
--- a/activerecord/lib/active_record/observer.rb
+++ b/activerecord/lib/active_record/observer.rb
@@ -2,56 +2,6 @@ require 'singleton'
 require 'set'
 
 module ActiveRecord
-  module Observing # :nodoc:
-    extend ActiveSupport::Concern
-
-    module ClassMethods
-      # Activates the observers assigned. Examples:
-      #
-      #   # Calls PersonObserver.instance
-      #   ActiveRecord::Base.observers = :person_observer
-      #
-      #   # Calls Cacher.instance and GarbageCollector.instance
-      #   ActiveRecord::Base.observers = :cacher, :garbage_collector
-      #
-      #   # Same as above, just using explicit class references
-      #   ActiveRecord::Base.observers = Cacher, GarbageCollector
-      #
-      # Note: Setting this does not instantiate the observers yet. +instantiate_observers+ is
-      # called during startup, and before each development request.
-      def observers=(*observers)
-        @observers = observers.flatten
-      end
-
-      # Gets the current observers.
-      def observers
-        @observers ||= []
-      end
-
-      # Instantiate the global Active Record observers.
-      def instantiate_observers
-        return if @observers.blank?
-        @observers.each do |observer|
-          if observer.respond_to?(:to_sym) # Symbol or String
-            observer.to_s.camelize.constantize.instance
-          elsif observer.respond_to?(:instance)
-            observer.instance
-          else
-            raise ArgumentError, "#{observer} must be a lowercase, underscored class name (or an instance of the class itself) responding to the instance method. Example: Person.observers = :big_brother # calls BigBrother.instance"
-          end
-        end
-      end
-
-      protected
-        # Notify observers when the observed class is subclassed.
-        def inherited(subclass)
-          super
-          changed
-          notify_observers :observed_class_inherited, subclass
-        end
-    end
-  end
-
   # Observer classes respond to lifecycle callbacks to implement trigger-like
   # behavior outside the original class. This is a great way to reduce the
   # clutter that normally comes when the model class is burdened with
@@ -137,56 +87,19 @@ module ActiveRecord
   # load their observers by calling <tt>ModelObserver.instance</tt> before. Observers are
   # singletons and that call instantiates and registers them.
   #
-  class Observer
-    include Singleton
-
-    class << self
-      # Attaches the observer to the supplied model classes.
-      def observe(*models)
-        models.flatten!
-        models.collect! { |model| model.is_a?(Symbol) ? model.to_s.camelize.constantize : model }
-        define_method(:observed_classes) { Set.new(models) }
-      end
-
-      # The class observed by default is inferred from the observer's class name:
-      #   assert_equal Person, PersonObserver.observed_class
-      def observed_class
-        if observed_class_name = name[/(.*)Observer/, 1]
-          observed_class_name.constantize
-        else
-          nil
-        end
-      end
-    end
-
-    # Start observing the declared classes and their subclasses.
+  class Observer < ActiveModel::Observer
     def initialize
-      Set.new(observed_classes + observed_subclasses).each { |klass| add_observer! klass }
-    end
-
-    # Send observed_method(object) if the method exists.
-    def update(observed_method, object) #:nodoc:
-      send(observed_method, object) if respond_to?(observed_method)
-    end
-
-    # Special method sent by the observed class when it is inherited.
-    # Passes the new subclass.
-    def observed_class_inherited(subclass) #:nodoc:
-      self.class.observe(observed_classes + [subclass])
-      add_observer!(subclass)
+      super
+      observed_subclasses.each { |klass| add_observer!(klass) }
     end
 
     protected
-      def observed_classes
-        Set.new([self.class.observed_class].compact.flatten)
-      end
-
       def observed_subclasses
         observed_classes.sum([]) { |klass| klass.send(:subclasses) }
       end
 
       def add_observer!(klass)
-        klass.add_observer(self)
+        super
         if respond_to?(:after_find) && !klass.method_defined?(:after_find)
           klass.class_eval 'def after_find() end'
         end