Simplified and renamed CallbackChain union method to replace_or_append!

actionpack/lib/action_controller/dispatcher.rb

@@ -44,7 +44,7 @@ def dispatch(cgi = nil, session_options = CgiRequest::DEFAULT_SESSION_OPTIONS, o
       def to_prepare(identifier = nil, &block)
         @prepare_dispatch_callbacks ||= ActiveSupport::Callbacks::CallbackChain.new
         callback = ActiveSupport::Callbacks::Callback.new(:prepare_dispatch, block, :identifier => identifier)
-        @prepare_dispatch_callbacks | callback
+        @prepare_dispatch_callbacks.replace_or_append!(callback)
       end
 
       # If the block raises, send status code as a last-ditch response.

activesupport/lib/active_support/callbacks.rb

@@ -96,15 +96,12 @@ def run(object, options = {}, &terminator)
         end
       end
 
-      def |(chain)
-        if chain.is_a?(CallbackChain)
-          chain.each { |callback| self | callback }
+      # TODO: Decompose into more Array like behavior
+      def replace_or_append!(chain)
+        if index = index(chain)
+          self[index] = chain
         else
-          if (found_callback = find(chain)) && (index = index(chain))
-            self[index] = chain
-          else
-            self << chain
-          end
+          self << chain
         end
         self
       end
@@ -157,6 +154,14 @@ def dup
         self.class.new(@kind, @method, @options.dup)
       end
 
+      def hash
+        if @identifier
+          @identifier.hash
+        else
+          @method.hash
+        end
+      end
+
       def call(*args, &block)
         evaluate_method(method, *args, &block) if should_run_callback?(*args)
       rescue LocalJumpError

activesupport/test/callbacks_test.rb

@@ -134,10 +134,10 @@ def test_find
     assert_equal :bacon, @chain.find(:bacon).method
   end
 
-  def test_union
-    assert_equal [:bacon, :lettuce, :tomato], (@chain | Callback.new(:make, :bacon)).map(&:method)
-    assert_equal [:bacon, :lettuce, :tomato, :turkey], (@chain | CallbackChain.build(:make, :bacon, :lettuce, :tomato, :turkey)).map(&:method)
-    assert_equal [:bacon, :lettuce, :tomato, :turkey, :mayo], (@chain | Callback.new(:make, :mayo)).map(&:method)
+  def test_replace_or_append
+    assert_equal [:bacon, :lettuce, :tomato], (@chain.replace_or_append!(Callback.new(:make, :bacon))).map(&:method)
+    assert_equal [:bacon, :lettuce, :tomato, :turkey], (@chain.replace_or_append!(Callback.new(:make, :turkey))).map(&:method)
+    assert_equal [:bacon, :lettuce, :tomato, :turkey, :mayo], (@chain.replace_or_append!(Callback.new(:make, :mayo))).map(&:method)
   end
 
   def test_delete