Allow access to a callback event's return result from around callbacks

activesupport/lib/active_support/callbacks.rb

@@ -225,7 +225,10 @@ module ActiveSupport
           # end
           [@compiled_options[0], @filter, @compiled_options[1]].compact.join("\n")
         when :around
-          "end"
+          <<-RUBY_EVAL
+            value
+          end
+          RUBY_EVAL
         end
       end
 
@@ -423,7 +426,7 @@ module ActiveSupport
       #
       #   set_callback :save, :before, :before_meth
       #   set_callback :save, :after,  :after_meth, :if => :condition
-      #   set_callback :save, :around, lambda { |r| stuff; yield; stuff }
+      #   set_callback :save, :around, lambda { |r| stuff; result = yield; stuff }
       #
       # The second arguments indicates whether the callback is to be run +:before+,
       # +:after+, or +:around+ the event. If omitted, +:before+ is assumed. This
@@ -442,6 +445,9 @@ module ActiveSupport
       #
       # Before and around callbacks are called in the order that they are set; after
       # callbacks are called in the reverse order.
+      # 
+      # Around callbacks can access the return value from the event, if it
+      # wasn't halted, from the +yield+ call.
       #
       # ===== Options
       #

activesupport/test/callbacks_test.rb

@@ -299,6 +299,22 @@ module CallbacksTest
       end
     end
   end
+  
+  class AroundPersonResult < MySuper
+    attr_reader :result
+
+    set_callback :save, :around, :tweedle_dum
+
+    def tweedle_dum
+      @result = yield
+    end
+
+    def save
+      run_callbacks :save do
+        :running
+      end
+    end
+  end
 
   class HyphenatedCallbacks
     include ActiveSupport::Callbacks
@@ -338,6 +354,14 @@ module CallbacksTest
       ], around.history
     end
   end
+  
+  class AroundCallbackResultTest < Test::Unit::TestCase
+    def test_save_around
+      around = AroundPersonResult.new
+      around.save
+      assert_equal :running, around.result
+    end
+  end
 
   class SkipCallbacksTest < Test::Unit::TestCase
     def test_skip_person