1 files changed, 47 insertions, 0 deletions
diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 25b8af7d34..812e18a253 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,50 @@
+*   Introduce Module#delegate_missing_to.
+
+    When building a decorator, a common pattern emerges:
+
+        class Partition
+          def initialize(first_event)
+            @events = [ first_event ]
+          end
+
+          def people
+            if @events.first.detail.people.any?
+              @events.collect { |e| Array(e.detail.people) }.flatten.uniq
+            else
+              @events.collect(&:creator).uniq
+            end
+          end
+
+          private
+            def respond_to_missing?(name, include_private = false)
+              @events.respond_to?(name, include_private)
+            end
+
+            def method_missing(method, *args, &block)
+              @events.send(method, *args, &block)
+            end
+        end
+
+    With `Module#delegate_missing_to`, the above is condensed to:
+
+        class Partition
+          delegate_missing_to :@events
+
+          def initialize(first_event)
+            @events = [ first_event ]
+          end
+
+          def people
+            if @events.first.detail.people.any?
+              @events.collect { |e| Array(e.detail.people) }.flatten.uniq
+            else
+              @events.collect(&:creator).uniq
+            end
+          end
+        end
+
+    *Genadi Samokovarov*, *DHH*
+
 *   Rescuable: If a handler doesn't match the exception, check for handlers
     matching the exception's cause.