Move caching to a new module

lib/active_model/serializer/caching.rb

@@ -0,0 +1,37 @@
+module ActiveModel
+  class Serializer
+    module Caching
+      def to_json(*args)
+        if caching_enabled?
+          key = expand_cache_key([self.class.to_s.underscore, cache_key, 'to-json'])
+          cache.fetch key do
+            super
+          end
+        else
+          super
+        end
+      end
+
+      def serialize(*args)
+        if caching_enabled?
+          key = expand_cache_key([self.class.to_s.underscore, cache_key, 'serialize'])
+          cache.fetch key do
+            serialize_object
+          end
+        else
+          serialize_object
+        end
+      end
+
+      private
+
+      def caching_enabled?
+        perform_caching && cache && respond_to?(:cache_key)
+      end
+
+      def expand_cache_key(*args)
+        ActiveSupport::Cache.expand_cache_key(args)
+      end
+    end
+  end
+end