moved attribute translation to an object

activerecord/lib/active_record/attribute_methods/read.rb

+require 'active_record/attributes/translator'
+
 module ActiveRecord
   module AttributeMethods
     module Read
@@ -126,28 +128,20 @@ def read_attribute(attr_name)
         self.class.type_cast_attribute(attr_name, @attributes, @attributes_cache)
       end
 
-
       private
-      def cached_cast_attribute(attr_name, method)
-        @attributes_cache[attr_name] ||= cast_attribute(attr_name, method)
-      end
-
-      def cast_attribute(attr_name, method)
-        v = @attributes.fetch(attr_name) { missing_attribute(attr_name, caller) }
-        v && send(method, attr_name, v)
-      end
 
-      def cast_serialized(attr_name, value)
-        value.unserialized_value
+      def attribute_translator
+        Attributes::Translator.new(@attributes, @columns_hash)
       end
 
-      def cast_tz_conversion(attr_name, value)
-        value = cast_column(attr_name, value)
-        value.acts_like?(:time) ? value.in_time_zone : value
+      def cached_cast_attribute(attr_name, method)
+        @attributes_cache[attr_name] ||= cast_attribute(attr_name, method)
       end
 
-      def cast_column(attr_name, value)
-        @columns_hash[attr_name].type_cast value
+      def cast_attribute(attr_name, method)
+        attribute_translator.cast_attribute(attr_name, method) do
+          missing_attribute(attr_name, caller)
+        end
       end
 
       def attribute(attribute_name)

activerecord/lib/active_record/attributes/translator.rb

+module ActiveRecord
+  module Attributes
+    class Translator # :nodoc:
+      def initialize(attributes, column_types)
+        @attributes   = attributes
+        @column_types = column_types
+      end
+
+      def cast_attribute(attr_name, method)
+        v = @attributes.fetch(attr_name) { yield }
+        v && send(method, attr_name, v)
+      end
+
+      def cast_serialized(attr_name, value)
+        value.unserialized_value
+      end
+
+      def cast_tz_conversion(attr_name, value)
+        value = cast_column(attr_name, value)
+        value.acts_like?(:time) ? value.in_time_zone : value
+      end
+
+      def cast_column(attr_name, value)
+        @column_types[attr_name].type_cast value
+      end
+    end
+  end
+end