stop adding a new method for touch callbacks

activerecord/lib/active_record/associations/builder/belongs_to.rb

@@ -91,15 +91,11 @@ def add_counter_cache_callbacks(reflection)
       klass.attr_readonly cache_column if klass && klass.respond_to?(:attr_readonly)
     end
 
-    def add_touch_methods(mixin)
-      return if mixin.method_defined?  :belongs_to_touch_after_save_or_destroy
-
-      mixin.class_eval do
-        def belongs_to_touch_after_save_or_destroy(foreign_key, name, touch)
-          old_foreign_id    = attribute_was(foreign_key)
+    def self.touch_record(o, foreign_key, name, touch) # :nodoc:
+      old_foreign_id = o.attribute_was(foreign_key)
 
       if old_foreign_id
-            klass      = association(name).klass
+        klass      = o.association(name).klass
         old_record = klass.find_by(klass.primary_key => old_foreign_id)
 
         if old_record
@@ -111,7 +107,7 @@ def belongs_to_touch_after_save_or_destroy(foreign_key, name, touch)
         end
       end
 
-          record = send name
+      record = o.send name
       unless record.nil? || record.new_record?
         if touch != true
           record.touch touch
@@ -120,18 +116,14 @@ def belongs_to_touch_after_save_or_destroy(foreign_key, name, touch)
         end
       end
     end
-      end
-    end
 
     def add_touch_callbacks(reflection)
-      add_touch_methods(mixin)
-
       foreign_key = reflection.foreign_key
       n           = name
       touch       = options[:touch]
 
       callback = lambda { |record|
-        record.belongs_to_touch_after_save_or_destroy foreign_key, n, touch
+        BelongsTo.touch_record(record, foreign_key, n, touch)
       }
 
       model.after_save    callback