Move Paperclip-specific callback definitions into HasAttachedFile

lib/paperclip.rb

@@ -174,8 +174,6 @@ module Paperclip
     #   end
     def has_attached_file(name, options = {})
       HasAttachedFile.define_on(self, name, options)
-
-      define_paperclip_callbacks :post_process, :"#{name}_post_process"
     end
   end
 end

lib/paperclip/has_attached_file.rb

@@ -17,6 +17,7 @@ module Paperclip
       define_query
       register_with_rake_tasks
       add_active_record_callbacks
+      add_paperclip_callbacks
     end
 
     private
@@ -75,5 +76,11 @@ module Paperclip
       @klass.send(:before_destroy) { send(name).send(:queue_all_for_delete) }
       @klass.send(:after_destroy) { send(name).send(:flush_deletes) }
     end
+
+    def add_paperclip_callbacks
+      @klass.send(
+        :define_paperclip_callbacks,
+        :post_process, :"#{@name}_post_process")
+    end
   end
 end

test/has_attached_file_test.rb

@@ -34,6 +34,10 @@ class HasAttachedFileTest < Test::Unit::TestCase
     should 'define an after_destroy callback' do
       assert_adding_attachment('avatar').defines_callback('after_destroy')
     end
+
+    should 'define the Paperclip-specific callbacks' do
+      assert_adding_attachment('avatar').defines_callback('define_paperclip_callbacks')
+    end
   end
 
   private
@@ -98,6 +102,7 @@ class HasAttachedFileTest < Test::Unit::TestCase
            after_save: nil,
            before_destroy: nil,
            after_destroy: nil,
+           define_paperclip_callbacks: nil,
            name: 'Billy')
     end
   end