+ def log_start_state
+ @old_etag = etag
+ @old_attributes = logged_attributes
+ end
+
+ def log_change(event_type)
+ log = Log.new(event_type: event_type).fill_object(self)
+ yield log
+ log.save!
+ log_start_state
+ end
+
+ def log_create
+ log_change('create') do |log|
+ log.fill_properties('old', nil, nil)
+ log.update_to self
+ end
+ end
+
+ def log_update
+ log_change('update') do |log|
+ log.fill_properties('old', @old_etag, @old_attributes)
+ log.update_to self
+ end
+ end
+
+ def log_destroy
+ log_change('destroy') do |log|
+ log.fill_properties('old', @old_etag, @old_attributes)
+ log.update_to nil
+ end
+ end