# File lib/dm-validations/validation_errors.rb, line 64
      def add(field_name, message)
        # see 6abe8fff in extlib, but don't enforce
        # it unless Edge version is installed
        if message.respond_to?(:try_call)

          # DM resource
          message = if resource.respond_to?(:model) && resource.model.respond_to?(:properties)
            message.try_call(resource, resource.model.properties[field_name])
          else
            # pure Ruby object
            message.try_call(resource)
          end
        end
        (errors[field_name] ||= []) << message
      end