# File lib/paperclip/attachment.rb, line 354
    def instance_write(attr, value)
      setter = "#{name}_#{attr}=""#{name}_#{attr}="
      responds = instance.respond_to?(setter)
      self.instance_variable_set("@_#{setter.to_s.chop}", value)
      instance.send(setter, value) if responds || attr.to_s == "file_name"
    end