# File lib/ruport/controller.rb, line 168
    def as(format,options={})
      raise ControllerNotSetError unless self.class.controller
      unless self.class.controller.formats.include?(format)
        raise UnknownFormatError
      end
      self.class.controller.render(format,
        self.class.rendering_options.merge(options)) do |rend|
          rend.data =
            respond_to?(:renderable_data) ? renderable_data(format) : self
          yield(rend) if block_given?  
      end
    end