module MJ;

    class Visitable

        def accept( visitor )
            method_name = nil
            klass = self.class.ancestors.find do |ancestor|
                method_name = "visit_#{ancestor.name.split('::')[-1]}"
                visitor.respond_to?( method_name )
            end

            if klass
                return visitor.send( method_name, self )
            else
                raise "#{visitor.class}: Should not happen!"
            end
        end

    end

end