# File lib/adaptation/message.rb, line 149
    def self.has_one *symbols
      xml_tag = symbols[0]
      case xml_tag
        when :object
          @objects = [] if @objects.nil?
          unless @objects.include?(symbols[1])
            @objects << symbols[1]

            klass = get_class_object(symbols[1])
            if klass.nil?
              require "#{ADAPTOR_ROOT}/app/messages/_#{symbols[1].to_s}.rb"
              klass = get_class_object(symbols[1])
            end

            xml_object symbols[1], klass
            validates_associated symbols[1]
          end
        when :attribute
          @attributes = [] if @attributes.nil?
          unless @attributes.include?(symbols[1])
            @attributes << symbols[1]
            s = ""
            @attributes.each do |a|
              s << a.to_s
            end
            xml_attribute symbols[1]
          end
        when :text
          @texts = [] if @texts.nil?
          unless @texts.include?(symbols[1])
            @texts << symbols[1]
            xml_text symbols[1]
          end
      end
    end