# File lib/xsd/mapping.rb, line 40
    def obj2xml(obj, elename = nil, io = nil)
      opt = MAPPING_OPT.dup
      unless elename
        if definition = @registry.elename_schema_definition_from_class(obj.class)
          elename = definition.elename
          opt[:root_type_hint] = false
        end
      end
      elename = SOAP::Mapping.to_qname(elename) if elename
      soap = SOAP::Mapping.obj2soap(obj, @registry, elename, opt)
      if soap.elename.nil? or soap.elename == XSD::QName::EMPTY
        soap.elename =
          XSD::QName.new(nil, SOAP::Mapping.name2elename(obj.class.to_s))
      end
      generator = SOAP::Generator.new(opt)
      generator.generate(soap, io)
    end