boost::shared_ptr<string_item> i = boost::shared_ptr<string_item>(new string_item(s));

items.push_back(i);

return i;

boost::shared_ptr<float_item> i = boost::shared_ptr<float_item>(new float_item(d));

items.push_back(i);

return i;

std::stringstream ss;

for (std::vector< boost::shared_ptr<item> >::const_iterator it = items.begin(); it != items.end(); ++it) {

ss << (**it).str();

}

return ss.str();