You might be right. I too thought overloading operator<< might be problematic but I haven't encountered any problems yet. I think that std::cout << std::vector<int> {1,2,3} << '\n'; is simpler than the alternative, but I see why people would be alarmed. I think simplicity is worth the extra work and I will look into the subject. For now I added a str method under boost::stringize and I put the global operator<< under #ifdef BOOST_STRINGIZE_GLOBAL_LEFT_SHIFT_OPERATOR. Ideas regarding how to define a safe global operator<< would be much appreciated. As has been said, currently I use Boost.EnableIf to enable/disable the overloads. I use Boost.TypeTraits and Boost.MPL to introspect the type of the object and disable if has_left_shift is already defined and enable only for types that have a const_iterator typedef or are fusion sequences. Currently the overloads are in the global namespace. P.S. Regarding the str method, for efficiency's sake it returns a detail::feeder object which simply holds a reference to the input and defines operator<< and operator std::string() as well as some other operators. Returning a string from boost::stringize::str would be inefficient if the user wants to just stream the object. Tal Zion -- View this message in context: http://boost.2283326.n4.nabble.com/Query-of-interest-for-a-container-output-... Sent from the Boost - Dev mailing list archive at Nabble.com.