Hi, aside from the fact that the new coroutines are - apparently intentionally - only unidirectional now (currently not much of an issue for me), I noticed that it is apparently no longer possible to yield values by reference as shown in the following example: #include <fstream> #include <string> #include <iostream> #include <boost/coroutine/all.hpp> using type = std::string; auto lines_from_file(char const * fname) -> boost::coroutines::coroutine<type>::pull_type { using namespace boost::coroutines; return coroutine<type>::pull_type{ [fname](coroutine<type>::push_type& yield) { std::string line; std::ifstream stream(fname); while(stream) std::getline(stream, line), yield(line); }, attributes(fpu_not_preserved) }; } int main(int, char**) { auto lines = lines_from_file("test.txt"); unsigned count = 0; for(auto& line : lines) std::cout << std::setw(4) << ++count << ": " << line << "\n"; } If one changes type to std::string const & the example no longer compiles. If I use the old BOOST_COROUTINES_V1 API boost::coroutines::coroutine<std::string const &()> works just fine. Is this limitation also intentional (why?) or is this an unintentional regression? Regards Johannes S. Mueller-Roemer -- Johannes S. Mueller-Roemer, MSc Wiss. Mitarbeiter - Interactive Engineering Technologies (IET) Fraunhofer-Institut für Graphische Datenverarbeitung IGD Fraunhoferstr. 5 | 64283 Darmstadt | Germany Tel +49 6151 155-606 | Fax +49 6151 155-139 johannes.mueller-roemer@igd.fraunhofer.de | www.igd.fraunhofer.de