Hello, I would like to use a optional<T>, where T is not copy constructible, with a default constructor (in my case, a xmlpp::Document). I read in the doc that one way to do that is to use in_place_factories. I tried to do so: myInstanceTemplateDocument = boost::in_place<xmlpp::Document>(); I got the compilation error: myFile.cpp(341) : error C2780: 'boost::typed_in_place_factory10<T,A0,A1,A2,A3,A4,A5,A6,A7,A8,A9> boost::in_place(const A0 &,const A1 &,const A2 &,const A3 &,const A4 &,const A5 &,const A6 &,const A7 &,const A8 &,const A9 &)' : expects 10 arguments - 0 provided boost\utility\typed_in_place_factory.hpp(50) : see declaration of 'boost::in_place' myFile.cpp(341) : error C2780: 'boost::typed_in_place_factory9<T,A0,A1,A2,A3,A4,A5,A6,A7,A8> boost::in_place(const A0 &,const A1 &,const A2 &,const A3 &,const A4 &,const A5 &,const A6 &,const A7 &,const A8 &)' : expects 9 arguments - 0 provided boost\utility\typed_in_place_factory.hpp(50) : see declaration of 'boost::in_place' myFile.cpp(341) : error C2780: 'boost::typed_in_place_factory8<T,A0,A1,A2,A3,A4,A5,A6,A7> boost::in_place(const A0 &,const A1 &,const A2 &,const A3 &,const A4 &,const A5 &,const A6 &,const A7 &)' : expects 8 arguments - 0 provided boost\utility\typed_in_place_factory.hpp(50) : see declaration of 'boost::in_place' myFile.cpp(341) : error C2780: 'boost::typed_in_place_factory7<T,A0,A1,A2,A3,A4,A5,A6> boost::in_place(const A0 &,const A1 &,const A2 &,const A3 &,const A4 &,const A5 &,const A6 &)' : expects 7 arguments - 0 provided boost\utility\typed_in_place_factory.hpp(50) : see declaration of 'boost::in_place' myFile.cpp(341) : error C2780: 'boost::typed_in_place_factory6<T,A0,A1,A2,A3,A4,A5> boost::in_place(const A0 &,const A1 &,const A2 &,const A3 &,const A4 &,const A5 &)' : expects 6 arguments - 0 provided boost\utility\typed_in_place_factory.hpp(50) : see declaration of 'boost::in_place' myFile.cpp(341) : error C2780: 'boost::typed_in_place_factory5<T,A0,A1,A2,A3,A4> boost::in_place(const A0 &,const A1 &,const A2 &,const A3 &,const A4 &)' : expects 5 arguments - 0 provided boost\utility\typed_in_place_factory.hpp(50) : see declaration of 'boost::in_place' myFile.cpp(341) : error C2780: 'boost::typed_in_place_factory4<T,A0,A1,A2,A3> boost::in_place(const A0 &,const A1 &,const A2 &,const A3 &)' : expects 4 arguments - 0 provided boost\utility\typed_in_place_factory.hpp(50) : see declaration of 'boost::in_place' myFile.cpp(341) : error C2780: 'boost::typed_in_place_factory3<T,A0,A1,A2> boost::in_place(const A0 &,const A1 &,const A2 &)' : expects 3 arguments - 0 provided boost\utility\typed_in_place_factory.hpp(50) : see declaration of 'boost::in_place' myFile.cpp(341) : error C2780: 'boost::typed_in_place_factory2<T,A0,A1> boost::in_place(const A0 &,const A1 &)' : expects 2 arguments - 0 provided boost\utility\typed_in_place_factory.hpp(50) : see declaration of 'boost::in_place' myFile.cpp(341) : error C2780: 'boost::typed_in_place_factory1<T,A0> boost::in_place(const A0 &)' : expects 1 arguments - 0 provided boost\utility\typed_in_place_factory.hpp(50) : see declaration of 'boost::in_place' In my case, the class can also accept an argument in its constructor, therefore I used : myInstanceTemplateDocument = boost::in_place<xmlpp::Document>(Glib::ustring("1.0")); and it worked, but I'd like to know if I missed something, of if it's a shortcomming of nullary in_place_factories. Best regards, -- Loïc