Hello all, I was following the boost.python tutorial but have this compile error that I don't know how to solve. The compiler says I need 4 template parameters for the class exposing class_ definition, but I only have one. (the other three are optional, aren't they?) BOOST_PYTHON_MODULE(world_ext) { using namespace boost::python; class_<World>("World") .def("greet", &World::greet) .def("set", &World::set) ; } I have asked the question on https://stackoverflow.com/questions/63803975/compile-error-during-boost-pyth on-tutorial-error-wrong-number-of-template-argu. If someone please tell me how to fix it, I would deeply appreciate it. Thank you. BTW, the tutorial is so old and doesn't fit with current boost code, and even the build method is different from the tutorial. For beginners to boost.python, it will take unnecessarily long to catch things. Chan Kim, Principal Research Member Processor Research Team, Intelligent Semiconductor Research ETRI(Electronics and Telecommunications Research Institute) O) +82-42-860-5773 C) +82-10-3418-9152 E) <mailto:ckim@etri.re.kr> ckim@etri.re.kr