[Boost-users] Boost.Parameter python and lazy evaluation of default arguments

Hello all, I have a question concerning the Boost.Parameter library and the python binding provided by this library. When I try to compile the attached code with clang I get: ------------------------------- /tmp$ clang -I/usr/include/python2.7/ -std=c++14 -c python_test.cpp In file included from python_test.cpp:7: In file included from /usr/include/boost/parameter/preprocessor.hpp:8: In file included from /usr/include/boost/parameter/parameters.hpp:40: /usr/include/boost/parameter/aux_/arg_list.hpp:361:16: error: no viable conversion from 'boost::parameter::aux::maybe' to 'const std::basic_string<char>' return arg.value; ^~~~~~~~~ ------------------------------- If I just compile main or use standard default arguments everything compiles fine. Can anybody explain to me what's wrong with using lazy default argument evaluation when exporting to python? Thanks a lot, Philipp