[boost] C++03 / C++11 compatibility question for compiled libraries

Dear list, I have a technical question I do not know how to address, and I would like to know how people deal with this. To put things in the background: boost.test uses heavily boost::function and boost::bind, however I would like to use in some circumstances std::function and std::bind, which are, for instance, variadic. Boost.test is compiled with b2. I believe if the user does not pass additional parameters to the build, the default is to use whatever is provided in the Jamfile, that compiles the static and shared libraries in C++03 mode. If the user of boost.test compiles in C++03, it is ok if the library is used in a C++11 project. The other way is obviously not true. Now, in the headers of boost.test, I can detect for the compiler version, and depending on the language settings, activate an API that is C++11. OTOH, if I do not want users to be confused, this API should be header only. But this hardly work in practice, as the C++03 and C++11 APIs are usually not separable. Say: struct test_case { // compiled member function test_case(boost::function function_to_test); #if Cpp11 // std::function variant to ensure compatibility with std::bind test_case(std::function function_to_test); #endif private: boost::function m_function_to_test; }; This API is obviously not good at all, and for having the slightest chance to make this work, the 2 APIs C++11 vs C++03 should be mutually exclusive. This also produces 2 different incompatible shared/static libraries, which is even more confusing for the user as the compiler options should be transitively passed to the user's code, or the user should be aware of which library to link with. So, the questions are: * how do other boost developers deal with this? * what is your experience on users in terms of compilation+linking? are usually people aware of this problem and they compile in C++11 all the code including boost? * is there any better option? All the other options I see are even worse. Thanks, Raffi