Hi, I'm having trouble expliciting instantiating the const get member-function of a tuple. I defined my tuple like this: typedef boost::tuple<std::string, std::string> parameter_tuple; And I'm trying to instantiate like this: template boost::tuples::access_traits<boost::tuples::element<0, parameter_tuple::inherited>::type>::const_type parameter_tuple::inherited::get<0>() const; But it gives me the following error in VC7.1. I cannot understand why it says it has the wrong return value... I've tried using std::string const& too but didnt worked... ..\..\..\include\mail\type_parameters.hpp(26) : error C2785: 'access_traits<element<N,boost::tuples::cons<HT,TT>>::type>::const_type boost::tuples::cons<HT,TT>::get(void) const' and 'boost::tuples::access_traits<T>::const_type boost::tuples::cons<HT,TT>::get(void) const' have different return types with [ HT=std::string, TT=boost::tuples::detail::map_tuple_to_cons<std::string,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>::type ] and [ T=boost::tuples::cons<std::string,boost::tuples::detail::map_tuple_to_cons<boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>::type>::stored_head_type, HT=std::string, TT=boost::tuples::detail::map_tuple_to_cons<std::string,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>::type ] ..\..\..\libs\boost\boost\tuple\detail\tuple_basic.hpp(405) : see declaration of 'boost::tuples::cons<HT,TT>::get' with [ HT=std::string, TT=boost::tuples::detail::map_tuple_to_cons<std::string,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>::type ] ..\..\..\include\mail\type_parameters.hpp(26) : see declaration of 'boost::tuples::cons<HT,TT>::get' with [ HT=std::string, TT=boost::tuples::detail::map_tuple_to_cons<std::string,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>::type ] ..\..\..\include\mail\multipart.hpp(90) : see reference to class template instantiation 'mail::multipart_detail::storage_selector_helper<MemoryStorageT,AsyncStorageT>' being compiled ..\..\..\include\mail\memory_storage.hpp(34) : see reference to class template instantiation 'mail::memory_storage_traits<T>' being compiled ..\..\..\include\mail\type_parameters.hpp(26) : error C2888: 'boost::tuples::access_traits<T>::const_type boost::tuples::cons<HT,TT>::get(void) const' : symbol cannot be defined within namespace 'mail' with [ T=boost::tuples::cons<std::string,boost::tuples::detail::map_tuple_to_cons<boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>::type>::stored_head_type, HT=std::string, TT=boost::tuples::detail::map_tuple_to_cons<std::string,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>::type ] ..\..\..\include\mail\type_parameters.hpp(26) : error C3190: 'boost::tuples::access_traits<T>::const_type boost::tuples::cons<HT,TT>::get(void) const' with the provided template arguments is not the explicit instantiation of any member function of '<Unknown>' with [ T=boost::tuples::cons<std::string,boost::tuples::detail::map_tuple_to_cons<boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>::type>::stored_head_type, HT=std::string, TT=boost::tuples::detail::map_tuple_to_cons<std::string,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>::type ] call "C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\bin\vcvars32.bat" >nul cl /Zm800 -nologo -TP /Z7 /Od /Ob0 /W4 /WX /GR /MDd /Zc:forScope /Zc:wchar_t /Wp64 /GB /wd4675 /EHs /wd4100 /wd4127 /wd4311 /wd4312 /wd4510 /wd4511 /wd4512 /wd4610 @"..\..\..\bin\projects\mail\test\multipart_basic.test\msvc-7.1\debug\multipart_basic.obj.rsp" -c -Fo"..\..\..\bin\projects\mail\test\multipart_basic.test\msvc-7.1\debug\multipart_basic.obj" Any help would be appreciated Thanks in advance, -- Felipe Magno de Almeida