c++ - From binary to xml serialization using boost -

i'm working on several classes used boost serialization binary archive using :

my_archive & my_variable; 

however want move add xml archive serialization support, while keeping backward compatibility. boost enforce (of course) use nvp wrapper reason.

unfortunately, seems impossible mix nvp() , direct binary serialization in same serialize fonction (with managing versioning).

so here code looks until :

friend class boost::serialization::access; template<class archive> void serialize(archive & ar, const unsigned int version) {     // serialize base class information     if (version == 4) {         ar & boost::serialization::make_nvp( "var", mvariable );     }     else if (version == 3) {         ar & mvariable;     } } 

with

boost_class_version(mytype, 4) 

when calling & operator xml archive template error on is_wrapper<>() because of serialization not using nvp wrapper.

so here question, there work around allow me regarding version number (know @ compile time) adapt serialize function use xml/binary version 4 , binary previous one.

you should add nvp wrapper; it's just metadata annotation , isn't used binary archives (or standard text archives, matter).

so don't need change versioning, binary archives

ar & boost_serialization_nvp(x); // or ar & boost::serialization_make_nvp("foo", x); 

is equivalent to

ar & x;