On 6/4/15 9:38 AM, Mccall, Kurt E. (JSC-EG411) wrote:

I'm trying to serialize a class with a non-default constructor and static const data members, so I have to override boost::serialization::save_construct_data() and load_construct_data(). I am getting a linking error:the static members referred to in save_construct_data() cannot be found ("undefined reference").

#include <boost/archive/tmpdir.hpp> #include <boost/archive/xml_iarchive.hpp> #include <boost/archive/xml_oarchive.hpp>

// forward declarations class A; namespace boost { namespace serialization { template<class Archive> inline void save_construct_data(Archive &ar, const A *t, const unsigned int file_version); } }

class A { friend class boost::serialization::access;

// friend function (omitting load_construct_data() for brevity) template<class Archive> friend void save_construct_data(Archive &ar, const A *t, const unsigned int file_version);

public: static const int var1 = 1; static const int var2 = 2;

template<class Archive> void serialize(Archive & ar, const unsigned int file_version) { // do nothing }; }

// overridden Boost function namespace boost { namespace serialization { template<class Archive> inline void save_construct_data( Archive &ar, const A *t, const unsigned int file_version) { // link errors happen at both of these two lines ("undefined reference" of var1, var2). ar << boost::serialization::make_nvp("var1", ::A::var1); // eliminate this ar << boost::serialization::make_nvp("var2", t->var2); // eliminate this - so might as well eliminate the whole function }; }} // namespace…

This puzzles me since I thought that static members have external linkage. This question seems to be more about namespaces than it is about Boost::Serialization, but I post here because some Serialization user must have run into it.

I'm not so sure about that. There no need to serialize the static const values since they are fixed and initialized before the first instance is constructed. It has always been that static variables had to be explicitly initialized outside the class. As in const int A::var1 = 1; // no longer necessary const int A::var2 = 2; But I guess C++11 changed that. Robert Ramey