I have a templated base class Base and a templated derived class Derived which I want to serialize.
The below simplified code compiles and run but do not serialize data members from base class.
#include <vector>
#include <string>
#include <iostream>
#include <sstream>
#include <boost/archive/xml_iarchive.hpp>
#include <boost/archive/xml_oarchive.hpp>
#include <boost/serialization/access.hpp>
#include <boost/serialization/nvp.hpp>
#include <boost/serialization/export.hpp>
template<class U, class V>
struct Base {
Base(U uu, V vv) : u(uu), v(vv) {}
U u;
V v;
};
template<class V, class T>
struct Derived : public Base<V, int>, public Base<V, std::string> {
Derived(T tt) : Base<V, int>(2.0, 4), Base<V, std::string>(3.0, std::string("hello")), t(tt) {}
T t;
};
// does not work
//BOOST_CLASS_EXPORT(Derived);
namespace boost { namespace serialization {
template<class Archive, class U, class V>
void serialize(Archive & ar, Base<U,V> &obj, const unsigned int version) {
ar& BOOST_SERIALIZATION_NVP(obj.u);
ar& BOOST_SERIALIZATION_NVP(obj.v);
}
template<class Archive, class V, class T>
void serialize(Archive & ar, Derived<V,T> &obj, const unsigned int version) {
boost::serialization::make_nvp("Base1",
boost::serialization::base_object<Base<V, int>>(obj) );
boost::serialization::make_nvp("Base2",
boost::serialization::base_object<Base<V, std::string>>(obj) );
// does not work
// ar& BOOST_SERIALIZATION_BASE_OBJECT_NVP(Base<V, int>);
// ar& BOOST_SERIALIZATION_BASE_OBJECT_NVP(Base<V, std::string>);
ar& BOOST_SERIALIZATION_NVP(obj.t);
}
}} // end namespace
int main() {
Derived<double, int> a(10);
std::ostringstream archive_ostream;
boost::archive::xml_oarchive oa(archive_ostream);
oa << BOOST_SERIALIZATION_NVP(a);
std::cout << archive_ostream.str() << std::endl;
}
Demo : Live On Coliru
Output is only :
<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<!DOCTYPE boost_serialization>
<boost_serialization signature="serialization::archive" version="12">
<a class_id="0" tracking_level="0" version="0">
<obj.t>10</obj.t>
</a>
So how can I get the serialization of Base::u and Base::v ? I have tried using BOOST_CLASS_EXPORT(Derived); without success.
Bonus question : How can I also use the macro BOOST_SERIALIZATION_BASE_OBJECT_NVP in this case ?
You forgot to actually write the NVP to the archive:
ar & boost::serialization::make_nvp("Base1", boost::serialization::base_object<Base<V, int>>(obj) );
ar & boost::serialization::make_nvp("Base2", boost::serialization::base_object<Base<V, std::string>>(obj) );
With that changed, it now prints
<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<!DOCTYPE boost_serialization>
<boost_serialization signature="serialization::archive" version="12">
<a class_id="0" tracking_level="0" version="0">
<Base1 class_id="1" tracking_level="0" version="0">
<obj.u>2.00000000000000000e+00</obj.u>
<obj.v>4</obj.v>
</Base1>
<Base2 class_id="2" tracking_level="0" version="0">
<obj.u>3.00000000000000000e+00</obj.u>
<obj.v>hello</obj.v>
</Base2>
<obj.t>10</obj.t>
</a>
See Live On Coliru
#include <vector>
#include <string>
#include <iostream>
#include <sstream>
#include <boost/archive/xml_iarchive.hpp>
#include <boost/archive/xml_oarchive.hpp>
#include <boost/serialization/access.hpp>
#include <boost/serialization/nvp.hpp>
#include <boost/serialization/export.hpp>
template<class U, class V>
struct Base {
Base(U uu, V vv) : u(uu), v(vv) {}
U u;
V v;
};
template<class V, class T>
struct Derived : public Base<V, int>, public Base<V, std::string> {
Derived(T tt) : Base<V, int>(2.0, 4), Base<V, std::string>(3.0, std::string("hello")), t(tt) {}
T t;
};
// does not work
//BOOST_CLASS_EXPORT(Derived);
namespace boost { namespace serialization {
template<class Archive, class U, class V>
void serialize(Archive & ar, Base<U,V> &obj, const unsigned int /*version*/) {
ar& BOOST_SERIALIZATION_NVP(obj.u);
ar& BOOST_SERIALIZATION_NVP(obj.v);
}
template<class Archive, class V, class T>
void serialize(Archive & ar, Derived<V,T> &obj, const unsigned int /*version*/) {
ar & boost::serialization::make_nvp("Base1", boost::serialization::base_object<Base<V, int>>(obj) );
ar & boost::serialization::make_nvp("Base2", boost::serialization::base_object<Base<V, std::string>>(obj) );
// does not work
// ar& BOOST_SERIALIZATION_BASE_OBJECT_NVP(Base<V, int>);
// ar& BOOST_SERIALIZATION_BASE_OBJECT_NVP(Base<V, std::string>);
ar& BOOST_SERIALIZATION_NVP(obj.t);
}
}} // end namespace
int main() {
Derived<double, int> a(10);
std::ostringstream archive_ostream;
boost::archive::xml_oarchive oa(archive_ostream);
oa << BOOST_SERIALIZATION_NVP(a);
std::cout << archive_ostream.str() << std::endl;
}
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