Boost XML archiving compiling error with polymorphic classes - c++

Question

I am trying to save my files in XML format using boost archiving.
I get these two errors at compile time.
Error C2664 'int boost::mpl::assertion_failed(boost::mpl::assert::type)': cannot convert argument 1 from 'boost::mpl::failed ***********boost::serialization::is_wrapper:: ***********' to 'boost::mpl::assert::type'
Error C2789 'mpl_assertion_in_line_6': an object of const-qualified type must be initialized
This happens because of these two lines.
BOOST_CLASS_EXPORT_GUID(SumKeyframeXYZ, "SumKeyframeXYZ")
BOOST_CLASS_EXPORT_GUID(SumPosition_Channel, "SumPosition_Channel")
This is the Main function.
#include "Container.h"
BOOST_CLASS_EXPORT_GUID(SumKeyframeXYZ, "SumKeyframeXYZ")
BOOST_CLASS_EXPORT_GUID(SumPosition_Channel, "SumPosition_Channel")
int main()
{
std::ofstream ofs("D:\\output.xml");
Container cont;
cont.AddPositionChannel();
boost::archive::xml_oarchive oa(ofs);
oa << BOOST_SERIALIZATION_NVP(cont);
return 0;
}
This is how the classes structure looks like.
Container.h
#include <string>
#include "SumChannel.h"
#include "SumPosition_Channel.h"
#include <fstream>
#include <iostream>
#include <boost/archive/xml_iarchive.hpp>
#include <boost/archive/xml_oarchive.hpp>
#include <boost/serialization/vector.hpp>
#include <boost/serialization/shared_ptr.hpp>
class Container
{
private:
std::string stdstrName;
std::vector<std::shared_ptr<SumChannel>> Channels;
public:
Container() { stdstrName = "Container Name"; }
void AddPositionChannel() {
std::shared_ptr< SumPosition_Channel> posChannel = std::make_shared<SumPosition_Channel>();
Channels.push_back(posChannel);
};
private:
friend class boost::serialization::access;
template<class Archive> void serialize(Archive & ar,
const unsigned int version) const {
ar & BOOST_SERIALIZATION_NVP(stdstrName);
ar & BOOST_SERIALIZATION_NVP(Channels);
}
};
//////////////////////////////////////////////////////////
SumChannel.h
#include <fstream>
#include <iostream>
#include <boost/archive/xml_iarchive.hpp>
#include <boost/archive/xml_oarchive.hpp>
#include <boost/serialization/vector.hpp>
class SumChannel
{
public:
float offset;
SumChannel() { offset = 1.0; }
private:
friend class boost::serialization::access;
template<class Archive> void serialize(Archive & ar,
const unsigned int version) const {
ar & BOOST_SERIALIZATION_NVP(offset);
}
};
SumPosition_Channel
#include "SumKeyframeXYZ.h"
#include "SumChannel.h"
#include <vector>
#include <boost/archive/xml_iarchive.hpp>
#include <boost/archive/xml_oarchive.hpp>
#include <boost/serialization/vector.hpp>
class SumPosition_Channel : public SumChannel
{
public:
std::vector<SumKeyframeXYZ> keyframes;
void AddKeyframe() { SumKeyframeXYZ key; keyframes.push_back(key); }
private:
friend class boost::serialization::access;
typedef SumChannel _Super;
template<class Archive> void serialize(Archive & ar,
const unsigned int version) const {
ar & boost::serialization::base_object<_Super>(*this);
ar & BOOST_SERIALIZATION_NVP(keyframes);
}
};
KeyFrameBase.h
#include <iostream>
#include <fstream>
#include <boost/archive/xml_oarchive.hpp>
#include <boost/archive/xml_iarchive.hpp>
class Keyframebase
{
public:
std::string stdstrName;
float time;
Keyframebase() { stdstrName = "BaseKey"; time = 50.0; }
private:
friend class boost::serialization::access;
template<class Archive> void serialize(Archive & ar,
const unsigned int version) {
ar & BOOST_SERIALIZATION_NVP(stdstrName);
ar & BOOST_SERIALIZATION_NVP(time);
}
};
SumKeyframeXYZ.h
#include "KeyframeBase.h"
#include <boost/archive/xml_iarchive.hpp>
#include <boost/archive/xml_oarchive.hpp>
#include <boost/serialization/vector.hpp>
class SumKeyframeXYZ : public Keyframebase
{
public:
float x;
float y;
float z;
SumKeyframeXYZ() { x = 150.0; y = 200.0; z = 300.0; }
private:
friend class boost::serialization::access;
template<class Archive> void serialize(Archive & ar,
const unsigned int version) const {
ar & boost::serialization::base_object<Keyframebase>(*this);
ar & BOOST_SERIALIZATION_NVP(x);
ar & BOOST_SERIALIZATION_NVP(y);
ar & BOOST_SERIALIZATION_NVP(z);
}
};

Answer 1

The issue with the code was that i was not writing NVP to the base class
I changed the Base class archiving code from
ar & boost::serialization::base_object<_Super>(*this);
to this for all the base classes.
typedef SumChannel _Super;
ar & boost::serialization::make_nvp("SumChannel", boost::serialization::base_object<_Super>(*this));
and removed the const from the serilize function.