[Boost-users] Serialization: Problem with registering derived classes

From: Luca Cappa (luca.cappa_at_[hidden])
Date: 2007-04-18 12:08:17

Hello,

I am boost-serializing some instances of polymorphic class using their  
base class pointer.

I get the 'archive_exception::unregistered_cast' exception at runtime when  
serializing one of them. The comment at line 407 of oserializer.hpp (where  
the exception is thrown) "convert pointer to more derived type. if this is  
thrown it means that the base/derived  relationship hasn't be registered".

The code is here below. I think i registered correctly the derived  
classes, but I have not been able to make it working: in few words, i  
cannot serialize a Serializable class using a pointer to its base  
SerializableBase base class. Any suggestion?

TIA,
Luca

using namespace std;
using namespace boost;
using namespace boost::serialization;

struct SerializableBase
{
   virtual ~SerializableBase ()
   {
   }

   template<typename Archive>
   void serialize (Archive& pAR, unsigned int version)
   {
     int i (0);
     pAR & make_nvp ("doesnotwork", i);
   }
};

struct Serializable : public SerializableBase
{
   int a;
   Serializable () :     a (1)
   {
   }
   virtual ~Serializable ()
   {
   }

   template<typename Archive>
   void serialize (Archive& pAR, unsigned int version)
   {
     pAR & BOOST_SERIALIZATION_NVP (a);
     pAR & make_nvp ("woowoo", b);
   }
};//struct

void save (const Serializable& pS, const char* pFileName)
{
   // make an archive
   std::ofstream ofs (pFileName);
   boost::archive::xml_oarchive oa (ofs);

   // Registering a lot of things here!
     oa.register_type (static_cast<Serializable*> (NULL));
     oa.register_type (static_cast<SerializableBase*> (NULL));
     oa.register_type<shared_ptr<SerializableBase> > ();
     oa.register_type<shared_ptr<Serializable> > ();
     oa.register_type<Serializable> ();
     oa.register_type<SerializableBase> ();

   SerializableBase* lS (new Serializable);
   oa << make_nvp ("lS", lS);
}

int main ()
{
   Serializable s;
   save (s, "serializable.xml");
}