[Boost-users] Re: Serialization and source code organization

From: Malte Clasen (news_at_[hidden])
Date: 2004-11-25 19:45:36

Robert Ramey wrote:
> The pimpl example demonstrates pretty much all I know about the issue.

Ok, I'm using that one now and it compiles fine.

But another issue appeared: The automatic serialization of nested 
std::vectors fails under certain circumstances. I managed to isolate the 
problem to the following case:

----------

// disable warnings that don't matter in this example
#pragma warning(disable:4511 4512 4244 4100 4267)

#include <boost/serialization/serialization.hpp>
#include <boost/serialization/shared_ptr.hpp>
#include <boost/serialization/vector.hpp>
#include <boost/archive/text_iarchive.hpp>
#include <boost/archive/text_oarchive.hpp>

#include <fstream>
#include <vector>

class A
{
private:
        friend class boost::serialization::access;
        template<class Archive>
        void serialize(Archive &, const unsigned int) {}
};

template<typename T>
class B
{
private:
        friend class boost::serialization::access;
        template<class Archive>
        void serialize(Archive & ar, const unsigned int /*version*/)
        {
                //ar.register_type< std::vector<T> >(); // workaround A
                //ar & vT; // workaround B, part 1/2
                ar & vvT; // this one fails
        }

        //std::vector<T> vT; // workaround B, part 2/2
        std::vector< std::vector<T> > vvT;
};

void save()
{
     std::ofstream ofs("test.dat");
     boost::archive::text_oarchive oa(ofs);

        B< boost::shared_ptr<A> > b_ptr_a;
        oa << b_ptr_a;
}

void load()
{
     std::ifstream ifs("test.dat");
     boost::archive::text_iarchive ia(ifs);

        B< boost::shared_ptr<A> > b_ptr_a;
        ia >> b_ptr_a;
}

----------

The serialization of std::vector< std::vector<T> > fails to compile 
(VC++ 7.1) unless one of the workarounds is used, that means some kind 
of registration of std::vector<T>. Is that a known limitation? I found 
nothing in the documentation about this case, but perhaps I overlooked 
something.

Malte