[Boost-users] [serialization] Handling of references into a std::map

From: Bernhard Maeder (bernhard.maeder_at_[hidden])
Date: 2008-05-22 09:39:04

Hello all

I'm trying to serialize a std::map along with some pointers that are referencing
onto some of the Value elements of that map. What I see now, is that those
references are not loaded correctly. Here's what I do:

#include <sstream>
#include <boost/archive/text_oarchive.hpp>
#include <boost/archive/text_iarchive.hpp>
#include <boost/serialization/map.hpp>

struct dummy 
{
    template<typename Archive> 
    void serialize(Archive & ar, const unsigned int version)
    {        
    }  
};

struct map_ref_test
{
    std::map<std::size_t, dummy> m;    
    dummy * ref;

    template<typename Archive>
    void serialize(Archive & ar, const unsigned int version)
    {
        ar & m;
        ar & ref;
    }      
};

int main()
{
    std::ostringstream os;

    map_ref_test m;
    m.m[0] = dummy();
    m.m[1] = dummy();
    m.m[2] = dummy();
    m.ref = &(m.m[1]);
    
    // serialize
    boost::archive::text_oarchive out(os);        
    out << const_cast<map_ref_test const &>(m);
            
    // De-serialize
    map_ref_test m2; 
    std::string ser = os.str();
    std::istringstream is(ser);
    boost::archive::text_iarchive in(is);   
     
    in >> m2;
        
    std::cout << "0:   " << &m.m[0] << std::endl;
    std::cout << "1:   " << &m.m[1] << std::endl;
    std::cout << "2:   " << &m.m[2] << std::endl;
    std::cout << "ref: " << m.ref << std::endl;
    
    std::cout << "0:   " << &m2.m[0] << std::endl;
    std::cout << "1:   " << &m2.m[1] << std::endl;
    std::cout << "2:   " << &m2.m[2] << std::endl;
    std::cout << "ref: " << m2.ref << std::endl;     
}

This creates the following output:

0:   0x805bfc4
1:   0x805bfe4
2:   0x805c004
ref: 0x805bfe4
0:   0x805ca04
1:   0x805ca24
2:   0x805ca44
ref: 0xbfacad5c

I'd expect the last line to read:

ref: 0x805ca24

So, what am I doing wrong? Should this even work?

BTW: I'm using Boost 1.33.1

Thanks a lot!
Bernhard