[Boost-users] [serialization] serialization of an empty weak_ptr

22 Nov 2006

      Hi,

I'm trying to serialize an object of class X that has a member 
boost::weak_ptr< X >. The weak pointer may as well be empty and the 
object is still in valid state - at least in this context. The 
serialization code, however, tries to make a shared_ptr out of the 
weak_ptr, which throws a bad_weak_ptr when the weak_ptr is empty. Should 
the weak_ptr be checked for expired() before trying to make a shared_ptr 
of it?

Using boost 1.33.1 on Fedora Core 6, gcc 4.1.1, glibc 2.5, though the 
platform should not matter here.

An example code demonstrating the problem follows:

#include <iostream>
#include <fstream>
#include <boost/archive/text_oarchive.hpp>
#include <boost/archive/text_iarchive.hpp>
#include <boost/serialization/serialization.hpp>
#include <boost/serialization/weak_ptr.hpp>

class X
{
public:

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

	boost::weak_ptr< X > myFellowClassmate;
	int some_data;
};

inline std::ostream& operator<<( std::ostream& os, const X& x )
{
	return os << "x.some_data = " << x.some_data << std::endl;
}

using namespace std;

int main ( int argc, char* argv[] )
{
	X x;
	x.some_data = 1;
	cout << x;
	std::ofstream ofs("filename");
	boost::archive::text_oarchive oa(ofs);
	oa & x;
	ofs.close();
	std::ifstream ifs("filename", std::ios::binary);
	boost::archive::text_iarchive ia(ifs);
	x.some_data = 3;
	cout << x;
	ia & x;
	cout << x; // should print out 'x.some_data = 1'
}

[Boost-users] [serialization] serialization of an empty weak_ptr

Mikko Vainio