Robert Ramey wrote:
This should work - How is your case different that test_cycle.cpp ?
I can't find test_cycle.cpp unfortunately, so I don't know. See my example below.
The pointer conflict means that something has been serializaed as first as a pointer then as an object. Normally this should be easily avoidable. This is flagged as an error because the de-serialization would be a problem. First the deserialization of a pointer creates an object - next the object itself is re-loaded - but now we have two objects when we started with one.
I see what you mean, but I fail how to see a convenient way to avoid it without changing all containers so that they have pointers instead of objects or something like that. Is perhaps BOOST_CLASS_TRACKING the key? --- #include <vector> #include <fstream> #include <boost/serialization/vector.hpp> #include <boost/archive/xml_oarchive.hpp> class A { friend class boost::serialization::access; public: A() : next(0) { }; A* next; private: template<class Archive> void serialize(Archive & ar, const unsigned int){ ar & BOOST_SERIALIZATION_NVP(next); } }; int main() { std::ofstream ofs("test_of_serialization.dat"); boost::archive::xml_oarchive oa(ofs); std::vector<A> a1(4); a1[0].next = &a1[0]; a1[1].next = &a1[1]; a1[2].next = &a1[2]; a1[3].next = &a1[3]; oa << BOOST_SERIALIZATION_NVP(a1); // everything worked fine with a1... std::vector<A*> a2(4); a2[0] = new A; a2[1] = new A; a2[2] = new A; a2[3] = new A; a2[0]->next = a2[1]; a2[1]->next = a2[2]; a2[2]->next = a2[3]; a2[3]->next = a2[0]; oa << BOOST_SERIALIZATION_NVP(a2); // everything worked fine with a2... std::vector<A> a3(4); a3[0].next = &a3[1]; a3[1].next = &a3[2]; a3[2].next = &a3[3]; a3[3].next = &a3[0]; // but this throws "pointer conflict" exception oa << BOOST_SERIALIZATION_NVP(a3); } --- // Henrik Jacobsson
Robert Ramey
Henrik Jacobsson wrote:
Hi!
I want to serialize objects that link to each other through pointers, like a linked list, but in this case a more complex graph with several different classes and proxies (a graph which can contain loops and and null-pointers).
But I get the "pointer conflict" exception since the serialization discovers that an object have been serialized once before through its pointer. The contents should be serialized/deserialized only once, and then the pointers should just be kept consistent.
An alternative is of course to replace all the pointers with indeces which are memory-independent. But that's a messy affair.
In the copy constructor I solved something similar through a map<Type*,Type*> which mapped from the old pointers to the newly allocated ones, so that they could be properly replaced. Is something like this hidden somewhere in the lib?
Any suggestions?
Best regards, Henrik Jacobsson
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