OK - I see the problem - good example. I don't see an obvious or easy fix. I'll look into it. Robert Ramey Sergey Skorniakov wrote:
Unfortunately, current tracking implementation can also leads to weird version incompatibility. The unlucky combination is object_serializable + track_selectivly. Suppose, someone have code that serizalizes vector<int> to file (by value). After some time, some code that serializes vector<int> as pointer is added to program. Its enough to make old files unreadable (or readable with errors). Sample code:
void TestTrack2Err(boost::archive::polymorphic_xml_iarchive &ar) { std::vector<int> *p; ar & BOOST_SERIALIZATION_NVP(p); // saving of vector<int>* is absent intentionaly to simulate different versions of saving and loading code } void TestTrack2() { std::stringstream s; std::vector<int> x; x.push_back(4); { boost::archive::polymorphic_text_oarchive ar(s); ar & BOOST_SERIALIZATION_NVP(x); } x.clear(); { boost::archive::polymorphic_text_iarchive ar(s); ar & BOOST_SERIALIZATION_NVP(x); assert(x.size() == 1); // The vector is empty at this point - unless loading of vector<int>* is commented out } }
The consequences of error can vary from noting (especially with xml archives) to program crashes in some more difficult cases. I have recently encountered this error when dealing with a big project (more than 500 serialized types) and have no idea how I can get out of a difficulty.