I'm trying to come to grips with using the boost intrusive containers, but I don't think I understand how the lifetime of hooks need to be managed. This piece of code fails the !hook.is_linked() assertion: Any pointers? Also, is there is a non-intrusive AVL tree container as part of boost? struct my_node_t {     int i_;     my_node_t(int i): i_(i) {}         friend bool operator<(const my_node_t& lhs, const my_node_t& rhs)  {         return lhs.i_ < rhs.i_;     }    friend ostream& operator<< (ostream& os,  const my_node_t& n) {        return os << n.i_;    } }; int main() {    avltree tree;    vector vec;    for (int i = 0; i < 10; ++i) vec.push_back(my_node_t(i));    for (int i = 0; i < 10; ++i) tree.insert_unique(vec[i]));    copy(tree.begin(), tree.end(), ostream_operator(cout, " "); }