What if something else has a shared_ptr to B? -----Original Message----- From: Scott Meyers [mailto:usenet@aristeia.com] Sent: Friday, August 18, 2006 10:05 AM To: boost-users@lists.boost.org Subject: [Boost-users] [SmartPointers] weak_ptrs, raw pointers, and cycles I've recently realized that I just don't get something. Cycles of shared_ptrs are bad, because they can lead to resource leaks. To break a cycle, we're encouraged to use weak_ptrs. Okay, but we could use raw pointers to break the cycle, too, and I can't see any advantage offered by the weak_ptr. If A uses a shared_ptr to B and B uses a weak_ptr to A, B's life will be shorter than A's (its destructor will be invoked from A's destructor and will run to completion before A's does), so there is no advantage to a weak_ptr being able to tell if it dangles. In this context, it never will. So it seems that using a raw pointer to break cycles has no disadvantage over a weak_ptr, and it's more efficient (i.e., smaller and faster). Clearly, I'm missing something. Can somebody please explain what it is? I understand that weak_ptrs have other uses (e.g., as observers), so my question is only about the advice to use weak_ptrs to break cycles. Thanks, Scott _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users