I'm thinking about replacing some uses of shared_ptr with intrusive_ptr, but I've got questions. One of the nice things about shared_ptr is the lock-free thread-safe ref counting. I want my intrusive_ptr to have the same safety and efficiency, but I don't see how to get it. I see $boost_root/detail/atomic_count.hpp, but shared_ptr doesn't use it. Why not? And why is it in detail/? Should I not consider using it? Taking in the bigger picture, intrusive_ptr requires people to write their own add_ref and release functions, most of which will probably end up using ++ and -- on a plain integer. This is totally broken in multi-threaded applications, right? Isn't it dangerous to not provide complementary utilities for correctly managing reference counts? It seems to me intrusive_ptr is impossible to use safely and portably. What have I missed? -- Eric Niebler Boost Consulting www.boost-consulting.com