Hi! There is a intrusive_ptr.cpp in boost 1.28, but I did not find any doc for that... exept for in the timing . Why? Guessing from the name, intrusive_ptr requires the pointed-to object to store the reference count or something like that, doesn't it? And what does anybody think of typedefing std::auto_ptr to boost::single_ptr? Finally I have a suggestion for a new type of smart pointer one could call "notifying_ptr": Sometimes all weak pointing objects need to be notified when the object pointed to is destroyed: e.g. in a game some units are set to attack some building, so they store a weak_ptr to the building, but when that building is destroyed, it would be easier to implement and faster performing, if the units got a message so they can look for a new target, instead of having strong pointers, marking the building as dead, and polling for that state every time the unit does something. It could be quite some time until all units have realized that the building is gone and it really can be released from memory. Regards