[boost] boost::shared_ptr<>::compare_and_swap() -- Am I insane for wanting this?

Hi, I have a question for the designers and implementers of boost::shared_ptr: Is there any plan afoot to support lock-free programming using shared_ptr? I was fooling around with wanting to attempt lock-free update of a tree structure that I have that uses shared_ptr. If no-one's thinking about this, how might I go about implementing: bool boost::shared_ptr<T>::compare_and_swap(T* original, shared_ptr<T>& new_one) Am I insane in asking for this? ;^) Does this have a prayer of being exception-safe? Thanks. -- George T. Talbot <gtalbot@locuspharma.com>