Asio's implementation can use std::shared_ptr<> and std::weak_ptr<> in preference to the Boost equivalents.

Support for the standard smart pointers is automatically enabled for g++ 4.3 and later, when the -std=c++0x or -std=gnu++0x compiler options are used, as well as for Microsoft Visual C++ 10. It may be disabled by defining ASIO_DISABLE_STD_SHARED_PTR, or explicitly enabled for other compilers by defining ASIO_HAS_STD_SHARED_PTR.