C++ smart_ptr enabled handle class w/ custom deleter

gistfile1.cpp

namespace win32 {
    // deleter traits
    template <class T> struct handle_deleter_t {
        typedef T handle_type;
    };
    struct win32_handle_deleter : public handle_deleter_t<HANDLE> {
        void operator()(handle_type handle) {
            if (handle && handle != INVALID_HANDLE_VALUE) ::CloseHandle(handle);
        };
    };

    // smart handle pointer
    template <class T, class D>
    struct smart_handle_t : public std::tr1::shared_ptr<typename std::tr1::remove_pointer<T>::type> {
        typedef smart_handle_t<T, D> type;
        typedef std::tr1::shared_ptr<typename std::tr1::remove_pointer<T>::type> base_type;
        typedef T handle_type;
        typedef D deleter_type;

        smart_handle_t() : base_type() {};
        explicit smart_handle_t(handle_type handle) : base_type(handle, deleter_type()) {};

        void reset() {
            base_type::reset();
        };
        void reset(handle_type handle) {
            base_type::reset(handle, deleter_type());
        };

        type& operator=(handle_type handle) {
            base_type::reset(handle, deleter_type());
            return *this;
        };
    };

    typedef smart_handle_t<HANDLE, win32_handle_deleter> shared_handle;
    typedef shared_handle pipe_handle;
    typedef shared_handle event_handle;
}