-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Monday 26 October 2009, Berserker wrote:
The "patched" code:
void init_weak_once() const { // Reinitialization support if( weak_this_.expired() ) { // shared_from_this in costructors support shared_this_.reset(static_cast <T*>(const_cast<enable_shared_from_this2>(this)), detail::esft2_deleter_wrapper()); weak_this_ = shared_this_; } }
I know that the static_cast/const_cast is "problematic" on VC6 (and maybe other compilers) but it could be solved using an offset from enable_shared_from_this2 * to T *. I've attached a testcase that shows the problems with the current enable_shared_from_this2 implementation (with the proposed patch it works). Any feedback about this?
IIRC, the original version of enable_shared_from_this that supported use in constructors did a static_cast to the derived type. But it failed some of the tests, so it was changed to a dynamic_cast. The version currently in svn looks broken, like it was from a later version which relied on a shared_from_this() free function like: template<typename T> shared_ptr<T> shared_from_this(T *); which used shared_ptr aliasing to create and return a shared_ptr which pointed at the same object as was passed in as an argument (so enable_shared_from_this didn't have to do a cast or store a pointer to the derived type). But I don't see any such free function in enable_shared_from_this2.hpp. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) iEYEARECAAYFAkrnL7QACgkQ5vihyNWuA4XFAACfZR2MYD0G5yVKwykKTq+BGwU1 Zm8An0ChaK+AZX/Pp3CRVKzWJKRS2JjL =Qxri -----END PGP SIGNATURE-----