"Fernando Cacciola" <fernando_cacciola@hotmail.com> escribió en el mensaje news:cutcrj$tcb$1@sea.gmane.org...
"Joe Gottman" <jgottman@carolina.rr.com> escribió en el mensaje news:curjg1$2vq$1@sea.gmane.org...
[SNIP]
It has the added advantage that if T's assignment operator has the strong exception safety guarantee, so does optional<T>'s assignment operator.
Well, this is a good point. It is typical for classes with a throwing copy ctor to have a strong assignment.
OK, I was sure there was a good reason why I didn't use T's assignment to begin with. I just didn't remeber it when I responded. The idea is that by using T's operator=() we are _entirely_ left to its own exception guarantees, with no guarantee at all from optional<T> itself. The current implementation gives you the basic guarantee, which is more than enough in most cases, no matter how ill T could be: if something goes wrong while reseting the value of *this, it is left uninitialized. So the correct path is to add the cannonical guard AFAICS. Cheers Fernando Cacciola