Fernando Cacciola wrote:
"Peter Dimov" <pdimov@mmltd.net> escribió en el mensaje news:003201c51395$4f587820$6501a8c0@pdimov2...
A correct assignment operator should typically handle self-assignment without an explicit test. Adding the test usually doesn't fix the problem, only its most obvious manifestation.
Which could be accounted as good enough for classes intended to be used in certain ways, thus making the swap idiom overkill.
It would (probably) be OK to offer a "limited" assignment operator that doesn't handle certain corner cases, but only if these cases are clearly documented as part of the preconditions of operator=. But I'm really not sure why should optional<> attempt to provide a basic guarantee when the contained type does not (unless the basic guarantee is free, which it isn't.) A type that doesn't provide the basic guarantee is pretty much unusable. It seems to me that the straightforward solution is to just defer to T::operator= when necessary. Those that want destroy+recreate semantics can always obtain them explicitly.