JOAQUIN LOPEZ MU?Z wrote:
In the rationale of Boost.Optional, optional<T> is proposed as a convenient replacement of the time-honored practice of returning a std::pair<T,bool> with the bool indicating whether the T object is meaningful or not. Notably, this is precisely what some STL containers' memfuns do.
So why not augment optional<T> with the following:
optional<T>::optional(std::pair<T,bool> const&);
and the obvious semantics? This would allow for instance to use optional<> like this:
std::set<int> s; ... boost::optional<int> oi=s.insert(10); // oi is initialized iff insertion took place.
Comments? Apologies if this has been discussed previously.
Hi, Others have pointed out that the "bool" there doesn't mean ".first" is uninitialized, but anyway I like your idea :-) There are interfaces which do use pair<T,bool> with .second indicating if .first actually exist, so I see your point. Can anybody think of a reason for NOT adding it? If no one complains, I'll add it. Fernando Cacciola SciSoft