20 General utilities library [utilities]

20.6 Optional objects [optional]

20.6.9 Specialized algorithms [optional.specalg]

🔗
template<class T> void swap(optional<T>& x, optional<T>& y) noexcept(noexcept(x.swap(y)));
1
#
Constraints: is_­move_­constructible_­v<T> is true and is_­swappable_­v<T> is true.
2
#
Effects: Calls x.swap(y).
🔗
template<class T> constexpr optional<decay_t<T>> make_optional(T&& v);
3
#
Returns: optional<decay_­t<T>>(std​::​forward<T>(v)).
🔗
template<class T, class...Args> constexpr optional<T> make_optional(Args&&... args);
4
#
Effects: Equivalent to: return optional<T>(in_­place, std​::​forward<Args>(args)...);
🔗
template<class T, class U, class... Args> constexpr optional<T> make_optional(initializer_list<U> il, Args&&... args);
5
#
Effects: Equivalent to: return optional<T>(in_­place, il, std​::​forward<Args>(args)...);