std::make_optional (3) Linux Manual Page

std::make_optional – std::make_optional

Synopsis

Defined in header<optional>

    template <class T>
    (1)(since C++ 17)

        constexpr std::optional<std::decay_t<T>> make_optional(T &&value);

template <class T, class... Args>
(2)(since C++ 17)

    constexpr std::optional<T> make_optional(Args &&...args);

template <class T, class U, class... Args>
(3)(since C++ 17)

    constexpr std::optional<T> make_optional(std::initializer_list<U> il, Args &&...args);
1) Creates an optional object from value. Effectively calls std::optional<std::decay_t<T>>(std::forward<T>(value))

2) Creates an optional object constructed in-place from args.... Equivalent to return std::optional<T>(std::in_place, std::forward<Args>(args)...);.

3) Creates an optional object constructed in-place from il and args.... Equivalent to return std::optional<T>(std::in_place, il, std::forward<Args>(args)...);
.

Parameters

value – the value to construct optional object with
il, args – arguments to be passed to the constructor of T.

Return value

The constructed optional object.

Exceptions

Throws any exception thrown by the constructor of T.

Notes

T need not be movable for overloads (2-3) due to guaranteed copy elision.

See also

              constructs the optional object
constructor (public member function)