std::make_optional
Defined in header <optional> | ||
|---|---|---|
template< class T > constexpr std::optional<std::decay_t<T>> make_optional( T&& value ); | (1) | (since C++17) |
template< class T, class... Args > constexpr std::optional<T> make_optional( Args&&... args ); | (2) | (since C++17) |
template< class T, class U, class... Args > constexpr std::optional<T> make_optional( std::initializer_list<U> il, Args&&... args ); | (3) | (since C++17) |
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 (public member function) |
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