NAME¶

std::expected::emplace - std::expected::emplace

Synopsis¶

T is not cv void
template< class... Args > (1) (since C++23)
constexpr T& emplace( Args&&... args ) noexcept;
template< class U, class... Args >
constexpr T& emplace( std::initializer_list<U> il, Args&&... args (2) (since C++23)
) noexcept;
T is cv void
constexpr void emplace() noexcept; (3) (since C++23)

Constructs an expected value in-place. After the call, has_value() returns true.

1) Destroys the contained value, then initializes the expected value contained in
*this as if by direct-initializing an object of type T from the arguments
std::forward<Args>(args)....
This overload participates in overload resolution only if
std::is_nothrow_constructible_v<T, Args...> is true.
2) Destroys the contained value, then initializes the expected value contained in
*this as if by direct-initializing an object of type T from the arguments il and
std::forward<Args>(args)....
This overload participates in overload resolution only if
std::is_nothrow_constructible_v<T, std::initializer_list<U>&, Args...> is true.
3) If *this contains an unexpected value, destroys that value.

Parameters¶

args - the arguments to pass to the constructor
il - the initializer list to pass to the constructor

Return value¶

1,2) A reference to the new contained value.
3) (none)

Notes¶

If the construction of T is potentially-throwing, this function is not defined. In
this case, it is the responsibility of the user to create a temporary object and
move or copy it.

Example¶

This section is incomplete
Reason: no example

See also¶

operator= assigns contents
(public member function)

Category:¶

* Todo no example