std::expected<T,E>::emplace
From cppreference.com
C++
Utilities library
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Primary template |
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template
<
class... Args
>
constexpr T& emplace( Args&&... args ) noexcept ; |
(1) | (since C++23) |
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template
<
class U, class... Args
>
constexpr T& emplace( std::initializer_list <U> il, Args&&... args ) noexcept ; |
(2) | (since C++23) |
void partial specialization |
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constexpr void emplace() noexcept;
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(3) | (since C++23) |
Constructs an expected value in-place. After the call, has_value() returns true.
1) Destroys the contained value, then direct-initializes the expected value contained in *this with
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 direct-initializes the expected value contained in *this with 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)
*
std::construct_at
(
std::addressof
(
val
), std::forward
<Args>
(args)...)
2)
*
std::construct_at
(
std::addressof
(
val
), il, std::forward
<Args>
(args)...)
Notes
If the construction of T is potentially-throwing, operator= can be used instead.
Example
| This section is incomplete Reason: no example |
See also
| assigns contents (public member function) |