std::expected<T,E>:: emplace
From cppreference.com
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Primary template
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template
<
class
...
Args
>
constexpr T & emplace ( Args && ... args ) noexcept ; |
(1) | (since C++23) |
|
template
<
class
U,
class
...
Args
>
constexpr T & emplace ( std:: initializer_list < U > il, Args && ... args ) noexcept ; |
(2) | (since C++23) |
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void
partial specialization
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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
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) |