std::experimental::optional<T>:: emplace
From cppreference.com
<
cpp
|
experimental
|
optional
|
template
<
class
...
Args
>
void emplace ( Args && ... args ) ; |
(library fundamentals TS) | |
|
template
<
class
U,
class
...
Args
>
void emplace ( std:: initializer_list < U > ilist, Args && ... args ) ; |
(library fundamentals TS) | |
Constructs the contained value in-place. If * this already contains a value before the call, the contained value is destroyed by calling its destructor.
1)
Initializes the contained value by
direct-initializing
(but not direct-list-initializing) with
std::
forward
<
Args
>
(
args
)
...
as parameters.
2)
Initializes the contained value by calling its constructor with
ilist,
std::
forward
<
Args
>
(
args
)
...
as parameters. This overload participates in overload resolution only if
std::
is_constructible
<
T,
std::
initializer_list
<
U
>
&
, Args
&&
...
>
::
value
is
true
.
Parameters
| args... | - | the arguments to pass to the constructor |
| ilist | - | the initializer list to pass to the constructor |
| Type requirements | ||
-
T
must be constructible from
Args...
|
||
-
T
must be constructible from
std::initializer_list
and
Args...
|
||
Return value
(none)
Exceptions
Any exception thrown by the selected constructor of
T
. If an exception is thrown,
*
this
does not contain a value after this call (the previously contained value, if any, had been destroyed).
See also
|
assigns contents
(public member function) |