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) |