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std::experimental::optional::emplace

From cppreference.com
 
 
Technical specifications
Filesystem library (filesystem TS)
Library fundamentals (library fundamentals TS)
Library fundamentals 2 (library fundamentals 2 TS)
Extensions for parallelism (parallelism TS)
Extensions for concurrency (concurrency TS)
Concepts (concepts TS)
Ranges (ranges TS)
Special mathematical functions (special math TR)
 
 
 
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 only participates in overload resolution if std::is_constructible<T, std::initializer_list<U>&, Args&&...>::value is true.

Contents

[edit] 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...

[edit] Return value

(none)

[edit] 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).

[edit] See also

assigns contents
(public member function) [edit]