4.8 KiB
[any.modifiers]
22 General utilities library [utilities]
22.7 Storage for any type [any]
22.7.4 Class any [any.class]
22.7.4.4 Modifiers [any.modifiers]
template<class T, class... Args> decay_t<T>& emplace(Args&&... args);
Let VT be decay_t.
Constraints: is_copy_constructible_v is true andis_constructible_v<VT, Args...> is true.
Preconditions: VT meets the Cpp17CopyConstructible requirements.
Effects: Calls reset().
Then direct-non-list-initializes the contained value of type VT with std::forward(args)....
Postconditions: *this contains a value.
Returns: A reference to the new contained value.
Throws: Any exception thrown by the selected constructor of VT.
Remarks: If an exception is thrown during the call to VT's constructor,*this does not contain a value, and any previously contained value has been destroyed.
template<class T, class U, class... Args> decay_t<T>& emplace(initializer_list<U> il, Args&&... args);
Let VT be decay_t.
Constraints: is_copy_constructible_v is true andis_constructible_v<VT, initializer_list&, Args...> is true.
Preconditions: VT meets the Cpp17CopyConstructible requirements.
Effects: Calls reset().
Then direct-non-list-initializes the contained value of type VT with il, std::forward(args)....
Postconditions: *this contains a value.
Returns: A reference to the new contained value.
Throws: Any exception thrown by the selected constructor of VT.
Remarks: If an exception is thrown during the call to VT's constructor,*this does not contain a value, and any previously contained value has been destroyed.
void reset() noexcept;
Effects: If has_value() is true, destroys the contained value.
Postconditions: has_value() is false.
void swap(any& rhs) noexcept;
Effects: Exchanges the states of *this and rhs.