23 General utilities library [utilities]

23.8 Storage for any type [any]

23.8.3 Class any [any.class]

23.8.3.1 Construction and destruction [any.cons]

constexpr any() noexcept;
Postconditions: has_­value() is false.
any(const any& other);
Effects: If other.has_­value() is false, constructs an object that has no value.
Otherwise, equivalent to any(in_­place<T>, any_­cast<const T&>(other)) where T is the type of the contained value.
Throws: Any exceptions arising from calling the selected constructor for the contained value.
any(any&& other) noexcept;
Effects: If other.has_­value() is false, constructs an object that has no value.
Otherwise, constructs an object of type any that contains either the contained value of other, or contains an object of the same type constructed from the contained value of other considering that contained value as an rvalue.
Postconditions: other is left in a valid but otherwise unspecified state.
template<class T> any(T&& value);
Let VT be decay_­t<T>.
Requires: VT shall satisfy the CopyConstructible requirements.
Effects: Constructs an object of type any that contains an object of type VT direct-initialized with std​::​forward<T>(value).
Remarks: This constructor shall not participate in overload resolution unless VT is not the same type as any, VT is not a specialization of in_­place_­type_­t, and is_­copy_­constructible_­v<VT> is true.
Throws: Any exception thrown by the selected constructor of VT.
template <class T, class... Args> explicit any(in_place_type_t<T>, Args&&... args);
Let VT be decay_­t<T>.
Requires: VT shall satisfy the CopyConstructible requirements.
Effects: Initializes the contained value as if direct-non-list-initializing an object of type VT with the arguments std​::​forward<Args>(args)....
Postconditions: *this contains a value of type VT.
Throws: Any exception thrown by the selected constructor of VT.
Remarks: This constructor shall not participate in overload resolution unless is_­copy_­constructible_­v<VT> is true and is_­constructible_­v<VT, Args...> is true.
template <class T, class U, class... Args> explicit any(in_place_type_t<T>, initializer_list<U> il, Args&&... args);
Let VT be decay_­t<T>.
Requires: VT shall satisfy the CopyConstructible requirements.
Effects: Initializes the contained value as if direct-non-list-initializing an object of type VT with the arguments il, std​::​forward<Args>(args)....
Postconditions: *this contains a value.
Throws: Any exception thrown by the selected constructor of VT.
Remarks: This constructor shall not participate in overload resolution unless is_­copy_­constructible_­v<VT> is true and is_­constructible_­v<VT, initializer_­list<U>&, Args...> is true.
~any();
Effects: As if by reset().