20 General utilities library [utilities]

20.8 Storage for any type [any]

20.8.4 Class any [any.class]

20.8.4.2 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_­type<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.
template<class T> any(T&& value);
Let VT be decay_­t<T>.
Constraints: 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.
Preconditions: VT meets the Cpp17CopyConstructible requirements.
Effects: Constructs an object of type any that contains an object of type VT direct-initialized with std​::​forward<T>(value).
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>.
Constraints: is_­copy_­constructible_­v<VT> is true and is_­constructible_­v<VT, Args...> is true.
Preconditions: VT meets the Cpp17CopyConstructible requirements.
Effects: Direct-non-list-initializes the contained value of type VT with std​::​forward<Args>(args)....
Postconditions: *this contains a value of type VT.
Throws: Any exception thrown by the selected constructor of VT.
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>.
Constraints: is_­copy_­constructible_­v<VT> is true and is_­constructible_­v<VT, initializer_­list<U>&, Args...> is true.
Preconditions: VT meets the Cpp17CopyConstructible requirements.
Effects: Direct-non-list-initializes the contained value of type VT with il, std​::​forward<Args>(​args)....
Postconditions: *this contains a value.
Throws: Any exception thrown by the selected constructor of VT.
~any();
Effects: As if by reset().