Boost C++ Libraries

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Class any

boost::any — A class whose instances can hold instances of any type that satisfies ValueType requirements.

Synopsis

// In header: <boost/any.hpp>


class any {
public:
  // construct/copy/destruct
  any();
  any(const any &);
  template<typename ValueType> any(const ValueType &);
  any & operator=(const any &);
  template<typename ValueType> any & operator=(const ValueType &);
  ~any();

  // modifiers
  any & swap(any &);

  // queries
  bool empty() const;
  const std::type_info & type() const;
};

Description

`any` public construct/copy/destruct

```
any();
```
Postconditions:
this->empty()

any(const any & other);

Effects:	Copy constructor that copies content of `other` into new instance, so that any content is equivalent in both type and value to the content of `other`, or empty if `other` is empty.
Throws:	May fail with a `std::bad_alloc` exception or any exceptions arising from the copy constructor of the contained type.

template<typename ValueType> any(const ValueType & value);

Effects:	Makes a copy of `value`, so that the initial content of the new instance is equivalent in both type and value to `value`.
Throws:	`std::bad_alloc` or any exceptions arising from the copy constructor of the contained type.

any & operator=(const any & rhs);

Effects:	Copies content of `rhs` into current instance, discarding previous content, so that the new content is equivalent in both type and value to the content of `rhs`, or empty if `rhs.empty()`.
Throws:	`std::bad_alloc` or any exceptions arising from the copy constructor of the contained type. Assignment satisfies the strong guarantee of exception safety.

template<typename ValueType> any & operator=(const ValueType & rhs);

Effects:	Makes a copy of `rhs`, discarding previous content, so that the new content of is equivalent in both type and value to `rhs`.
Throws:	`std::bad_alloc` or any exceptions arising from the copy constructor of the contained type. Assignment satisfies the strong guarantee of exception safety.

```
~any();
```
Effects:
Releases any and all resources used in management of instance.

Throws:
Nothing.

`any` modifiers

```
any & swap(any & rhs);
```
Effects:
Exchange of the contents of *this and rhs.

Returns:
*this

Throws:
Nothing.

`any` queries

```
bool empty() const;
```
Returns:
true if instance is empty, otherwise false.

Throws:
Will not throw.

const std::type_info & type() const;

Returns:	the `typeid` of the contained value if instance is non-empty, otherwise `typeid(void)`.
Notes:	Useful for querying against types known either at compile time or only at runtime.