std::auto_ptr(3)

NAME
std::auto_ptr - A simple smart pointer providing strict ownership semantics.

SYNOPSIS

  Public Types
typedef _Tp element_type

  Public Member Functions
auto_ptr (auto_ptr_ref< element_type > __ref) throw ()
template<typename _Tp1 > auto_ptr (auto_ptr< _Tp1 > &__a) throw ()
auto_ptr (auto_ptr &__a) throw ()
auto_ptr (element_type *__p=0) throw ()
element_type * get () const throw ()
template<typename _Tp1 > operator auto_ptr< _Tp1 > () throw ()
template<typename _Tp1 > operator auto_ptr_ref< _Tp1 > () throw ()
element_type & operator* () const throw ()
element_type * operator-> () const throw ()
auto_ptr & operator= (auto_ptr_ref< element_type > __ref) throw ()
template<typename _Tp1 > auto_ptr & operator= (auto_ptr< _Tp1 > &__a) throw ()
auto_ptr & operator= (auto_ptr &__a) throw ()
element_type * release () throw ()
void reset (element_type *__p=0) throw ()
~auto_ptr ()

Detailed Description

  template<typename _Tp> class std::auto_ptr< _Tp >
A simple smart pointer providing strict ownership semantics. The Standard says:

  An auto_ptr owns the object it holds a pointer to.  Copying
  an auto_ptr copies the pointer and transfers ownership to the
  destination.  If more than one auto_ptr owns the same object
  at the same time the behavior of the program is undefined.

  The uses of auto_ptr include providing temporary
  exception-safety for dynamically allocated memory, passing
  ownership of dynamically allocated memory to a function, and
  returning dynamically allocated memory from a function.  auto_ptr does not meet the CopyConstructible and Assignable
  requirements for Standard Library container elements and thus
  instantiating a Standard Library container with an auto_ptr results in undefined behavior.

 Quoted from [20.4.5]/3.

Good examples of what can and cannot be done with auto_ptr can be found in the libstdc++ testsuite.

_GLIBCXX_RESOLVE_LIB_DEFECTS 127. auto_ptr<> conversion issues These resolutions have all been incorporated.

Definition at line 90 of file auto_ptr.h.

Member Typedef Documentation

  template<typename _Tp> typedef _Tp std::auto_ptr< _Tp >::element_type

The pointed-to type.

Definition at line 97 of file auto_ptr.h.

Constructor & Destructor Documentation

  template<typename _Tp> std::auto_ptr< _Tp >::auto_ptr (element_type * __p = 0) throw () [inline, explicit]

An auto_ptr is usually constructed from a raw pointer.

Parameters:
    p A pointer (defaults to NULL).

This object now owns the object pointed to by p.

Definition at line 106 of file auto_ptr.h.

  template<typename _Tp> std::auto_ptr< _Tp >::auto_ptr (auto_ptr< _Tp > & __a) throw () [inline]

An auto_ptr can be constructed from another auto_ptr.

Parameters:
    a Another auto_ptr of the same type.

This object now owns the object previously owned by a, which has given up ownership.

Definition at line 115 of file auto_ptr.h.

  template<typename _Tp> template<typename _Tp1 > std::auto_ptr< _Tp >::auto_ptr (auto_ptr< _Tp1 > & __a) throw () [inline]

An auto_ptr can be constructed from another auto_ptr.

Parameters:
    a Another auto_ptr of a different but related type.

A pointer-to-Tp1 must be convertible to a pointer-to-Tp/element_type.

This object now owns the object previously owned by a, which has given up ownership.

Definition at line 128 of file auto_ptr.h.

  template<typename _Tp> std::auto_ptr< _Tp >::~auto_ptr () [inline]

When the auto_ptr goes out of scope, the object it owns is deleted. If it no longer owns anything (i.e., get() is NULL), then this has no effect.

The C++ standard says there is supposed to be an empty throw specification here, but omitting it is standard conforming. Its presence can be detected only if _Tp::~_Tp() throws, but this is prohibited. [17.4.3.6]/2

Definition at line 173 of file auto_ptr.h.

  template<typename _Tp> std::auto_ptr< _Tp >::auto_ptr (auto_ptr_ref< element_type > __ref) throw () [inline]

Automatic conversions.

These operations convert an auto_ptr into and from an auto_ptr_ref automatically as needed. This allows constructs such as

    auto_ptr<Derived>  func_returning_auto_ptr(.....);
    ...
    auto_ptr<Base> ptr = func_returning_auto_ptr(.....);

Definition at line 263 of file auto_ptr.h.

Member Function Documentation

  template<typename _Tp> element_type* std::auto_ptr< _Tp >::get (void) const throw () [inline]

Bypassing the smart pointer.

Returns:
    The raw pointer being managed.

You can get a copy of the pointer that this object owns, for situations such as passing to a function which only accepts a raw pointer.

Note:
    This auto_ptr still owns the memory.

Definition at line 214 of file auto_ptr.h.

  template<typename _Tp> element_type& std::auto_ptr< _Tp >::operator* () const throw () [inline]

Smart pointer dereferencing.

If this auto_ptr no longer owns anything, then this operation will crash. (For a smart pointer, 'no longer owns anything' is the same as being a null pointer, and you know what happens when you dereference one of those...)

Definition at line 184 of file auto_ptr.h.

References std::operator*().

  template<typename _Tp> element_type* std::auto_ptr< _Tp >::operator-> () const throw () [inline]

Smart pointer dereferencing.

This returns the pointer itself, which the language then will automatically cause to be dereferenced.

Definition at line 197 of file auto_ptr.h.

  template<typename _Tp> template<typename _Tp1 > auto_ptr& std::auto_ptr< _Tp >::operator= (auto_ptr< _Tp1 > & __a) throw () [inline]

auto_ptr assignment operator.

Parameters:
    a Another auto_ptr of a different but related type.

A pointer-to-Tp1 must be convertible to a pointer-to-Tp/element_type.

This object now owns the object previously owned by a, which has given up ownership. The object that this one used to own and track has been deleted.

Definition at line 157 of file auto_ptr.h.

  template<typename _Tp> auto_ptr& std::auto_ptr< _Tp >::operator= (auto_ptr< _Tp > & __a) throw () [inline]

auto_ptr assignment operator.

Parameters:
    a Another auto_ptr of the same type.

This object now owns the object previously owned by a, which has given up ownership. The object that this one used to own and track has been deleted.

Definition at line 139 of file auto_ptr.h.

  template<typename _Tp> element_type* std::auto_ptr< _Tp >::release () throw () [inline]

Bypassing the smart pointer.

Returns:
    The raw pointer being managed.

You can get a copy of the pointer that this object owns, for situations such as passing to a function which only accepts a raw pointer.

Note:
    This auto_ptr no longer owns the memory. When this object goes out of scope, nothing will happen.

Definition at line 228 of file auto_ptr.h.

  template<typename _Tp> void std::auto_ptr< _Tp >::reset (element_type * __p = 0) throw () [inline]

Forcibly deletes the managed object.

Parameters:
    p A pointer (defaults to NULL).

This object now owns the object pointed to by p. The previous object has been deleted.

Definition at line 243 of file auto_ptr.h.

Author

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