auto_ptr.h File Reference

This is an internal header file, included by other library headers. More...

#include <bits/c++config.h>
#include <debug/debug.h>

Include dependency graph for auto_ptr.h:

Functions
namespace std	_GLIBCXX_VISIBILITY (default)

Detailed Description

This is an internal header file, included by other library headers.

Do not attempt to use it directly. {memory}

Function Documentation

namespace std _GLIBCXX_VISIBILITY

(

default

)

A wrapper class to provide auto_ptr with reference semantics. For example, an auto_ptr can be assigned (or constructed from) the result of a function which returns an auto_ptr by value.

All the auto_ptr_ref stuff should happen behind the scenes.

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

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

The pointed-to type.

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.

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.

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.

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.

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.

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

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...)

Smart pointer dereferencing.

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

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.

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.

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.

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(.....);

References __glibcxx_function_requires, and _GLIBCXX_DEBUG_ASSERT.