libstdc++
Public Types | Public Member Functions | Related Symbols | List of all members
std::weak_ptr< _Tp > Class Template Reference
Utilities » Memory » Pointer Abstractions

#include <memory>

Inherits std::__weak_ptr< _Tp, _Lp >.

Public Types

using element_type = typename remove_extent< _Tp >::type
 

Public Member Functions

template<typename _Yp , typename = _Constructible<const shared_ptr<_Yp>&>>
 weak_ptr (const shared_ptr< _Yp > &__r) noexcept
 
 weak_ptr (const weak_ptr &) noexcept=default
 
template<typename _Yp , typename = _Constructible<const weak_ptr<_Yp>&>>
 weak_ptr (const weak_ptr< _Yp > &__r) noexcept
 
 weak_ptr (weak_ptr &&) noexcept=default
 
template<typename _Yp , typename = _Constructible<weak_ptr<_Yp>>>
 weak_ptr (weak_ptr< _Yp > &&__r) noexcept
 
bool expired () const noexcept
 
shared_ptr< _Tp > lock () const noexcept
 
template<typename _Yp >
_Assignable< const shared_ptr< _Yp > & > operator= (const shared_ptr< _Yp > &__r) noexcept
 
weak_ptr & operator= (const weak_ptr &__r) noexcept=default
 
template<typename _Yp >
_Assignable< const weak_ptr< _Yp > & > operator= (const weak_ptr< _Yp > &__r) noexcept
 
weak_ptr & operator= (weak_ptr &&__r) noexcept=default
 
template<typename _Yp >
_Assignable< weak_ptr< _Yp > > operator= (weak_ptr< _Yp > &&__r) noexcept
 
template<typename _Tp1 >
bool owner_before (const __shared_ptr< _Tp1, _Lp > &__rhs) const noexcept
 
template<typename _Tp1 >
bool owner_before (const __weak_ptr< _Tp1, _Lp > &__rhs) const noexcept
 
void reset () noexcept
 
void swap (__weak_ptr &__s) noexcept
 
long use_count () const noexcept
 

Related Symbols

(Note that these are not member symbols.)

template<typename _Tp >
void swap (weak_ptr< _Tp > &__a, weak_ptr< _Tp > &__b) noexcept
 

Detailed Description

template<typename _Tp>
class std::weak_ptr< _Tp >

A non-owning observer for a pointer owned by a shared_ptr.

Since
C++11

A weak_ptr provides a safe alternative to a raw pointer when you want a non-owning reference to an object that is managed by a shared_ptr.

Unlike a raw pointer, a weak_ptr can be converted to a new shared_ptr that shares ownership with every other shared_ptr that already owns the pointer. In other words you can upgrade from a non-owning "weak" reference to an owning shared_ptr, without having access to any of the existing shared_ptr objects.

Also unlike a raw pointer, a weak_ptr does not become "dangling" after the object it points to has been destroyed. Instead, a weak_ptr becomes expired and can no longer be converted to a shared_ptr that owns the freed pointer, so you cannot accidentally access the pointed-to object after it has been destroyed.

Definition at line 811 of file bits/shared_ptr.h.

Member Typedef Documentation

◆ element_type

template<typename _Tp , _Lock_policy _Lp>
using std::__weak_ptr< _Tp, _Lp >::element_type = typename remove_extent<_Tp>::type
inherited

Definition at line 1985 of file shared_ptr_base.h.

Constructor & Destructor Documentation

◆ weak_ptr() [1/3]

template<typename _Tp >
template<typename _Yp , typename = _Constructible<const shared_ptr<_Yp>&>>
std::weak_ptr< _Tp >::weak_ptr ( const shared_ptr< _Yp > &  __r)
inlinenoexcept

Definition at line 828 of file bits/shared_ptr.h.

◆ weak_ptr() [2/3]

template<typename _Tp >
template<typename _Yp , typename = _Constructible<const weak_ptr<_Yp>&>>
std::weak_ptr< _Tp >::weak_ptr ( const weak_ptr< _Yp > &  __r)
inlinenoexcept

Definition at line 834 of file bits/shared_ptr.h.

◆ weak_ptr() [3/3]

template<typename _Tp >
template<typename _Yp , typename = _Constructible<weak_ptr<_Yp>>>
std::weak_ptr< _Tp >::weak_ptr ( weak_ptr< _Yp > &&  __r)
inlinenoexcept

Definition at line 840 of file bits/shared_ptr.h.

Member Function Documentation

◆ expired()

template<typename _Tp , _Lock_policy _Lp>
bool std::__weak_ptr< _Tp, _Lp >::expired ( ) const
inlinenoexceptinherited

Definition at line 2075 of file shared_ptr_base.h.

◆ lock()

template<typename _Tp >
shared_ptr< _Tp > std::weak_ptr< _Tp >::lock ( ) const
inlinenoexcept

Definition at line 874 of file bits/shared_ptr.h.

◆ operator=() [1/3]

template<typename _Tp >
template<typename _Yp >
_Assignable< const shared_ptr< _Yp > & > std::weak_ptr< _Tp >::operator= ( const shared_ptr< _Yp > &  __r)
inlinenoexcept

Definition at line 856 of file bits/shared_ptr.h.

◆ operator=() [2/3]

template<typename _Tp >
template<typename _Yp >
_Assignable< const weak_ptr< _Yp > & > std::weak_ptr< _Tp >::operator= ( const weak_ptr< _Yp > &  __r)
inlinenoexcept

Definition at line 848 of file bits/shared_ptr.h.

◆ operator=() [3/3]

template<typename _Tp >
template<typename _Yp >
_Assignable< weak_ptr< _Yp > > std::weak_ptr< _Tp >::operator= ( weak_ptr< _Yp > &&  __r)
inlinenoexcept

Definition at line 867 of file bits/shared_ptr.h.

◆ owner_before() [1/2]

template<typename _Tp , _Lock_policy _Lp>
template<typename _Tp1 >
bool std::__weak_ptr< _Tp, _Lp >::owner_before ( const __shared_ptr< _Tp1, _Lp > &  __rhs) const
inlinenoexceptinherited

Definition at line 2080 of file shared_ptr_base.h.

◆ owner_before() [2/2]

template<typename _Tp , _Lock_policy _Lp>
template<typename _Tp1 >
bool std::__weak_ptr< _Tp, _Lp >::owner_before ( const __weak_ptr< _Tp1, _Lp > &  __rhs) const
inlinenoexceptinherited

Definition at line 2085 of file shared_ptr_base.h.

◆ reset()

template<typename _Tp , _Lock_policy _Lp>
void std::__weak_ptr< _Tp, _Lp >::reset ( )
inlinenoexceptinherited

Definition at line 2089 of file shared_ptr_base.h.

◆ swap()

template<typename _Tp , _Lock_policy _Lp>
void std::__weak_ptr< _Tp, _Lp >::swap ( __weak_ptr< _Tp, _Lp > &  __s)
inlinenoexceptinherited

Definition at line 2093 of file shared_ptr_base.h.

◆ use_count()

template<typename _Tp , _Lock_policy _Lp>
long std::__weak_ptr< _Tp, _Lp >::use_count ( ) const
inlinenoexceptinherited

Definition at line 2071 of file shared_ptr_base.h.

The documentation for this class was generated from the following file: