libstdc++
std::weak_ptr< _Tp > Class Template Reference

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_ptroperator= (const weak_ptr &__r) noexcept=default
 
template<typename _Yp >
_Assignable< const weak_ptr< _Yp > & > operator= (const weak_ptr< _Yp > &__r) noexcept
 
weak_ptroperator= (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 Functions

(Note that these are not member functions.)

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.

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 686 of file bits/shared_ptr.h.


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