23 General utilities library [utilities]

23.11 Smart pointers [smartptr]

23.11.2 Shared-ownership pointers [util.smartptr]

23.11.2.3 Class template weak_­ptr [util.smartptr.weak]

23.11.2.3.1 weak_­ptr constructors [util.smartptr.weak.const]

constexpr weak_ptr() noexcept;

1
#

Effects: Constructs an empty weak_­ptr object.

2
#

Postconditions: use_­count() == 0.

weak_ptr(const weak_ptr& r) noexcept; template<class Y> weak_ptr(const weak_ptr<Y>& r) noexcept; template<class Y> weak_ptr(const shared_ptr<Y>& r) noexcept;

3
#

Remarks: The second and third constructors shall not participate in overload resolution unless Y* is compatible with T*.

4
#

Effects: If r is empty, constructs an empty weak_­ptr object; otherwise, constructs a weak_­ptr object that shares ownership with r and stores a copy of the pointer stored in r.

5
#

Postconditions: use_­count() == r.use_­count().

weak_ptr(weak_ptr&& r) noexcept; template<class Y> weak_ptr(weak_ptr<Y>&& r) noexcept;

6
#

Remarks: The second constructor shall not participate in overload resolution unless Y* is compatible with T*.

7
#

Effects: Move constructs a weak_­ptr instance from r.

8
#

Postconditions: *this shall contain the old value of r. r shall be empty. r.use_­count() == 0.