20 General utilities library [utilities]

20.11 Smart pointers [smartptr]

20.11.4 Class template weak_­ptr [util.smartptr.weak]

20.11.4.1 Constructors [util.smartptr.weak.const]

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constexpr weak_ptr() noexcept;
1
#
Effects: Constructs an empty weak_­ptr object.
2
#
Postconditions: use_­count() == 0.
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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
#
Constraints: For the second and third constructors, 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().
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weak_ptr(weak_ptr&& r) noexcept; template<class Y> weak_ptr(weak_ptr<Y>&& r) noexcept;
6
#
Constraints: For the second constructor, 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.