cppdraft_translate/cppdraft/util/smartptr/enab.md

[util.smartptr.enab]

20 Memory management library [mem]

20.3 Smart pointers [smartptr]

20.3.2 Shared-ownership pointers [util.sharedptr]

20.3.2.7 Class template enable_shared_from_this [util.smartptr.enab]

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A class T can inherit from enable_shared_from_this to inherit the shared_from_this member functions that obtain a shared_ptr instance pointing to *this.

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[Example 1: struct X: public enable_shared_from_this { };

int main() { shared_ptr p(new X); shared_ptr q = p->shared_from_this(); assert(p == q); assert(p.owner_equal(q)); // p and q share ownership} — end example]

namespace std {template class enable_shared_from_this {protected:constexpr enable_shared_from_this() noexcept; constexpr enable_shared_from_this(const enable_shared_from_this&) noexcept; constexpr enable_shared_from_this& operator=(const enable_shared_from_this&) noexcept; constexpr ~enable_shared_from_this(); public:constexpr shared_ptr shared_from_this(); constexpr shared_ptr shared_from_this() const; constexpr weak_ptr weak_from_this() noexcept; constexpr weak_ptr weak_from_this() const noexcept; private:mutable weak_ptr weak-this; // exposition only};}

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The template parameter T of enable_shared_from_this may be an incomplete type.

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constexpr enable_shared_from_this() noexcept; constexpr enable_shared_from_this(const enable_shared_from_this<T>&) noexcept;

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Effects: Value-initializes weak-this.

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constexpr enable_shared_from_this<T>& operator=(const enable_shared_from_this<T>&) noexcept;

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Returns: *this.

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[Note 1:

weak-this is not changed.

— end note]

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constexpr shared_ptr<T> shared_from_this(); constexpr shared_ptr<T const> shared_from_this() const;

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Returns: shared_ptr(weak-this).

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constexpr weak_ptr<T> weak_from_this() noexcept; constexpr weak_ptr<T const> weak_from_this() const noexcept;

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Returns: weak-this.