std::enable_shared_from_this::shared_from_this
From cppreference.com
< cpp | memory | enable shared from this
shared_ptr<T> shared_from_this(); |
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shared_ptr<T const> shared_from_this() const; |
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Returns a std::shared_ptr<T> that shares ownership of *this with all existing std::shared_ptr that refer to *this.
Effectively executes std::shared_ptr<T>(weak_this), where weak_this
is the private mutable std::weak_ptr<T> member of enable_shared_from_this
.
Notes
It is permitted to call shared_from_this
only on a previously shared object, i.e. on an object managed by std::shared_ptr. Otherwise the behavior is undefined (until C++17)std::bad_weak_ptr is thrown (by the shared_ptr constructor from a default-constructed weak_this
) (since C++17).
Return value
std::shared_ptr<T> that shares ownership of *this with pre-existing std::shared_ptrs
Example
Run this code
#include <iostream> #include <memory> struct Foo : public std::enable_shared_from_this<Foo> { Foo() { std::cout << "Foo::Foo\n"; } ~Foo() { std::cout << "Foo::~Foo\n"; } std::shared_ptr<Foo> getFoo() { return shared_from_this(); } }; int main() { Foo *f = new Foo; std::shared_ptr<Foo> pf1; { std::shared_ptr<Foo> pf2(f); pf1 = pf2->getFoo(); // shares ownership of object with pf2 } std::cout << "pf2 is gone\n"; }
Output:
Foo::Foo pf2 is gone Foo::~Foo
See also
(C++11) |
smart pointer with shared object ownership semantics (class template) |