std::get_deleter
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std::shared_ptr
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get_deleter
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Defined in header
<memory>
template< class Deleter, class T >
Deleter* get_deleter( const std::shared_ptr <T>& p ) noexcept;
(since C++11)
Deleter* get_deleter( const std::shared_ptr <T>& p ) noexcept;
Access to the p's deleter. If the shared pointer p owns a deleter of type cv-unqualified Deleter (e.g. if it was created with one of the constructors that take a deleter as a parameter), then returns a pointer to the deleter. Otherwise, returns a null pointer.
Contents
[edit] Parameters
p
-
a shared pointer whose deleter needs to be accessed
[edit] Return value
A pointer to the owned deleter or nullptr. The returned pointer is valid at least as long as there remains at least one shared_ptr instance that owns it.
[edit] Notes
The returned pointer may outlive the last shared_ptr if, for example, std::weak_ptr s remain and the implementation doesn't destroy the deleter until the entire control block is destroyed.
[edit] Example
Demonstrates that std::shared_ptr deleter is independent of the shared_ptr 's type.
Run this code
#include <iostream> #include <memory> struct Foo { int i; }; void foo_deleter(Foo* p) { std::cout << "foo_deleter called!\n"; delete p; } int main() { std::shared_ptr <int> aptr; { // create a shared_ptr that owns a Foo and a deleter auto foo_p = new Foo; std::shared_ptr <Foo> r(foo_p, foo_deleter); aptr = std::shared_ptr <int>(r, &r->i); // aliasing ctor // aptr is now pointing to an int, but managing the whole Foo } // r gets destroyed (deleter not called) // obtain pointer to the deleter: if (auto del_p = std::get_deleter<void(*)(Foo*)>(aptr)) { std::cout << "shared_ptr<int> owns a deleter\n"; if (*del_p == foo_deleter) std::cout << "...and it equals &foo_deleter\n"; } else std::cout << "The deleter of shared_ptr<int> is null!\n"; } // deleter called here
Output:
shared_ptr<int> owns a deleter ...and it equals &foo_deleter foo_deleter called!
[edit] See also
returns the deleter that is used for destruction of the managed object
(public member function of
(public member function of
std::unique_ptr<T,Deleter>) [edit]