std::get_deleter
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C++
Memory management library
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std::shared_ptr
| Member functions | ||||
| Modifiers | ||||
| Observers | ||||
(C++17) | ||||
(until C++20*) | ||||
(C++26) | ||||
(C++26) | ||||
| Non-member functions | ||||
get_deleter | ||||
(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20) | ||||
functions (until C++26*) | ||||
| Helper classes | ||||
(C++20) | ||||
| Deduction guides(C++17) |
| Defined in header <memory>
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| template< class Deleter, class T > Deleter* get_deleter( const std::shared_ptr<T>& p ) noexcept; |
(since C++11) | |
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.
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[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_ptrs 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
| std::shared_ptr constructors (public member function) | |
| returns the deleter that is used for destruction of the managed object (public member function of std::unique_ptr<T,Deleter>) [edit]
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