Defined in header <memory> | ||
|---|---|---|
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.
| p | - | a shared pointer whose deleter needs to be accessed |
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.
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.
Demonstrates that std::shared_ptr deleter is independent of the shared_ptr's type.
#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 hereOutput:
shared_ptr<int> owns a deleter ...and it equals &foo_deleter foo_deleter called!
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>) |
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