Difference between revisions of "cpp/memory/unique ptr/get deleter"
From cppreference.com
< cpp | memory | unique ptr
m (C++23 constexpr / P2273R3) |
(improved example, how to use deleter (not just custom ones)) |
||
| Line 26: | Line 26: | ||
struct Foo | struct Foo | ||
{ | { | ||
| − | Foo() { std::cout << "Foo | + | Foo() { std::cout << "Foo() 0x" << std::hex << (void*)this << '\n'; } |
| − | ~Foo() { std::cout << "~Foo | + | ~Foo() { std::cout << "~Foo() 0x" << std::hex << (void*)this << '\n'; } |
}; | }; | ||
struct D | struct D | ||
{ | { | ||
| − | void bar() { std::cout << " | + | int number; |
| + | |||
| + | void bar() { std::cout << "call D::bar(), my nubmer is: " << std::dec << number << '\n'; } | ||
void operator()(Foo* p) const | void operator()(Foo* p) const | ||
{ | { | ||
| − | std::cout << " | + | std::cout << "call deleter for Foo object 0x" << std::hex << (void*)p << "...\n"; |
delete p; | delete p; | ||
} | } | ||
| Line 42: | Line 44: | ||
int main() | int main() | ||
{ | { | ||
| − | std::unique_ptr<Foo, D> | + | std::cout << "main start\n"; |
| − | D& | + | |
| − | + | std::unique_ptr<Foo, D> up1(new Foo(), D(42)); | |
| + | D& del1 = up1.get_deleter(); | ||
| + | del1.bar(); | ||
| + | |||
| + | std::unique_ptr<Foo, D> up2(new Foo(), D(43)); | ||
| + | D& del2 = up2.get_deleter(); | ||
| + | auto* released = up2.release(); | ||
| + | del2(released); | ||
| + | |||
| + | std::cout << "main end\n"; | ||
} | } | ||
| output= | | output= | ||
| − | Foo | + | main start |
| − | + | Foo() 0x0x90cc30 | |
| − | + | call D::bar(), my nubmer is: 42 | |
| − | ~Foo... | + | Foo() 0x0x90cc50 |
| + | call deleter for Foo object 0x0x90cc50... | ||
| + | ~Foo() 0x0x90cc50 | ||
| + | main end | ||
| + | call deleter for Foo object 0x0x90cc30... | ||
| + | ~Foo() 0x0x90cc30 | ||
}} | }} | ||
Revision as of 01:46, 26 May 2023
| Deleter& get_deleter() noexcept; |
(since C++11) (constexpr since C++23) |
|
| const Deleter& get_deleter() const noexcept; |
(since C++11) (constexpr since C++23) |
|
Returns the deleter object which would be used for destruction of the managed object.
Contents |
Parameters
(none)
Return value
The stored deleter object.
Example
Run this code
#include <iostream> #include <memory> struct Foo { Foo() { std::cout << "Foo() 0x" << std::hex << (void*)this << '\n'; } ~Foo() { std::cout << "~Foo() 0x" << std::hex << (void*)this << '\n'; } }; struct D { int number; void bar() { std::cout << "call D::bar(), my nubmer is: " << std::dec << number << '\n'; } void operator()(Foo* p) const { std::cout << "call deleter for Foo object 0x" << std::hex << (void*)p << "...\n"; delete p; } }; int main() { std::cout << "main start\n"; std::unique_ptr<Foo, D> up1(new Foo(), D(42)); D& del1 = up1.get_deleter(); del1.bar(); std::unique_ptr<Foo, D> up2(new Foo(), D(43)); D& del2 = up2.get_deleter(); auto* released = up2.release(); del2(released); std::cout << "main end\n"; }
Output:
main start Foo() 0x0x90cc30 call D::bar(), my nubmer is: 42 Foo() 0x0x90cc50 call deleter for Foo object 0x0x90cc50... ~Foo() 0x0x90cc50 main end call deleter for Foo object 0x0x90cc30... ~Foo() 0x0x90cc30
See also
| returns the deleter of specified type, if owned (function template) |
