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std::unique_ptr<T,Deleter>:: swap

From cppreference.net
C++
Memory management library
( exposition only* )
Allocators
Uninitialized memory algorithms
Constrained uninitialized memory algorithms
Memory resources
Uninitialized storage (until C++20)
( until C++20* )
( until C++20* )
( until C++20* )

Garbage collector support (until C++23)
(C++11) (until C++23)
(C++11) (until C++23)
(C++11) (until C++23)
(C++11) (until C++23)
(C++11) (until C++23)
(C++11) (until C++23)
std::unique_ptr
void swap ( unique_ptr & other ) noexcept ;
(desde C++11)

Intercambia los objetos gestionados y los eliminadores asociados de * this y otro objeto unique_ptr other .

Parámetros

otro - otro objeto unique_ptr con el cual intercambiar el objeto gestionado y el deleter

Valor de retorno

(ninguno)

Ejemplo

Ejecutar este código 
#include <iostream>
#include <memory>
struct Foo
{
    Foo(int _val) : val(_val) { std::cout << "Foo...\n"; }
    ~Foo() { std::cout << "~Foo...\n"; }
    int val;
};
int main()
{
    std::unique_ptr<Foo> up1(new Foo(1));
    std::unique_ptr<Foo> up2(new Foo(2));
    up1.swap(up2);
    std::cout << "up1->val:" << up1->val << '\n';
    std::cout << "up2->val:" << up2->val << '\n';
}

Salida: 

Foo...
Foo...
up1->val:2
up2->val:1
~Foo...
~Foo...