I have a class with a private unique_ptr member and I want to expose a public swap function which will swap ownership of its unique_ptr member with that of the provided other. How can I do so?
class A{ // a is polymorphic type, derivatives A1, A2, etc
private:
unique_ptr<B> b;
public:
void swap_b(A??? other) {
A.b.swap_c(other.b) // I want to swap A.b.c with other.b.c
}
};
class B{ // b is polymorphic type
private:
unique_ptr<C> c; // c is also polymorphic type
public:
void swap_C(B??? other) {
B.c.swap(other.c)
}
};
int main() {
unique_ptr<A> alphaOne = make_unique<A1>(...);
unique_ptr<A> alphaTwo = make_unique<A2>(...);
alphaOne.swap(alphaTwo); // the unique_ptr alphaOne.b.c should swap ownership with alphaTwo.b.c
}
I have a vector<unique_ptr<A>>
, from which I want to grab any two elements and call swap on them to swap their b.c unique_ptrs. How can I achieve this?
I am unsure if I am missing something, but a simple reference should suffice:
#include <memory>
using namespace std;
class C {};
class B {
private:
unique_ptr<C> c;
public:
void swap(B& other){ c.swap(other.c); }
};
class A {
private:
unique_ptr<B> b;
public:
virtual ~A() = default; // See note 1.
void swap(A& other){ b.swap(other.b); }
};
class A1:public A{};
class A2:public A{};
int main() {
unique_ptr<A> alphaOne = make_unique<A1>();
unique_ptr<A> alphaTwo = make_unique<A2>();
alphaOne.swap(alphaTwo);
}
virtual
when you destroy instances via a base class pointer.