How can I pass std::unique_ptr into a function

Question

How can I pass a std::unique_ptr into a function? Lets say I have the following class:

class A
{
public:
    A(int val)
    {
        _val = val         


        

Answer 1

As MyFunc doesn't take ownership, it would be better to have:

void MyFunc(const A* arg)
{
    assert(arg != nullptr); // or throw ?
    cout << arg->GetVal() << endl;
}

or better

void MyFunc(const A& arg)
{
    cout << arg.GetVal() << endl;
}

If you really want to take ownership, you have to move your resource:

std::unique_ptr ptr = std::make_unique(1234);
MyFunc(std::move(ptr));

or pass directly a r-value reference:

MyFunc(std::make_unique(1234));

std::unique_ptr doesn't have copy on purpose to guaranty to have only one owner.