Question

In reading TCPL, I got a problem, as the title refered, and then ‘private’ class is:

class Unique_handle {
private:
    Unique_handle& operator=(const Unique_handle &rhs);
    Unique_handle(const Unique_handle &rhs);
public:
    //...
};

the using code is:

struct Y {
    //...
    Unique_handle obj;
};

and I want to execute such operations:

int main()
{
    Y y1;
    Y y2 = y1;
}

although, these code are come from TCPL, but I still can not got the solution…
Can anybody help me, appreciate.

Answer 1

As its name suggests, the Unique_handle isn’t meant to be copied. Its implementation ensures it by disabling the copy constructor and copy assignment operator.

One solution for multiple instances having access to a Unique_handle is holding a pointer to it, and copying the pointer. Then multiple instances of Y point to the same unique handle.

Take care, however, to manage resources properly in this case.