C++ cyclic destructors

Question

in file a.h:

class B;
class A
{
public:
    B *b;
    A(B *b = nullptr)
    {
        this->b = b;
    }
    ~A()
    {
        delete this->b;
    }
};

in file b.h:

class A;
class B   
{
public:
    A *a;
    B(A *a = nullptr)
    {
        this->a = a;
    }
    ~B()
    {
        delete this->a;
    };
};

lets pretend that we have a pointer to an A *object, and we want to delete it:

// ...
A *a = new A();
B *b = new B();
A->b = b;
B->a = a;
// ...

delete a;

// ...

A's deconstructor will say delete B; i.e. call B's deconstructor. B's deconstructor will say delete A. death loop lé infinitè.

Is there a better way to write code to solve this problem? This isn't pressing question, just curious.

Thanks!

Answer 1

Use smart pointers (i.e. std::shared_ptr) and weak pointers (i.e. std::weak_ptr) instead of pure pointers.

You have to define which class really owns which one. If none is owning the other, both should be weak pointers.