// Forward declarations
class A;

class B
{
public:
    B(A* aPtr) : m_pA(aPtr)

    void Schedule();
    void Update();

private:
    A* m_pA;
}

void B::Schedule()
{
    Timer::ref().Schedule(1000, [this]() { Update(); });
}

void B::Update()
{
    m_pA->DoSomething();
}

class A
{
public:
    void Create() { m_B = std::make_unique<B>(); }
    void DoSomething() {}

private:
    std::unique_ptr<B> m_B;
}