Shared pointers to a singleton do not recognize each other

Question

I am currently learning how to use the C++11 smart pointers while programming a 2D game engine as a hobby using SDL. However, I ran into a problem while implementing an OOp wrap

Answer 1

Rather than keeping a raw pointer in your static member, you should keep a weak_ptr. Use the lock() function to convert back to a shared_ptr; if it comes back empty then you need to allocate a new singleton object.

    static shared_ptr getInstance()
    {
        shared_ptr p = instance_.lock();
        if (!p)
        {
            p = new Foo;
            instance_ = p;
        }
        return p;
    }
private:
    static weak_ptr instance_;