Question

I have a class that employs a reference counting mechanism. The objects of this class are eventually destroyed by calling delete this when the reference count drops to zero. My question is: can I use local on-stack variable after delete this? Here’s a more specific example:

class RefCountedClass
{
public:
    RefCountedClass(Mutex& m) :
        mutex_(m)
    {}

    .
    .
    .

private:
    Mutex& mutex_;

    void RemoveReference()
    {
        // As I understand, mutex_ will be destroyed after delete,
        // but using m is all right because it is on-stack and
        // references an external object. Am I right?
        Mutex& m = mutex_; 
        m.Acquire();

        --recount_;
        if (refcount <= 0) delete this;

        m.Release();
    }
};

Answer 1

Yes, you may do this, as long as the member variable itself is really only a reference to an external object.

(Please forgive the previous wrong answer, I was confused about the mutex_ variable.)