Question

I recall reading somewhere that using references to smart pointers can cause memory corruption. Is this simply because of using the reference of the smart pointer after its been destroyed? Or does the reference counting get messed up?

Thanks for clarifying

Answer 1

Assuming you are talking about shared_ptr here…

Is this simply because of using the reference of the smart pointer after its been destroyed?

This is a good answer. You may not know absolutely the lifetime of the pointer your reference refers too.

To get around this, you’d want to look into boost::weak_ptr. It doesn’t participate in reference counting. When you need to use it, it gives you a shared_ptr which goes away once your done with it. It will also let you know when the refered to pointer has been collected.

From the weak_ptr documentation

The weak_ptr class template stores a ‘weak reference’ to an object that’s already managed by a shared_ptr. To access the object, a weak_ptr can be converted to a shared_ptr using the shared_ptr constructor or the member function lock. When the last shared_ptr to the object goes away and the object is deleted, the attempt to obtain a shared_ptr from the weak_ptr instances that refer to the deleted object will fail: the constructor will throw an exception of type boost::bad_weak_ptr, and weak_ptr::lock will return an empty shared_ptr.

Note the method expired() will also tell you if your ptr is still around.