Object::Destroyer allows for the creation of "Destroy" handles. The
handle is "attached" to the circular relationship, but is not a part
of it. When the destroy handle falls out of scope, it will be cleaned
up correctly, and while being cleaned up, it will also force the data
structure it is attached to be destroyed as well. Object::Destroyer
can call a specified release method on an object (or method DESTROY by
default). Alternatively, it can execute an arbitrary user code passed
to constructor as a code reference.