Remove reference to deleted node

[Rafael Aguiar]

In the stack challenge (stacks_queues/stack/stack_challenge), more specifically in the pop() method, shouldn't we be removing references from the node we want to pop? Only updating the top reference doesn't remove the reference the old top (popped item) has to the new top.

[Donne Martin]

Hi Rafael,

Only updating the top reference doesn't remove the reference the old top (popped item) has to the new top

Can you point me to a link that discusses this further?

For reference, I believe this is the function we are discussing:

    def pop(self):
        if self.top is not None:
            data = self.top.data
            self.top = self.top.next
            return data
        return None

It is my understanding that:

• Python's garbage collector will automatically handle this without the need to "remove references from the node we want to pop".
• If this were C/C++ and that node were created with malloc/new then we should deallocate that memory.

-Donne

[Rafael Aguiar]

Hi Donne, I misunderstood the way Python gc works. I was thinking that any reference pointing in or out the object would keep it alive, but it's not the case (only references to the object work for that matter).

[Donne Martin]

Sounds good, thanks Rafael :)