Is “delete p; p = NULL(nullptr);” an antipattern?

Question

Searching something on SO, I stumbled across this question and one of the comments to the most voted answer (the fifth comment to that most voted answer) suggests that del

Answer 1

It depends on how the pointer is used. If all the code that can see the pointer should "know" that it's no longer valid — especially in a destructor where the pointer is about to go out of scope anyway — there's no need to set it to null.

On the other hand, the pointer may represent an object that sometimes exists, sometimes doesn't, and you have code like if (p) { p->doStuff(); } to act upon the object when it exists. In that case, obviously, you should set it to null after deleting the object.

The important distinction in the latter case is that the lifetime of the pointer variable is much longer than the lifetime of the objects it (sometimes) points to, and its null-ness carries some significant meaning that has to be communicated to other parts of the program.