I have no idea how you're reading what you're reading out of what I wrote, but somehow we're not communicating, so we'll let that go.
The link you posted does not have a person declaring a list in a header file, so that's remarkably irrelevant. (It does have a person creating a class that contains a list inside it -- and look! that person is only declaring a class and not instantiating it! even better/worse, depending on your perspective.)