Given a pointer to a C++ object, what is the preferred way to call a static member function?

Question

Say I have:

class A {
public:
    static void DoStuff();

    // ... more methods here ...
};

And later on I have a function that wants to call DoStuff:

B::SomeFunction(A* a_ptr) {

Is it better to say:

    a_ptr->DoStuff();
}

Or is the following better even though I have an instance pointer:

    A::DoStuff()
}

This is purely a matter of style, but I'd like to get some informed opinions before I make a decision.

Answer 1

I think I'd prefer "A::DoStuff()", as it's more clear that a static method is being called.

Answer 2

It's better to call the static method by its name, not through an object, since it doesn't actually use that object at all. In Java, the same problem exists. A not-too-uncommon problem in Java is the following:

Thread t = getSomeOtherThread();
t.sleep(1000);

This compiles fine but is almost always an error -- Thread.sleep() is a static method that causes the current thread to sleep, not the thread being acted on as the code seems to imply.