typedef type * type::* , what is it?

Question

I have the following code:

  struct myType { myType * ptr; };
  typedef myType * myType ::* other_type;

What is the second line typedef'ining? Is that a member function that returns a myType pointer or something else?

Answer 1

That defines other_type as a pointer to a member of myType where said member is itself a pointer to myType. For example, you could use it this way:

other_type x = &myType::ptr;
myType mine;
mine.*x = &mine;

Why you would do that, I can't say.