About stl exercise

[chavid]

As currently written, the students starts with std::generate, which is complex because
of the need of some internal persistent state. Several solutions:

• find another generation algorithm which do not require internal state.
  why not directly random values ?
• move it as intermediary/advanced later step.
  By the way, I strongly disagree with the current solution, based on an object-function class. You will frigthen beginners and let them think that the good old code is better ! It is far from perfect, but one can avoid this with an internal static int, or capture by reference an external int.
  Or we should declare as a requirement the knowledge of object-functions ?