#include <vector>

class Vec {
public :
  Vec () : val_ (std::vector<size_t> (1000, 0)) {}
  Vec (const Vec& v) : val_ (v.val_) {}
  ~Vec () {}
  //couple of const opposite methods
  void inc () {
    std::for_each (val_.begin (), val_.end (), [] (size_t&s) {++s;});
  }
  void dec () {
    std::for_each (val_.begin (), val_.end (), [] (size_t&s) {--s;});
  }

  void write2 (std::ostream& os) const {
    os << "val_ [2] == " << val_ [2] << std::endl;
  }
  void write_next2const (std::ostream& os) const {
    Vec v (*this);
    v.inc ();
    v.write2 (os);
  }
  void write_next2pseudoconst (std::ostream& os) { //pseudo const method
    inc ();
    write2 (os);
    dec ();
  }
//private :
  std::vector<size_t> val_;
};

int main (int argc, char* argv []) {
  size_t duration (0);
  clock_t t (clock ());
  Vec v;
  v.write_next2const (std::cout);
  duration = (clock() - t);
  std::cout << "write_next2const took " << duration << " ticks" << std::endl;
  t = clock ();
  v.write_next2pseudoconst (std::cout);
  duration = (clock() - t);
  std::cout << "write_next2pseudoconst took " << duration << " ticks" << std::endl;
  return 0;
}

val_ [2] == 1
write_next2const took 124 ticks
val_ [2] == 1
write_next2pseudoconst took 3 ticks