методы

#include <iostream>


class Pointers {
public:
  Pointers(int y)
    : m_y(y)
  {
    /* пусто */
  }
  double test1(int x) {
    return x * m_y;
  }
  double test2(int x) {
    return x + m_y;
  }

  void run() {
    std::cout << "Run: " << (this->*m_meth)(3) << std::endl;
  }

  void set_method(double (Pointers::*meth)(int x)) {
    m_meth = meth;
  }

private:
  int m_y;
  double (Pointers::*m_meth)(int x);
};

int main() {
  Pointers p(3);
  p.set_method(&Pointers::test1);
  p.run();
  p.set_method(&Pointers::test2);
  p.run();
  return 0;
}