template_method.cpp

#include <iostream>
#include <string>
using namespace std;

// General Algorithm for a Game
class Game {
public:
  explicit Game(int number_of_players) : number_of_players(number_of_players) {}

  // general implementation
  void run() {
    start();
    while (!have_winner())
      take_turn();
    cout << "Player " << get_winner() << " wins.\n";
  }

protected:
  // template methods for turn based games.
  virtual void start() = 0;
  virtual bool have_winner() = 0;
  virtual void take_turn() = 0;
  virtual int get_winner() = 0;

  int current_player{0};
  int number_of_players;
};

// Particular implementation for a Chess game.
class Chess : public Game {
public:
  explicit Chess() : Game{2} {}

protected:
  void start() override {
    cout << "Starting a game of chess with " << number_of_players
         << " players\n";
  }

  bool have_winner() override { return turns == max_turns; }

  void take_turn() override {
    cout << "Turn " << turns << " taken by player " << current_player << "\n";
    turns++;
    current_player = (current_player + 1) % number_of_players;
  }

  int get_winner() override { return current_player; }

private:
  int turns{0}, max_turns{10};
};

int main() {
  Chess chess;
  chess.run();
  return 0;
}