players.py

class SubprocessPlayer(object):
  def __init__(self,command):
    .... launch subprocess and setup stdin/stdout
    
  def new_game(initial_state):
    ...
    return None
    
  def take_turn(game_state):
    ...
    return <action taken>
  
  def game_finished():
    ... tear down subprocess

class DemoPlayer(object):
  def __init__(self):
    .... launch subprocess and setup stdin/stdout
    
  def new_game(initial_state):
    ...
    return None
    
  def take_turn(game_state):
    ...
    return <action taken>
  
  def game_finished():
    ... tear down subprocess

class Engine(object):
  def __init__(self,player1,player2):
    ...
  
  def play(self):
    while self.play_round():
      print "Playing!"
    
  def play_round(self):
    player1.take_turn(self.state)
    player2.take_turn(self.state)
    self.check_if_done()
    
eng = Engine(SubprocessPlayer("/usr/bin/python my_player"),DemoPlayer())
eng.play()