title: Class cross referencing?
body: <p>I come from a C++ background and I am a bit lost without the whole pointer concept in python. Or at least it's unclear.
  For instance, I want to create a game of tick tack toe using OOP in Python. I have a couple classes like so:</p>
  
  <pre><code>class Game(object):
      def __init__(self, player1, player2):
          self.board = [['','',''],
                        ['','',''],
                        ['','','']]
          self.players = [player1, player2]
  
  class Player(object):
      def __init__(self, game, marking):
          self.game = game
          self.marking = marking  # either 'X' or 'O'
  </code></pre>
  
  <p>It seems obvious that the game needs to have a reference to the two players and that a player is also part of a game, and should, therefore, have a reference to the game. However, the above code doesn't work because there is no way I can create a player without a creating a game first. But to create a game I need two players.
  I could add in these references afterwards by doing something like: <code>player.game = some_game_reference</code> but this seems unpythonic and tedious to keep up with.</p>
  
  <p>What is the best and most pythonic way of accomplishing this? </p>