Mastering GUI Programming with Python

The engine class

Our game engine object's main responsibility is to keep track of plays and to check whether there is a winner or whether the game is a draw. The players will be represented simply by the 'X' and 'O' strings, and the board will be modeled as a list of nine items that will either be a player or None.

It begins like this:

class TicTacToeEngine(qtc.QObject):    winning_sets = [        {0, 1, 2}, {3, 4, 5}, {6, 7, 8},        {0, 3, 6}, {1, 4, 7}, {2, 5, 8},        {0, 4, 8}, {2, 4, 6}    ]    players = ('X', 'O')    game_won = qtc.pyqtSignal(str)    game_draw = qtc.pyqtSignal()    def __init__(self):        super().__init__()        self.board = [None] * 9        self.current_player = self.players[0]

The winning_sets list contains set objects with every combination of board indexes that ...