tictactoe.py

# Written by: Ryan Yan
# Date: October 10th, 2016
#
# This program lets two players play tic tac toe in the console using keyboard input.


class Player:
    '''Player objects keep track of the spaces they control on the grid (add_square and get_squares)
    and has their symbol, default X's and O's as their string representation'''

    def __init__(self, symbol):
        self._squares = set() #Set of controlled spaces. Holds indices from 0-8 held by player in Board._grid
        self._symbol = symbol
    def add_square(self, ind):
        self._squares.add(ind)
    def get_squares(self):
        return self._squares
    def __str__(self):
        return self._symbol


class Board:
    '''Tictactoe game class. Contains the grid to be printed, a list of available spaces, and makes moves
    occur and determines the victor.'''

    def __init__(self):
        self._grid = list(range(1, 10, 1)) #Grid to be printed. filled with X and Os
        self._squares = list(range(9)) #List of available spaces. Holds indices from 0-8 open in _grid
        self._win_conditions = [{0,1,2}, {3,4,5}, {6,7,8}, #rows
                                {0,3,6}, {1,4,7}, {2,5,8}, #columns
                                {0,4,8}, {2,4,6}]          #diagonals
        self._victor = None

    def clear_grid(self):
        self._grid = [""] * 9

    def make_move(self, player):
        #Asks for input and updates all the square lists in Player and in Board, then checks win condition
        while(True):
            #Checks and validates input
            try:
                move = int(input("%s's move: " % str(player))) - 1
                self._squares.index(move)
                break
            except ValueError:
                print("Please enter an integer between 1 and 9")

        #Updates lists containing squares and checks victory conditions.
        self._squares.remove(move)
        player.add_square(move)
        self._grid[move] = str(player)
        self.check_win(player)

    def check_win(self, player):
        #Checks if any victorious set of squares is a subset of squares held by a particular player
        held_squares = player.get_squares()
        for condition in self._win_conditions:
            if condition.issubset(held_squares):
                self._victor = player
                return

    def play(self):
        #Sets up the game
        player_one = Player("X")
        player_two = Player("O")
        players = [player_one, player_two]
        current_player = 0
        print(self)
        self.clear_grid()
        print("Use integers 1-9 to specify the location on the board")

        #Gameplay
        while(self._victor == None):
            self.make_move(players[current_player%2])
            print(self)
            current_player = current_player + 1

        print("The %s's have it!" % str(self._victor))

    def __str__(self):
        #Prints out the game board
        for row in range(3):
            adjust = 3 * row
            print("%2s%2s%2s%2s%2s" % (self._grid[adjust+0], "|", self._grid[adjust+1], "|", self._grid[adjust+2]))
            if(row != 2):
                print("___|___|___")
            else:
                print("%4s%4s" % ("|", "|"))

        return ""

if __name__ == "__main__":
    new_game = Board()
    new_game.play()

This is a tic-tac-toe game I wrote in python to be played by two human players in the console.

As I saw it, this would be a good place for an OOP approach with the work divided into two classes:

1. Player: Keeps track of held squares and their team's symbol. Exposes an "add_square" method to allow Board object to update Players after a move is made.
2. Board: Implements a game loop which instantiates Player objects. Additionally, implements a method to make player moves by prompting for input and updating the squares in properties based on user input prompts to make moves. This is called repeatedly in the game loop until a victor condition is met. Lastly, since this is console tic-tac-toe, the Board keeps a string representation of the playing board, printing to the console with each update.