This is my implementation of a Tic Tac Toe game with Tkinter GUI. So far I've set up the game to play with another player. For an interview coming up, I am suppose to build additional feature such as play with AI.

I would like some general feedback on my code. Does my code smell? Can I organize the Player, Board, GameApp objects and methods better? Is permutation on sets a bad idea? Any suggestion is welcomed.

So far I've sent up my classes and methods in this order:

Player class


  • name as string
  • color as string
  • selected_sq as empty set



Board class


  • parent (instance of Tkinter class)
  • sq_size
  • color
  • container, canvas - (from Tkinter class to draw board)
  • winning_combo - (dictionary of winning combo in relation to location of rowcol)


  • get_unused_squares_dict(self)
  • reset_unused_squares_dict(self)
  • draw_board(self)
  • get_row_col(self, evt)
  • loor_of_row_col(self, col, rw)
  • convert_to_key(self, col_floor, row_floor)
  • find_coords_of_selected_sq(self, evt)
  • color_selected_sq(self, evt, second_corner_col, second_corner_row, player_color)

GameApp class


  • parent (instance of Tkinter class)
  • board
  • player1
  • player2
  • computer


  • initialize_buttons
  • show_menu
  • init_two_players_game
  • restart
  • play
  • check_for_winner
  • show_game_result
  • add_player_to_sq
  • delete_used_sq
  • init_computer_game (later feature)
  • play_computer (later feature)

# Name:        Tic Tac Toe
# Purpose:     Simple game of tic tac toe with tkinter library for GUI

import tkinter
import random
from itertools import permutations

class Player:
    Player class to be used in the Game obj

    name: text to distinguish name of player ie player1, player2, computer
    color: hex code to color each player square on click event
    selected_sq: set data structure to keep track of player squares

    def __init__(self, name, color):
        self.name = name
        self.color = color
        self.selected_sq = set()

class Board:
    Board class to be used in the Game obj

    sq_size: integer to set size of each squares
    color: hex code to color the board size

    def __init__(self, parent, sq_size, color):
        self.parent = parent   # parent is root
        self.sq_size = sq_size
        self.color = color

        # use as a pseudo private attribute, read only
        self._winning_combos = [{1, 2, 3}, {4, 5, 6}, {7, 8, 9},
                      {1, 4, 7}, {2, 5, 8}, {3, 6, 9},
                      {1, 5, 9}, {3, 5, 7}]

        # design to fit tkinter grid(row, col)two params
        self.unused_squares_dict = { '00': 1, '10': 2, '20': 3,
                                     '01': 4, '11': 5, '21': 6,
                                     '02': 7, '12': 8, '22': 9  }

        # create a main container for board
        self.container = tkinter.Frame(self.parent)

        # create canvas for container
        self.canvas = tkinter.Canvas(self.container,
                                     width= self.sq_size * 3,
                                     height= self.sq_size * 3)
        # register main canvas

    def get_unused_squares_dict(self):
        return self.unused_squares_dict

    def reset_unused_squares_dict(self):
        self.unused_squares_dict = { '00': 1, '10': 2, '20': 3,
                                     '01': 4, '11': 5, '21': 6,
                                     '02': 7, '12': 8, '22': 9  }

    def draw_board(self):
        for row in range(3):
            for column in range(3):
                self.canvas.create_rectangle(self.sq_size  * column,
                                        self.sq_size  * row,
                                        self.sq_size  * (column + 1),
                                        self.sq_size  * (row + 1),
                                        fill = self.color)

    def get_row_col(self, evt):
        # get the row and col from event's x and y coords
        return evt.x, evt.y

    def floor_of_row_col(self, col, rw):
        normalize col and row number for all board size by taking
        the floor of event's x and y coords as col and row, respectively
        col_flr = col // self.sq_size
        rw_flr = rw // self.sq_size
        return col_flr, rw_flr

    def convert_to_key(self, col_floor, row_floor):
        # turn col and row's quotient into a string for the key
        return str(col_floor) + str(row_floor)

    def find_coords_of_selected_sq(self, evt):
        finding coords in a 9-sq grid

        params: event triggered by user's click
        return: tuple of two values for second corner's col, row
        # saves row and col tuple into two variables
        column, row = self.get_row_col(evt)
        # normalize for all square size by keeping the floor
        column_floor, row_floor = self.floor_of_row_col(column, row)

        # convert to key, use key to locate position in 3x3 grid
        rowcol_key_str = self.convert_to_key(column_floor, row_floor)

        corner_column = (column_floor * self.sq_size) + self.sq_size
        corner_row =  (row_floor  * self.sq_size) + self.sq_size
        print("rowcol_key_str: " + str(rowcol_key_str))
        return corner_column, corner_row

    def color_selected_sq(self, evt, second_corner_col,
                          second_corner_row, player_color):

        print(" ---- inside color_selected_sq method ----")
            (evt.x // self.sq_size) * self.sq_size,
            (evt.y // self.sq_size) * self.sq_size,
            fill = player_color)

    def winning_combos(self):
        return self._winning_combos

class GameApp(object):
    GameApp class as controller for board and player objects

    parent: (tkinter.Tk) the root window, parent of the frame
    board: instance of the board class
    unused_squares_dict: keep track of squares left on the board
    player1: instance of player class
    player2: ibid
    computer: ibid

    def __init__(self, parent):
        self.parent = parent  # parent is root

        # create a board
        self.board = Board(self.parent, 100, "#ECECEC")  # hex color gray

        self.unused_squares_dict = self.board.get_unused_squares_dict()

        # create all players instances
        self.player1 = Player("Player 1", "#446CB3") # hex blue
        self.player2 = Player("Player 2", "#F4D03F") # hex yellow
        self.computer = Player("Computer", "#E67E22") # hex orange

        # create a menu for game option

    def initialize_buttons(self):
        #  --- create buttons for menu ---
        self.two_players_button = tkinter.Button(self.board.container,
                                text = "PLAY WITH A FRIEND",
                                width = 25,
                                command = self.init_two_players_game)

        # bind button to self.play_computer method (FUTURE FEATURE)
        self.computer_button = tkinter.Button(self.board.container,
                                            text = "PLAY WITH THE COMPUTER",
                                            width = 25,
                                            command = self.init_computer_game)

        self.reset_button = tkinter.Button(self.board.container,
                                           text = "RESET",
                                           width = 25,
                                           command = self.restart)

    def show_menu(self):
         # register buttons to board's container

    def init_computer_game(self):
        print(" --- init computer game, future feature---")

        # reset unused squares on the board
        self.unused_squares_dict = self.board.reset_unused_squares_dict()

        # reset players' squares
        self.player1.selected_sq = set()
        self.computer.selected_sq = set()
        self.computer_turn = True

        # show reset button


    def play_computer(self):
        print(" <-- in play_computer --> ")
        # if self.computer_turn == True:
        #     call computers_turn()
        #     self.computer_turn = False
        # else:
        #     call player1 play()
        #     need special case for computer's turn in play

    def init_two_players_game(self):
        # reset board's unused squares

        # reset players' squares to empty set
        self.player1.selected_sq = set()
        self.player2.selected_sq = set()

        # keep track of turns
        self.player1_turn = True

        # show reset button

        #bind play() to the leftmost button click, for macs
        #windows or other pcs might be "<Button-2>"
        self.board.canvas.bind("<Button-1>", self.play)

    def restart(self):
        """ Reinitialize the game and board after restart button is pressed """
        # create a new board object and draw board + buttons again
        self.board = Board(self.parent, 100, "#ECECEC")

    def add_to_player_sq(self, key, player_sq):
        use key of col and row to locate position of square
        and add square to player's selected_sq set
        :param key: str concat of col and row key str
        current_selected_sq = self.board.unused_squares_dict[key]
        print("current selected sq  ---->", current_selected_sq)
        print("BEFORE player selected_sq: ", player_sq)
        player_sq.add(current_selected_sq)   # player 1 = {1}
        print("AFTER player selected_sq: ", player_sq)

    def delete_used_sq(self, key):
        # delete selected sq in self.board.unused_squares_dict
        print(" ---- square to delete ---: ", self.board.unused_squares_dict[key])
        print("unused squares dictionary before: ", self.board.unused_squares_dict)
        del self.board.unused_squares_dict[key]
        print("unused squares dictionary after: ", self.board.unused_squares_dict)

    def play(self, event):
        """  method is invoked when the user clicks on a square
        handles click event on UI for player
        Params: event (as mouse click, with x/y coords)

        # locate second column and row when player click on a square
        colrow_tuple = self.board.find_coords_of_selected_sq(event)

        # save the col and row as variable
        corner_two_col, corner_two_row = colrow_tuple[0], colrow_tuple[1]

        # calculations to get the key to help locate specific square on
        # the unused dictionary of squares left to play
        col_fl, row_fl = self.board.floor_of_row_col(event.x, event.y)
        rowcol_key = self.board.convert_to_key(col_fl, row_fl)

        except KeyError:

        if self.player1_turn == True:
            self.add_to_player_sq(rowcol_key, self.player1.selected_sq)

            # delete from game unused dictionary of set


            # check game for 3 conditions: a tie, player1 win, or player2 win
            self.check_for_winner(self.player1.selected_sq, self.player1.name)

            # switch turn
            self.player1_turn = False

        else:  # player2's turn

            self.add_to_player_sq(rowcol_key, self.player2.selected_sq)
            self.check_for_winner(self.player2.selected_sq, self.player2.name)
            self.player1_turn = True

    def check_for_winner(self, player_sq, player_name):

        if len(self.board.unused_squares_dict) > 0:
            # if player selected at least 3 squares
            if len(player_sq) > 2:
                # start permutation of selected squares
                for combo in permutations(player_sq, 3):
                    # loop through all possible combination of 3 from player_sq set
                    # return as tuples ex: (1,2,4), (1,2,9), (2,1,9)...
                    # change tuple to set and match against winning condition
                    # by another inner loop to get through all winning condition list
                    for wc in self.board.winning_combos:
                        if set(combo) == wc :
                            self.show_game_result(player_name + " WIN!")

        if len(self.board.unused_squares_dict) == 0:
            self.show_game_result("ARGG, IT'S A TIE. ")

    def show_game_result(self, txt):
        make a label to display three possible winning conditions
        params: txt to display the winner
                player_color to display matching color as player's sq
        result_label = tkinter.Label(self.board.container,
                                            text= txt,
                                            width = 32,
                                            height = 10,
                                            foreground = "red",
                                            background = "gray",
                                            borderwidth = 3)

        result_label.grid(row = 0, column = 0)
        # unbind button so player cannot click on square
        self.board.canvas.unbind("<Button-1>", self.play)

def main():
    root = tkinter.Tk()
    root.title("Tic Tac Toe")
    tictac_game = GameApp(root)  # root is parent

if __name__ == '__main__':

1 Answer 1


There's quite a lot of code here, so I'm just going to review one of your methods, check_for_winner. You'll see that there's plenty here for one answer. Maybe some other reviewers can look at the rest of the code.

  1. There's no docstring. It's useful to write docstrings for all your methods, because (i) it's easy to forget what a method does and having a docstring will help remind you; (ii) you can check the docstring against the code to see if you've implemented it correctly; (iii) writing a specification forces you to think about whether that specification makes sense.

  2. In the case of check_for_winner, the docstring would have to look something like this:

    """Given that the player whose name is player_name has played at
    the squares in the sequence player_sq, determine if that
    player has won, or if the game has ended in a tie, and if
    either of these conditions applies, create a label with the
    appropriate game over message, wait for the restart button to
    be pressed, and restart the game."""

    This is pretty complicated specification, and not something that you might guess from the name of the method. In particular it shows a lack of model–view separation. This is an important technique in user interface programming, where you separate the code into a model, which describes the abstract data structures and logic (here, the tic-tac-toe board and its rules), and a view, which presents these data structures to the user via some kind of interface.

    There are several benefits of separation, including (i) keeping things simple and maintainable; (ii) testing the model; (iii) easily replacing one kind of view with another (for example, using a different user interface toolkit).

    So here we would want to divide check_for_winner into two pieces: a method on the Board class that determines the state of the board (game not over? game tied? win for player 1? win for player 2?); and a method on the Game class that deals with the result.

  3. This line appears twice:


    but has no effect: it's missing the parentheses that are needed for a method call. Remove it.

  4. There's a bug in the win determination. The code only checks to see if the player has won if len(self.board.unused_squares_dict) > 0. But this means that if a player wins by playing in the last empty square on the board, this win won't be detected.

  5. The win determination is inefficient: (i) it loops over all combinations of three places where the player has played, even though many of these triples can't possibly result in a win; (ii) it searches for each triple in the list _winning_combos, which might require comparing against every element in the list; (iii) it repeatedly converts the combination into a set, once for each element in the _winning_combos list; (iv) it keeps going even after it has determined the winner.

    Tic-tac-toe is such a small game that this inefficiency doesn't matter very much. But there are two reasons to be concerned: (i) thinking about efficiency is an important skill, so it's good to practice that skill in easy situations like this; (ii) you say that your next step is to add computer play, which might involve game tree search and when many positions are being searched, the speed of evaluation of those positions is important.

    A couple of simple improvements: (i) use the subset operation <= to determine if the player's selected squares include all the squares in a winning combination; (ii) return immediately after determining the winner, without going on to check other combinations. (We could do even better by taking advantage of the fact that the winning combination, if it exists, must include the last square played. But that would require a change to the check_for_winner interface, and so it's out of scope for my review.)

    Revised code below. Note that since _winning_combos never changes, it can be made into a global constant:

        {1, 2, 3}, {4, 5, 6}, {7, 8, 9},
        {1, 4, 7}, {2, 5, 8}, {3, 6, 9},
        {1, 5, 9}, {3, 5, 7},
    def check_for_winner(self, player_sq, player_name):
        """Given that the player whose name is player_name has played at the
        squares in the sequence player_sq, determine if that player
        has won, or if the game has ended in a tie, and if either of
        these conditions applies, create a label with the appropriate
        game over message, wait for the restart button to be pressed,
        and restart the game.
        if len(player_sq) < 3:
            pass # not enough squares for a winning line
        elif any(combo <= player_sq for combo in WINNING_COMBOS):
            self.show_game_result(player_name + " WIN!")
        elif self.board.unused_squares_dict:
            pass # game not over yet
            self.show_game_result("ARGG, IT'S A TIE.")

    But really this code should be separated into its model and view components as discussed in §2 above.

  • \$\begingroup\$ thank you so much for taking the time to review my code. I will work on refactoring it right now and and update the new version soon. I haven't thought about memoizing the check_for_winner method, or thinking about separating my code into mvc-model at all. there is plenty to work with here. \$\endgroup\$ May 28, 2015 at 21:34

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.