Python Game | TypeError: argument of type 'NoneType' is not iterable

Question

So I'm working through a python book and was asked to create a tic-tac-toe game and understand the code which I do, relatively. Come time to run the program and I was given this weird error

TypeError: argument of type 'NoneType' is not iterable

with the full error being:

Traceback (most recent call last):
   File "Tac Tac Toe Game revised.py", line 182, in <module>
     main()
   File "Tac Tac Toe Game revised.py", line 173, in main
     move = human_move(board, human)
   File "Tac Tac Toe Game revised.py", line 100, in human_move
     while move not in legal:
TypeError: argument of type 'NoneType' is not iterable

Here is the code it refers to in line 173

def main():
    display_instruction()
    computer,human = pieces()
    turn = X
    board = new_board()
    display_board(board)

   while not winner(board):
       if turn == human:
           move = human_move(board, human)
           board[move] == human
       else:
           move = computer_move(board,computer,human)
           board[move] == computer
       display_board(board)
       congrats_winner(the_winner,computer, human)

The error occurs in the following function:

def human_move(board,human):
'''Get human move'''
legal = legal_moves(board)
move = None
while move not in legal:
    move = ask_number('Where will you move? (0-8): ',0, NUM_SQUARES)
    if move not in legal:
        print ('\nThat square is already occupied, foolish human. Choose another.\n')
print('Fine...')
return move

I've tried changing move = None to move = ' ' but that made no difference. any ideas?

As requested here's the function for legal_moves

def legal_moves(board):
'''Creates a legal list of moves'''
   moves = []
   for square in range(NUM_SQUARES):
      if board[square] == EMPTY:
          moves.append(square)

what is `legal`? that is what is not iterable, not `move`. Clearly, `legal` is None but what should it be? — Julien Spronck, Nov 08 '16 at 11:32
If you need additional help, please post the definition of `legal_moves` — Julien Spronck, Nov 08 '16 at 11:38

Henry Heath · Accepted Answer · 2016-11-08T12:07:06.253

1

You need to return the moves list:

def legal_moves(board):
    '''Creates a legal list of moves'''
    moves = []
    for square in range(NUM_SQUARES):
        if board[square] == EMPTY:
            moves.append(square)
    return moves

edited Nov 08 '16 at 12:07

answered Nov 08 '16 at 12:01

Henry Heath

1,072
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score 0 · Answer 2 · answered Nov 08 '16 at 11:59

0

You forgot to return anything in legal_moves

An elegant solution would be to use 'yield square' instead of the moves list

answered Nov 08 '16 at 11:59

Maarten Fabré

6,938
1
17
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I'm not sure what `yield square` is but hopefully I'll learn it. This answer was quite helpful but Henry's seemed more appropiate – Lucky38i Nov 08 '16 at 12:05
The for-loop needs an iterable. A generator is an easy and efficient way to make one. – Maarten Fabré Nov 08 '16 at 12:22
A generator creates the return values on the fly instead of storing them in a list (like your 'moves') you can check http://stackoverflow.com/a/1756156/1562285 or https://wiki.python.org/moin/Generators – Maarten Fabré Nov 08 '16 at 12:28

score -2 · Answer 3 · answered Nov 08 '16 at 11:39

-2

your problem is you cant do a while loop on none variable you try to count nothing so this is the problem...

if you give a fidle of your code ill help you

answered Nov 08 '16 at 11:39

InitialCrow

323
1
5

what do you mean fiddle? Like pop in my entire code? – Lucky38i Nov 08 '16 at 11:47
that is misleading - you cannot do a test for membership (i.e. use `in`) on `None`. `while None` is valid Python – Henry Heath Nov 08 '16 at 11:49
what do you suggest it be re-written as? – Lucky38i Nov 08 '16 at 11:51

Python Game | TypeError: argument of type 'NoneType' is not iterable

3 Answers3