TicTacToe Telnet server in Python

Question

The code below works. The timings are as close as I can get to the system not packing out.

Basically telnet to a server to play tic-tac-toe. Automated it. Bottom left is 1, middle left is 2, middle right is 3 etc

Once a game is finished, I say "yes" and go again.

Anyway I can optimise it?

#!/usr/bin/env python
from telnetlib import Telnet
import sys
from pprint import pprint
from random import randint
HOST = '127.0.0.1'
PORT = 6666
tn = Telnet(HOST, PORT)
board=['','','','','','','','','']
winLines = [[0,1,2], [3,4,5], [6,7,8], [0,3,6], [1,4,7], [2,5,8], [0,4,8], [2,4,6]]
def main():
 startup()
 while True:
 readBoard()
 selectMove()
 tn.close()
def startup():
 print tn.read_until("WordsWeNeverSee",0.1) 
 tn.write("O\n") 
 print tn.read_until("go first.", 0.1) 
def foobar():
 tn.write("yes\n")
 print tn.read_until("WordsWeNeverSee",0.1) 
 tn.write("O\n") 
 readBoard()
def readBoard():
 tIn = tn.read_until("WordsWeNeverSee",0.3)
 tLines = tIn.split('\n') 
 sys.stdout.write(tIn)
 tLines = tLines[::-1]
 if len(tLines)==13:
 row = tLines[3].replace(' ', '').split('|')
 #X|X|O
 board[0] = row[0]
 board[1] = row[1]
 board[2] = row[2]
 row = tLines[7].replace(' ', '').split('|')
 #X|X|O
 board[3] = row[0]
 board[4] = row[1]
 board[5] = row[2]
 row = tLines[11].replace(' ', '').split('|')
 #X|X|O
 board[6] = row[0]
 board[7] = row[1]
 board[8] = row[2]
 elif len(tLines)==14:
 row = tLines[3].replace(' ', '').split('|')
 #X|X|O
 board[0] = row[0]
 board[1] = row[1]
 board[2] = row[2]
 row = tLines[7].replace(' ', '').split('|')
 #X|X|O
 board[3] = row[0]
 board[4] = row[1]
 board[5] = row[2]
 row = tLines[11].replace(' ', '').split('|')
 #X|X|O
 board[6] = row[0]
 board[7] = row[1]
 board[8] = row[2]
 else:
 readBoard()
 if tIn.find("play again") != -1:
 foobar()
def countCharInCells(char, tup): # X, [2,4,6]
 count = 0
 for n in tup:
 if board[n] == char:
 count += 1
 return count
def findEmpty(tup): # [2,4,6]
 for n in tup:
 if board[n] == '':
 return n
 return -1
def selectMove():
 xCount = board.count('X') 
 # Strong first turn move
 if xCount == 0:
 tn.write('9')
 return
 # Best response to center start
 if board.count('X') == 1:
 if board[4] == 'X':
 tn.write('9')
 return
 # See if we can win
 for wl in winLines: #[[0,1,2], [3,4,5], [6,7,8], [0,3,6], [1,4,7], [2,5,8], [0,4,8], [2,4,6]]
 if countCharInCells('O', wl) == 2:
 choice = findEmpty(wl)
 if choice != -1:
 tn.write(str(choice+1))
 return
 # Try to block opposition winning moves
 for wl in winLines:
 if countCharInCells('X', wl) == 2:
 choice = findEmpty(wl)
 if choice != -1:
 tn.write(str(choice+1))
 return
 # Try to snag a corner
 choice = findEmpty([0,2,6,8])
 if choice != -1:
 tn.write(str(choice+1))
 return
 # Pick a random valid square when stumped
 while True:
 choice = randint(0,8)
 if board[choice] == '':
 tn.write(str(choice+1))
 return
if __name__ == "__main__":
 main()
 main()

• 200_success: Did you intentionally call main() twice?

Answer 1

I am not particularly a python expert but can offer some feedback from a fairly generic perspective.

• There are no useful (plain English) comments until line 105. There is definitely room to improve the commenting of this code.

• Unless StackExchange is affecting the formatting, this doesn't appear to adhere to PEP 8 (the definitive Python style guide). For example, you are using three spaces per indentation level, not four.

• As @200_success spotted in a comment, you are calling main() twice at the end: is this intentional? I cannot understand why this would be.

• foobar() does not sound like a sensible name for a function: it gives me absolutely no clue as to what the function's purpose is.

• What is the significance of "WordsWeNeverSee"? This might be well documented in the Telnet library but it might be helpful to offer a brief explanation here, so somebody can follow this code without knowing that library well. Failing that, at least a reference to the main documentation would be good.

• Your main game engine architecture smells funny to me. When main() first calls readBoard(), this can then lead to readBoard() being called recursively, and/or control passing to foobar() which then calls readBoard() again. This feels like it might lead to a deeply-nested call stack. Without following the logic through carefully I have no idea what the rationale is for this, but it seems unlikely to be the best design approach.

• Relatedly, your key functions readBoard() and selectMove() take no input and return no output. They are operating on data structures that exist globally, aside from their function scope - i.e. they are having side effects. This also seems unlikely to be the best approach; I'm not really qualified to say what the best or most-pythonic way might be, but a more object-oriented approach could be one way to go.

• readBoard() seems to have two blocks of identical code, inside the first if and following elif. In other words, you're saying: if len(tLines)==13, then do some stuff; if len(tLines)==14, then do the same stuff; else do something different. Can you see the quick way to simplify this code?