simple tictactoe game

tictactoe.py

class tictactoe(object):
    def __init__(self):
        self.x = []
        self.o = []
        self.validmoves = [1,2,3,4,5,6,7,8,9]
        self.turncounter = 0
        self.winningpos = [(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 drawpos(self,x,o,pos):
        """
        :param x: a list of moves X has done 
        :param o: a list of moves O has done
        :param pos: the position to draw an X or O
                    Values from 1 to 9 as follows:
                     -----------
                    | 7 | 8 | 9 |
                     -----------
                    | 4 | 5 | 6 |
                     -----------
                    | 1 | 2 | 3 |
                     -----------
        :return: 
        """
        if pos in self.x:
            print("x", end='')
        elif pos in self.o:
            print("o", end='')
        else:
            print(" ", end='')


    def drawboard(self):
        """
        Draw the Tick Tack Toe board
        """
        print("-------------")
        # print first xo line
        print("| ", end='')
        self.drawpos(self.x, self.o, 7)
        print(" | ", end='')
        self.drawpos(self.x, self.o, 8)
        print(" | ", end='')
        self.drawpos(self.x, self.o, 9)
        print(" |", end='\n')
        print("-------------")
        # print second xo line
        print("| ", end='')
        self.drawpos(self.x, self.o, 4)
        print(" | ", end='')
        self.drawpos(self.x, self.o, 5)
        print(" | ", end='')
        self.drawpos(self.x, self.o, 6)
        print(" |", end='\n')
        print("-------------")
        # print third xo line
        print("| ", end='')
        self.drawpos(self.x, self.o, 1)
        print(" | ", end='')
        self.drawpos(self.x, self.o, 2)
        print(" | ", end='')
        self.drawpos(self.x, self.o, 3)
        print(" |", end='\n')
        print("-------------")

    def isvalid(self, allmoves, userinput):
        """
        Checks whether a move is valid or not
        
        :param allmoves: a list of all moves done so far
        :param userinput: move to check
        :return: True if valid move, False if invalid move
        """
        if userinput not in self.validmoves:
            return False
        elif userinput in allmoves:
            print("That move has already been made")
            return False
        else:
            return True

    def checkwinner(self):
        """

        :return: "x" if x is the winner, "o" if o is the winner, else False if no winner
        """
        for n in self.winningpos:
            if n[0] in self.x and n[1] in self.x and n[2] in self.x:
                return "x"
            if n[0] in self.o and n[1] in self.o and n[2] in self.o:
                return "o"
        return False

    def getinput(self):
        userinput = ""
        try:
            userinput = int(input("Enter a position: "))
        except ValueError:
            print("Invalid input, try again.")

        if self.isvalid(self.x + self.o, userinput):
            if self.turncounter % 2:
                self.o.append(userinput)
                self.turncounter += 1
            else:
                self.x.append(userinput)
                self.turncounter += 1


def main():
    finished = False
    t = tictactoe()
    t.drawboard()
    while not finished:
        t.getinput()
        t.drawboard()
        if t.checkwinner():
            print("{} is the winner".format(t.checkwinner()))
            finished = True
        if len(t.o) + len(t.x) == 9:
            print("The game is a draw!")
            finished = True


if __name__ == "__main__":
    main()