Question

class Board:
    def __init__(self):
        self.pieces = [[None for i in range(8)] for j in range(8)]

    def __str__(self):
        s = ""
        for j in range(7, -1, -1): #for each row
            for i in range(8): # for each column
                if self.pieces[j][i] is None: # if self.pieces[j][i] is None
                    s += "." # populate the row with '.' val for each column
                else:
                    s += self.pieces [j][i].get_symbol()
            s += "\n" #after each row add a new line
        return s # return after iterating through all rows and columns

class Piece:

        def __init__(self, board, row, col, is_white):
            self.row = row
            self.col = col
            self.is_white = is_white
            board.pieces[row][col] = self


        def get_symbol(self):
            pass


class Rook(Piece):
    def __init__(self, board, row, col, is_white):
        Piece.__init__(board, row, col, is_white)

    def get_symbol(self):
        if self.is_white:
            return '\u2656'
        else:
            return '\u265C'

board = Board()
Rook(board, 0, 0, True)
Rook(board, 0, 7, True)
Rook(board, 7, 0, False)
Rook(board, 7, 7, False)
print(str(board))

It comes up as a problem with is_white can you tell me whats wrong. it's supose to print out an 8x8 matrix with the rooks on the board.

Answer 1

You forgot to pass self when you are calling the super class constructor in line 31 in class Rook.

Your code

class Rook(Piece):
    def __init__(self, board, row, col, is_white):
        Piece.__init__(board, row, col, is_white)

    def get_symbol(self):
        if self.is_white:
            return '\u2656'
        else:
            return '\u265C'

Correct Code

class Rook(Piece):
    def __init__(self, board, row, col, is_white):
        Piece.__init__(self,board, row, col, is_white)

    def get_symbol(self):
        if self.is_white:
            return '\u2656'
        else:
            return '\u265C'

Explanation

In your code, Rook is a subclass of Piece, so when we call the Piece's constructor from Rook's constructor we have to supply the self object as well because this is not an object creation instead this object is created and we are just passing the reference.

When we create a new object, in that case we dont need to pass the self object.

Sample Output