takes from 3 to 5 positional arguments but 6 were given?

Question

My program is supposed to draw a chessboard using user input. The drawing has to occur with the call of draw(). I am getting an error:

line 18, in main
 chessboard = Chessboard(tr, startX, startY, eval(width),  val(height)) 
TypeError: __init__() takes from 3 to 5 positional arguments but 6 were given

The thing is that my main module cannot change. I have to leave it as it is. It's a requirement. So, how can I solve that problem when I cannot change a thing from it? It only gives me an error on line 18.

main module:

import turtle
from chessboard import Chessboard

def main():
    startX, startY = eval(input("Enter a starting point: "))
    width = input("Input a width: ")
    height = input("Input a height: ")

    tr = turtle.Turtle()

    if width == "" and height == "":
        chessboard = Chessboard(tr, startX, startY)
    elif height == "":
        chessboard = Chessboard(tr, startX, startY, width=eval(width))
    elif width == "":
        chessboard = Chessboard(tr, startX, startY, height=eval(height))
    else:
        chessboard = Chessboard(tr, startX, startY, eval(width), eval(height))

        chessboard.draw()

        tr.hideturtle()
        turtle.done()

main()

I leave my chessboard.py module in case it has to do something with it:

import turtle


class Chessboard:
    def __init__(self, startX, startY, width=250, height=250):
        self.__startX = startX
        self.__startY = startY
        self.__width = width
        self.__height = height

    def draw(self, __startX, __startY, __width=250, __height=250):
        turtle.clear
        self.__drawChessboard(__startX, __startY, __width, __height)

    def __drawChessboard(self, __startX, __startY, __width=250, __height=250):
        # uses height x width, default 250
        turtle.setheading(0)  
        turtle.penup() 
        turtle.goto(__startX, __startY) 
        turtle.pendown() 
        turtle.goto(__startX + __width, __startY)
        turtle.goto(__startX + __width, __startY + __height)
        turtle.goto(__startX, __startY + __height)
        turtle.goto(__startX, __startY)

        self.__drawAllRectangles(self, __startX, __startY, __width, __height)

        turtle.exitonclick()

    def __drawAllRectangles(self, __startX, __startY, __width, __height):
        __checkerWidth = __width / 8
        __checkerHeight = __height / 8
        for row in range(8):
            for column in range(4):
                if row % 2 == 0:
                    self.__drawRectangle(self, __startX + (2 * column * __checkerWidth),
                                         __startY + (row * __checkerHeight), __checkerWidth, __checkerHeight)
                else:
                    self.__drawRectangle(self, __startX + __checkerWidth + (2 * column * __checkerWidth),
                                         __startY + (row * __checkerHeight), __checkerWidth, __checkerHeight)

    def __drawRectangle(self, __startX, __startY, __checkerWidth, __checkerHeight):
        turtle.penup()
        turtle.setheading(0)
        turtle.goto(__startX, __startY)
        turtle.fillcolor("black")
        turtle.begin_fill()
        turtle.pendown()
        turtle.goto(__startX + __checkerWidth, __startY)
        turtle.goto(__startX + __checkerWidth, __startY + __checkerHeight)
        turtle.goto(__startX, __startY + __checkerHeight)
        turtle.goto(__startX, __startY)
        turtle.end_fill()

Thanks for your help!

Answer 1

The first argument of every class method, including init, is always a reference to the current instance of the class. By convention, this argument is always named self. In the init method, self refers to the newly created object; in other class methods, it refers to the instance whose method was called.

EDIT: I didnt read the part where you said you can't change the main module, I apologize

class Chessboard:
    def __init__(self, tr, startX, startY, width=250, height=250):
        self.tr = tr
        self.__startX = startX
        self.__startY = startY
        self.__width = width
        self.__height = height

    def draw(self):
        self.tr.clear()
        self.__drawChessboard(self.__startX, self.__startY, self.__width, self.__height)

    def __drawChessboard(self, __startX, __startY, __width=250, __height=250):
        # uses height x width, default 250
        self.tr.setheading(0)  
        self.tr.penup() 
        self.tr.goto(__startX, __startY) 
        self.tr.pendown() 
        self.tr.goto(__startX + __width, __startY)
        self.tr.goto(__startX + __width, __startY + __height)
        self.tr.goto(__startX, __startY + __height)
        self.tr.goto(__startX, __startY)

        self.__drawAllRectangles(__startX, __startY, __width, __height)

        self.tr.exitonclick()

    def __drawAllRectangles(self, __startX, __startY, __width, __height):
        __checkerWidth = __width / 8
        __checkerHeight = __height / 8
        for row in range(8):
            for column in range(4):
                if row % 2 == 0:
                    self.__drawRectangle(__startX + (2 * column * __checkerWidth),
                                         __startY + (row * __checkerHeight), __checkerWidth, __checkerHeight)
                else:
                    self.__drawRectangle(__startX + __checkerWidth + (2 * column * __checkerWidth),
                                         __startY + (row * __checkerHeight), __checkerWidth, __checkerHeight)

    def __drawRectangle(self, __startX, __startY, __checkerWidth, __checkerHeight):
        self.tr.penup()
        self.tr.setheading(0)
        self.tr.goto(__startX, __startY)
        self.tr.fillcolor("black")
        self.tr.begin_fill()
        self.tr.pendown()
        self.tr.goto(__startX + __checkerWidth, __startY)
        self.tr.goto(__startX + __checkerWidth, __startY + __checkerHeight)
        self.tr.goto(__startX, __startY + __checkerHeight)
        self.tr.goto(__startX, __startY)
        self.tr.end_fill()