Polymorphism.py

import turtle

class GoToCommand:
    def __init__(self, x, y, width=1, color='black'):
        self.x = x
        self.y = y
        self.width = width
        self.color = color

    def draw(self, turtle):
        turtle.width(self.width)
        turtle.pencolor(self.color)
        turtle.goto(self.x, self.y)

class CircleCommand:
    def __init__(self, radius, width=1, color='black'):
        self.radius = radius
        self.width = width
        self.color = color

    def draw(self, turtle):
        turtle.width(self.width)
        turtle.pencolor(self.color)
        turtle.circle(self.radius)

class BeginFillCommand:
    def __init__(self, color):
        self.color = color

    def draw(self, turtle):
        turtle.fillcolor(self.color)
        turtle.begin_fill()

class EndFillCommand:
    def __init__(self):
        pass

    def draw(self, turtle):
        turtle.end_fill()

class PenUpCommand:
    def __init__(self):
        pass

    def draw(self, turtle):
        turtle.penup()

class PenDownCommand:
    def __init__(self):
        pass

    def draw(self, turtle):
        turtle.pendown()

class PyList:
    def __init__(self):
        self.items = []

    def append(self, item):
        self.items = self.items + [item]

    def __iter__(self):
        for c in self.items:
            yield c

def main():
    filename = ('turtle_file.txt')

    t = turtle.Turtle()
    screen = t.getscreen()
    file = open(filename, 'r')

    # Create a PYlist of hold the graphic command
    graphicsCommand = PyList()
    command = file.readline().strip()

    while command != '':
        if command == 'goto':
            x = float(file.readline())
            y = float(file.readline())
            width = float(file.readline())
            color = file.readline().strip()
            cmd = GoToCommand(x, y, width, color)

        elif command == 'circle':
            radius = float(file.readline())
            width = float(file.readline())
            color = file.readline().strip()
            cmd = CircleCommand(radius, width, color)

        elif command == 'beginfill':
            color = file.readline().strip()
            cmd = BeginFillCommand(color)

        elif command == 'endfill':
            cmd = EndFillCommand()

        elif command == 'penup':
            cmd = PenUpCommand()

        elif command == 'pendown':
            cmd = PenDownCommand()

        else:
            raise RuntimeError('Unknown Command {}'.format(command))

        graphicsCommand.append(cmd)
        command = file.readline().strip()

    for cmd in graphicsCommand:
        cmd.draw(t)

    file.close()
    t.ht()
    screen.exitonclick()
    print ('Program executed Successfully')

if __name__ == '__main__':
    main()