Listing 12.4

In Listing 12.4 the signature for the _draw method in line 19 should include a parameter to reference a turtle, since the turtle is in fact needed by the child classes.

def _draw(self, someTurtle):

   print("error:…")

Chapter 12 -- Listing 12.8

There is a typo in Listing 12.8. In the init method the instance variable is visibleObjects. The b is missing in the text. In addition, the calls to up() and tracer should be added to the drawAll() method as they are in listing 12.4

Here is a complete, corrected version of Listing 12.8

class Canvas:

    def __init__(self,w,h):
        self.width = w
        self.height = h
        self.visibleObjects = []
        self.turtle = cTurtle.Turtle()
        self.turtle.setup(width=self.width,height=self.height)
        self.turtle.hideturtle()

    def drawAll(self):
        self.turtle.reset()
        self.turtle.tracer(0)
        for shape in self.visibleObjects:
            shape._draw(self.turtle)
        self.turtle.tracer(1)
        self.turtle.hideturtle()

    def addShape(self,shape):
        self.visibleObjects.append(shape)

    def draw(self,gObject):
        gObject.setCanvas(self)
        gObject.setVisible(True)
        self.turtle.up()
        self.turtle.tracer(0)
        gObject._draw(self.turtle)
        self.turtle.tracer(1)
        self.addShape(gObject)

Listing 12.1

Lines 4, 6, and 16 incorrectly call a method named fillColor. the name of the method should be setFill. For example line 4 should read house.setFill('blue')