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)