Threader.py

"""This code is for an exercise from
Think Python: An Introduction to Software Design

Copyright 2010 Allen B. Downey
License: GNU GPLv3 http://www.gnu.org/licenses/gpl.html

This program requires Gui.py, which is part of
Swampy; you can download it from thinkpython.com/swampy.

"""

from swampy.Gui import Callable
from swampy.TurtleWorld import Turtle, TurtleWorld


class Threader(Turtle):
 def __init__(self, world):
 Turtle.__init__(self, world)
 self.delay = 0.005
 self.set_color('purple')

 def step():
 """Threaders don't need no stinkin' step method.

 See http://en.wikipedia.org/wiki/Stinking_badges
 """
 
 def moveto(self, x, y):
 """Teleports to the given coordinates and redraws."""
 self.x = x
 self.y = y
 self.redraw()

 def koch(self, n):
 """Draws a Koch curve with length n.

 See http://en.wikipedia.org/wiki/Koch_snowflake
 """
 if n<8:
 self.fd(n)
 return
 for angle in [-60, 120, -60, 0]:
 self.koch(n/3.0)
 self.rt(angle)

 def snowflake(self):
 """Draws a Koch snowflake."""
 for i in range(3):
 self.koch(300)
 self.rt(120)
 self.undraw()


def make_threader(world):
 """Creates a Threader and makes it draw a snowflake."""
 t = Threader(world)
 t.moveto(-150, 90)

 # TODO: modify this so it runs in a new thread
 t.snowflake()


world = TurtleWorld()
world.setup_interactive()

# add a button that calls make_threader
world.bu(text='Make Threader', command=Callable(make_threader, world))
world.mainloop()