Teach Your Kids To Code: A Parent-friendly Guide to Python Programming

Functions: There’s a Name for That 145

Here’s the whole program together; type this into IDLE and

save it as RandomSpiralsFunction.py or download it from h t t p : //

http://www.nostarch.com/teachkids/.

RandomSpiralsFunction.py

import random

import turtle

t = turtle.Pen()

t.speed(0)

turtle.bgcolor("black")

colors = ["red", "yellow", "blue", "green", "orange", "purple",

"white", "gray"]

def random_spiral():

t.pencolor(random.choice(colors))

size = random.randint(10,40)

x = random.randrange(-turtle.window_width()//2,

turtle.window_width()//2)

y = random.randrange(-turtle.window_height()//2,

turtle.window_height()//2)

t.penup()

t.setpos(x,y)

t.pendown()

for m in range(size):

t.forward(m*2)

t.left(91)

for n in range(50):

random_spiral()

In addition to a more readable program, we also get a reusable

random_spiral() function that we can copy, modify, and easily use in

other programs.

If you find yourself reusing a chunk of code again and again,

convert it into a function like we did with random_spiral() using def,

and you’ll find it much easier to port the code—that is, carry it

over and reuse it—into new applications.

n ote You can even create your own module full of
functions and import your module just like
we’ve imported turtle and random in our pro-
grams (see Appendix C on how to create a
module in Python). That way you can share
your code with friends.