Think Python

Chapter 4. Case Study: Interface Design

Code examples from this chapter are available from http://thinkpython.com/code/polygon.py.

TurtleWorld

To accompany this book, I have written a package called Swampy. You can download Swampy from http://thinkpython.com/swampy; follow the instructions there to install Swampy on your system.

A package is a collection of modules; one of the modules in Swampy is TurtleWorld, which provides a set of functions for drawing lines by steering turtles around the screen.

If Swampy is installed as a package on your system, you can import TurtleWorld like this:

from swampy.TurtleWorld import *

If you downloaded the Swampy modules but did not install them as a package, you can either work in the directory that contains the Swampy files, or add that directory to Python’s search path. Then you can import TurtleWorld like this:

from TurtleWorld import *

The details of the installation process and setting Python’s search path depend on your system, so rather than include those details here, I will try to maintain current information for several systems at http://thinkpython.com/swampy

Create a file named mypolygon.py and type in the following code:

from swampy.TurtleWorld import *

world = TurtleWorld()
bob = Turtle()
print bob

wait_for_user()

The first line imports everything from the TurtleWorld module in the swampy package.

The next lines create a TurtleWorld assigned to world and a Turtle assigned to bob. Printing bob yields something like:

<TurtleWorld.Turtle instance ...