Modular Programming with Python

Creating your first module

Now that we've seen what modules are and how they can be used, let's implement our first real Python module. While this module is simple, you may find it a useful addition to the programs you write.

Caching

In computer programming, a cache is a way of storing previously calculated results so that they can be retrieved more quickly. For example, imagine that your program had to calculate shipping costs based on three parameters:

• The weight of the ordered item
• The dimensions of the ordered item
• The customer's location

Calculating the shipping cost based on the customer's location might be quite involved. For example, you may have a fixed charge for deliveries within your city but charge a premium for out-of-town orders based ...