Design Patterns in Ruby

Chapter 8. Getting Things Done with Commands

I mentioned in Chapter 1 that I spent a lot of my high school and early college waking hours working in a grocery store. My tiny store was struggling to compete with the big supermarkets, so we tried to offer services that you wouldn’t find at the local MegaMart. In particular, you could call us and dictate your shopping list over the phone, and we would be more than happy to gather up your beans, butter, and baloney and deliver it right to your door for free. Some of our customers even had standing orders. They would call us up and ask that we deliver their regular shipment—and there I would be, list in hand, pulling together yet another delivery order.

The grocery lists of my youth are a lot like ...