Head First Design Patterns, 2nd Edition

Chapter 13. Patterns in the Real World: Better Living with Patterns

Ahhhh, now you’re ready for a bright new world filled with Design Patterns. But, before you go opening all those new doors of opportunity, we need to cover a few details that you’ll encounter out in the real world—that’s right, things get a little more complex than they are here in Objectville. Come along, we’ve got a nice guide to help you through the transition on the next page...

Design Pattern defined

We bet you’ve got a pretty good idea of what a pattern is after reading this book. But we’ve never really given a definition for a Design Pattern. Well, you might be a bit surprised by the definition that is in common use:

Note

A Pattern is a solution to a problem in a context.

That’s not the most revealing definition, is it? But don’t worry, we’re going to step through each of these parts: context, problem, and solution:

Note

Example: You have a collection of objects.

• The context is the situation in which the pattern applies. This should be a recurring situation.

• The problem refers to the goal you are trying to achieve in this context, but it also refers to any constraints that occur in the context.

• The solution is what you’re after: a general design that anyone can apply that resolves the goal and set ...