Design Patterns Explained: A New Perspective on Object-Oriented Design

An Observation About Using Design Patterns

When people begin to look at design patterns, they often focus on the solutions the patterns offer. This seems reasonable because they are advertised as providing good solutions to the problems at hand.

However, this is starting at the wrong end. When you learn patterns by focusing on the solutions they present, it makes it hard to determine the situations in which a pattern applies. This only tells us what to do but not when to use it or why to do it.

I find it much more useful to focus on the context of the pattern—the problem it is trying to solve. This lets me know the when and the why. It is more consistent with the philosophy of Alexander's patterns: “Each pattern describes a problem which occurs ...