Functional Programming Patterns in Scala and Clojure

Pattern 7

Replacing Strategy

Intent

To define an algorithm in abstract terms so it can be implemented in several different ways, and to allow it to be injected into clients so it can be used across several different clients

Overview

Strategy has a few parts. The first is an interface that represents some algorithm, such as a bit of validation logic or a sorting routine. The second is one or more implementations of that interface; these are the strategy classes themselves. Finally, one or more clients use the strategy objects.

For instance, we may have several different ways we want to validate a set of data input from a form on a website, and we may want to use that validation code in several places. We could create a Validator interface with ...