Strategy pattern

The strategy pattern is useful when there is a need to separate the implementation of a process from the class that uses it. There are several reasons that this can be useful.

File:Strategy pattern.jpg

The strategy pattern

• There are several different versions of the algorithm to implement.
• The algorithms are used in more than one place. Once and only once
• There is a need to create an encapsulation boundary around the algorithm to hide implementation details.
• The class using the strategy implements many different behaviours choosing which behaviour to use with if statements. Each choice can be represented as a strategy instead simplifying code and making the intent explicit.

In Design Patterns by the Gang of Four the object using the strategy is called the Context