Strategy

Synopsis

I am playing a fighting game and I do not know my opponent. Should I prefer an offensive or defensive style?

Problem

Since the opponent is unknown, the player has to choose a fighting strategy on the fly. In programming terms, we can say that an algorithm has to be selected at runtime, among several available algorithms.

Solution

The Strategy design pattern is exactly what we need in this kind of situation. To implement this pattern, we can have:

• An object literal to represent the context (the fighting game)
• Object literals to represent available strategies (offense and defense)

Offensive and defensive strategies seem to share a "fight" method, but the performed action is obviously different. Moreover, the context (fighting game) must have a reference to the current strategy because its main method ("play") is directly influenced by the selected strategy in the client code.