4.6 FishBot

Purpose

The purpose of this assignment is to motivate the use of Strategies instead of “hard-coding” individual behavior into an object.

Introduction

A fish that is startled moves to get away from a predator. If a fish always does the same behavior to escape, it is easy for a predator to predict what will happen and the fish will get eaten. In order to avoid getting eaten, a fish alternates between darting forward and darting to the left.

• DartForward: a Strategy of moving forward three times

• DartLeft :a Strategy of turning left and moving forward once

• FishBot is a kind of (our) StrategyLayer that remembers two different strategies and alternates betweewn them.

  • public void startle() activates the startle reflex, running the current strategy for escape
  • public void swapStrategy() switches between the two strategies that the fish knows

Difficulties

• Confusion between StrategyLayer and Strategy.
  • How are they actually related?
  • Can both be created? (new Strategy() vs new StrategyLayer(...))
• What is the relationship between FishBot and StrategyLayer?
• Too-specific names for things:
  • iFishBotStrategy for the interface
  • variables of type DartStrategy and DodgeLeftStrategy instead of just Strategy

Some of these difficulties should have come up with the ArmyCaricature, so we need to revisit that!