类类型作为在Scala中的地图中的键 [英] Class type as key in map in Scala

问题描述

我的游戏有

  class Enemy 
   
 
谁是AI /功能我可以改变
  trait移动
 trait VerticalMover扩展移动
 trait RandomMover扩展移动
  
等。现在我需要基于trait获取预加载的东西。我想做的是有一个地图，接受所有的traits，扩展移动作为键，然后一些EnemyContainer作为值将具有trait相关内容预加载。
 
 
 
但是如何我定义这样的地图，以及如何格式化我的.get（）来获取容器的一些敌人的实例。像：
  val myEnemy = new Enemy with RandomMover 
 val myDetails：EnemyContainer = enemyDetailsS​​tore.get（myEnemy.getClass ）
  
 
 
解决方案
  Map [Class [_< ;: Moving]，EnemyDetails] 类型。我怀疑像：
  //给出一个Map [Class [_< ;: Moving]，EnemyDetails]键
 enemyDetailsS​​tore.filterKeys（_ isInstance myEnemy）
  
或：
  // Iterable [EnemyDetails] 
 enemyDetailsS​​tore collect {case（c，d）if c isInstance myEnemy => d} 
  
或者只是：
  //选项[EnemyDetails] 
 enemyDetailsS​​tore collectFirst {case（c，d）if c isInstance myEnemy => d} 
  
会为你做。这个代码的唯一问题是它是O（N），因为它需要一个遍历的地图，而不是简单的查找，这将是O（1）或O（log N）
 
My game has
class Enemy
who's AI/functionality I can change with
trait Moving
trait VerticalMover extends Moving
trait RandomMover extends Moving
and so on. Now I need to fetch preloaded stuff based on trait. What I would like to do is have a Map that accepts all traits that extend Moving as keys and then some EnemyContainer as value that would have trait related content preloaded.

But how do I define such a Map and how do format my .get() to get the container by an instance of some Enemy. Something like:
val myEnemy = new Enemy with RandomMover 
val myDetails:EnemyContainer = enemyDetailsStore.get(myEnemy.getClass)

解决方案
Well, I assume that your enemy details store is of type Map[Class[_ <: Moving], EnemyDetails]. I suspect that something like:
//gives a Map[Class[_ <: Moving], EnemyDetails] for all matching keys
enemyDetailsStore.filterKeys(_ isInstance myEnemy) 
Or:
//Iterable[EnemyDetails]
enemyDetailsStore collect { case (c, d) if c isInstance myEnemy => d }
Or even just:
//Option[EnemyDetails]
enemyDetailsStore collectFirst { case (c, d) if c isInstance myEnemy => d }
Will do for you. The only "issue" with this code is that it's O(N), in that it requires a traversal of the map, rather than a simple lookup, which would be O(1), or O(log N)

                        
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