Haxe

Question

假设我有两个 classes:

class PlayerManagerParent {
   public function new(){
   }  
}

class GameManagerParent {
   public var playerManager:PlayerManagerParent();

   public function new(){
   }  
}

然后我将class分

class PlayerManagerChild extends PlayerManagerParent {
   public function new(){
      super();
   }  

   public function someMethod(){
   }
}

class GameManagerChild extends GameManagerParent {

   public function new(){
      super();
      this.playerManager = new PlayerManagerChild();
   }  
}

然后我创建 GameManagerChild 的实例并想要访问 someMethod():

var gameManager:GameManagerChild = new GameManagerChild();
gameManager.playerManager.someMethod();

我当然不能这样做，因为 gameManager.playerManager 是 playerManager:PlayerManagerParent 的类型，没有定义 someMethod() 并且编译器/类型检查器给我错误。

如何在不在父 class 中声明 someMethod() 或将 playerManager 类型设置为 Dynamic 的情况下解决此问题（这是一个选项，但我不能遍历 playerManager 中的可迭代字段，例如)?

Answer 1

您可以为此使用受约束的参数化类型：

class PlayerManagerParent {
   public function new(){
   }  
}

class GameManagerParent<T:PlayerManagerParent> {
   public var playerManager:T;

   public function new(){
   }  
}

有了这个，你可以像这样扩展：

class PlayerManagerChild extends PlayerManagerParent {
   public function new(){
      super();
   }  

   public function someMethod(){
   }
}

class GameManagerChild extends GameManagerParent<PlayerManagerChild> {

   public function new(){
      super();
      this.playerManager = new PlayerManagerChild();
   }  
}

这允许你这样做：

var child = new GameManagerChild();
child.playerManager.someMethod();

实例：
http://try.haxe.org/#21bfC

See also:
http://haxe.org/manual/type-system-type-parameters.html

Protip: You could even mark it as @:generic, which might be gain extra performance at some platforms: http://haxe.org/manual/type-system-generic.html

Answer 2

您可能应该使用类型参数，例如：

class GameManagerParent<PM:PlayerManagerParent> {
     public var playerManager : PM;
}

class GameManagerChild 
extends GameManagerParent<PlayerManagerChild> {
     public function new() {
         playerManager = new PlayerManagerChild();
     }
}

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inheritance