如何获得泛型类型的实际类型？ [英] How to get the actual type of a generic type?

问题描述

有一个具有泛型类型的类：

  class Action [T] 
  
 
 
 
创建它的一些实例，放在一个列表中： 
 
 
  val list = List（new Action [String]，new Action [Int]）
  
迭代它，以及如何获得实际的实例类型？
  list foreach {action => 
 //我如何知道该动作是针对String还是Int？ 
 
 $ / code> 
 
 
解决方案
编译，所以除了传统反射提供的东西外，您还需要在其中提供一些其他证据。见： 
 
 
 如何解决Scala上的类型擦除问题？或者，为什么我不能获取我的集合的类型参数？ 
 
 
 
这个问题似乎意味着在某些情况下可能会有一些神奇的应用： 
 
 
 
  
 
There is a class with generic type:
class Action[T]
Create some instances of it, put in a list:
val list = List(new Action[String], new Action[Int])
Iterate it, and how to get the actual type of the instances?
list foreach { action =>
     // how do I know the action is for a String or an Int?
}

解决方案
Scala erases generic type parameters at compilation, so you would need to have some additional evidence in you object other than what traditional reflection provides. See:

How do I get around type erasure on Scala? Or, why can't I get the type parameter of my collections?

This questions seems to imply there might be some magic to apply in some circumstances:

Accounting for type parameters in a Scala generic class 'equals' method... are manifests the only way?

                        
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