相关疑难解决方法(0)

例:

import scala.actors._  
import Actor._  

class BalanceActor[T <: Actor] extends Actor {  
  val workers: Int = 10  

  private lazy val actors = new Array[T](workers)  

  override def start() = {  
    for (i <- 0 to (workers - 1)) {  
      // error below: classtype required but T found  
      actors(i) = new T  
      actors(i).start  
    }  
    super.start()  
  }  
  // error below:  method mailboxSize cannot be accessed in T
  def workerMailboxSizes: List[Int] = (actors map (_.mailboxSize)).toList  
.  
.  
.  

注意第二个错误表明它知道actor项是"T",但不是"T"是actor的子类,而是在类通用定义中受到约束.

如何纠正此代码(使用Scala 2.8)？

我正在尝试做一些我不确定Scala的类型系统是否允许我这样做的事情.

我基本上想要从泛型定义创建一个闭包并返回该闭包,同时在同一类型内部执行一个函数.

例如:

val f = async[(str:String, i:Int, b:BigInt) => Unit]({ (String, Int, BigInt) =>
  // Code here...
})

// 'f' would have a type of (String, Int, BigInt) => Unit and would wrap the passed anonymous function

定义的理论范例:

  def async[T](
    shell: Shell,
    success: T,
    failure: (Throwable) => Unit): T = {
        new T {
          val display = shell.getDisplay()
          display.asyncExec(new Runnable() {
            def run(): Unit = {
              try {
                success(_)
              } catch {
                case e:Throwable =>
                  failure(e)
              } …