scala - “Scala 编程”一书中第 699 页的 Actor 示例引发了太多参数错误

Question

书中的代码：

object NameResolver extends Actor{
    import java.net.{InetAddress, UnknownHostException}

    def act(){
        react{
            case(name:String, actor:Actor) =>
                actor ! getIp(name)
                act()
            case "EXIT" => 
                println("Name resolver is exiting.")//quit
            case msg =>
                println("Unhandled message: "+msg)
                act()
        }
    }

    def getIp(name:String):Option[InetAddress]={
        try{
            Some(InetAddress.getByName(name))
        } catch {
            case _ : UnknownHostException => None
        }
    }

}

口译行：

NameResolver ! ("http://stackoverflow.com", self)

但我得到了错误：

scala> NameResolver ! ("http://stackoverflow.com", self)
<console>:8: error: too many arguments for method !: (msg: Any)Unit
              NameResolver ! ("http://stackoverflow.com", self)

根据书，它应该工作。我从书中复制的代码中是否存在会导致异常的错误？

Answer 1

您正在尝试传递一个元组，但编译器认为您正在!使用两个参数进行调用。因为有时可以省略括号，所以有时元组需要额外的括号，例如 in ((1, 2))。这可能会引起混淆。尝试NameResolver !(("http://stackoverflow.com", self))