彼得·施密茨(Peter Schmitz)简单地删除val的解决方案(以及希望将RichElapsed转换为值类的方法)当然是最简单且干扰最小的要做.

Peter Schmitz's solution to simply drop the val (along with the hope of turning RichElapsed into a value class) is certainly the simplest and least intrusive thing to do.

如果您确实感觉需要值类，那么另一种选择是:

If you really feel like you need a value class, another alternative is this:

class RichElapsed[A](val f: () => A) extends AnyVal {

  def elapsed(): (A, Double) = {
    val start = System.nanoTime()
    val res = f()
    val end = System.nanoTime()

    (res, (end-start)/1e6)
  }
}

implicit def toRichElapsed[A]( f: => A ) = new RichElapsed[A](() => f )

请注意，虽然使用上面的值类可以删除临时RichElapsed实例的实例化，但仍然存在一些包装操作(包括我的解决方案和Peter Schmitz的解决方案). 即，将以名称传递为f的主体包装到一个函数实例中(在Peter Schmitz的情况下，这在代码中并不明显，但无论如何都将在后台进行). 如果您也想删除此包装，我相信唯一的解决方案是使用宏.

Note that while using a value class as above allows to remove the instantiation of a temporary RichElapsed instance, there is still some wrapping going on (both with my solution and with Peter Schmitz's solution). Namely, the body passed by name as f is wrapped into a function instance (in Peter Schmitz's case this is not apparent in the code but will happen anyway under the hood). If you want to remove this wrapping too, I believe the only solution would be to use a macro.