如何将变换的参数提供给超类构造函数,同时避免使用Scala进行内联计算

Question

这是我目前不能令人满意的解决方案,在传递给超类构造函数之前操纵传递给子类构造函数的值的问题,

class MissingItemsException(items: Set[String], itemsCategory: String)
  extends RuntimeException(MissingItemsException.makeMessage(items, itemsCategory))

private object MissingItemsException {

  private def makeMessage(items: Set[String], itemsCategory: String): String = {
    /* Format set as ['?','?','?'] */
    val Items = items mkString ("['", "','", "']")
    "the following items %s were missing from '%s'" format (items, itemsCategory)
  }

}

是否有一种方法可以分解转换,以便转换代码保持接近使用点,同时保持代码清晰？

Answer 1

您可以使用早期初始化程序:

class MissingItemsException(items: Set[String], itemsCategory: String) extends {
  val customMessage = {
    val Items = items mkString ("['", "','", "']")
    "the following items %s were missing from '%s'" format (items, itemsCategory)
  }
} with RuntimeException( customMessage );

从老式的词汇范围角度来看,它甚至可以编译.但编译它确实,它做你想要的!然而,它是否比你的解决方案"更好"是一个品味问题.