如何覆盖隐含值？

Question

假设我有代码:

class A(implicit s:String = "foo"){println(s)}

object X {
   implicit val s1 = "hello"
}
object Y {
   import X._
   // do something with X
   implicit val s2 = "hi"
   val a = new A
}

我收到错误:

<console>:14: error: ambiguous implicit values:
 both value s2 in object Y of type => String
 and value s1 in object X of type => String
 match expected type String
           val a = new A

有什么办法,我可以告诉斯卡拉利用价值s2的Y？(如果我重新命名s2到s1,它工作正常,但是这不是我想要的).

另一个解决方案是不要做import X._,我想要避免的事情.

Answer 1

你可以做的另一件事是导入所有东西,但s1:import X.{s1 => _, _}.

Answer 2

我同意另一个答案,明确提供隐含在这些类型的情况下是首选,但如果你坚持想要"降级"另一个隐含的,那么它不再被视为隐含的那么它实际上是可能的:

class A(implicit s:String = "foo"){println(s)}

object X {
  implicit val s1 = "hello"
}
object Y {
  import X._
  val s1 = X.s1 //downgrade to non-implicit

  // do something with X
  implicit val s2 = "hi"
  val a = new A
}

再次,这有点hackish,但它的工作原理.