如何从伴生对象引用Scala内部类

我想要这样的代码:

package test

object Outer {
    import Outer._

    implicit class OuterInt(val self: Int) extends AnyVal {
        def *(that: test.Outer.Inner) = that * self
        def +(that: Outer.Inner) = that + self
        def -(that: Inner) = that - self
    }
}

class Outer {
    class Widget(w: Widget) extends Inner(w) {}

    class Inner(private[Outer] val widget: Widget) {
        def *(that: Int) = this
        def +(that: Int) = this
        def -(that: Int) = this
    }
}

我正在写一个DSL,我想在这里我可以写像

val i = new Inner(...)
2 * i

2*i 编译并调用 * 方法论 Inner 反对。但是,我无法得到 内部 由编译器找到。

type Inner is not a member of object test.Outer (for *)
type Inner is not a member of object test.Outer (for +)
not found: type Inner                           (for -)

前两条错误消息表明它在对象中而不是类中查找类型。我尝试将隐式类移到类中,但这会导致一个错误,即隐式类型不能在类中。

内部 上课?