Question

我有一个具有自定义特征的类型定义：

trait Foo {
  def bar: String
}

val BooleanType: Class[Boolean] with Foo = classOf[Boolean] with Foo {
  def bar = ""
}

//Error: error: ';' expected but 'with' found.

但是，这不起作用。我也尝试过：

val BooleanType: Class[Boolean] with Foo = classOf[Boolean] {...}
//Error:  Class[Boolean](classOf[scala.Boolean]) does not take parameters

和

val BooleanType: Class[Boolean] with Foo = classOf[Boolean] with new Foo {...}
//Error:  error: ';' expected but 'with' found.

均无效。如何实现？

编辑：我也尝试使用scala类型：

val Boolean: Type with Foo = typeOf[Boolean] with Foo {...}
//error: ';' expected but 'with' found.

Answer 1

您无法创建Class的子类，因为它是最终类。如果可以，并且如果有构造函数，则语法为：

val BooleanType: Class[Boolean] with Foo = new Class[Boolean](< args >) with Foo {
  def bar = ""
}

据我所知，不可能对特定实例进行子类化（就像您尝试使用classOf[Boolean]一样）。

如何初始化复合类型？

1 个答案: