如何通过实现tailDefined来扩展Stream [英] how to extend Stream by implementing tailDefined

问题描述

我想扩展 scala.Stream.当我尝试时，它告诉我我不能，因为我没有所需的方法 tailDefined.

I'd like to extend scala.Stream. When I try, it tells me I can't, because I don't have the required method tailDefined.

class S[T](s:Stream[T]) extends Stream[T] {

}

当我尝试这个时，它告诉我 tailDefined 是受保护的:

When I try this, it tells me tailDefined is protected:

class S[T](s:Stream[T]) extends Stream[T] {
  def tailDefined = s.tailDefined
}

如何绕过这个限制并实现 Stream 的扩展?

How do I get around this limitation and implement an extension of Stream?

推荐答案

如果你想添加新方法"到 Stream，使用隐式类:

If you want to "add new methods" to Stream, use implicit classes:

implicit class S[T](s:Stream[T]) {
  def method1 = ...
}

val s: Stream[Int] = ...
s.method1

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