如何在 Scala 中使用泛型 [英] how to use generics in Scala

问题描述

我已经对这个组件进行了编码，可以在不同的语言之间切换:

I have coded this component, to alternate between different languages:

import scala.collection.mutable.Map

sealed trait Language
case object English extends Language {
  val messages: Map[String, String] =
    Map("M01" -> "Ready for cooking - press START",
      "M02" -> "Close the door to start cooking")
}
case object French extends Language {
  val messages: Map[String, String] =
    Map("M01" -> "Pret pour la cuisson - presse START",
      "M02" -> "Fermez la porte pour commencer la cuisson")
}

class Lang {

  //The default Language
  private var language: Language = English

  def chosen(lang: Language) = language = lang

  def displayMessage(msg: String) = language match {
    case English => English messages msg
    case French => French messages msg 
  }

}

我关心的是如何使用参数化来构建这样的组件，然后使用为其参数提供的不同语言对其进行配置?

My concern is how to use parameterization to build such a component and then to configure it with different languages given to its parameter?

推荐答案

我认为在这种情况下你真的不需要泛型.

I don't think you really need generic in this case.

另外...你的设计感觉有些不对劲.无论如何...如果您认为您有泛型的用例...您可以这样做.

Also... your design feels to have something off about it. Anyways... if you think you have a use case for generics... you can do it this way.

稍微改变你的性格

sealed trait Language {
  val messages: Map[ String, String ]
}

现在像这样定义你的泛型类，

Now define your generic class like this,

class Lang[ A <: Language ]( var language: A = English ) {

  def chosen( lang: A ): Unit = {
    language = lang
  }

  def displayMessage(msg: String): Unit = {
    language messages msg 
  }

}

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