如何使用仅在运行时已知的值初始化对象 val? [英] How do I initialize object vals with values known only at runtime?

问题描述

假设我正在尝试编写一个简单的井字游戏.它有一个 M x N 字段.游戏只有一个字段，所以它可能应该用一个单独的 object 来表示.像这样:

Let's say I'm trying to write a simple Tic-Tac-Toe game. It has an M x N field. The game has only one field, so it probably should be represented with a singleton object. Like this:

object Field {
    val height : Int = 20
    val width : Int = 15
    ...
}

但我不想硬编码高度和宽度，所以如果它们可以在运行时通过构造函数或其他东西传递给对象，那就太好了.但是 object 不能有构造函数.

But I don't want to hardcode the height and width, so it would be nice if those could be passed to the object at runtime, via a constructor or something. But objects cannot have constructors.

好吧，我可以将 height 和 width 改为 vars，而不是 vals 并引入一种新方法

Well, I could change height and width to be vars, and not vals and introduce a new method

def reconfigure (h:Int, w:Int) = {
    height = h
    width = w
}

并在游戏开始时调用它.但它也不优雅.

and call it at the begining of the game. But it's not elegant as well.

那么，有没有一种巧妙的方法可以做到这一点 - 即使用运行前未知的值初始化对象 val ?

So, is there a neat way of doing this - i.e. having object vals initialized with values not known before runtime?

推荐答案

为什么不使用 class 并在 main 中初始化一个实例?

Why not use a class and initialize one instance in main?

case class Field(width: Int, height: Int) {
  //...
}

object Main {
  def main(args: Array[String]): Unit = {
    val field = Field(30, 25)
  }
}

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