Scala 元组解构 [英] Scala Tuple Deconstruction

问题描述

我是 Scala 的新手，遇到了一个让我烦恼的小问题.

I am new to Scala, and ran across a small hiccup that has been annoying me.

并行初始化两个变量效果很好:var (x,y) = (1,2)

Initializing two vars in parallel works great: var (x,y) = (1,2)

但是我找不到并行分配新值的方法:(x,y) = (x+y,y-x)//invalid syntax

However I can't find a way to assign new values in parallel: (x,y) = (x+y,y-x) //invalid syntax

我最终写成这样:val xtmp = x+y;y = x-y;x = xtmp

我意识到编写函数式代码是避免这种情况的一种方法，但在某些情况下，var 更有意义.

I realize writing functional code is one way of avoiding this, but there are certain situations where vars just make more sense.

我有两个问题:

1) 有没有更好的方法来做到这一点?我错过了什么吗?

1) Is there a better way of doing this? Am I missing something?

2) 不允许真正并行赋值的原因是什么?

2) What is the reason for not allowing true parallel assignment?

推荐答案

遗憾的是，您不能在 Scala 中进行多项作业.但是您可以使用元组，如果它们适合您的问题:

Unfortunately, you cannot do multiple assignments in Scala. But you may use tuples, if they fit your problem:

scala> var xy = (1,2)
xy: (Int, Int) = (1,2)

scala> xy = (xy._1 + xy._2, xy._2 - xy._1)
xy: (Int, Int) = (3,1)

这样，xy 是一个有两个值的元组.第一个值可以使用 xy._1 访问，第二个值可以使用 xy._2 访问.

This way, xy is one tuple with two values. The first value can be accessed using xy._1, the second one using xy._2.

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