Kotlin破坏了五个以上的组成部分 [英] Kotlin destructuring more than five components

问题描述

我得到了一个正则表达式的结果，该表达式将七个捕获组返回到一个数组中.

I have the result of a regex that returns seven capturing groups into an array.

问题是我似乎只能使用五个组件，而不是使用数组元素的下标来构造对象，我以为我会使用解构.

Rather than using the subscript of the array elements to construct my object I thought I would use destructuring, the problem is it seems I can only have five components.

一个最小的例子:

//  val (a, b, c, d, e) = listOf(1, 2, 3, 4, 5)
val (a, b, c, d, e, f, g) = listOf(1, 2, 3, 4, 5, 6, 7)

编译器输出:

> Error:(70, 41) Kotlin: Destructuring declaration initializer of type
> List<Int> must have a 'component6()' function 
> Error:(70, 41) Kotlin: Destructuring declaration initializer of type 
> List<Int> must have a 'component7()' function

是否有一种方法可以包含五个以上的组件，或者这是最大值?

Is there a way to have more than five components or is this the max?

推荐答案

为 List 接口定义了5个组件功能(作为扩展功能).

There are only 5 component functions defined for the List interface (as extension functions).

您可以添加自己的组件功能作为扩展功能:

You can add your own component functions as extension functions:

operator fun <T> List<T>.component6() = this[5]
operator fun <T> List<T>.component7() = this[6]
// ...

现在可以使用:

val (a, b, c, d, e, f, g) = listOf(1, 2, 3, 4, 5, 6, 7)

来自文档:

当然，可以有component3()和component4()等等.

And, of course, there can be component3() and component4() and so on.

请注意，componentN()函数需要用运算符关键字，以允许在解构声明中使用它们.

Note that the componentN() functions need to be marked with the operator keyword to allow using them in a destructuring declaration.

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