Kotlin中的嵌套Lambda调用 [英] Nested lambda calls in Kotlin

问题描述

在Kotlin中嵌套lambda调用时，如何明确引用孩子和父母的it元素?例如:

When nesting lambda calls in Kotlin, how can I unambiguously refer to child's and parent's it element? For instance:

data class Course(var weekday: Int, var time: Int, var duration: Int)
var list1 = mutableListOf<Course>()
var list2 = mutableListOf<Course>()
// populate list1 and list2
// exclude any element from list1 if it has the same time and weekday as any element from list2
list1.filter { list2.none{it.weekday == it.weekday && it.time == it.time} }

推荐答案

it始终引用最内部的lambda参数，要访问外部参数，则必须命名它们.例如:

it always refers to the innermost lambda's parameter, to access outer ones, you have to name them. For example:

list1.filter { a -> list2.none { b -> a.weekday == b.weekday && a.time == b.time} }

(您可以将内部的内容保留为it，但我认为也可以更好一点).

(You could leave the inner one as it, but it's a bit nicer if you name that too, in my opinion.)

编辑:@ mfulton26链接了下面的相关文档，请参阅该文档以获取更多详细信息.

@mfulton26 linked the relevant documentation below, see that for more details.

这篇关于Kotlin中的嵌套Lambda调用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！