如何习惯性地在Kotlin中调用可为空的Lambda? [英] How do I idiomatically call a nullable lambda in Kotlin?

问题描述

给出以下lambda:

Given the following lambda:

val lambda: () -> Unit = null

以下哪些调用对于Kotlin来说是空泛的，因为它调用了可为空的lambda?

Which of the following calls is idomatic to Kotlin for calling a nullable lambda?

lambda?.let { it() }

vs

lambda?.invoke()

推荐答案

让我们问一下Kotlin编译器:

Let's ask Kotlin compiler:

 val lambda: (() -> Unit)? = null    
 lambda()

编译器说:

Reference has a nullable type '(() -> Unit)?', use explicit '?.invoke()' to make a function-like call instead

是的，似乎?.invoke()是可行的方式.

So yeah, seems that ?.invoke() is the way to go.

尽管这对我(和编译器)来说似乎都还不错:

Although even this seems fine by me (and by compiler too):

 if (lambda != null) {
      lambda()     
 }

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