Scala 变量参数列表可以按名称调用吗? [英] Scala variable argument list with call-by-name possible?

问题描述

我有一些这样的代码:

def foo (s: => Any) = println(s)

但是当我想将其转换为可变长度的参数列表时，它将不再编译(在 Scala 2.10.0-RC2 上测试):

But when I want to transform this to an argument list with variable length, it won't compile anymore (tested on Scala 2.10.0-RC2):

def foo (s: => Any*) = println(s)

我必须写什么才能像这样工作?

What must I write, that it works like this?

推荐答案

您必须改用零参数函数.如果你愿意，你可以

You have to use zero-argument functions instead. If you want, you can

implicit def byname_to_noarg[A](a: => A) = () => a

然后

def foo(s: (() => Any)*) = s.foreach(a => println(a()))

scala> foo("fish", Some(7), {println("This still happens first"); true })
This still happens first
fish
Some(7)
true

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