Scala变量参数列表是否可以按名称调用?
我有一些这样的代码:Scala变量参数列表是否可以按名称调用?,scala,Scala,我有一些这样的代码: def foo (s: => Any) = println(s) 但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): 我必须写什么,它是这样工作的?您必须使用零参数函数。如果你愿意,你可以 implicit def byname_to_noarg[A](a: => A) = () => a 然后 def foo(s: (() => Any)*) = s.foreach(a => println
def foo (s: => Any) = println(s)
但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):
我必须写什么,它是这样工作的?您必须使用零参数函数。如果你愿意,你可以
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
有一个问题:
对于已接受的答案,要恢复所需的行为:
object Test {
import scala.language.implicitConversions
implicit def byname_to_noarg[A](a: => A) = () => a
implicit class CBN[A](block: => A) {
def cbn: A = block
}
//def foo(s: (() => Any)*) = s.foreach(a => println(a()))
def foo(s: (() => Any)*) = println(s(1)())
def goo(a: =>Any, b: =>Any, c: =>Any) = println(b)
def main(args: Array[String]) {
foo("fish", Some(7), {println("This still happens first"); true })
goo("fish", Some(7), {println("This used to happens first"); true })
foo("fish", Some(7), {println("This used to happens first"); true }.cbn)
}
}
请原谅lolcats语法。它也不能在2.9.2上编译(也不确定它是否应该编译)。
object Test {
import scala.language.implicitConversions
implicit def byname_to_noarg[A](a: => A) = () => a
implicit class CBN[A](block: => A) {
def cbn: A = block
}
//def foo(s: (() => Any)*) = s.foreach(a => println(a()))
def foo(s: (() => Any)*) = println(s(1)())
def goo(a: =>Any, b: =>Any, c: =>Any) = println(b)
def main(args: Array[String]) {
foo("fish", Some(7), {println("This still happens first"); true })
goo("fish", Some(7), {println("This used to happens first"); true })
foo("fish", Some(7), {println("This used to happens first"); true }.cbn)
}
}