带有call-by-name参数的重载函数和带有by-value参数的函数

Question

Why does doSmth(() => s) not compile? Why does the rest of the code output "value"? Is there a way to call the second function(with call-by-name parameter)?

object Test {
  def main (args: Array[String]){
    lazy val s: String = ""
    doSmth(s)
    doSmth("")
    doSmth(() => s)
  }

  def doSmth(p: String): Unit = {
    println("value!")
  }
  def doSmth(p: => String): Unit = {
    println("call by name!")
  }
}

Answer 1

The following code works and compiles as expected:

def doSmth(p: String): Unit = {
  println("value!")
}
def doSmth(p: () => String): Unit = {
  println("call by name!")
}

lazy val s: String = ""
doSmth(s)
doSmth("")
doSmth(() => s)

Note that if you have two versions of the method, one which is by-name and one which is by-value, there is no way for Scala to know which one you mean. Instead above, the second version of the method takes a function from unit to string.