Scala面试题：call-by-value和call-by-name求值策略的区别？

示例代码

//声明第一个函数
def func(): Int = {
  println("computing stuff....")
  42 // return something
}
//声明第二个函数，scala默认的求值就是call-by-value
def callByValue(x: Int) = {
  println("1st x: " + x)
  println("2nd x: " + x)
}
//声明第三个函数，用=>表示call-by-name求值
def callByName(x: => Int) = {
  println("1st x: " + x)
  println("2nd x: " + x)
}

//开始调用

//call-by-value求值
callByValue(func())   
//输出结果
//computing stuff....  
//1st x: 42  
//2nd x: 42

//call-by-name求值
callByName(func())   
//输出结果
//computing stuff....  
//1st x: 42  
//computing stuff....
//2nd x: 42