Scala:无法将类方法参数标记为var/val

Question

class Time(var h: Int, val m: Int) {
  def before(val other: Time) = { //compile error due to keyword val
    (this.h < other.h) ||  (this.m < other.m)
  }
}

我要怎样的说法其它的方法之前为VAR/VAL？如果我在其他之前删除val,它会成功编译.

Answer 1

您无法修改引用,other因为它是函数的参数.

def before(val other: Time) = ...

相当于(如果它是合法的)

def before(other: Time) = ...

如果你想要一个var,只需在函数内创建它:

def before(other: Time) = {
  var otherVar = other
  ...
}