Scala 解释器找不到我的类？

Question

我试图在解释器中加载一个Scala文件:

trait MyOrdered {
  def <(that: MyInt):Boolean = compare(that) < 0
  def >(that: MyInt):Boolean = compare(that) > 0
  def <=(that: MyInt):Boolean = compare(that) < 0 || this == that
  def >=(that: MyInt):Boolean = compare(that) > 0 || this == that
  def compare(that: MyInt): Int
}
class MyInt(val value: Int) extends MyOrdered {
  def compare(that: MyInt) =
    if (this.value < that.value) -1 
    else if (this.value == that.value) 0
    else 1
}

object App extends Application{
  val a = new MyInt(2)
  val b = new MyInt(4)
  println(a < b)
  println(a > b)
}

但是我收到一个愚蠢的错误:

Loading traits.scala...
<console>:8: error: not found: type MyInt
         def <(that: MyInt):Boolean = compare(that) < 0
                     ^
<console>:12: error: not found: type MyInt
         def compare(that: MyInt): Int

我如何使解释器知道MyInt类，它是在路上定义的?

Answer 1

我认为你想要:paste的行为。:load的行为就像你在解释器中输入一样，即，它一旦找到闭括号就会进行解释。您可以通过将代码包装在某个对象中来模拟:paste，如下所示:

object Test {
  trait MyOrdered {
def <(that: MyInt):Boolean = compare(that) < 0
def >(that: MyInt):Boolean = compare(that) > 0
def <=(that: MyInt):Boolean = compare(that) < 0 || this == that
def >=(that: MyInt):Boolean = compare(that) > 0 || this == that
def compare(that: MyInt): Int
}
class MyInt(val value: Int) extends MyOrdered {
  def compare(that: MyInt) =
  if (this.value < that.value) -1 
  else if (this.value == that.value) 0
  else 1
}

object App extends Application{
  val a = new MyInt(2)
  val b = new MyInt(4)
  println(a < b)
  println(a > b)
 }
}

现在你可以在:load Test.scala和import Test._之后随意使用