Scala 解释器找不到我的课程？答案

【问题标题】：Scala interpreter can't find my class?Scala 解释器找不到我的课程？
【发布时间】：2011-12-13 07:14:00
【问题描述】：

我正在尝试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

我怎样才能让解释器知道 MyInt 类，这是在路上定义的？

【问题讨论】：

标签： scala types polymorphism

【解决方案1】：

我想你想要:paste 的行为。 :load 的行为就像您在解释器中输入一样，即，它会在找到右大括号后立即进行解释。您可以通过将代码包装在这样的对象中来模拟:paste：

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)
 }
}

现在您可以在:load Test.scala 和import Test._ 之后随意使用它

【讨论】：

好的，谢谢。我认为对整个文件进行分析，而不是逐类分析。 :paste 也能正常工作。