Question

目前我使用scalaz和shapeless来生成一个只更新更改值的case类，但是对于某些扩展功能我需要知道哪些字段（名称）发生了变化，有没有简单的方法呢？

或者通常有更好的方法来检查每个字段是否相等？

示例：

case class A(quanity: Option[Long], lose: Option[Long])

val a0 = A(Option(50), Option(10))
val a1 = A(Option(50), Option(20))

// Here it will be merged to a2 which is done by scalaz
// Now I need the fields that changed, ie. quanity or lose 
// (or any other field   if there are more
// a list or anything would be good enough:

val mergedList: List[String] = "lose" :: List()

Answer 1

首先想到的是 - productIterator：

    scala> A(5, "asd")
    res6: A = A(5,asd)

    scala> A(5, "asd")
    res7: A = A(5,asd)

    scala> A(1, "asd")
    res8: A = A(1,asd)

    scala> res6.productIterator.toList
    res9: List[Any] = List(5, asd)

    scala> res7.productIterator.toList
    res10: List[Any] = List(5, asd)

    scala> res8.productIterator.toList
    res11: List[Any] = List(1, asd)

    scala> res9 == res10
    res12: Boolean = true

    scala> res9 == res11
    res13: Boolean = false

    scala> res11.diff(res10)
    res18: List[Any] = List(1)

Scala比较案例类并获取更改的字段

1 个答案: