Question

我正在尝试在Scala中找出正确的语法，将一组函数应用于对象。说我上课了：

class MiTestClass {
   def isValid() : Bool = {...}
   def isGreen() : Bool= {...}
   def isYellow() : Bool = {...}
}

我创建了一个新对象val miTestObj = new MiTestClass现在我想将一个方法的子集应用到我的对象，如

val conditions:List[MiTestClass => Boolean] = List(_.isGreen, _.isYellow)

并执行某些操作，比如说检查所有属性是否保持

val result:Bool  = resultOfApplyingFunctions.foldLeft(true)(and)

获取此类功能的语法是什么？在Haskell中你会写类似

的东西

map (\f -> f miTestObj) conditions

但我无法正确使用Scala语法

Answer 1

scala> val conditions: List[MiTestClass => Boolean] = List(_.isGreen, _.isYellow) 
conditions: List[(MiTestClass) => Boolean] = List(<function1>, <function1>)

scala> val obj = new MiTestClass
obj: MiTestClass = MiTestClass@3dc049d

scala> conditions.forall(_(obj))
res1: Boolean = false

scala> conditions.forall(f => f(obj)) // slightly more verbose way
res2: Boolean = false

Answer 2

conditions.map(f => f(miTestObj))

或

conditions map (_(miTestObj))

将一组函数应用于对象的语法

2 个答案: