Scala 如何防止作为参数传递的函数求值？
MyScala 如何防止作为参数传递的函数求值？,scala,anonymous-function,Scala,Anonymous Function,Myaddvf函数根据value\u name键将added参数添加到映射中的值存储中 我希望看到打印出来的“你还没有煮咖啡”和 println（值（“咖啡中的糖”）） 是1 只有当值（“coffee”）为>=1时，才能调用addvf（“coffee中的糖”），如readvf函数所示。相反，这个addvf被称为它的声明 如果我在addvf前面加上（）=>，那么操作（“向咖啡中添加糖”）（）不会返回任何结果 如何防止对作为参数传递的函数进行求值 import scala.collection.
addvfvalue\u nameadded
println（值（“咖啡中的糖”））
值（“coffee”）addvf（“coffee中的糖”）readvf（）=>操作（“向咖啡中添加糖”）（）import scala.collection.mutable.HashMap
object dumbhash {
val actions = new HashMap[String, ()=>Unit]
def e(action_name: String) = {
actions(action_name)()
}
val values = new HashMap[String, Int]
values += "coffee" -> 0
values += "bread" -> 0
values += "sugar_in_coffee" -> 0
println(values("coffee"))
def readf(value_name: String, sufficient:Int, t:()=>Unit, f:() => Unit): ()=>Unit = {
if (values(value_name) >= sufficient) t else f
}
def addvf(value_name: String, added:Int, f:() =>Unit): ()=>Unit = {
val v = values(value_name)
values(value_name) = v + added
f
}
val acts = new HashMap[String, ()=> Unit]
def desc(str: String) {
println(str)
}
values("coffee") = 0
values("sugar_in_coffee") = 1
values += "made_coffee" -> 0
acts += "check_coffee" -> readf("coffee", 1,
readf("sugar_in_coffee", 1, () => desc("The coffee smells brown, like you spilled too much sugar in the cup."),
() => desc("Strong as love black coffee, waking you into this morning." )),
readf("made_coffee", 1, () => desc("You drained the cup."), () => desc("You're the type who needs coffee to make coffee")))
acts("check_coffee")()
acts += "add_sugar_to_coffee" -> readf("made_coffee", 1, addvf("sugar_in_coffee", 8, () => desc("You dump sugar into the raspberry tree coffee mug.")),
() => desc("You haven't made coffee yet"))
acts("add_sugar_to_coffee")()
println(values("sugar_in_coffee")) //returns 9!
}
def addvf(value_name: String, added:Int, f:() =>Unit): ()=>Unit = () => {
val v = values(value_name)
values(value_name) = v + added
f()
}