我正在尝试将数值运算添加到我定义的名为Quantity
. 我正在使用的代码如下...
import scala.language.implicitConversions
case class Quantity(value: Double) extends AnyVal
object Quantity {
implicit def mkNumericOps(lhs: Quantity): QuantityIsNumeric.Ops = QuantityIsNumeric.mkNumericOps(lhs)
}
object QuantityIsNumeric extends Numeric[Quantity] {
def plus(x: Quantity, y: Quantity): Quantity = Quantity(x.value + y.value)
def minus(x: Quantity, y: Quantity): Quantity = Quantity(x.value - y.value)
def times(x: Quantity, y: Quantity): Quantity = Quantity(x.value * y.value)
def negate(x: Quantity): Quantity = Quantity(-x.value)
def fromInt(x: Int): Quantity = Quantity(x.toDouble)
def toInt(x: Quantity): Int = x.value.toInt
def toLong(x: Quantity): Long = x.value.toLong
def toFloat(x: Quantity): Float = x.value.toFloat
def toDouble(x: Quantity): Double = x.value
def compare(x: Quantity, y: Quantity): Int = x.value compare y.value
}
我使用此代码如下...
class SortedAskOrders[T <: Tradable] private(orders: immutable.TreeSet[LimitAskOrder[T]], val numberUnits: Quantity) {
def + (order: LimitAskOrder[T]): SortedAskOrders[T] = {
new SortedAskOrders(orders + order, numberUnits + order.quantity)
}
def - (order: LimitAskOrder[T]): SortedAskOrders[T] = {
new SortedAskOrders(orders - order, numberUnits - order.quantity)
}
def head: LimitAskOrder[T] = orders.head
def tail: SortedAskOrders[T] = new SortedAskOrders(orders.tail, numberUnits - head.quantity)
}
...当我尝试编译此代码时,我收到以下错误..
Error:(29, 63) type mismatch;
found : org.economicsl.auctions.Quantity
required: String
new SortedAskOrders(orders + order, numberUnits + order.quantity)
以下+
显式使用隐式转换的方法实现(我认为应该已经在范围内!)有效。
def + (order: LimitAskOrder[T]): SortedAskOrders[T] = {
new SortedAskOrders(orders + order, Quantity.mkNumericOps(numberUnits) + order.quantity)
}
编译器似乎无法找到数字+
运算符的隐式转换。想法?
我认为使用隐式转换和Numeric
trait 为值类创建数字运算是非常标准的。我究竟做错了什么?