flatMap 可能是您正在寻找的,但是 map 函数具有日志记录副作用,如果点是视图,这些副作用可能不会立即发生:
val convertedPoints = points.view.flatMap { p =>
try {
Some(p.convert)
} catch {
case e : Exception =>
// Log error
None
}
}
println("Conversion complete")
println(convertedPoints.size + " were converted correctly")
这将打印:
Conversion complete
[Error messages]
x were converted correctly
在您的情况下,放下视图,您可能会没事。:)
要使转换成为纯函数(没有副作用),您可能会使用 Either。虽然我认为这里不值得付出努力(除非你真的想对错误做点什么),但这里有一个非常完整的使用示例:
case class Point(x: Double, y: Double) {
def convert = {
if (x == 1.0) throw new ConversionException(this, "x is 1.0. BAD!")
else ConvertedPoint(x, y)
}
}
case class ConvertedPoint(x: Double, y: Double)
class ConversionException(p: Point, msg: String) extends Exception(msg: String)
val points = List(Point(0,0), Point(1, 0), Point(2,0))
val results = points.map { p =>
try {
Left(p.convert)
} catch {
case e : ConversionException => Right(e)
}
}
val (convertedPoints, errors) = results.partition { _.isLeft }
println("Converted points: " + convertedPoints.map(_.left.get).mkString(","))
println("Failed points: " + errors.map( _.right.get).mkString(","))