Are Maybes a good pattern for scala?
문제
For a while I have been struggling to integrate scala with java methods that might return null. I came up with the following utility which helps a lot:
// produce an Option, nulls become None
object Maybe {
def apply[T](t:T) = if (t==null) None else Some(t)
}
Maybe(javaClass.getResultCouldBeNull()).map( result => doSomeWork(result) )
I have a few questions about this solution:
- Is there a better or more standard pattern to use?
- Am I duplicating something that already exists?
- Does this functionality have hidden gotchas?
해결책
Scala's built-in Option is what you're setting out to reinvent.
In that case:
scala> val sOpt: Option[String] = Option(null)
sOpt: Option[String] = None
다른 팁
Why bother making a whole companion object out of it? It's just a function, so you don't need to implement it as an object that looks like a function.
object MyUtilities{
// a whole bunch of other utilities that you use all over can also be put in this class.
def maybe[T](t:T) = if (t==null) None else Some(t)
}
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