How to pattern match large Scala case classes?
I don't know if this is appropriate, but you can also build an object just to match that field, or that set of fields (untested code):
object WideLoadActorRef {
def unapply(wl: WideLoad): Option[ActorRef] = { Some(wl.d) }
}
someVal match {
case WideLoadActorRef(d) => d ! someMessage
}
or even
object WideLoadBnD {
def unapplySeq(wl: WideLoad): Option[(Int,ActorRef)] = { Some((wl.b,wl.d)) }
}
someVal match {
case WideLoadBnD(b, d) => d ! SomeMessage(b)
}
You can always fall back to guards. It's not really nice, but better than normal pattern matching for you monster case classes :-P
case class Foo(a:Int, b:Int, c:String, d:java.util.Date)
def f(foo:Foo) = foo match {
case fo:Foo if fo.c == "X" => println("found")
case _ => println("arrgh!")
}
f(Foo(1,2,"C",new java.util.Date())) //--> arrgh!
f(Foo(1,2,"X",new java.util.Date())) //--> found
That said I think you should rethink your design. Probably you can logically group some parameters together using case classes, tuples, lists, sets or maps. Scala does support nested pattern matching:
case class Bar(a: Int, b:String)
case class Baz(c:java.util.Date, d:String)
case class Foo(bar:Bar, baz:Baz)
def f(foo:Foo) = foo match {
case Foo(Bar(1,_),Baz(_,"X")) => println("found")
case _ => println("arrgh!")
}
f(Foo(Bar(1,"c"),Baz(new java.util.Date, "X"))) //--> found
f(Foo(Bar(1,"c"),Baz(new java.util.Date, "Y"))) //--> arrgh!
You can just specify the type in the matched pattern:
case class WideLoad(a: String, b: Int, c: Float, d: ActorRef, e: Date)
val someVal = WideLoad(...)
someVal match {
case w: WideLoad => w.d ! SomeMessage(...)
}