Scala multiple type pattern matching

Question

I'm wondering how can I use multiple type pattern matching. I have:

abstract class MyAbstract  case class MyFirst extends MyAbstract case class MySecond extends MyAbstract case class MyThird extends MyAbstract // shouldn't be matched and shouldn't call doSomething()  val x: MyAbstract = MyFirst  x match {   case a: MyFirst => doSomething()  case b: MySecond => doSomething()  case _ => doSomethingElse() } 

So I'd like to write something like:

x match {  case a @ (MyFirst | MySecond) => doSomething()  case _ => doSomethingElse() } 

I saw similar construction in some tutorial, but it gives me error:

pattern type is incompatible with expected type; [error]  found   : object MyFirst [error]  required: MyAbstract 

So is there a way to define few different types in on case clause? I think it would make code prettier. As if I will have 5 of them, I will write same code 5 times (calling doSomething()).

Thanks in advance!

Answer 1

You are missing the parenthesis for your case classes. Case classes without parameter lists are deprecated.

Try this:

abstract class MyAbstract case class MyFirst() extends MyAbstract case class MySecond() extends MyAbstract  val x: MyAbstract = MyFirst()   x match {    case aOrB @ (MyFirst() | MySecond()) => doSomething(aOrB)    case _ => doSomethingElse() } 

If you have too many params for your case classes and don't like having to write long Foo(_,_,..) patterns, then maybe:

x match {    case aOrB @ (_:MyFirst | _:MySecond) => doSomething(aOrB)    case _ => doSomethingElse() } 

Or just:

x match {    case _:MyFirst | _:MySecond => doSomething(x) // just use x instead of aOrB    case _ => doSomethingElse(x) } 

But perhaps you just wanted singleton case objects?

abstract class MyAbstract case object MyFirst extends MyAbstract case object MySecond extends MyAbstract  val x: MyAbstract = MyFirst  x match {    case aOrB @ (MyFirst | MySecond) => doSomething()    case _ => doSomethingElse() }