Is there Scala equivalent of C# "as" keyword?

Question

Is there Scala equivalent of C# as keyword?

var something = obj as MyClass;

Scala's asInstanceOf throws java.lang.ClassCastException:

val something = obj.asInstanceOf[MyClass]

You should post the code that throws a ClassCastException. The object you're trying to cast simply isn't of that type. — Kim Stebel, Jun 23 '11 at 09:32
possible duplicate: http://stackoverflow.com/questions/931463/scala-how-do-i-cast-a-variable — Alois Cochard, Jun 23 '11 at 09:37

score 9 · Accepted Answer · answered Jun 23 '11 at 09:35

9

After reading up on C# a bit, I realized you probably meant this:

val foo = if (bar.isInstaceOf[Foo]) bar.asInstanceOf[Foo] else null.asInstanceOf[Foo]

It should be noted that using null is discouraged in Scala. You should really do this:

val foo = if (bar.isInstaceOf[Foo]) Some(bar.asInstanceOf[Foo]) else None

answered Jun 23 '11 at 09:35

Kim Stebel

2

It should be noted too that casting in discouraged in Scala ;) – Alois Cochard Jun 23 '11 at 09:40
@Alois: Of course it is, but you can't write something equivalent to C#'s `as` without it. – Kim Stebel Jun 23 '11 at 10:06

score 9 · Answer 2 · edited May 23 '17 at 11:46

9

You can use pattern matching, like explained here: How do I cast a variable in Scala?

edited May 23 '17 at 11:46

Community

answered Jun 23 '11 at 09:37

Alois Cochard

2 Answers2