Type aliasing a case class in Scala 2.10

Question

I'm using Scala 2.10.2, and have two case classes that have identical fields:

case class Foo(id: String, name: String)
case class Bar(id: String, name: String)

I'd like to do something like this:

case class Thing(id: String, name: String)
type Foo = Thing
type Bar = Thing

This compiles, but when I try to create a Foo, I get:

scala> Bar("a", "b")
<console>:8: error: not found: value Bar
              Bar("a", "b")
              ^

Does type aliasing not work with case classes?

Answer 1

When you create a case class Scala automatically creates a companion object for it. In your code you define an alias for the type Thing, i.e. for the class Thing only. Your companion object Thing still has only 1 name and no aliases.

One way to "fix" it is to create a reference to the companion object (not a type alias) like this:

scala> val Bar = Thing
Bar: Thing.type = Thing

scala> Bar("a", "b")
res1: Thing = Thing(a,b)

Another way to "fix" it would be to rename the imported object with import package.{Thing => Bar}.