CODEWITHSUNDEEP
scalapackagetype-alias
deadbird11
deadbird11

Reputation: 141

Type alias in scala for use in a separate package

I have two files, Vec3.scala and Main.scala. In Vec3.scala, I define the Vec3 case class that implements all sorts of nice operators like +, unary_-, dot product, and so on. Since I will be using both colors and points in the project I am working on, my C++ instincts want me to type alias Vec3 as Color and Point3 like so:

// Vec3.scala
package vec3

final case class Vec3(x: Float, y: Float, z: Float) {
  ...math functions...
}

type Color = Vec3
type Point3 = Vec3

However, when I attempt to compile using sbt, I get the following error that I somewhat expected:

expected class or object definition
type Color = Vec3
^

I assume this is because these type aliases do not reside in a class or object, but I don't want them to since I would much prefer Color and Point3 to have the same ease of use as Vec3 itself. If I was using C++, I'd just put these definitions in a header file and call it a day, but alas. Is there a way to do this in Scala, without having the users of my vec3 package make these type aliases themselves every time they are used in a file? Or is there some nifty Scala maneuver that solves this problem in a different way?

Upvotes: 1

Views: 1839

Answers (1)

Martijn
Martijn

Reputation: 12102

type aliases can't exist outside of a class, trait or object in scala 2. Define them in the package object instead.

Upvotes: 6

Related Questions