Trait Basics

Trait Basics

A trait is similar to an interface but can also provide concrete method implementations and fields, not just abstract signatures. Traits cannot take constructor parameters (before Scala 3), unlike abstract classes. Traits are the primary way Scala shares reusable behavior across otherwise unrelated classes.

Note: Unlike a class, a trait cannot take constructor parameters in Scala 2 -- keep any needed configuration as abstract members instead.

Example: Trait Basics

trait Greetable {
  def name: String

  def greet(): Unit = {
    println(s"Hello, I'm $name")
  }
}

class Person(val name: String) extends Greetable

object Main extends App {
  val p = new Person("Alice")
  p.greet()
}