Question

I have a trait:

trait A {
  /*Some methods*/
}

And I have a lot of classes:

class B(val argument: SomeClass) extends A {
  /*Some methods*/
}

I want to get an argument from trait. I can create method getArgument in each class and trait:

trait A {
  def getArgument: SomeClass
  /*Some methods*/
}
class B(val argument: SomeClass) extends A {
  def getArgument = argument
  /*Some methods*/
}

Or use reflection:

trait A {
  def getArgument = {
    val f =  this.getClass.getDeclaredField("argument")
    f.setAccessible(true)
    f.get(this).asInstanceOf[SomeClass]
  }
  /*Some methods*/
}
class B(val argument: SomeClass) extends A {
  /*Some methods*/
}

Are there any better ways to do that?

Answer 1

You can have abstract vals:

trait A {
  val argument: SomeClass
}

class B(val argument: SomeClass) extends A

You need even not constraint it to be a val:

trait A {
  def argument: SomeClass
}

class B(val argument: SomeClass) extends A

class C extends A {
  def argument : SomeClass = ....
}