Can't access method of companion class from companion object

Question

I thought that I can access every method of the companion class from my companion object. But I can't?

class EFCriteriaType(tag:String) extends CriteriaType
{
  // implemented method of CriteriaType
  def getTag = this.tag   
}

object EFCriteriaType
{
  var TEXT: CriteriaType = new EFCriteriaType("text")

  override def toString = getTag
}

Compiler error: not found: value getTag

What I'm doing wrong?

Answer 1

You are trying to call the method getTag in object EFCriteriaType. There is no such method in that object. You could do something like:

object EFCriteriaType extends EFCriteriaType("text") {
  override def toString = getTag
}

Thus making the companion object a kind of template.

You can access members not normally accessible in a class from a companion object, but you still need to have an instance of the class to access them. E.g:

class Foo {
  private def secret = "secret"
  def visible = "visible"
}
object Foo {
  def printSecret(f:Foo) = println(f.secret) // This compiles
}
object Bar {
  def printSecret(f:Foo) = println(f.secret) // This does not compile
}

Here the private method secret is accessible from Foo's companion object. Bar will not compile since secret is inaccessible.

Answer 2

I'm not quite sure what you're trying to do here, but you need to call getTag on an instance of the class:

override def toString(x:EFCriteriaType)  = x.getTag