Scala: is it possible to restrict access to the function definitions of a trait to its direct callers?

Question

I have a Trait LoggerHelper. Inside I have some function definitions. I want them to be accessible by the classes extending this trait but I would like to restrict the access for the classes injecting the classes extending this trait.

Example:

Trait LoggerHelper {
  def log() = ???
} 

Class A extends LoggerHelper {
  log() //OK
}

Class B @Inject() (a: A) {
  a.log() //I want this line does not compile
}

Is it possible to achieve this?

Answer 1

A protected member can be accessed only from subclasses of the class where the member is defined:

scala> trait LoggerHelper {
     |   protected def log() = ???
     | }
defined trait LoggerHelper

scala> class A extends LoggerHelper {
     |   log()
     | }
defined class A

scala> class B(a: A) {
     |   a.log()
     | }
<console>:13: error: method log in trait LoggerHelper cannot be accessed in A
 Access to protected method log not permitted because
 enclosing class B is not a subclass of
 trait LoggerHelper where target is defined
         a.log()
           ^