How does Scala get all the child objects that inherit trait

trait Base

object A extends Base // 
object B extends Base // 
object C extends Base // 
class D extents Base // 

object Base {
  //TODO  trait Base  object
  //TODO  akka actor  event  Base 
}

when using akka to throw a Event event, I want to inform all objects that inherit the attribute Base that they each perform their own actions on the event.
now is that the events thrown by akka are uniformly distributed by the companion objects of Base , and verify that all inheritors of Base are object singletons.

Java scala akka

Mar.04,2021

the reflection mechanism is needed here: use getSubTypesOf in the Java class library reflections to get all the subclasses, but to get their corresponding objects, you need to get the MODULE$ field through getField , and you can get the corresponding objects according to this field.

package com.gcusky.util.reflect

import org.reflections.Reflections
import scala.collection.JavaConverters._

object Base {
  def subObject[T](underlying: Class[T]): Seq[T] = {
    val reflects = new Reflections("com.gcusky.util.reflect")
    reflects.getSubTypesOf(underlying).asScala.map { sub =>
      sub.getField("MODULE$").get(null).asInstanceOf[T]
    }.toSeq
  }
}

because in Scala, two class files are generated after the singleton object and the accompanying object are compiled: Base.class and Base$.class . The Base$.class class has a constant field MODULE$ , whose type is the class type of the current class Test$ .

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