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  1. object Main extends App {
  2.  
  3.   trait Replica {
  4.     def identity: ReplicaIdentity
  5.  
  6.     abstract trait ReplicaIdentity
  7.   }
  8.  
  9.   trait LocalReplica extends Replica {
  10.     final val identity = LocalIdentity
  11.  
  12.     object LocalIdentity extends ReplicaIdentity
  13.   }
  14.  
  15.  
  16.   trait NamedReplica extends Replica {
  17.     val name: String
  18.     final lazy val identity = NamedIdentity(name)
  19.  
  20.     case class NamedIdentity (name: String) extends ReplicaIdentity {
  21.       override def equals(other: Any): Boolean = other match {
  22.           case (that: NamedReplica#NamedIdentity) => // we have to use 'NamedReplica#' (type projection), otherwise the `other` would have path dependent type and would not match with just 'NamedIdentity'
  23.            that.isInstanceOf[NamedIdentity] && name == that.name
  24.  
  25.           case _ =>
  26.            false
  27.       }
  28.     }
  29.   }
  30.  
  31.   class CRDT {
  32.     this: Replica =>
  33.  
  34.     def getId = identity
  35.   }
  36.  
  37.   val o = new CRDT() with LocalReplica 
  38.  
  39.   val o2 = new CRDT() with NamedReplica {
  40.     val name = "2"
  41.   }
  42.  
  43.   val o3 = new CRDT() with NamedReplica {
  44.     val name = "3"
  45.   }
  46.  
  47.   val o4 = new CRDT() with NamedReplica {
  48.     val name = "2"
  49.   }
  50.  
  51.   assert(o2.getId != o.getId)
  52.   assert(o2.getId != o3.getId)
  53.   assert(o2.getId == o4.getId)
  54.   assert(o2.getId == o2.getId)
  55. }
Success #stdin #stdout 0.38s 382016KB
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https://ideone.com/CFrsxp
language:
Scala (scala 2.12.8)
created:
9 years ago
visibility:
public

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