Issues with recursive structures

[fancellu]

Compiles file, pickles fine, stack overflow on unpickle

import scala.pickling._
import json._

object Pick1 extends App {
  case class Person(name:String, age:Int, li:List[Int], var parent:Person)

  val mum=Person("Mum",69,Nil,null)
  val me=Person("Me",47,List(1,2,99),mum)  
  mum.parent=me  
  val out=me.pickle  
  println(out)  
  val in=out.unpickle[Person]  
  println(in)
}

JSONPickle({
  "tpe": "pickling.Pick1.Person",
  "name": "Me",
  "age": 47,
  "li": {
    "tpe": "scala.collection.immutable.$colon$colon[scala.Int]",
    "elems": [
      1,
      2,
      99
    ]
  },
  "parent": {
    "name": "Mum",
    "age": 69,
    "li": {
      "tpe": "scala.collection.immutable.Nil.type"
    },
    "parent": { "$ref": 0 }
  }
})

+

Exception in thread "main" java.lang.StackOverflowError
    at scala.runtime.ScalaRunTime$$anon$1.cmax(ScalaRunTime.scala:178)
    at scala.runtime.ScalaRunTime$$anon$1.hasNext(ScalaRunTime.scala:179)
    at scala.collection.Iterator$class.foreach(Iterator.scala:727)
    at scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
    at scala.collection.TraversableOnce$class.addString(TraversableOnce.scala:320)
    at scala.collection.AbstractIterator.addString(Iterator.scala:1157)
    at scala.collection.TraversableOnce$class.mkString(TraversableOnce.scala:286)
    at scala.collection.AbstractIterator.mkString(Iterator.scala:1157)
    at scala.runtime.ScalaRunTime$._toString(ScalaRunTime.scala:170)
    at pickling.Pick1$Person.toString(Pick1.scala:7)
    at java.lang.String.valueOf(String.java:2854)
etc

[ScalaWilliam]

:+1:

Also double recursion, e.g. A referring to B, B referring to C, and C referring to A.

[phaller]

Note that you're invoking toString via println here which is the method that produces the stack overflow. Can you try accessing fields of the unpickled instance without printing it? It might not be an issue related to pickling. Thanks!

[fancellu]

  val in=out.unpickle[Person]

  println (in.name)
  println (in.parent.name)

Works fine. Of course, nothing to stop the println drilling to the centre of the earth! What did I expect to see?

Thanks.

[phaller]

Good to hear it works. Thanks for your quick response!