Confusing AnyRef equals

[Georgii Dernovyi]

I found that subj returns false for the same object. It is a terrible mistake for me

case class a(i:Int)
{
  override def canEqual(a: Any) = a.isInstanceOf[a]

  override def equals(o:Any) = AnyRef.equals(o)

  override def hashCode = AnyRef.hashCode
}

val aa = new a(1)
aa == aa //false

Am I right? )

[Vlad Patryshev]

This is beautiful.

val AnyRef = new Specializable {
  override def toString = "object AnyRef"
}

Thanks,
-Vlad

On Wed, Dec 14, 2016 at 8:05 AM, Georgii Dernovyi <g.der...@gmail.com> wrote:

--
You received this message because you are subscribed to the Google Groups "scala-language" group.
To unsubscribe from this group and stop receiving emails from it, send an email to scala-language+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[Oliver Ruebenacker]

     Hello,

  It looks like you may have intended to call the AnyRef-implementation of equals of this object, but in fact AnyRef.equals(o) calls the equals method of the AnyRef object, which is a different object, so it returns false.

Welcome to Scala 2.11.8 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_45).
Type in expressions for evaluation. Or try :help.

scala> :paste
// Entering paste mode (ctrl-D to finish)

case class a(i:Int)
{
  override def canEqual(a: Any) = a.isInstanceOf[Int]

  override def equals(o:Any) = AnyRef.equals(o)

  override def hashCode = AnyRef.hashCode
}

// Exiting paste mode, now interpreting.

defined class a

scala> val aa = new a(1)
aa: a = a(1)

scala> aa == aa
res0: Boolean = false

scala> aa == AnyRef
res1: Boolean = true

scala> AnyRef
res2: Specializable = object AnyRef

     Best, Oliver

On Wed, Dec 14, 2016 at 11:00 AM, Georgii Dernovyi <g.der...@gmail.com> wrote:

I found that subj returns false for the same object. It is a terrible mistake for me

case class a(i:Int)
{
  override def canEqual(a: Any) = a.isInstanceOf[Int]

  override def equals(o:Any) = AnyRef.equals(o)

  override def hashCode = AnyRef.hashCode
}

val aa = new a(1)
aa == aa //false

Am I right? )

--
You received this message because you are subscribed to the Google Groups "scala-language" group.
To unsubscribe from this group and stop receiving emails from it, send an email to scala-language+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

--

Oliver Ruebenacker

Senior Software Engineer, Diabetes Portal, Broad Institute

[Oliver Ruebenacker]

     Hello,

  What you seem to want can be written like this:

case class a(i:Int)
{
  override def equals(o:Any) = super[Object].equals(o)
  override def hashCode = super[Object].hashCode
}

     Best, Oliver

[Georgii Dernovyi]

Thanks! )

To unsubscribe from this group and stop receiving emails from it, send an email to scala-languag...@googlegroups.com.

For more options, visit https://groups.google.com/d/optout.

--

Oliver Ruebenacker

Senior Software Engineer, Diabetes Portal, Broad Institute