Surprising filter on node failure

[fancellu]

With the following code:

https://gist.github.com/fancellu/03bb694c920898613795

---

So as you can see, with hard coded XML, the filter works fine. With a seemingly equivalent structure, it doesn't find anything.

Probably due to different hashCodes, even though elements render the same

(root"number").hashCode //> Int = 1598709610
(root2"number").hashCode //> Int = 1439920665

(root"number").head.text==(root2"number").head.text //> Boolean=true

[ScalaWilliam]

scala> val a = <number>{2}</number>
a: scala.xml.Elem = <number>2</number>

scala> val b = <number>2</number>
b: scala.xml.Elem = <number>2</number>

scala> a == b
res0: Boolean = false

scala> (a.hashCode, b.hashCode)
res0: (Int, Int) = (-1257096872,361570984)

[fancellu]

Thanks William, back to my version, you can "fix" by stringifying then loading back. Ha! (I'm cringing)

(scala.xml.XML.loadString(root2.toString) "number").filter(find2)

So that is why when you're getting your XML from a string/url/file/dom, it will be fine, its just the Scala escaped stuff which seems broken.

Or. generate like this:

val root2=
{for (x<- 1 to 3) yield {scala.xml.Text(x.toString)}}

{x} emits an Atom. But renders the same. Either way, it doesn't follow the principle of least surprise

[ScalaWilliam]

package com.scalawilliam.examples

object Equality extends App {
  val a = <number>{2}</number>
  val b = <number>2</number>
  println(a.xml_==(b))
  println(a.equals(b))
  println(a == b)
  println((<numbers><number>{2}</number><number>2</number></numbers> \ "number").distinct)
}

false
false
Set(<number>2</number>, <number>2</number>)

[ScalaWilliam]

package com.scalawilliam.examples

object Equality extends App {
  val number = <numbers><number>{2}</number><number>2</number></numbers> \ "number"
  val numbers = for {
    item <- number
    i <- item
    j <- i
    node <- j.child
  } yield (node, node.hashCode(), node.getClass.getName, node.map(_.asInstanceOf[scala.xml.Atom[_]].data.getClass.getName))
  numbers foreach println
}

(2,-548373507,scala.xml.Atom,List(java.lang.Integer))
(2,-301266488,scala.xml.Text,List(java.lang.String))

[fancellu]

   <node>{2}</node> == <node>2</node>
   > false
   <node>{Text(2.toString)}</node> == <node>2</node>
   > true
   <node>{2}</node> == <node>{2}</node> 
   >true

So if using XML literals and curly braces to inject values, best test against similar escaped value, and not what looks the same when serialized.

[HuStmpHrrr]

get caught by it.

ant chance to fix it? it's too surprising. i was wondering what happened and spent 1-2 hrs on this.

[SethTisue]

@HuStmpHrrr pull request welcome. this repo is community-maintained, the only fixes coming in these days are coming from the community.