gistfile1.txt

Razvan Cojocaru [email protected]
to	[email protected]
date	Tue, Sep 13, 2011 at 11:07 AM
subject	[scala-user] unexpected REPL equals

The REPL unexpectedly calls equals with a String - this behavior is new in 2.9.1. – in the code below, I know the equals sucks but is short and used to work since 2.8
 
What to do? What to do?
 
$ scala
Failed to created JLineReader: java.lang.NoClassDefFoundError: Could not initialize class org.fusesource.jansi.internal.
Kernel32
Falling back to SimpleReader.
Welcome to Scala version 2.9.1.final (Java HotSpot(TM) 64-Bit Server VM, Java 1.6.0_22).
Type in expressions to have them evaluated.
Type :help for more information.
 
scala> class Num (val i:Int) {
           def + (other:Num)      = new Num (this.i + other.i) // operators
  override def toString : String  = "Numero " + i.toString     // inherit Java methods
  override def equals (other:Any) = other.asInstanceOf[Num].i == i
}
     |      |      |      | defined class Num
 
scala> new Num(3)
java.lang.ClassCastException: java.lang.String cannot be cast to Num
        at Num.equals(<console>:10)
        at scala.runtime.ScalaRunTime$.inner$1(ScalaRunTime.scala:318)
        at scala.runtime.ScalaRunTime$.stringOf(ScalaRunTime.scala:334)
        at scala.runtime.ScalaRunTime$.replStringOf(ScalaRunTime.scala:341)
        at .<init>(<console>:14)
        at .<clinit>(<console>)
        at $print(<console>)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)