| code |
trait Complex extends Product2[double,double]
class ComplexRect(val _1:double, _2:double) extends Complex {
override def toString = "ComplexRect("+_1+","+_2+")"
}
class ComplexPolar(val _1:double, _2:double) extends Complex {
override def toString = "ComplexPolar("+_1+","+_2+")"
}
object ComplexRect {
def unapply(z:Complex): Option[Complex] = {
if(z.isInstanceOf[ComplexRect]) Some(z) else z match {
case ComplexPolar(mod, arg) =>
Some(new ComplexRect(mod*Math.cos(arg), mod*Math.sin(arg)))
} } }
object ComplexPolar {
def unapply(z:Complex): Option[Complex] = {
if(z.isInstanceOf[ComplexPolar]) Some(z) else z match {
case ComplexRect(re,im) =>
Some(new ComplexPolar(Math.sqrt(re*re + im*im), Math.atan(re/im)))
} } }
object Test {
def main(args:Array[String]) = {
new ComplexRect(1,1) match {
case ComplexPolar(mod,arg) => // z @ ???
Console.println("mod"+mod+"arg"+arg)
}
val Komplex = ComplexRect
new ComplexPolar(Math.sqrt(2),Math.PI / 4.0) match {
case Komplex(re,im) => // z @ ???
Console.println("re"+re+" im"+im)
}
}
}
|
| what happened |
concerns the -Xunapply compiler option.
the program is not correct, because "_2" should have been defined as "val _2". There is no public implementation\
of the _2 method which is required by trait Product2, however this thing compiles.
buraq$ build/quick/bin/scalac -d /tmp test/pending/pos/unapplyComplex.scala -Xunapply
buraq$ build/quick/bin/scala -classpath /tmp Test
java.lang.AbstractMethodError: ComplexRect._2()Ljava/lang/Object;
|
