|
[#903] |
project: compiler |
priority: low |
category: bug |
|---|
|
submitter |
assigned to |
status |
date submitted |
|
Nikolay |
Burak |
fixed |
2007-01-19 10:06:44.0 |
| subject |
[contrib #294] Problem using '@' with unapply pattern |
| code |
class Person(_name : String, _father : Person) {
def name = _name
def father = _father
}
object PersonFather {
def unapply(p : Person) : Option[Tuple1[Person]] =
if (p.father == null)
None
else
Some(Tuple1(p.father))
}
object Test {
def main(args : Array[String]) = {
val p1 = new Person("p1",null)
val p2 = new Person("p2",p1)
p2 match {
case aPerson@PersonFather(f) =>
System.out.println(aPerson.name + "'s father is "+f.name);
case _ => System.out.println("No father")
}
}
}
|
| what happened |
No compilation errors (compiled using -Xunapply), but the program fails at runtime with the following error:
$ scala -classpath . Test
java.lang.ClassCastException: scala.Tuple1
at Test$.main(ExtrTest.scala:22)
at Test.main(ExtrTest.scala)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at scala.tools.nsc.ObjectRunner$.run(ObjectRunner.scala:76)
at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:100)
at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)
|
| what expected |
Expected to print:
"p2's father is p1"
|
|
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