Methods of PartialFunction object

This topic looks at the functionality provide in the object PartialFunction.

This example uses Scala 2.8 which I believe is required.

Only two methods are focused on. PartialFunction.cond and PartialFunction.condOpt.
As per request the signature for said methods are:

1. def cond[T](x: T)(pf: PartialFunction[T, Boolean]): Boolean
2. def condOpt[T, U](x: T)(pf: PartialFunction[T, U]): Option[U]

Now for some examples:

1. scala>  import PartialFunction._
2. import PartialFunction._
4. scala> def strangeConditional(other: Any): Boolean = cond(other) {
5.      |  case x: String if x == "abc" || x == "def"  => true
6.      |  case x: Int => true
7.      | }
8. strangeConditional: (other: Any)Boolean
10. scala> strangeConditional("abc")
11. res0: Boolean = true
13. scala> strangeConditional("hello")
14. res1: Boolean = false
16. scala> strangeConditional(3)      
17. res2: Boolean = true
19. scala> def onlyInt(v: Any): Option[Int] = condOpt(v) { case x: Int => x }
20. onlyInt: (v: Any)Option[Int]
22. scala> onlyInt("hi")
23. res3: Option[Int] = None
25. scala> onlyInt(3)
26. res4: Option[Int] = Some(3)
28. scala> import util.control.Exception.catching
29. import util.control.Exception.catching
31. scala> object IntNum { 
32.      |  val number = catching(classOf[NumberFormatException])
33.      |  def unapply(x : Any) = condOpt(x) {
34.      |      case x : Int => x
35.      |      case y : String if number.opt(y.toInt).isDefined => y.toInt
36.      |    }
37.      | }
38. defined module IntNum
40. scala> 1 match { case IntNum(x) => println(x+" i win!")}   
41. 1 i win!
43. scala> 3 match { case IntNum(x) => println(x+" i win!")}
44. 3 i win!