Scala Language Annotations Annotating the main constructor
Example
/**
* @param num Numerator
* @param denom Denominator
* @throws ArithmeticException in case `denom` is `0`
*/
class Division @throws[ArithmeticException](/*no annotation parameters*/) protected (num: Int, denom: Int) {
private[this] val wrongValue = num / denom
/** Integer number
* @param num Value */
protected[Division] def this(num: Int) {
this(num, 1)
}
}
object Division {
def apply(num: Int) = new Division(num)
def apply(num: Int, denom: Int) = new Division(num, denom)
}
The visibility modifier (in this case protected) should come after the annotations in the same line. In case the annotation accepts optional parameters (as in this case @throws accepts an optional cause), you have to specify an empty parameter list for the annotation: () before the constructor parameters.
Note: Multiple annotations can be specified, even from the same type (repeating annotations).
Similarly with a case class without auxiliary factory method (and cause specified for the annotation):
case class Division @throws[ArithmeticException]("denom is 0") (num: Int, denom: Int) {
private[this] val wrongValue = num / denom
}
