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/** Illustrate the use of custom 'apply/update' methods. */
object properties {
/** A mutable property whose getter and setter may be customized. */
case class Property[T](init: T) {
private var value: T = init
/** The getter function, defaults to identity. */
private var setter: T => T = identity[T]
/** The setter function, defaults to identity. */
private var getter: T => T = identity[T]
/** Retrive the value held in this property. */
def apply(): T = getter(value)
/** Update the value held in this property, through the setter. */
def update(newValue: T) /*?*/ = value = setter(newValue)
/** Change the getter. */
def get(newGetter: T => T) /*?*/ = { getter = newGetter; this }
/** Change the setter */
def set(newSetter: T => T) = { setter = newSetter; this }
}
class User {
// Create a property with custom getter and setter
val firstname = Property("")./*!*/get { v => v.toUpperCase() }./*!*/set { v => "Mr. " + v }
val lastname = Property("<noname>")
/** Scala provides syntactic sugar for calling 'apply'. Simply
* adding a list of arguments between parenthesis (in this case,
* an empty list) is translated to a call to 'apply' with those
* arguments.
*/
override def toString() = firstname() + " " + lastname()
}
def main(args: Array[String]) {
val user1 = new User
// Syntactic sugar for 'update': an assignment is translated to a
// call to method 'update'
user1./*!*/firstname() = "Robert"
val user2 = new User
user2.firstname() = "bob"
user2.lastname() = "KUZ"
println("user1: " + user1)
println("user2: " + user2)
}
}
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