dsl - Scala: store call-by-name variable as class field -

in progress in scala learning try implement simple dsl callbacks

object button {...} // apply  class button(val name: string) {     private val: => unit; // doesn't work      def click(f: => unit) = {         _click_cb = f             }      def onclick() = this._click_cb() }  button("click me!") click {println("clicked!")} 

i create new object, pass callback store. demo framework fires onclick method, should call stored one

it works () => unit dsl looks ugly:

button("click me!") click (() => println("clicked!")) 

sure, onclick abstract , implement anonymous class later

new button("click me!") {def onclick = println("clicked!")} 

but want play dsl , such

the questions are:

• how store f in _click_cb?
• how provide initial "empty" function _click_cb?
• and maybe there's more scala-way achieve this? (without anonymous classes)

an uglier version show lazy val can hold name parameter value without evaluating it:

case class button(val name: string) {   def clickcallback(): unit = ()    def click(f: => unit) = {     lazy val notevaluated = f     new button(name) { override def clickcallback() = notevaluated }   }    def onclick(): unit = clickcallback() } 

a cleaner , more functional implementation:

class button(val name: string) {   def click(f: => unit) = new button(name) { override def onclick() = f }    def onclick(): unit = () }