scala.DelayedInit.scala Maven / Gradle / Ivy
/*
* Scala (https://www.scala-lang.org)
*
* Copyright EPFL and Lightbend, Inc.
*
* Licensed under Apache License 2.0
* (http://www.apache.org/licenses/LICENSE-2.0).
*
* See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*/
package scala
/** Classes and objects (but note, not traits) inheriting the `DelayedInit`
* marker trait will have their initialization code rewritten as follows:
* `code` becomes `delayedInit(code)`.
*
* Initialization code comprises all statements and all value definitions
* that are executed during initialization.
*
* Example:
* {{{
* trait Helper extends DelayedInit {
* def delayedInit(body: => Unit) = {
* println("dummy text, printed before initialization of C")
* body // evaluates the initialization code of C
* }
* }
*
* class C extends Helper {
* println("this is the initialization code of C")
* }
*
* object Test extends App {
* val c = new C
* }
* }}}
*
* Should result in the following being printed:
* {{{
* dummy text, printed before initialization of C
* this is the initialization code of C
* }}}
*
* @see "Delayed Initialization" subsection of the Scala Language Specification (section 5.1)
*
* @author Martin Odersky
*/
@deprecated("DelayedInit semantics can be surprising. Support for `App` will continue. See the release notes for more details: https://github.com/scala/scala/releases/tag/v2.11.0", "2.11.0")
trait DelayedInit {
def delayedInit(x: => Unit): Unit
}