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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2002-2011, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala
import scala.compat.Platform.currentTime
/** The `Application` trait can be used to quickly turn objects
* into executable programs, but is ''not recommended''.
* Here is an example:
* {{{
* object Main extends Application {
* Console.println("Hello World!")
* }
* }}}
* Here, object `Main` inherits the `main` method of `Application`.
* The body of the `Main` object defines the main program. This technique
* does not work if the main program depends on command-line arguments
* (which are not accessible with the technique presented here).
*
* It is possible to time the execution of objects that inherit from class
* `Application` by setting the global `scala.time`
* property. Here is an example for benchmarking object `Main`:
* {{{
* java -Dscala.time Main
* }}}
* In practice the `Application` trait has a number of serious pitfalls:
*
* - Threaded code that references the object will block until static
* initialization is complete. However, because the entire execution
* of an `object` extending `Application` takes place during
* static initialization, concurrent code will ''always'' deadlock if
* it must synchronize with the enclosing object.
* - As described above, there is no way to obtain the
* command-line arguments because all code in body of an `object`
* extending `Application` is run as part of the static initialization
* which occurs before `Application`'s `main` method
* even begins execution.
* - Static initializers are run only once during program execution, and
* JVM authors usually assume their execution to be relatively short.
* Therefore, certain JVM configurations may become confused, or simply
* fail to optimize or JIT the code in the body of an `object` extending
* `Application`. This can lead to a significant performance degradation.
*
* It is recommended to use the [[scala.App]] trait instead.
* {{{
* object Main {
* def main(args: Array[String]) {
* //..
* }
* }
* }}}
*
* @author Matthias Zenger
* @version 1.0, 10/09/2003
*/
@deprecated("use App instead", "2.9.0")
trait Application {
/** The time when the execution of this program started,
* in milliseconds since 1 January 1970 UTC. */
val executionStart: Long = currentTime
/** The default main method.
*
* @param args the arguments passed to the main method
*/
def main(args: Array[String]) {
if (util.Properties propIsSet "scala.time") {
val total = currentTime - executionStart
Console.println("[total " + total + "ms]")
}
}
}
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