The Scala Application.scala source code
/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2002-2010, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala
import scala.compat.Platform.currentTime
/** <p>
* The <code>Application trait can be used to quickly turn objects
* into executable programs, but is <em>not recommended.
* Here is an example:
* </p> * <b>object Main extends Application {
* Console.println("Hello World!")
* }
* </pre>
* <p>
* Here, object <code>Main inherits the main method
* of <code>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).
* </p>
* <p>
* It is possible to time the execution of objects that inherit from class
* <code>Application by setting the global scala.time
* property. Here is an example for benchmarking object <code>Main:
* </p> * java -Dscala.time Main
* </pre>
* <p>
* In practice the <code>Application trait has a number of serious
* pitfalls:
* </p>
* <ul>
* <li> Threaded code that references the object will block until static
* initialization is complete. However, because the entire execution of an
* <code>object extending Application takes place during
* static initialization, concurrent code will <em>always deadlock if
* it must synchronize with the enclosing object.</li>
* <li>As described above, there is no way to obtain the
* command-line arguments because all code in body of an <code>object
* extending <code>Application is run as part of the static initialization
* which occurs before <code>Application's main method
* even begins execution.</li>
* <li>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 <code>object extending
* <code>Application. This can lead to a significant
* performance degradation.</li>
* </ul>
*
* It is recommended to use the `App` trait instead.
* <pre>
* <b>object Main {
* <b>def main(args: Array[String]) {
* //..
* }
* }
* </pre>
*
* @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]")
}
}
}
Other Scala examples (source code examples)
Here is a short list of links related to this Scala Application.scala source code file:
The search page
Other Scala source code examples at this package level
Click here to learn more about this project
