App

A composable application trait that includes flag parsing as well as basic application lifecycle (pre- and post- main). Flag parsing is done via com.twitter.app.Flags, an instance of which is defined in the member flag. Applications should be constructed with modularity in mind, and common functionality should be extracted into mixins.

Flags should only be constructed in the constructor, and should only be read in the premain or later, after they have been parsed.

object MyApp extends App {
val n = flag("n", 100, "Number of items to process")

def main() {
  for (i <- 0 until n()) process(i)
}
}

Note that a missing main is OK: mixins may provide behavior that does not require defining a custom main method.

Linear Supertypes

CloseAwaitably, Awaitable[Unit], Closable, AnyRef, Any

Value Members

final def !=(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def !=(arg0: Any): Boolean

Definition Classes
Any
final def ##(): Int

Definition Classes
AnyRef → Any
final def ==(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def ==(arg0: Any): Boolean

Definition Classes
Any
final val MinGrace: Duration

Minimum duration to allow for exits to be processed.
def allowUndefinedFlags: Boolean

Whether or not to accept undefined flags
Whether or not to accept undefined flags

Attributes
protected
def args: Array[String]

The remaining, unparsed arguments
final def asInstanceOf[T0]: T0

Definition Classes
Any
def clone(): AnyRef

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( ... )
final def close(deadline: Time): Future[Unit]

Notify the application that it may stop running.
Notify the application that it may stop running. Returns a Future that is satisfied when the App has been torn down or errors at the deadline.

Definition Classes
App → Closable
def close(after: Duration): Future[Unit]

Definition Classes
Closable
final def close(): Future[Unit]

Definition Classes
Closable
def closeAwaitably(f: ⇒ Future[Unit]): Future[Unit]

Attributes
protected
Definition Classes
CloseAwaitably
final def closeOnExit(closable: Closable): Unit

Close closable when shutdown is requested.
Close closable when shutdown is requested. Closables are closed in parallel.

Attributes
protected
def defaultCloseGracePeriod: Duration

Default amount of time to wait for shutdown.
Default amount of time to wait for shutdown. This value is not used as a default if close() is called without parameters. It simply provides a default value to be passed as close(grace).
final def eq(arg0: AnyRef): Boolean

Definition Classes
AnyRef
def equals(arg0: Any): Boolean

Definition Classes
AnyRef → Any
def exitOnError(reason: String): Unit

Attributes
protected
def failfastOnFlagsNotParsed: Boolean

Attributes
protected
def finalize(): Unit

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( classOf[java.lang.Throwable] )
val flag: Flags

The com.twitter.app.Flags instance associated with this application
final def getClass(): Class[_]

Definition Classes
AnyRef → Any
def hashCode(): Int

Definition Classes
AnyRef → Any
final def init(f: ⇒ Unit): Unit

Invoke f before anything else (including flag parsing).
Invoke f before anything else (including flag parsing).

Attributes
protected
final def isInstanceOf[T0]: Boolean

Definition Classes
Any
def isReady(implicit permit: CanAwait): Boolean

Definition Classes
CloseAwaitably → Awaitable
final def main(args: Array[String]): Unit
val name: String

The name of the application, based on the classname
final def ne(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def notify(): Unit

Definition Classes
AnyRef
final def notifyAll(): Unit

Definition Classes
AnyRef
final def onExit(f: ⇒ Unit): Unit

Invoke f when shutdown is requested.
Invoke f when shutdown is requested. Exit hooks run in parallel and all must complete before postmains are executed.

Attributes
protected
final def postmain(f: ⇒ Unit): Unit

Invoke f after the user's main has exited.
Invoke f after the user's main has exited.

Attributes
protected
final def premain(f: ⇒ Unit): Unit

Invoke f right before the user's main is invoked.
Invoke f right before the user's main is invoked.

Attributes
protected
def ready(timeout: Duration)(implicit permit: CanAwait): App.this.type

Definition Classes
CloseAwaitably → Awaitable
def result(timeout: Duration)(implicit permit: CanAwait): Unit

Definition Classes
CloseAwaitably → Awaitable
final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
AnyRef
def toString(): String

Definition Classes
AnyRef → Any
final def wait(): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )
final def wait(arg0: Long, arg1: Int): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )
final def wait(arg0: Long): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )

trait App extends Closable with CloseAwaitably

Value Members

final def !=(arg0: AnyRef): Boolean

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: AnyRef): Boolean

final def ==(arg0: Any): Boolean

final val MinGrace: Duration

def allowUndefinedFlags: Boolean

def args: Array[String]

final def asInstanceOf[T0]: T0

def clone(): AnyRef

final def close(deadline: Time): Future[Unit]

def close(after: Duration): Future[Unit]

final def close(): Future[Unit]

def closeAwaitably(f: ⇒ Future[Unit]): Future[Unit]

final def closeOnExit(closable: Closable): Unit

def defaultCloseGracePeriod: Duration

final def eq(arg0: AnyRef): Boolean

def equals(arg0: Any): Boolean

def exitOnError(reason: String): Unit

def failfastOnFlagsNotParsed: Boolean

def finalize(): Unit

val flag: Flags

final def getClass(): Class[_]

def hashCode(): Int

final def init(f: ⇒ Unit): Unit

final def isInstanceOf[T0]: Boolean

def isReady(implicit permit: CanAwait): Boolean

final def main(args: Array[String]): Unit

val name: String

final def ne(arg0: AnyRef): Boolean

final def notify(): Unit

final def notifyAll(): Unit

final def onExit(f: ⇒ Unit): Unit

final def postmain(f: ⇒ Unit): Unit

final def premain(f: ⇒ Unit): Unit

def ready(timeout: Duration)(implicit permit: CanAwait): App.this.type

def result(timeout: Duration)(implicit permit: CanAwait): Unit

final def synchronized[T0](arg0: ⇒ T0): T0

def toString(): String

final def wait(): Unit

final def wait(arg0: Long, arg1: Int): Unit

final def wait(arg0: Long): Unit

Inherited from CloseAwaitably

Inherited from Awaitable[Unit]

Inherited from Closable

Inherited from AnyRef

Inherited from Any

Ungrouped