abstract class Callback[-E, -A] extends (Either[E, A]) ⇒ Unit
Represents a callback that should be called asynchronously with the result of a computation.
This is an Either[E, A] => Unit with an OOP interface that
avoids extra boxing, along with overloads of apply.
The onSuccess method should be called only once, with the successful
result, whereas onError should be called if the result is an error.
Obviously Callback describes unsafe side-effects, a fact that is
highlighted by the usage of Unit as the return type. Obviously
callbacks are unsafe to use in pure code, but are necessary for
describing asynchronous processes.
THREAD-SAFETY: callback implementations are NOT thread-safe by contract, this depends on the implementation. Callbacks can be made easily thread-safe via wrapping with:
NOTE that callbacks injected in the Task async builders (e.g. Task.async) are thread-safe.
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Instance Constructors
- new Callback()
Abstract Value Members
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abstract
def
onError(e: E): Unit
Signals an error.
Signals an error.
Can be called at most once by contract. Not necessarily thread-safe, depends on implementation.
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abstract
def
onSuccess(value: A): Unit
Signals a successful value.
Signals a successful value.
Can be called at most once by contract. Not necessarily thread-safe, depends on implementation.
Concrete Value Members
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final
def
!=(arg0: Any): Boolean
- Definition Classes
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final
def
##(): Int
- Definition Classes
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final
def
==(arg0: Any): Boolean
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def
andThen[A](g: (Unit) ⇒ A): (Either[E, A]) ⇒ A
- Definition Classes
- Function1
- Annotations
- @unspecialized()
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def
apply(result: Try[A])(implicit ev: <:<[Throwable, E]): Unit
Signals a value via Scala's
Try.Signals a value via Scala's
Try.Can be called at most once by contract. Not necessarily thread-safe, depends on implementation.
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def
apply(result: Either[E, A]): Unit
Signals a value via Scala's
Either(Leftis error,Rightis the successful value).Signals a value via Scala's
Either(Leftis error,Rightis the successful value).Can be called at most once by contract. Not necessarily thread-safe, depends on implementation.
- Definition Classes
- Callback → Function1
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final
def
asInstanceOf[T0]: T0
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def
clone(): AnyRef
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- protected[lang]
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- @throws( ... ) @native()
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def
compose[A](g: (A) ⇒ Either[E, A]): (A) ⇒ Unit
- Definition Classes
- Function1
- Annotations
- @unspecialized()
-
def
contramap[B](f: (B) ⇒ A): Callback[E, B]
Return a new callback that will apply the supplied function before passing the result into this callback.
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final
def
eq(arg0: AnyRef): Boolean
- Definition Classes
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def
equals(arg0: Any): Boolean
- Definition Classes
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def
finalize(): Unit
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- protected[lang]
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- @throws( classOf[java.lang.Throwable] )
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final
def
getClass(): Class[_]
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- @native()
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def
hashCode(): Int
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final
def
isInstanceOf[T0]: Boolean
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final
def
ne(arg0: AnyRef): Boolean
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final
def
notify(): Unit
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final
def
notifyAll(): Unit
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final
def
synchronized[T0](arg0: ⇒ T0): T0
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def
toString(): String
- Definition Classes
- Function1 → AnyRef → Any
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def
tryApply(result: Either[E, A]): Boolean
Attempts to call Callback.apply.
Attempts to call Callback.apply.
In case the underlying callback implementation protects against protocol violations, then this method should return
falsein case the final result was already signaled once via onSuccess or onError.The default implementation relies on catching
CallbackCalledMultipleTimesException in case of violations, which is what thread-safe implementations of
onSuccessoronErrorare usually throwing.WARNING: this method is only provided as a convenience. The presence of this method does not guarantee that the underlying callback is thread-safe or that it protects against protocol violations.
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def
tryApply(result: Try[A])(implicit ev: <:<[Throwable, E]): Boolean
Attempts to call Callback.apply.
Attempts to call Callback.apply.
In case the underlying callback implementation protects against protocol violations, then this method should return
falsein case the final result was already signaled once via onSuccess or onError.The default implementation relies on catching
CallbackCalledMultipleTimesException in case of violations, which is what thread-safe implementations of
onSuccessoronErrorare usually throwing.WARNING: this method is only provided as a convenience. The presence of this method does not guarantee that the underlying callback is thread-safe or that it protects against protocol violations.
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def
tryOnError(e: E): Boolean
Attempts to call Callback.onError.
Attempts to call Callback.onError.
In case the underlying callback implementation protects against protocol violations, then this method should return
falsein case the final result was already signaled once via onSuccess or onError.The default implementation relies on catching
CallbackCalledMultipleTimesException in case of violations, which is what thread-safe implementations of
onSuccessoronErrorare usually throwing.WARNING: this method is only provided as a convenience. The presence of this method does not guarantee that the underlying callback is thread-safe or that it protects against protocol violations.
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def
tryOnSuccess(value: A): Boolean
Attempts to call Callback.onSuccess.
Attempts to call Callback.onSuccess.
In case the underlying callback implementation protects against protocol violations, then this method should return
falsein case the final result was already signaled once via onSuccess or onError.The default implementation relies on catching
CallbackCalledMultipleTimesException in case of violations, which is what thread-safe implementations of
onSuccessoronErrorare usually throwing.WARNING: this method is only provided as a convenience. The presence of this method does not guarantee that the underlying callback is thread-safe or that it protects against protocol violations.
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final
def
wait(): Unit
- Definition Classes
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- @throws( ... )
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final
def
wait(arg0: Long, arg1: Int): Unit
- Definition Classes
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- @throws( ... )
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final
def
wait(arg0: Long): Unit
- Definition Classes
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- @throws( ... ) @native()