Packages

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.

Source
Callback.scala
Linear Supertypes
(Either[E, A]) => Unit, AnyRef, Any
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  1. Callback
  2. Function1
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Visibility
  1. Public
  2. Protected

Instance Constructors

  1. new Callback()

Abstract Value Members

  1. 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.

  2. 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

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##(): Int
    Definition Classes
    AnyRef → Any
  3. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  4. def andThen[A](g: (Unit) => A): (Either[E, A]) => A
    Definition Classes
    Function1
    Annotations
    @unspecialized()
  5. 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.

  6. def apply(result: Either[E, A]): Unit

    Signals a value via Scala's Either (Left is error, Right is the successful value).

    Signals a value via Scala's Either (Left is error, Right is the successful value).

    Can be called at most once by contract. Not necessarily thread-safe, depends on implementation.

    Definition Classes
    Callback → Function1
  7. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  8. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.CloneNotSupportedException]) @native() @HotSpotIntrinsicCandidate()
  9. def compose[A](g: (A) => Either[E, A]): (A) => Unit
    Definition Classes
    Function1
    Annotations
    @unspecialized()
  10. 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.

  11. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  12. def equals(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef → Any
  13. final def getClass(): Class[_ <: AnyRef]
    Definition Classes
    AnyRef → Any
    Annotations
    @native() @HotSpotIntrinsicCandidate()
  14. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native() @HotSpotIntrinsicCandidate()
  15. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  16. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  17. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native() @HotSpotIntrinsicCandidate()
  18. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native() @HotSpotIntrinsicCandidate()
  19. final def synchronized[T0](arg0: => T0): T0
    Definition Classes
    AnyRef
  20. def toString(): String
    Definition Classes
    Function1 → AnyRef → Any
  21. 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 false in 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 onSuccess or onError are 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.

  22. 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 false in 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 onSuccess or onError are 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.

  23. 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 false in 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 onSuccess or onError are 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.

  24. 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 false in 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 onSuccess or onError are 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.

  25. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  26. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException]) @native()
  27. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])

Deprecated Value Members

  1. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.Throwable]) @Deprecated @deprecated
    Deprecated

    (Since version ) see corresponding Javadoc for more information.

Inherited from (Either[E, A]) => Unit

Inherited from AnyRef

Inherited from Any

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