Airstream
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Airstream/com.raquo.airstream/com.raquo.airstream.state/Var

Var

com.raquo.airstream.state.Var
See theVar companion object
trait Var[A] extends SignalSource[A], Sink[A], Named

Var is essentially a Signal that you can write to, so it's a source of state, like EventBus is a source of events.

There are two kinds of Vars: SourceVar and DerivedVar. The latter you can obtain by calling zoom on any Var, however, unlike SourceVar, DerivedVar requires an Owner in order to run.

Attributes

Companion
object
Graph
Supertypes
trait Named
trait Sink[A]
trait SignalSource[A]
trait Source[A]
class Object
trait Matchable
class Any
Show all
Known subtypes
class DerivedVar[A, B]
class SourceVar[A]

Members list

Value members

Concrete methods

def invert()(implicit ev: A =:= Boolean): Unit

Update a boolean Var by flipping its value (true -> false, or false -> true)

Update a boolean Var by flipping its value (true -> false, or false -> true)

Attributes

def invertWriter(implicit ev: A =:= Boolean): Observer[Unit]

Observer that writes !var.now(), for vars of booleans.

Observer that writes !var.now(), for vars of booleans.

Attributes

def now(): A

Attributes

Throws
Exception

if currentValue is a Failure

final def set(value: A): Unit
final def setError(error: Throwable): Unit
def setTry(tryValue: Try[A]): Unit
def someWriter[V](implicit evidence: Option[V] <:< A): Observer[V]

Write values into a Var of Option[V] without manually wrapping in Some()

Write values into a Var of Option[V] without manually wrapping in Some()

Attributes

override def toObservable: Signal[A]

Attributes

Definition Classes
override def toObserver: Observer[A]

Attributes

Definition Classes
def tryNow(): Try[A]
def tryUpdate(mod: Try[A] => Try[A]): Unit

Value parameters

mod

Note: must not throw

Attributes

def tryUpdater[B](mod: (Try[A], B) => Try[A]): Observer[B]

Value parameters

mod

(currValue, nextInput) => nextValue Note: Must not throw!

Attributes

def update(mod: A => A): Unit

Do not use on failed Vars. Use tryUpdate on those.

Do not use on failed Vars. Use tryUpdate on those.

Value parameters

mod

Note: guarded against exceptions

Attributes

def updater[B](mod: (A, B) => A): Observer[B]

An observer much like writer, but can compose input events with the current value of the var, for example:

An observer much like writer, but can compose input events with the current value of the var, for example:

val v = Var(List(1, 2, 3)) val appender = v.updater((acc, nextItem) => acc :+ nextItem) appender.onNext(4) // v now contains List(1, 2, 3, 4)

Do not use on failed Vars. Use tryUpdater on those.

Value parameters

mod

(currValue, nextInput) => nextValue

Attributes

def zoom[B](in: A => B)(out: (A, B) => A)(implicit owner: Owner): Var[B]

Inherited methods

protected def defaultDisplayName: String

This is the method that subclasses override to preserve the user's ability to set custom display names.

This is the method that subclasses override to preserve the user's ability to set custom display names.

Attributes

Inherited from:
Named
final def displayName: String

Attributes

Inherited from:
Named
def setDisplayName(name: String): Named.this.type

Set the display name for this instance (observable or observer).

Set the display name for this instance (observable or observer).

  • This method modifies the instance and returns this. It does not create a new instance.
  • New name you set will override the previous name, if any. This might change in the future. For the sake of sanity, don't call this more than once for the same instance.
  • If display name is set, toString will output it instead of the standard type@hashcode string

Attributes

Inherited from:
Named
final override def toString: String

Override defaultDisplayName instead of this, if you need to.

Override defaultDisplayName instead of this, if you need to.

Attributes

Definition Classes
Named -> Any
Inherited from:
Named

Abstract fields

Concrete fields

val writer: Observer[A]
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