alchemist/it.unibo.alchemist.model.observables/AbstractObservable

AbstractObservable

abstract class AbstractObservable<T>(emitOnDistinct: Boolean = true) : Observable<T>

The base implementation of Observable: it keeps the registered callbacks, hands out their handles, and notifies them of the values published through updateAndNotify.

Observables holding their own state publish it whenever it changes. Observables derived from other sources compute their value through computeFresh, and observe their sources, through observeSource, only while they are observed.

Parameters

emitOnDistinct

whether to emit only when the new derived value is different from the current one. If so, the first registration computes the current value even when not delivering it, so that the first emission can be compared against it; otherwise, a registration that does not deliver the current value computes nothing.

Type Parameters

The type of data being observed.

Inheritors

EventObservable

ObservableMutableList

ObservableMutableMap

ObservableMutableSet

Constructors

AbstractObservable

constructor(emitOnDistinct: Boolean = true)

Properties

current

open override val current: T

The current value: while observed, the latest value published; otherwise, a freshly computed one. Observables holding their own state may read it directly.

isObserved

open val isObserved: Boolean

Whether any callback is currently registered.

observerCount

override val observerCount: Int

How many callbacks are currently registered.

Functions

currentOrNull

fun <T> Observable<Option<T>>.currentOrNull(): T?

Retrieves the current value of the observable if present, or null if no value is available.

dispose

open override fun dispose()

Unregisters every callback registered with this observable.

map

open override fun <S> map(transform: (T) -> S): Observable<S>

Transforms the current observable into a new observable by applying the specified transformation function to its emitted values.

mergeWith

open override fun <O, R> mergeWith(other: Observable<O>, merge: (T, O) -> R): Observable<R>

Combines the current observable with another observable, producing a new observable that emits values derived by applying the provided merge function to the current values of both observables.

onChange

open override fun onChange(notifyOnRegistration: Boolean = true, callback: (T) -> Unit): Disposable

Registers callback to be invoked with every new value of this observable, and right away with the current one if notifyOnRegistration.

switchMap

@JvmStatic

fun <T, R> Observable<T>.switchMap(transform: (T) -> Observable<R>): Observable<R>

Maps the current value of this Observable to an inner observable through transform, and mirrors the inner observable of the most recent value only: whenever this observable emits, the previous inner observable is unsubscribed and the new one is followed.