Class ObserverSignal<T>

Signal which observes the given observable.

Type Parameters

  • T

Hierarchy (View Summary)

Implements

Methods

[observable] destroy get getVersion isValid isWatched set subscribe unwatch validate watch from

Methods

[observable]

destroy

  • destroy(): void

  • Destroys the observer signal by unsubscribing from the observable and removing any reference to it and also unregistering it from the current signal context (if present).

    Returns void

get

  • get(): T

  • Returns the current signal value which is retained even when the observed observable is complete. When the observable emitted an error then this method throws this error.

    Returns T

    The current signal value.

    Throws

    Error - The error emitted by the observable, if any.

getVersion

  • getVersion(): number

  • Returns the current signal value version. This version is incremented every time the signal value has really changed. The version starts by 0 and wraps to Number.MIN_SAFE_INTEGER when Number.MAX_SAFE_INTEGER is reached, allowing unique versions for eighteen quadrillion signal updates.

    Returns number

    The current signal version.

isValid

  • isValid(): boolean

  • Checks if signal value is still valid. When signal has no dependencies then this method can always return true. If signal has dependencies then it must check if any dependency has changed or became invalid. If yes, then this method must return false and the signal will be re-validated by calling (). If all dependency are valid/unchanged then this method must return true to indicate that the signal value is still valid.

    Returns boolean

    True if signal value is valid, false if it must be re-validated.

isWatched

Protectedset

  • set(value: T): this

  • Sets the value. Does nothing when new value equals the old one. If new value is different, then the signal version is increased and observers are informed.

    Parameters

    • value: T

      The value to set.

    Returns this

subscribe

  • subscribe(observer: Observer<T> | (next: T) => void): Subscription

  • Subscribes the given observer to this object.

    Parameters

    • observer: Observer<T> | (next: T) => void

      The observer to subscribe.

    Returns Subscription

    Object which can be used to unsubscribe the observer.

Protectedunwatch

validate

  • validate(): void

  • Called when () returned false and the current value of this signal is needed. Must compute/fetch and cache the new value so the next call to () returns a valid value. When signal has no dependencies and () is implemented to always return true then this method can stay empty as it has nothing to validate/update.

    Returns void

Protectedwatch

Staticfrom

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