Reactive.Boolean 0.3.0

Reactive.Boolean

Reactive Extensions meant specifically for implementations of IObservable<bool>

This documentation uses marble diagrams to explain the transformations of IObservable<bool>. More on marble diagrams can be found in the documentation of ReactiveX.

Article containing examples in relation to home automation: Article with examples.

Logical Operators

This library has extension methods for logical operators:

Not

And

And (not distinct)

Or

Or (not distinct)

XOr

Scheduling

This library also has extension methods for scheduling:

TrueForAtLeast

Returns an observable that won't emit false for at least timespan after an initial "true" is emitted by source.

Example Use Case

Turn on a light for at least 3 seconds after a button was pressed. If 3 seconds are passed, only keep it on if the button is still being pressed, but immediately turn if off if not.

// buttonPressed is a IObservable<bool>
var buttonPressed = button.StateChanges().Select(s => s.State == "pressed");
buttonPressed
    .TrueForAtLeast(TimeSpan.FromSeconds(3), scheduler)
    .SubscribeTrueFalse(
        () => light.TurnOn(),
        () => light.TurnOff());

PersistTrueFor

Returns an observable that stays true for a time span once the source observable turns back to false.

Example Use Case

Keep a light on for 3 more seconds after last motion was detected.

// motionDetected is a IObservable<bool>
var motionDetected = motionSensor.StateChanges().Select(s => s.State == "motion detected");
motionDetected
    .PersistTrueFor(TimeSpan.FromSeconds(3), scheduler)
    .SubscribeTrueFalse(
        () => light.TurnOn(),
        () => light.TurnOff());

WhenTrueFor

Returns an observable that emits true once the source observable emits true for a minimum time span.

Example Use Case

Send notification when washing machine power has been 0 for at least 1 minute.

// washingMachineCurrentIsZero is a IObservable<bool>
var washingMachineCurrentIsZero = washingMachineCurrent.StateChanges().Select(s => s.State == 0);
washingMachineCurrentIsZero
    .WhenTrueFor(TimeSpan.FromMinutes(1), scheduler)
    .SubscribeTrue(() => notification.Send("Washing machine is done!"));

LimitTrueDuration

Returns an observable that stays true for a maximum of time span. If the source observable emits false before the time has passed, the resulting observable also emits false.

Example Use Case

Keep closet lights on for a maximum amount of time.

// closetDoorOpen is a IObservable<bool>
var closetDoorOpen = closetDoor.StateChanges().Select(s => s.State == "open");
closetDoorOpen
    .LimitTrueDuration(TimeSpan.FromMinutes(2), scheduler)
    .SubscribeTrueFalse(
        () => closetLight.TurnOn(),
        () => closetLight.TurnOff());

Subscribing

Besides transformations, this library has extension methods that help with common cases of subscribing to implementations of IObservable<bool>: SubscribeTrueFalse, SubscribeFalse and SubscribeTrue.

Example

boolObservable.SubscribeTrueFalse(
    () => {
        // Logic for when observable emits true.
    },
    () => {
        // Logic for when observable emits false.
    }
)