Almanach

TinyProperty ​

TinyProperty<T> (from scenerystack/axon) is a lightweight observable value wrapper that implements enough of the Property interface (.value, .get()/.set(), link()/lazyLink()/unlink()) to be used interchangeably in many places, but without Property's validation, PhET-iO instrumentation, or reset()/initialValue bookkeeping. It directly extends TinyEmitter rather than composing one, specifically to save memory — scenery uses a TinyProperty for every Node's dozens of internal state values (opacityProperty, visibleProperty's underlying storage, pickableProperty, etc.), so the per-instance overhead matters at that scale.

ts
import { TinyProperty } from 'scenerystack/axon';

const opacityProperty = new TinyProperty( 1 );

opacityProperty.link( opacity => console.log( 'opacity:', opacity ) ); // logs "opacity: 1"
opacityProperty.value = 0.5;                                          // logs "opacity: 0.5"

Constructor ​

ts
new TinyProperty<T>(
  value: T,
  onBeforeNotify?: TinyEmitterOptions<...>['onBeforeNotify'] | null,
  hasListenerOrderDependencies?: boolean | null,
  reentrantNotificationStrategy?: 'stack' | 'queue' | null,
  disableListenerLimit?: boolean | null
)

The trailing four parameters are forwarded straight to the underlying TinyEmitter — TinyProperty itself only adds the first value argument. Unlike plain TinyEmitter (which defaults to 'stack'), TinyProperty defaults reentrantNotificationStrategy to 'queue', so that if a listener changes the value again while still notifying (a → b, and a listener sets b → c), all listeners see the a→b change in order before any b→c notification begins.

Methods and members ​

MemberEffect
value (getter/setter)Reads or writes the current value; setting is a no-op if the new value areValuesEqual the old one
get() / set( value )Same as .value, provided as explicit methods for hot inner loops
link( listener )Adds a listener and immediately calls it with ( value, null, this )
lazyLink( listener )Adds a listener without an immediate callback
unlink( listener ) / unlinkAll()Removes one or all listeners
linkAttribute( object, attributeName )Sets object[attributeName] = value whenever the value changes
valueComparisonStrategyGet/set the equality strategy (defaults to 'reference') used by areValuesEqual to decide whether to notify
isSettable()Always returns true for TinyProperty
dispose()Unlinks all listeners, then disposes the underlying TinyEmitter