ComputedNode<T> class

A read-only reactive node whose value is automatically derived from other ZenithNodes.

During the initial compute call and every subsequent re-computation, a ZenithZone observer is installed to auto-track which source nodes are read. When any tracked source changes, compute runs again and, if the result differs from the previous value, downstream subscribers are notified.

final firstName = ZenithNode<String>('John');
final lastName  = ZenithNode<String>('Doe');
final fullName  = ComputedNode<String>(
  () => '${firstName.value} ${lastName.value}',
);

// fullName.value == 'John Doe'
firstName.set('Jane');
// fullName.value == 'Jane Doe' — downstream ZenithBuilders rebuild.

Important: Do not call set on a ComputedNode. The value is managed exclusively by the compute function. Calling set will throw a StateError.

Inheritance

• Object
• ZenithNode<T>
• ComputedNode

Implemented types

• ZenithSubscriber
• ZenithObserverTracker

Available extensions

• SafeAsyncNodeX
• StreamNodeX

Constructors

ComputedNode(T _compute())

Creates a ComputedNode that derives its value from compute.

Properties

debugSubscriberCount → int

The current number of subscribers (including potentially dead weak references that have not yet been pruned).

no setter, inherited

hashCode → int

The hash code for this object.

no setter, inherited

isDisposed → bool

Whether this node has been disposed.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

value ↔ T

The current value held by this node.

getter/setter pair, inherited

Methods

dispose({bool purgeZeroize = false}) → void

Permanently disposes this node, clearing all subscribers.

override

guard(ZenithRef ref, Future<T> future()) → Future<void>

Available on ZenithNode<AsyncValue<T>>, provided by the SafeAsyncNodeX extension

Executes future and writes its result to this node, guarding every mutation with ref's lifecycle. Equivalent to ref.runAsync(this, future).

invalidate() → void

Forces a notification pass without changing the value.

inherited

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

notifySubscribers() → void

Notifies all live subscribers that this node has changed.

inherited

onNodeChanged(ZenithNode node) → void

Called when any tracked source node changes.

override

onNodeRead(ZenithNode node, ZenithSubscription subscription) → void

Called when a ZenithNode.value getter is invoked while this tracker is the active ZenithZone.currentObserver.

override

set(T newValue) → void

Computed nodes are read-only. Calling set throws a StateError.

override

subscribe(ZenithSubscriber subscriber) → ZenithSubscription

Adds subscriber to this node's listener set.

inherited

toString() → String

A string representation of this object.

inherited

trySet(T newValue) → bool

Attempts to update the value of this node.

inherited

unsubscribe(ZenithSubscriber subscriber) → void

Removes subscriber from this node's listener set.

inherited

watch(ZenithRef ref, Stream<T> stream) → StreamSubscription<T>

Available on ZenithNode<AsyncValue<T>>, provided by the StreamNodeX extension

Subscribes to stream and writes each event to this node, guarding every mutation with ref's lifecycle.

Operators

operator ==(Object other) → bool

The equality operator.

inherited