Ref<T> class

A reactive container that holds a single value of type T and provides notifications whenever the value changes.

This class implements ValueListenable to notify listeners when the value updates. It also extends ReactiveNotifier to integrate with the reactive ecosystem.

Example Usage:

// Create a reactive reference with an initial value
final count = Ref<int>(0);

// Listen for changes using a ValueListenableBuilder
ValueListenableBuilder<int>(
  valueListenable: count,
  builder: (context, value, child) {
    return Text('Current Count: $value');
  },
);

// Update the value and trigger notifications
count.value += 1; // UI updates automatically

// Reactivity: A dependent function can automatically respond to changes
watchEffect(() {
  print('Count changed: ${count.value}');
});

Features:

Reactive State: When value is accessed, it registers dependencies.
Efficient Updates: Notifies listeners only if the value actually changes.
Seamless Integration: Works with watchEffect() and Flutter's ValueListenable.

Inheritance

Implemented types

ValueListenable<T>

Available extensions

Constructors

Ref(T _value): Initializes a new Ref with the given initial value.

Properties

$ → T: Alias .value
no setterinherited
hashCode → int: The hash code for this object.
no setterinherited
hasListeners → bool: Whether any listeners are currently registered.
no setterinherited
length ← int: Available on Ref<List<T>>, provided by the RefListExt extension
Sets the new list length.
no getter
mounted → bool: Whether the notifier is mounted.
no setterinherited
notifyChange ↔ VoidCallback: latefinalinherited
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited
value ↔ T: The current value of this Ref.
getter/setter pairoverride-getter

Methods

add(T value) → void: Available on Ref<Queue<T>>, provided by the RefQueueExt extension
Adds an element to the end of the queue.
add(T value) → void: Available on Ref<List<T>>, provided by the RefListExt extension
Adds a value and notifies listeners.
add(T value) → bool: Available on Ref<Set<T>>, provided by the RefSetExt extension
Adds a single value to the set.
addAll(Iterable<T> elements) → void: Available on Ref<Set<T>>, provided by the RefSetExt extension
Adds all items in elements.
addAll(Iterable<T> values) → void: Available on Ref<List<T>>, provided by the RefListExt extension
Adds multiple elements.
addAll(Map<K, V> other) → void: Available on Ref<Map<K, V>>, provided by the RefMapExt extension
addFirst(T value) → void: Available on Ref<Queue<T>>, provided by the RefQueueExt extension
Adds an element to the front of the queue.
addListener(VoidCallback listener) → void: Register a closure to be called when the object changes.
inherited
clear() → void: Available on Ref<Queue<T>>, provided by the RefQueueExt extension
Clears all elements in the queue.
clear() → void: Available on Ref<List<T>>, provided by the RefListExt extension
Clears the list.
clear() → void: Available on Ref<Set<T>>, provided by the RefSetExt extension
Clears the entire set.
clear() → void: Available on Ref<Map<K, V>>, provided by the RefMapExt extension
containsKey(K key) → bool: Available on Ref<Map<K, V>>, provided by the RefMapExt extension
containsValue(V value) → bool: Available on Ref<Map<K, V>>, provided by the RefMapExt extension
dispose() → void: Discards any resources used by the object. After this is called, the object is not in a usable state and should be discarded (calls to addListener will throw after the object is disposed).
inherited
fillRange(int start, int end, T value) → void: Available on Ref<List<T>>, provided by the RefListExt extension
Fills a range with a value.
insert(int index, T element) → void: Available on Ref<List<T>>, provided by the RefListExt extension
Inserts an element at a given index.
insertAll(int index, Iterable<T> elements) → void: Available on Ref<List<T>>, provided by the RefListExt extension
Inserts all elements starting at index.
mapInPlace(T convert(T)) → void: Available on Ref<Set<T>>, provided by the RefSetExt extension
Maps every element using convert, in-place.
mapInPlace(T convert(T element)) → void: Available on Ref<List<T>>, provided by the RefListExt extension
Maps each element in-place. Useful for transforms without creating a new list.
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
notifyListeners() → void: Call all the registered listeners.
inherited
putIfAbsent(K key, V value()) → V: Available on Ref<Map<K, V>>, provided by the RefMapExt extension
remove(T value) → bool: Available on Ref<List<T>>, provided by the RefListExt extension
Removes the first matching value.
remove(K key) → V?: Available on Ref<Map<K, V>>, provided by the RefMapExt extension
remove(T value) → bool: Available on Ref<Set<T>>, provided by the RefSetExt extension
Removes a single value.
removeAll(Iterable<T> elements) → void: Available on Ref<Set<T>>, provided by the RefSetExt extension
Removes all items in elements.
removeAt(int index) → T: Available on Ref<List<T>>, provided by the RefListExt extension
Removes element at an index.
removeFirst() → T: Available on Ref<Queue<T>>, provided by the RefQueueExt extension
Removes and returns the first element.
removeLast() → T: Available on Ref<List<T>>, provided by the RefListExt extension
Removes and returns the last element.
removeLast() → T: Available on Ref<Queue<T>>, provided by the RefQueueExt extension
Removes and returns the last element.
removeListener(VoidCallback listener) → void: Remove a previously registered closure from the list of closures that are notified when the object changes.
inherited
removeRange(int start, int end) → void: Available on Ref<List<T>>, provided by the RefListExt extension
Removes a range of elements.
removeWhere(bool test(T element)) → void: Available on Ref<Set<T>>, provided by the RefSetExt extension
Removes every element that satisfies test.
removeWhere(bool test(T element)) → void: Available on Ref<List<T>>, provided by the RefListExt extension
Removes elements that match the predicate.
removeWhere(bool test(K key, V value)) → void: Available on Ref<Map<K, V>>, provided by the RefMapExt extension
replaceRange(int start, int end, Iterable<T> replacement) → void: Available on Ref<List<T>>, provided by the RefListExt extension
Replaces a range with new elements.
retainAll(Iterable<T> elements) → void: Available on Ref<Set<T>>, provided by the RefSetExt extension
Retains only elements that exist in elements.
retainWhere(bool test(T element)) → void: Available on Ref<Set<T>>, provided by the RefSetExt extension
Keeps only elements that satisfy test.
retainWhere(bool test(T element)) → void: Available on Ref<List<T>>, provided by the RefListExt extension
Keeps only elements that satisfy test.
reverse() → void: Available on Ref<List<T>>, provided by the RefListExt extension
Replaces the list with its reversed order.
select<U>(U getter(T value)) → Computed<U>: Creates a Computed that selects a value from the notifier.
inherited
setAt(int index, T value) → void: Available on Ref<List<T>>, provided by the RefListExt extension
Sets value at index (identical to operator[]=).
setRange(int start, int end, Iterable<T> source, [int skipCount = 0]) → void: Available on Ref<List<T>>, provided by the RefListExt extension
Sets a range of values from source.
shuffle([Random? random]) → void: Available on Ref<List<T>>, provided by the RefListExt extension
Randomly shuffles the list.
sort([int compare(T a, T b)?]) → void: Available on Ref<List<T>>, provided by the RefListExt extension
Sorts the list in-place.
toggle(T value) → void: Available on Ref<Set<T>>, provided by the RefSetExt extension
Toggles presence of value.
toggle(K key, V buildValue()) → void: Available on Ref<Map<K, V>>, provided by the RefMapExt extension
toString() → String: Returns a string representation containing the runtime type and the current value.
override
update(K key, V update(V value), {V ifAbsent()?}) → V: Available on Ref<Map<K, V>>, provided by the RefMapExt extension
updateAllValues(V updater(K key, V value)) → void: Available on Ref<Map<K, V>>, provided by the RefMapExt extension
updateValue(K key, V updater(V old)) → void: Available on Ref<Map<K, V>>, provided by the RefMapExt extension

Operators

operator +(T value) → void: Available on Ref<List<T>>, provided by the RefListExt extension
Adds a single value to the end of the list.
operator +(MapEntry<K, V> entry) → void: Available on Ref<Map<K, V>>, provided by the RefMapExt extension
operator +(T value) → void: Available on Ref<Set<T>>, provided by the RefSetExt extension
Adds value to the set.
operator -(T value) → void: Available on Ref<List<T>>, provided by the RefListExt extension
Removes the first matching value from the list.
operator -(K key) → void: Available on Ref<Map<K, V>>, provided by the RefMapExt extension
operator -(T value) → void: Available on Ref<Set<T>>, provided by the RefSetExt extension
Removes value from the set.
operator ==(Object other) → bool: The equality operator.
inherited
operator [](int index) → T?: Available on Ref<List<T>>, provided by the RefListExt extension
Returns the element at the given index.
operator [](K key) → V?: Available on Ref<Map<K, V>>, provided by the RefMapExt extension
Get value like normal
operator []=(int index, T value) → void: Available on Ref<List<T>>, provided by the RefListExt extension
Sets the element at the given index.
operator []=(K key, V value) → void: Available on Ref<Map<K, V>>, provided by the RefMapExt extension
Set value for key