ListSignal<E> class

A reactive Signal that holds a List and implements the List interface.

ListSignal lets you listen to changes on a list reactively and mutate it directly using standard list operations (like add, addAll, remove, operators [] and []=, etc.). Any mutations automatically trigger reactive updates to all active listeners (e.g., inside an effect or computed).

Additionally, ListSignal defines convenient operators:

  • << injects/adds all items from an iterable into the list.
  • & forks/concatenates the list with an iterable into a new ListSignal.
  • | pipes/concatenates the list with another signal holding an iterable into a new ListSignal.

Example Usage

import 'package:signals/signals.dart';

void main() {
  final numbers = listSignal<int>([1, 2, 3]);

  effect(() {
    print('List content: $numbers, Length: ${numbers.length}');
  }); // Prints: "List content: [1, 2, 3], Length: 3"

  // Standard mutation (triggers updates)
  numbers.add(4); // Prints: "List content: [1, 2, 3, 4], Length: 4"

  // Update via index operator (triggers updates)
  numbers[0] = 10; // Prints: "List content: [10, 2, 3, 4], Length: 4"

  // Injection operator (triggers updates)
  numbers << [5, 6]; // Prints: "List content: [10, 2, 3, 4, 5, 6], Length: 6"
}

:::tip Mutating the collection directly calls the reactive set() routine under the hood automatically. You do not need to assign numbers.value = ... manually! :::

Inheritance
Implemented types
Mixed-in types
Available extensions

Constructors

ListSignal(List<E> value, {ListSignalOptions<E>? options, @Deprecated('Use options: ListSignalOptions(autoDispose: ...) instead') bool? autoDispose, @Deprecated('Use options: ListSignalOptions(name: ...) instead') String? debugLabel})
Creates a ListSignal with the given value.

Properties

$ → Signal<Iterable<E>>

Available on Iterable<E>, provided by the SignalIterableExtensions extension

Return a signal from a Iterable value
no setter
$ → Signal<List<E>>

Available on List<E>, provided by the SignalListExtensions extension

Return a signal from a List value
no setter
autoDispose ↔ bool
Throws and error if read after dispose and can be disposed on last unsubscribe.
getter/setter pairinherited
debugLabel → String?
Debug label for Debug Mode Debug label for Debug Mode
no setterinherited
disposed ↔ bool
Check if the effect is disposed
getter/setter pairinherited
equalityCheck → SignalEquality<List<E>>
Optional method to check if to values are the same
no setterinherited
first ← E

Available on Signal<List<E>>, provided by the ListSignalExtension extension

no getter
first ↔ E
The first element.
getter/setter pairinherited
firstOrNull → T?

Available on Iterable<T>, provided by the IterableExtensions extension

The first element of this iterator, or null if the iterable is empty.
no setter
globalId → int
finalinherited
hashCode → int
The hash code for this object.
no setteroverride
indexed → Iterable<(int, T)>

Available on Iterable<T>, provided by the IterableExtensions extension

Pairs of elements of the indices and elements of this iterable.
no setter
internalValue → List<E>
@internal Internal getter for the raw value without subscription tracking.
no setterinherited
isEmpty → bool
Whether this collection has no elements.
no setterinherited
isInitialized → bool
Check if a signal value is set (does not subscribe)
no setterinherited
isNotEmpty → bool
Whether this collection has at least one element.
no setterinherited
iterator → Iterator<E>
A new Iterator that allows iterating the elements of this Iterable.
no setterinherited
last → E

Available on ReadonlySignal<List<E>>, provided by the ReadonlyListSignalExtension extension

no setter
last ↔ E
The last element.
getter/setter pairinherited
last ← E

Available on Signal<List<E>>, provided by the ListSignalExtension extension

no getter
lastOrNull → T?

Available on Iterable<T>, provided by the IterableExtensions extension

The last element of this iterable, or null if the iterable is empty.
no setter
length ↔ int
The number of elements in this Iterable.
getter/setter pairinherited
length ← int

Available on Signal<List<E>>, provided by the ListSignalExtension extension

no getter
name → String?
finalinherited
nonNulls → Iterable<T>

Available on Iterable<T?>, provided by the NullableIterableExtensions extension

The non-null elements of this iterable.
no setter
reversed → Iterable<E>
An Iterable of the objects in this list in reverse order.
no setterinherited
reversed → Iterable<E>

Available on ReadonlySignal<List<E>>, provided by the ReadonlyListSignalExtension extension

no setter
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
single → E
Checks that this iterable has only one element, and returns that element.
no setterinherited
singleOrNull → T?

Available on Iterable<T>, provided by the IterableExtensions extension

The single element of this iterator, or null.
no setter
toJS → JSArray<T>

Available on List<T>, provided by the ListToJSArray extension

Converts this List to a JSArray by either casting, unwrapping, or cloning the List.
no setter
toJSIterable → JSIterable<T>

Available on Iterable<T>, provided by the IterableToJSIterable extension

A JSIterable wrapper that proxies to the Dart iterable API.
no setter
toJSProxyOrRef → JSArray<T>

Available on List<T>, provided by the ListToJSArray extension

Converts this List to a JSArray by either casting, unwrapping, or proxying the List.
no setter
unwatched → void Function()?
finalinherited
value ↔ List<E>
Gets the current value of the signal.
getter/setter pairinherited
version ↔ int
Version numbers should always be >= 0, because the special value -1 is used by Nodes to signify potentially unused but recyclable nodes.
getter/setter pairinherited
wait → Future<List<T>>

Available on Iterable<Future<T>>, provided by the FutureIterable extension

Waits for futures in parallel.
no setter
watched → void Function()?
finalinherited

Methods

add(E value) → void
Adds value to the end of this list, extending the length by one.
inherited
add(E value) → void

Available on Signal<List<E>>, provided by the ListSignalExtension extension

addAll(Iterable<E> iterable) → void

Available on Signal<List<E>>, provided by the ListSignalExtension extension

addAll(Iterable<E> iterable) → void
Appends all objects of iterable to the end of this list.
inherited
any(bool test(E element)) → bool
Checks whether any element of this iterable satisfies test.
inherited
asMap() → Map<int, E>

Available on ReadonlySignal<List<E>>, provided by the ReadonlyListSignalExtension extension

asMap() → Map<int, E>
An unmodifiable Map view of this list.
inherited
asNameMap() → Map<String, T>

Available on Iterable<T>, provided by the EnumByName extension

Creates a map from the names of enum values to the values.
byName(String name) → T

Available on Iterable<T>, provided by the EnumByName extension

Finds the enum value in this list with name name.
call() → List<E>
Return the value when invoked
inherited
cast<R>() → List<R>
Returns a view of this list as a list of R instances.
inherited
cast<R>() → List<R>

Available on ReadonlySignal<List<E>>, provided by the ReadonlyListSignalExtension extension

clear() → void
Removes all objects from this list; the length of the list becomes zero.
inherited
clear() → void

Available on Signal<List<E>>, provided by the ListSignalExtension extension

contains(Object? value) → bool
Whether the collection contains an element equal to element.
inherited
dispose() → void
Dispose the signal
inherited
elementAt(int index) → E
Returns the indexth element.
inherited
elementAtOrNull(int index) → T?

Available on Iterable<T>, provided by the IterableExtensions extension

The element at position index of this iterable, or null.
every(bool test(E element)) → bool
Checks whether every element of this iterable satisfies test.
inherited
expand<R>(Iterable<R> toElements(E element)) → Iterable<R>
Expands each element of this Iterable into zero or more elements.
inherited
expand<R>(Iterable<R> toElements(E element)) → Iterable<R>

Available on ReadonlySignal<List<E>>, provided by the ReadonlyListSignalExtension extension

fillRange(int start, int end, [E? fillValue]) → void
Overwrites a range of elements with fillValue.
inherited
fillRange(int start, int end, [E? fillValue]) → void

Available on Signal<List<E>>, provided by the ListSignalExtension extension

firstWhere(bool test(E element), {E orElse()?}) → E
The first element that satisfies the given predicate test.
inherited
firstWhere(bool test(E element), {E orElse()?}) → E

Available on ReadonlySignal<List<E>>, provided by the ReadonlyListSignalExtension extension

fold<R>(R initialValue, R combine(R previousValue, E element)) → R
Reduces a collection to a single value by iteratively combining each element of the collection with an existing value
inherited
fold<R>(R initialValue, R combine(R previousValue, E element)) → R

Available on ReadonlySignal<List<E>>, provided by the ReadonlyListSignalExtension extension

followedBy(Iterable<E> other) → Iterable<E>

Available on ReadonlySignal<List<E>>, provided by the ReadonlyListSignalExtension extension

followedBy(Iterable<E> other) → Iterable<E>
Creates the lazy concatenation of this iterable and other.
inherited
forEach(void action(E element)) → void
Invokes action on each element of this iterable in iteration order.
inherited
get() → List<E>
Helper method to get the current value
inherited
getRange(int start, int end) → Iterable<E>
Creates an Iterable that iterates over a range of elements.
inherited
getRange(int start, int end) → Iterable<E>

Available on ReadonlySignal<List<E>>, provided by the ReadonlyListSignalExtension extension

indexOf(E element, [int start = 0]) → int

Available on ReadonlySignal<List<E>>, provided by the ReadonlyListSignalExtension extension

indexOf(E element, [int start = 0]) → int
The first index of element in this list.
inherited
indexWhere(bool test(E element), [int start = 0]) → int

Available on ReadonlySignal<List<E>>, provided by the ReadonlyListSignalExtension extension

indexWhere(bool test(E element), [int start = 0]) → int
The first index in the list that satisfies the provided test.
inherited
insert(int index, E element) → void

Available on Signal<List<E>>, provided by the ListSignalExtension extension

insert(int index, E element) → void
Inserts element at position index in this list.
inherited
insertAll(int index, Iterable<E> iterable) → void
Inserts all objects of iterable at position index in this list.
inherited
insertAll(int index, Iterable<E> iterable) → void

Available on Signal<List<E>>, provided by the ListSignalExtension extension

internalRefresh() → bool
@internal Refreshes the signal's value internally.
inherited
join([String separator = ""]) → String
Converts each element to a String and concatenates the strings.
inherited
lastIndexOf(E element, [int? start]) → int

Available on ReadonlySignal<List<E>>, provided by the ReadonlyListSignalExtension extension

lastIndexOf(E element, [int? start]) → int
The last index of element in this list.
inherited
lastIndexWhere(bool test(E element), [int? start]) → int
The last index in the list that satisfies the provided test.
inherited
lastIndexWhere(bool test(E element), [int? start]) → int

Available on ReadonlySignal<List<E>>, provided by the ReadonlyListSignalExtension extension

lastWhere(bool test(E element), {E orElse()?}) → E
The last element that satisfies the given predicate test.
inherited
map<R>(R toElement(E e)) → Iterable<R>
The current elements of this iterable modified by toElement.
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
onDispose(void cleanup()) → void Function()
Add a cleanup function to be called when the signal is disposed
inherited
overrideWith(List<E> val) → Signal<List<E>>
Override the current signal with a new value as if it was created with it.
inherited
peek() → List<E>
In the rare instance that you have an effect that should write to another signal based on the previous value, but you don't want the effect to be subscribed to that signal, you can read a signals's previous value via signal.peek().
inherited
readonly() → ReadonlySignal<List<E>>
Returns a readonly signal
inherited
reduce(E combine(E value, E element)) → E
Reduces a collection to a single value by iteratively combining elements of the collection using the provided function.
inherited
remove(Object? value) → bool
Removes the first occurrence of value from this list.
inherited
remove(Object? value) → bool

Available on Signal<List<E>>, provided by the ListSignalExtension extension

removeAt(int index) → E
Removes the object at position index from this list.
inherited
removeAt(int index) → E

Available on Signal<List<E>>, provided by the ListSignalExtension extension

removeLast() → E

Available on Signal<List<E>>, provided by the ListSignalExtension extension

removeLast() → E
Removes and returns the last object in this list.
inherited
removeRange(int start, int end) → void
Removes a range of elements from the list.
inherited
removeRange(int start, int end) → void

Available on Signal<List<E>>, provided by the ListSignalExtension extension

removeWhere(bool test(E element)) → void
Removes all objects from this list that satisfy test.
inherited
removeWhere(bool test(E element)) → void

Available on Signal<List<E>>, provided by the ListSignalExtension extension

replaceRange(int start, int end, Iterable<E> replacements) → void

Available on Signal<List<E>>, provided by the ListSignalExtension extension

replaceRange(int start, int end, Iterable<E> replacements) → void
Replaces a range of elements with the elements of replacements.
inherited
retainWhere(bool test(E element)) → void

Available on Signal<List<E>>, provided by the ListSignalExtension extension

retainWhere(bool test(E element)) → void
Removes all objects from this list that fail to satisfy test.
inherited
set(List<E> val, {bool force = false}) → bool
Updates the signal's value by method call.
inherited
setAll(int index, Iterable<E> iterable) → void
Overwrites elements with the objects of iterable.
inherited
setAll(int index, Iterable<E> iterable) → void

Available on Signal<List<E>>, provided by the ListSignalExtension extension

setRange(int start, int end, Iterable<E> iterable, [int skipCount = 0]) → void
Writes some elements of iterable into a range of this list.
inherited
setRange(int start, int end, Iterable<E> iterable, [int skipCount = 0]) → void

Available on Signal<List<E>>, provided by the ListSignalExtension extension

shuffle([Random? random]) → void
Shuffles the elements of this list randomly.
inherited
shuffle([Random? random]) → void

Available on Signal<List<E>>, provided by the ListSignalExtension extension

singleWhere(bool test(E element), {E orElse()?}) → E
The single element that satisfies test.
inherited
skip(int count) → Iterable<E>
Creates an Iterable that provides all but the first count elements.
inherited
skipWhile(bool test(E value)) → Iterable<E>
Creates an Iterable that skips leading elements while test is satisfied.
inherited
sort([int compare(E a, E b)?]) → void
Sorts this list according to the order specified by the compare function.
inherited
sort([int compare(E a, E b)?]) → void

Available on Signal<List<E>>, provided by the ListSignalExtension extension

sorted([int compare(E a, E b)?]) → List<E>
Return a new array that is sorted by the compare function
inherited
sorted([int compare(E a, E b)?]) → List<E>

Available on ReadonlySignal<List<E>>, provided by the ReadonlyListSignalExtension extension

Return a new array that is sorted by the compare function
sublist(int start, [int? end]) → List<E>
Returns a new list containing the elements between start and end.
inherited
sublist(int start, [int? end]) → List<E>

Available on ReadonlySignal<List<E>>, provided by the ReadonlyListSignalExtension extension

subscribe(void fn(List<E> value)) → void Function()
Subscribe to value changes with a dispose function
inherited
subscribeToNode(Node node) → void
@internal Subscribes this signal to notifications from a given dependency node.
inherited
take(int count) → Iterable<E>
Creates a lazy iterable of the count first elements of this iterable.
inherited
takeWhile(bool test(E value)) → Iterable<E>
Creates a lazy iterable of the leading elements satisfying test.
inherited
toJson() → dynamic
Convert value to JSON
inherited
toList({bool growable = true}) → List<E>
Creates a List containing the elements of this Iterable.
inherited
toSet() → Set<E>
Creates a Set containing the same elements as this iterable.
inherited
toSignal({IterableSignalOptions<T>? options, bool? autoDispose, String? debugLabel}) → IterableSignal<T>

Available on Iterable<T>, provided by the SignalIterableUtils extension

Convert an existing Iterable to an IterableSignal.
toSignal({ListSignalOptions<T>? options, bool? autoDispose, String? debugLabel}) → ListSignal<T>

Available on List<T>, provided by the SignalListUtils extension

Convert this existing List to a reactive ListSignal.
toString() → String
A string representation of this object.
inherited
unsubscribeFromNode(Node node) → void
@internal Unsubscribes this signal from notifications from a given dependency node.
inherited
where(bool test(E element)) → Iterable<E>
Creates a new lazy Iterable with all elements that satisfy the predicate test.
inherited
whereType<R>() → Iterable<R>
Creates a new lazy Iterable with all elements that have type T.
inherited

Operators

operator &(Iterable<E> other) → ListSignal<E>
Fork: create a new signal which value is the concatenation of source signal and iterable parameter
operator +(List<E> other) → List<E>
Returns the concatenation of this list and other.
inherited
operator +(List<E> other) → List<E>

Available on ReadonlySignal<List<E>>, provided by the ReadonlyListSignalExtension extension

operator <<(Iterable<E> other) → ListSignal<E>
Inject: Update current signal value with iterable
operator ==(Object other) → bool
The equality operator.
override
operator [](int index) → E
The object at the given index in the list.
inherited
operator [](int index) → E

Available on ReadonlySignal<List<E>>, provided by the ReadonlyListSignalExtension extension

operator []=(int index, E value) → void
Sets the value at the given index in the list to value.
inherited
operator []=(int index, E value) → void

Available on Signal<List<E>>, provided by the ListSignalExtension extension

operator |(Signal<Iterable<E>> other) → ListSignal<E>
Pipe: create a new signal by sending value from source to other