SignallingRef<A> abstract

abstract class SignallingRef<A> implements Ref<A>, Signal<A>

Implemented types

• Ref<A>
• Signal<A>

Available Extensions

• SignalMapOps<A>

Constructors

SignallingRef()

SignallingRef()

Properties

continuous no setter inherited

Rill<A> get continuous

Emits the current value repeatedly, regardless of whether it changed.

Inherited from Signal.

Implementation

Rill<A> get continuous;

discrete no setter inherited

Rill<A> get discrete

Emits the current value, then emits only when the value changes. Note: If the source updates faster than the consumer reads, intermediate updates are dropped. It guarantees you always get the latest value.

Inherited from Signal.

Implementation

Rill<A> get discrete;

hashCode no setter inherited

int get hashCode

The hash code for this object.

A hash code is a single integer which represents the state of the object that affects operator == comparisons.

All objects have hash codes. The default hash code implemented by Object represents only the identity of the object, the same way as the default operator == implementation only considers objects equal if they are identical (see identityHashCode).

If operator == is overridden to use the object state instead, the hash code must also be changed to represent that state, otherwise the object cannot be used in hash based data structures like the default Set and Map implementations.

Hash codes must be the same for objects that are equal to each other according to operator ==. The hash code of an object should only change if the object changes in a way that affects equality. There are no further requirements for the hash codes. They need not be consistent between executions of the same program and there are no distribution guarantees.

Objects that are not equal are allowed to have the same hash code. It is even technically allowed that all instances have the same hash code, but if clashes happen too often, it may reduce the efficiency of hash-based data structures like HashSet or HashMap.

If a subclass overrides hashCode, it should override the operator == operator as well to maintain consistency.

Inherited from Object.

Implementation

external int get hashCode;

runtimeType no setter inherited

Type get runtimeType

A representation of the runtime type of the object.

Inherited from Object.

Implementation

external Type get runtimeType;

Methods

access() inherited

IO<Record> access()

Obtains a snapshot of the current value, and a setter for updating it.

The setter attempts to modify the contents from the snapshot to the new value (and return true). If it cannot do this (because the contents changed since taking the snapshot), the setter is a noop and returns false.

Inherited from Ref.

Implementation

IO<(A, Function1<A, IO<bool>>)> access();

changes() inherited

Signal<A> changes({(bool Function(A, A))? eq})

Inherited from Signal.

Implementation

Signal<A> changes({Function2<A, A, bool>? eq}) => _ChangesSignal(this, eq ?? (a, b) => a == b);

flatModify() inherited

IO<B> flatModify<B>(Record Function(A) f)

Like modify, but also schedules the resulting effect right after modification. The modification and finalizer are both within an uncancelable region to prevent out-of-sync issues.

See flatModifyFull to create a finalizer that can potentially be canceled.

Inherited from Ref.

Implementation

IO<B> flatModify<B>(Function1<A, (A, IO<B>)> f) => IO.uncancelable((_) => modify(f).flatten());

flatModifyFull() inherited

IO<B> flatModifyFull<B>(Record Function(Record) f)

Like flatModify, but the modification function also receives a Poll so the resulting effect can have cancelable regions within the uncancelable block.

Inherited from Ref.

Implementation

IO<B> flatModifyFull<B>(Function1<(Poll, A), (A, IO<B>)> f) =>
    IO.uncancelable((poll) => modify((a) => f((poll, a))).flatten());

getAndDiscreteUpdates() inherited

Resource<Record> getAndDiscreteUpdates()

Inherited from Signal.

Implementation

Resource<(A, Rill<A>)> getAndDiscreteUpdates() =>
    discrete.pull.uncons1.flatMap(Pull.outputOption1).rillNoScope.compile.resource.onlyOrError;

getAndSet() inherited

IO<A> getAndSet(A a)

Sets the value of this ref to a and returns the previous value.

Inherited from Ref.

Implementation

IO<A> getAndSet(A a) => getAndUpdate((_) => a);

getAndUpdate() inherited

IO<A> getAndUpdate(A Function(A) f)

Updates the value of this ref using f and returns the previous value.

Inherited from Ref.

Implementation

IO<A> getAndUpdate(Function1<A, A> f) => modify((a) => (f(a), a));

modify() inherited

IO<B> modify<B>(Record Function(A) f)

Modifies the value of this ref according to f and returns the new value.

Inherited from Ref.

Implementation

IO<B> modify<B>(Function1<A, (A, B)> f);

noSuchMethod() inherited

dynamic noSuchMethod(Invocation invocation)

Invoked when a nonexistent method or property is accessed.

A dynamic member invocation can attempt to call a member which doesn't exist on the receiving object. Example:

dynamic object = 1;
object.add(42); // Statically allowed, run-time error

This invalid code will invoke the noSuchMethod method of the integer 1 with an Invocation representing the .add(42) call and arguments (which then throws).

Classes can override noSuchMethod to provide custom behavior for such invalid dynamic invocations.

A class with a non-default noSuchMethod invocation can also omit implementations for members of its interface. Example:

class MockList<T> implements List<T> {
  noSuchMethod(Invocation invocation) {
    log(invocation);
    super.noSuchMethod(invocation); // Will throw.
  }
}
void main() {
  MockList().add(42);
}

This code has no compile-time warnings or errors even though the MockList class has no concrete implementation of any of the List interface methods. Calls to List methods are forwarded to noSuchMethod, so this code will log an invocation similar to Invocation.method(#add, [42]) and then throw.

If a value is returned from noSuchMethod, it becomes the result of the original invocation. If the value is not of a type that can be returned by the original invocation, a type error occurs at the invocation.

The default behavior is to throw a NoSuchMethodError.

Inherited from Object.

Implementation

@pragma("vm:entry-point")
@pragma("wasm:entry-point")
external dynamic noSuchMethod(Invocation invocation);

setValue() inherited

IO<Unit> setValue(A a)

Sets the value of this ref to a.

Inherited from Ref.

Implementation

IO<Unit> setValue(A a);

toString() inherited

String toString()

A string representation of this object.

Some classes have a default textual representation, often paired with a static parse function (like int.parse). These classes will provide the textual representation as their string representation.

Other classes have no meaningful textual representation that a program will care about. Such classes will typically override toString to provide useful information when inspecting the object, mainly for debugging or logging.

Inherited from Object.

Implementation

external String toString();

tryModify() inherited

IO<Option<B>> tryModify<B>(Record Function(A) f)

Attempts to modify the value of this ref according to f. If the modification succeeds, the new value is returned as a Some. If it fails, None is returned.

Inherited from Ref.

Implementation

IO<Option<B>> tryModify<B>(Function1<A, (A, B)> f);

tryUpdate() inherited

IO<bool> tryUpdate(A Function(A) f)

Attempts to update the value of this ref according to f. If the update succeeds, true is returned, otherwise false is returned.

Inherited from Ref.

Implementation

IO<bool> tryUpdate(Function1<A, A> f) => tryModify((a) => (f(a), Unit())).map((a) => a.isDefined);

update() inherited

IO<Unit> update(A Function(A) f)

Updates the value of this ref by applying f to the current value.

Inherited from Ref.

Implementation

IO<Unit> update(Function1<A, A> f);

updateAndGet() inherited

IO<A> updateAndGet(A Function(A) f)

Updates the value of this ref by applying f to the current value and returns the new value.

Inherited from Ref.

Implementation

IO<A> updateAndGet(Function1<A, A> f) => modify((a) {
  final newA = f(a);
  return (newA, newA);
});

value() inherited

IO<A> value()

Returns the current value of this ref.

Inherited from Ref.

Implementation

IO<A> value();

waitUntil() inherited

IO<Unit> waitUntil(bool Function(A) p)

Inherited from Signal.

Implementation

IO<Unit> waitUntil(Function1<A, bool> p) => discrete.forall((a) => !p(a)).compile.drain;

Extension Methods

map() extension

Signal<B> map<B>(B Function(A) f)

Available on Signal<A>, provided by the SignalMapOps<A> extension

Implementation

Signal<B> map<B>(Function1<A, B> f) => _MappedSignal(this, f);

Operators

operator ==() inherited

bool operator ==(Object other)

The equality operator.

The default behavior for all Objects is to return true if and only if this object and other are the same object.

Override this method to specify a different equality relation on a class. The overriding method must still be an equivalence relation. That is, it must be:

• Total: It must return a boolean for all arguments. It should never throw.

• Reflexive: For all objects o, o == o must be true.

• Symmetric: For all objects o1 and o2, o1 == o2 and o2 == o1 must either both be true, or both be false.

• Transitive: For all objects o1, o2, and o3, if o1 == o2 and o2 == o3 are true, then o1 == o3 must be true.

The method should also be consistent over time, so whether two objects are equal should only change if at least one of the objects was modified.

If a subclass overrides the equality operator, it should override the hashCode method as well to maintain consistency.

Inherited from Object.

Implementation

external bool operator ==(Object other);

Static Methods

of() override

IO<SignallingRef<A>> of<A>(A initial)

Creates a new ref, wrapping the instance in IO to preserve referential transparency.

Implementation

static IO<SignallingRef<A>> of<A>(A initial) => Ref.of(
  _State<A>(initial, 0, imap({})),
).product(Ref.of(1)).mapN((state, ids) => _SignallingRefImpl(state, ids));