LuaEventAPI abstract

abstractclassLuaEventAPI

Abstract interface for the bidirectional event system.

Implemented by LuaStateImpl so that host (Dart) code can register, trigger, and remove event listeners that are visible to both Dart and Lua sides.

Note that this is not a standard Lua API. But Lua can implement a similar API using the table-based event system. Implement here for convenience.

Implementers

• LuaState

Constructors

LuaEventAPI()

LuaEventAPI()

Properties

hashCode no setter inherited

intgethashCode

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

TypegetruntimeType

A representation of the runtime type of the object.

Inherited from Object.

Implementation

external Type get runtimeType;

Methods

emit()

voidemit(Stringevent, [List<dynamic>args= const []])

Emit event synchronously, firing all registered listeners from both Dart and Lua sides.

args are passed to each listener. Only Dart-primitive types (null, bool, int, double, String) are automatically converted to Lua stack values when calling Lua listeners.

Normally, listeners must not mutate args. This will affect subsequent listeners.

Implementation

void emit(String event, [List<dynamic> args = const []]);

emitAsync()

Future<void>emitAsync(Stringevent, [List<dynamic>args= const []])

Emit event asynchronously, firing all registered listeners.

Async listeners (both Dart and Lua) are awaited. Sync listeners are called synchronously within the async flow.

Implementation

Future<void> emitAsync(String event, [List<dynamic> args = const []]);

noSuchMethod() inherited

dynamicnoSuchMethod(Invocationinvocation)

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);

off()

voidoff(Stringevent, {voidFunction(List<dynamic>args)?callback,Future<void>Function(List<dynamic>args)?asyncCallback,int?listenerId,});

Remove a listener from event.

If callback is provided, removes the first sync Dart listener whose callback matches by reference equality. If asyncCallback is provided, removes the first async Dart listener whose callback matches by reference equality. If listenerId is provided, removes the listener with that id regardless of event name.

Implementation

void off(String event,
    {EventCallback? callback,
    EventCallbackAsync? asyncCallback,
    int? listenerId});

offById()

voidoffById(intlistenerId)

Remove a listener by its unique id.

Implementation

void offById(int listenerId);

on()

inton(Stringevent,voidFunction(List<dynamic>args)callback)

Register a synchronous Dart listener for event. Returns a listener id that can be passed to offById.

Implementation

int on(String event, EventCallback callback);

onAsync()

intonAsync(Stringevent,Future<void>Function(List<dynamic>args)callback,);

Register an asynchronous Dart listener for event. Returns a listener id that can be passed to offById.

Implementation

int onAsync(String event, EventCallbackAsync callback);

once()

intonce(Stringevent,voidFunction(List<dynamic>args)callback)

Register a one-time synchronous Dart listener for event. The listener is automatically removed after its first invocation. Returns a listener id.

Implementation

int once(String event, EventCallback callback);

removeAllListeners()

voidremoveAllListeners([String?event])

Remove all listeners for event, or all listeners for all events if event is null.

WARNING: Removing all listeners is a dangerous operation. Use at your own risk.

Implementation

void removeAllListeners([String? event]);

toString() inherited

StringtoString()

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();

Operators

operator ==() inherited

booloperator ==(Objectother)

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);