============================================================================ ASYNC SIGNAL<T> - ASYNC STATE MANAGEMENT

Async state wrapper for handling loading, data, and error states.

AsyncSignal simplifies async operations by managing three states:

• loading: Operation in progress (isLoading == true)
• data: Operation completed successfully (hasData == true)
• error: Operation failed (hasError == true)

Uses the pure Dart AsyncState sealed class, allowing business logic to remain framework-agnostic.

Basic Usage

class UserController extends NeuronController {
  late final user = AsyncSignal<User>(null).bind(this);

  Future<void> loadUser() async {
    user.emitLoading();
    try {
      final data = await api.getUser();
      user.emitData(data);
    } catch (e, stack) {
      user.emitError(e, stack);
    }
  }
}

Automatic Execution

Use execute to handle the try-catch-emit flow automatically:

Future<void> loadUser() async {
  await user.execute(() => api.getUser());
}

Refresh Capability

Use refresh to re-execute the last operation:

user.refresh(); // Re-runs the last operation passed to execute()

Pattern Matching

Use Dart 3's pattern matching for exhaustive state handling:

switch (user.state) {
  case AsyncLoading():
    return CircularProgressIndicator();
  case AsyncData(:final value):
    return Text(value.name);
  case AsyncError(:final error):
    return Text('Error: $error');
}

Binding to UI

Use AsyncSlot to handle all three states declaratively:

AsyncSlot<User>(
  connect: controller.user,
  onData: (ctx, user) => Text(user.name),
  onLoading: (ctx) => CircularProgressIndicator(),
  onError: (ctx, err) => Text('Error: $err'),
)

See also:

• AsyncState - Pure Dart sealed class for async state
• AsyncSlot - Widget for binding async signals to UI
• execute - Helper method to manage async operations