declare<T extends BusEvent> method

@override Registration declare<T extends BusEvent>(String name, { BusChannel channel = BusChannel.step, String? description, EventCodec<T>? codec, })

Says that events of type T are published under name, so a tool can list them and two plugins cannot claim one name.

codec, when given, is how the event is written for a run file, the network, a tool and the view's PublishedState, and what its digest is taken of (see EventCodec).

A step-channel event has one. The view reads a step's events encoded, and a replay digests what the codec writes, so an event published on the step channel without a declared codec is a bug: the engine's bus asserts it in a debug build, naming the event. Only a frame-channel event, which no replay sees, may go without.

Throws a NameTakenException naming both claimants when name is taken.

Implementation

@override
Registration declare<T extends BusEvent>(
  String name, {
  BusChannel channel = BusChannel.step,
  String? description,
  EventCodec<T>? codec,
}) {
  if (_scope?.manifest.nameProblem(name, what: 'the event')
      case final problem?) {
    throw PluginException(problem);
  }
  if (_store.declared.any((d) => d.name == name)) {
    throw NameTakenException(name, what: 'the event');
  }
  final declaration = EventDeclaration(
    name: name,
    type: T,
    channel: channel,
    declaredBy: _scope?.manifest.id ?? 'app',
    description: description,
    codec: codec as EventCodec<BusEvent>?,
  );
  _store.declared.add(declaration);
  return _track(Registration(() => _store.declared.remove(declaration)));
}