addSystem method

@override Registration addSystem(String name, LoopPhase phase, LoopSystem system, { SystemSettings settings = const SystemSettings(), })

Adds system to phase under name, unique in the loop, ordered against the phase's other systems by settings' after/before.

settings' reads and writes name the state the system touches; both default to empty, which declares nothing and is never checked. What a later minor lets a system say arrives as a field of SystemSettings, never as a parameter here.

Declared so an unordered pair can be named. A replay is bit for bit only while two systems that touch one state run in one order on every machine; where the constraints leave a choice, registration order decides, and an install order that differs between the run and its replay is a different picture. The engine's loop names every pair of systems in one step phase where one writes what the other reads or writes and neither is ordered against the other, through after and before or a chain of them.

Throws a NameTakenException for a name already used, and an ArgumentError for a phase that does not exist.

Implementation

@override
Registration addSystem(
  String name,
  LoopPhase phase,
  LoopSystem system, {
  SystemSettings settings = const SystemSettings(),
}) {
  _named(name, 'the system', _store.systems.keys);
  final entry = TestSystem(
    name: name,
    phase: phase,
    system: system,
    after: settings.after,
    before: settings.before,
    reads: settings.reads,
    writes: settings.writes,
    owner: _owner,
  );
  _store.systems[name] = entry;
  return _track(
    Registration(() {
      if (identical(_store.systems[name], entry)) _store.systems.remove(name);
    }),
  );
}