spawnedMain function Null safety

void spawnedMain(
  1. List<String> args,
  2. SendPort parentPort,
  3. int id,
  4. Function run,
  5. [FutureOr<bool> stop(
      )?]
    )

    Helper to executed a spawned Dart script by DartSpawner.

    Implementation

    void spawnedMain(List<String> args, SendPort parentPort, int id, Function run,
        [FutureOr<bool> Function()? stop]) async {
      final messagePort = ReceivePort();
    
      var debugName = Isolate.current.debugName;
    
      var isolateId = debugName != null ? 'Isolate#$id($debugName)' : 'Isolate#$id';
    
      messagePort.listen((msg) {
        if (msg['cmd'] == 'stop') {
          _stopSpawned(isolateId, messagePort, stop, parentPort);
        }
      });
    
      print('[$isolateId] Running: $run');
    
      FutureOr ret;
    
      if (run is Function()) {
        ret = run();
      } else if (run is Function(List<String> a)) {
        ret = run(args);
      }
    
      print('[$isolateId] Return: $ret');
    
      parentPort.send({'status': 'ok', 'port': messagePort.sendPort});
    
      if (ret is Future) {
        print('[$isolateId] Waiting return: $ret');
        await ret;
      }
    
      _stopSpawned(isolateId, messagePort, stop, parentPort);
    }