tea_late.dart

class Tea {
  final String teaBag;
  Milk? milk;
  late String allergyInfo;

  Tea(this.teaBag, [this.milk]);
}

class Milk {
  String name = "서울우유";
  int amount = 100;
}

String fetchAllergyInfo(Tea tea) {
  // search allergy information...
  const result = api.fetchAllergyInfo(tea);
  return result;
}

void main() { 
  var tea = Tea('얼그레이');
  tea.milk = Milk();
  // print(tea.allergyInfo); // LateInitializationError: Field 'allergyInfo' has not been initialized.

  tea.allergyInfo = fetchAllergyInfo(tea);
  print(tea.allergyInfo);
}