Nullable default parameter

main.dart

void main() {
  String? nullableButHasValue = 'hello';
  String? nullableAndIsNull;
  func1(password: nullableButHasValue); //<-- Works, because the check registers, that is has a value
  //func1(password: nullableAndIsNull); //<-- Errors, bc param is non-nullable and has no value.
  //func1(param: null);  //<-- Errors, bc param is non-nullable
  
  func2(); // Works as expected
  func2(password: null); // password is set to null, instead of 'test-nullable'
  
  bestFunc(); // Uses default
  bestFunc(password: null); // Uses default
  bestFunc(password: 'My password'); // Uses parameter
}

void func1({String password = 'test'}) {
  print(password);
}

void func2({String? password = 'test-nullable'}) {
  print(password);
}

void bestFunc({String? password}) {
  print(password ?? 'real default value, which is not overwritten by null');
}