>>>
class MyClassLongName {
    MyClassLongName(Argument arg1, Argument arg2, Argument arg3) :
      super.con1(arg1, arg2, arg3,
          namedArgument: (r) => new FooClassLongName(r));
}

class MyClassVeryVeryLongName {
    MyClassVeryVeryLongName(
        Argument arg1, Argument arg2, Argument arg3, Argument arg4)
      : super.con1(arg1, arg2, arg3,
          namedArgument: (r) => new FooClassLongName(r));
}
<<<
class MyClassLongName {
  MyClassLongName(Argument arg1, Argument arg2, Argument arg3)
      : super.con1(arg1, arg2, arg3,
            namedArgument: (r) => new FooClassLongName(r));
}

class MyClassVeryVeryLongName {
  MyClassVeryVeryLongName(
      Argument arg1, Argument arg2, Argument arg3, Argument arg4)
      : super.con1(arg1, arg2, arg3,
            namedArgument: (r) => new FooClassLongName(r));
}