Constructor of subclass is incredibly verbose

[MilesAdamson]

Issue when invoking super of parent class. You have to write out every viable twice, once in the child constructor and then again inside super(). This is very verbose for classes with many variables. A constructor I just wrote at work was 32 lines.

But if I had syntax to say "you must pass every variable the super class needs" it would be only 1 line.

void main() {
     var child = Child(one: 1, two: 2, three: '3', childVar: 4);  
     print(child.childVar);
}

class Parent {
    final varOne;
    final varTwo;
    final varThree;
  Parent({this.varOne, this.varTwo, this.varThree});
}

class Child extends Parent {

  final childVar;

  // No way to implicitly require/pass everything for super
  Child(
      {int one,
      int two,
      String three,
      this.childVar})
        : super(
          varOne: one,
          varTwo: two,
          varThree: three);
}

I would like to be able to do something like this:

  // You must pass in every variable the super class requires
  Child({this.childVar}) : super(...);

[Levi-Lesches]

See dart-lang/language#493 (comment), which proposes:

void main() {
  var child = Child(one: 1, two: 2, three: '3', childVar: 4);  
  print(child.childVar);
}

class Parent {
  final varOne;
  final varTwo;
  final varThree;
  Parent({this.varOne, this.varTwo, this.varThree});
}

class Child extends Parent {
  final childVar;

  Child({this.childVar, super.varOne, super.varTwo, super.varThree});
}