Dart/Flutter remove boilerplate parameters in named constructor to reduce code size

Question

I have a class with multiple named constructors. All of them have a set of defined parameters and for now I have to rewrite them all over again when I add a new named constructor.

Is there a way to reduce the boilerplate of the below code to not enter all parameters over again ?

class Person {
  final String name;
  final String lastName;
  final String login;
  final String anotherValue;
  final String address;
  final int age;
  final String _text;

  const Person.sayHello(
    this.name,
    this.age,
    this.lastName,
    this.login,
    this.anotherValue,
    this.address,
  ) : _text = "Hello";

  const Person.sayBye(
    this.name,
    this.age,
    this.lastName,
    this.login,
    this.anotherValue,
    this.address,
  ) : _text = "Bye";
  
  void readText() {
    debugPrint(_text);
  }
}

I tried with abstract or extend method but I don't find a proper way to do it.

Answer 1

It may not be what you want, but we can divide the code about named constructor like this.

class Person {
  const Person(
    this.name,
    this.age,
    this.lastName,
    this.login,
    this.anotherValue,
    this.address,
    this._personText,
  );

  final String name;
  final String lastName;
  final String login;
  final String anotherValue;
  final String address;
  final int age;
  final PersonText _personText;

  void readText() {
    debugPrint(_personText.text);
  }
}

class PersonText {
  const PersonText.sayHello() : text = 'Hello';
  const PersonText.sayBye() : text = 'Bye';

  final String text;
}

You can also replace it like this.

enum PersonText {
  hello,
  bye,
}

extension PersonTextHelper on PersonText {
  String get text {
    switch (this) {
      case PersonText.hello:
        return 'Hello';
      case PersonText.bye:
        return 'Bye';
    }
  }
}