Flutter: Superclass variable to upper case without touching subclass

Question

Here i have some pseudo code with this scenario.

The UpperCaseElement superclass has the text variable. If upperCase is true, the text variable should be turned into upperCase.

I have tried setting it in the constructor, but it is only the default value if it isn't defined.

import "package:flutter/material.dart";

abstract class UpperCaseElement extends StatelessWidget {
  // Should be uppercase if upperCase = true
  final String text;

  final bool upperCase;

  // My attempt to set this.text to upperCase, but it doesn't work.
  const UpperCaseElement({Key? key, this.text = text.toUpperCase(), this.upperCase = false})
      : super(key: key);
}

class TestWidget extends UpperCaseElement {
  const TestWidget({
    Key? key,
    super.text,
    super.upperCase,
  }) : super(key: key);

  @override
  Widget build(context) {
    // Yes, the checking and converting to upper case can be done here. But doing that on all subclasses would be a pain. That's why I want to do it on the superclass.
    return Text(text);
  }
}

class TestPage extends StatelessWidget {
  const TestPage({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(context) {
    return Scaffold(
      body: Column(children: const [
        // Should be TEST
        TestWidget(
          text: "test",
          upperCase: true,
        )
      ]),
    );
  }
}

Answer 1

Update: force on abstract class, you can't use const constructor.

@immutable
abstract class UpperCaseElement extends StatelessWidget {
  String text;
  final bool upperCase;
  UpperCaseElement({Key? key, required this.text, this.upperCase = false})
      : super(key: key) {
    text = upperCase ? text.toUpperCase() : text;
  }
}

For the UpperCaseElement is an abstract class, we can handle conditional inside TestWidget.

class TestWidget extends UpperCaseElement {
  const TestWidget({
    Key? key,
    required super.text,
    super.upperCase,
  }) : super(key: key);

  @override
  Widget build(context) {
    return Text(upperCase ? text.toUpperCase() : text);
  }
}

abstract class UpperCaseElement extends StatelessWidget {
  final String text;
  final bool upperCase;
  const UpperCaseElement({
    Key? key,
    required this.text,
    this.upperCase = false,
  }) : super(key: key);
}