Dart make sure optional boolean in class is not null

Question

Since it's an optional value, it will sometimes be null, so how can I avoid it throwing an error? Is this the only way to do it?

class QText extends StatelessWidget {
  QText(this.text, this.size, [this.bold]);

  final String text;
  final double size;
  bool bold;

  @override
  Widget build(BuildContext context) {
    bold = (bold == null) ? false : bold;
    return Whatever..
  }
}

I'd like to do this but of course it doesn't work:

class QText extends StatelessWidget {
  QText(this.text, this.size, [this.bold]);

  final String text;
  final double size;
  final bool bold ?? false;

  @override
  Widget build(BuildContext context) {
    return Whatever..
  }
}

Answer 1

As the fields are final try passing the default during constructor initialization.

Also add an assert statement to make sure it's never initialized to null.

Example:

class QText extends StatelessWidget {
  QText(this.text, this.size, [this.bold = false]) : assert(bold != null);

  final String text;
  final double size;
  final bool bold;

  @override
  Widget build(BuildContext context) {}
}

Hope that helps!