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prefer-widget-private-members

added in: 1.3.0
style
⚙️🛠
Pro+

Warns when a widget or widget state have public methods, getter or setters. For widget state, it additionally checks whether its fields are private.

⚙️ Config​

Set ignore-static (default is false) to allow widgets to have static public members (example).

Set ignored-names (default is empty) to ignore specific member names (example).

analysis_options.yaml
dart_code_metrics:
  rules:
    - prefer-widget-private-members:
        ignore-static: false
        ignored-names:
          - some
          - name

Example​

❌ Bad:

class SomeStatefulWidget extends StatefulWidget {
  @override
  _someStatefulWidgetState createState() => _SomeStatefulWidgetState();
}

class _SomeStatefulWidgetState extends State<InspirationCard> {
  String _privateState;
  bool publicState; // LINT: Prefer declaring widget or state class members as private.

  @override
  void initState() {
    super.initState();
  }

  void _somePrivateCallback() {}

  // LINT: Prefer declaring widget or state class members as private.
  void somePublic() {}

  @override
  Widget build(BuildContext context) {
    return StatefulWidget();
  }
}

✅ Good:

class SomeStatefulWidget extends StatefulWidget {
  @override
  _someStatefulWidgetState createState() => _SomeStatefulWidgetState();
}

class _SomeStatefulWidgetState extends State<InspirationCard> {
  String _privateState;

  @override
  void initState() {
    super.initState();
  }

  void _somePrivateCallback() {}

  @override
  Widget build(BuildContext context) {
    return StatefulWidget();
  }
}

Example with "ignore-static"​

Config
analysis_options.yaml
dart_code_metrics:
  rules:
    - prefer-widget-private-members:
        ignore-static: true

✅ Good:

class SomeStatefulWidget extends StatefulWidget {
  @override
  _someStatefulWidgetState createState() => _SomeStatefulWidgetState();
}

class _SomeStatefulWidgetState extends State<InspirationCard> {
  static String? someState; // Correct, ignored
}

Example with "ignored-names"​

Config
analysis_options.yaml
dart_code_metrics:
  rules:
    - prefer-widget-private-members:
        ignored-names:
          - someCallback

✅ Good:

class SomeStatefulWidget extends StatefulWidget {
  @override
  _someStatefulWidgetState createState() => _SomeStatefulWidgetState();
}

class _SomeStatefulWidgetState extends State<InspirationCard> {
  @override
  void initState() {
    super.initState();
  }

  // Correct, 'someCallback' is ignored
  void someCallback() {}

  @override
  Widget build(BuildContext context) {
    return StatefulWidget();
  }
}