avoid-non-configurable-callbacks-in-init-state

added in: 4.2.0 warning

Warns when initState configures a widget-supplied object with callbacks that never use the widget's fields.

This makes the behavior hardcoded, so callers cannot customize it. Expose the callbacks as widget parameters when callers need to change the behavior.

Example

Bad:

class BrowserView extends StatefulWidget {
  const BrowserView({required this.controller});

  final WebViewController controller;

  @override
  State<BrowserView> createState() => _BrowserViewState();
}

class _BrowserViewState extends State<BrowserView> {
  @override
  void initState() {
    super.initState();

    widget.controller.setNavigationDelegate(
      NavigationDelegate(
        onNavigationRequest: (_) => NavigationDecision.navigate, // LINT
      ),
    );
  }
}

Good:

class BrowserView extends StatefulWidget {
  const BrowserView({
    required this.controller,
    required this.onNavigationRequest,
  });

  final WebViewController controller;
  final NavigationRequestCallback onNavigationRequest;

  @override
  State<BrowserView> createState() => _BrowserViewState();
}

class _BrowserViewState extends State<BrowserView> {
  @override
  void initState() {
    super.initState();

    widget.controller.setNavigationDelegate(
      NavigationDelegate(
        onNavigationRequest: widget.onNavigationRequest,
      ),
    );
  }
}

The rule checks callback objects passed to calls on widget fields from initState. It ignores local objects, configuration outside initState, and callbacks it cannot inspect.