[Help]: Migrating from Freezed's map/when Methods to Dart 3 Pattern Matching

[Bojan227]

https://github.com/rrousselGit/freezed/blob/master/packages/freezed/migration_guide.md

I am attempting to migrate my Dart code to utilize version 3's pattern matching features, specifically replacing the map and when methods generated by the freezed package. My current state is defined using freezed as follows:

@freezed
abstract class DevicesState with _$DevicesState {
  const factory DevicesState.initial() = _Initial;
  const factory DevicesState.loading() = _Loading;
  const factory DevicesState.success(List<DeviceModel> devices) = _Success;
  const factory DevicesState.error(String message, Failure failureType) =
      _Error;
}

During the migration, I encountered the following error:

DevicesState.success isn't a type.
Try correcting the name to match an existing type.dart[not_a_type](https://dart.dev/diagnostics/not_a_type)

This error occurs in the following context:

BlocBuilder<DevicesBloc, DevicesState>(
              builder: (context, devicesState) {
                return switch (devicesState) {
                  DevicesState.success(:final devices) => ListView.builder(
                      itemCount: devices.length,
                      itemBuilder: (context, index) {
                        final device = devices[index];
                        return Text(device.name);
                      },
                    ),
                };

[rrousselGit]

BlocBuilder<DevicesBloc, DevicesState>(
              builder: (context, devicesState) {
                return switch (devicesState) {
-                  DevicesState.success(:final devices) => ListView.builder(
+                 _Success(:final devices) => ListView.builder(
                      itemCount: devices.length,
                      itemBuilder: (context, index) {
                        final device = devices[index];
                        return Text(device.name);
                      },
                    ),
                };

[Bojan227]

"In my devices_bloc file, the _Success class seems to be working fine. However, in dashboard_page.dart, I’m getting an error: Undefined class '_Success'.
How can I make dashboard_page.dart recognize and use this class?"

[lishaduck]

Don't name it _Success, name it Success. _ delineates a private name in Dart.