Singleton with parameters in Dart.

singleton_with_parameters.dart

class HttpRequest {
  factory HttpRequest({required String baseUrl}) {
    _instance.baseUrl = baseUrl;
    return _instance;
  }

  HttpRequest._internal();

  late String baseUrl;

  static final HttpRequest _instance = HttpRequest._internal();

  static HttpRequest get instance => _instance;
}

void main() {
  var http = HttpRequest(baseUrl: "google.com");
}