unwrapping-multiple-optionals-in-flutter-and-dart.dart

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void main(List<String> args) {
  /// unwrapping multiple optionals
  print(getFullName(null, null)); // Empty
  print(getFullName('John', null)); // Empty
  print(getFullName(null, 'Doe')); // Empty
  print(getFullName('John', 'Doe')); // John Doe
}

String getFullName(
  String? firstName,
  String? lastName,
) =>
    withAll([
      firstName,
      lastName,
    ], (names) => names.join(' ')) ??
    'Empty';

T? withAll<T>(
  List<T?> optionals,
  T Function(List<T>) callback,
) =>
    optionals.any((e) => e == null) ? null : callback(optionals.cast<T>());