when<TResult extends Object?> method

@optionalTypeArgs TResult when<TResult extends Object?>({ required TResult initial(), required TResult loading(double progress), required TResult success(T1 data1, T2 data2, T3 data3, T4 data4, T5 data5,), required TResult failure(String error, bool show), })

A switch-like method, using callbacks.

As opposed to map, this offers destructuring. It is equivalent to doing:

switch (sealedClass) {
  case Subclass(:final field):
    return ...;
  case Subclass2(:final field2):
    return ...;
}

Implementation

@optionalTypeArgs
TResult when<TResult extends Object?>({
  required TResult Function() initial,
  required TResult Function(double progress) loading,
  required TResult Function(T1 data1, T2 data2, T3 data3, T4 data4, T5 data5)
      success,
  required TResult Function(String error, bool show) failure,
}) {
  final _that = this;
  switch (_that) {
    case _Sub5Initial():
      return initial();
    case _Sub5Loading():
      return loading(_that.progress);
    case _Sub5Success():
      return success(
          _that.data1, _that.data2, _that.data3, _that.data4, _that.data5);
    case _Sub5Failure():
      return failure(_that.error, _that.show);
    case _:
      throw StateError('Unexpected subclass');
  }
}