when<TResult extends Object?> method

@optionalTypeArgs TResult when<TResult extends Object?>({ required TResult initial(), required TResult loading(), required TResult success(Todo todo), required TResult error(String? message), })

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()  loading,required TResult Function( Todo todo)  success,required TResult Function( String? message)  error,}) {final _that = this;
switch (_that) {
case _Initial():
return initial();case _Loading():
return loading();case _Success():
return success(_that.todo);case _Error():
return error(_that.message);case _:
  throw StateError('Unexpected subclass');

}
}