when<TResult extends Object?> method

@optionalTypeArgs TResult when<TResult extends Object?>({ required TResult server(String? message), required TResult cache(String? message), required TResult unexpected(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( String? message)  server,required TResult Function( String? message)  cache,required TResult Function( String? message)  unexpected,}) {final _that = this;
switch (_that) {
case ServerFailure():
return server(_that.message);case CacheFailure():
return cache(_that.message);case UnexpectedFailure():
return unexpected(_that.message);case _:
  throw StateError('Unexpected subclass');

}
}