whenOrNull<TResult extends Object?> method

@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>({ TResult? server(String? message)?, TResult? network(String? message)?, TResult? unauthorized(String? message)?, TResult? timeout(String? message)?, TResult? cache(String? message)?, TResult? unexpected(String? message)?, })

A variant of when that fallback to returning null

It is equivalent to doing:

switch (sealedClass) {
  case Subclass(:final field):
    return ...;
  case _:
    return null;
}

Implementation

@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>({TResult? Function( String? message)?  server,TResult? Function( String? message)?  network,TResult? Function( String? message)?  unauthorized,TResult? Function( String? message)?  timeout,TResult? Function( String? message)?  cache,TResult? Function( String? message)?  unexpected,}) {final _that = this;
switch (_that) {
case ServerFailure() when server != null:
return server(_that.message);case NetworkFailure() when network != null:
return network(_that.message);case UnauthorizedFailure() when unauthorized != null:
return unauthorized(_that.message);case TimeoutFailure() when timeout != null:
return timeout(_that.message);case CacheFailure() when cache != null:
return cache(_that.message);case UnexpectedFailure() when unexpected != null:
return unexpected(_that.message);case _:
  return null;

}
}