when<TResult extends Object?> method

  1. @optionalTypeArgs
TResult when<TResult extends Object?>(
  1. TResult $default(
    1. List<NameServerConfig>? servers,
    2. HostsWrapper? hosts,
    3. XrayAddress? clientIp,
    4. String? tag,
    5. DnsQueryStrategy? queryStrategy,
    6. bool? disableCache,
    7. bool? serveStale,
    8. int? serveExpiredTTL,
    9. bool? disableFallback,
    10. bool? disableFallbackIfMatch,
    11. bool? enableParallelQuery,
    12. bool? useSystemHosts,
    )
)

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?>(
  TResult Function(
    List<NameServerConfig>? servers,
    HostsWrapper? hosts,
    XrayAddress? clientIp,
    String? tag,
    DnsQueryStrategy? queryStrategy,
    bool? disableCache,
    bool? serveStale,
    int? serveExpiredTTL,
    bool? disableFallback,
    bool? disableFallbackIfMatch,
    bool? enableParallelQuery,
    bool? useSystemHosts,
  )
  $default,
) {
  final _that = this;
  switch (_that) {
    case _DNSConfig():
      return $default(
        _that.servers,
        _that.hosts,
        _that.clientIp,
        _that.tag,
        _that.queryStrategy,
        _that.disableCache,
        _that.serveStale,
        _that.serveExpiredTTL,
        _that.disableFallback,
        _that.disableFallbackIfMatch,
        _that.enableParallelQuery,
        _that.useSystemHosts,
      );
    case _:
      throw StateError('Unexpected subclass');
  }
}