whenOrNull<TResult extends Object?> method

  1. @optionalTypeArgs
TResult? whenOrNull<TResult extends Object?>({
  1. TResult? empty()?,
  2. TResult? sp(
    1. String type,
    2. SpView model
    )?,
  3. TResult? ping(
    1. String type
    )?,
})

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()? empty,
  TResult? Function(@JsonKey(name: "type") String type,
          @JsonKey(name: "jsonString", toJson: modelToString) SpView model)?
      sp,
  TResult? Function(@JsonKey(name: "type") String type)? ping,
}) {
  final _that = this;
  switch (_that) {
    case SocketSendModelEmpty() when empty != null:
      return empty();
    case SpViewSendModel() when sp != null:
      return sp(_that.type, _that.model);
    case PingViewSendModel() when ping != null:
      return ping(_that.type);
    case _:
      return null;
  }
}