whenOrNull<TResult extends Object?> method

  1. @optionalTypeArgs
TResult? whenOrNull<TResult extends Object?>(
  1. TResult? $default(
    1. String placeholder,
    2. String title,
    3. String okBtnText,
    4. String cancelBtnText,
    )?
)

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 placeholder, String title, String okBtnText,
          String cancelBtnText)?
      $default,
) {
  final _that = this;
  switch (_that) {
    case _AskStringDialogParams() when $default != null:
      return $default(_that.placeholder, _that.title, _that.okBtnText,
          _that.cancelBtnText);
    case _:
      return null;
  }
}