maybeWhen<TResult extends Object?> method

  1. @optionalTypeArgs
TResult maybeWhen<TResult extends Object?>({
  1. TResult left(
    1. L value
    )?,
  2. TResult right(
    1. R value
    )?,
  3. required TResult orElse(),
})

A variant of when that fallback to an orElse callback.

It is equivalent to doing:

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

Implementation

@optionalTypeArgs
TResult maybeWhen<TResult extends Object?>({
  TResult Function(L value)? left,
  TResult Function(R value)? right,
  required TResult orElse(),
}) {
  final _that = this;
  switch (_that) {
    case Left() when left != null:
      return left(_that.value);
    case Right() when right != null:
      return right(_that.value);
    case _:
      return orElse();
  }
}