when<TResult extends Object?> method

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

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?>({
  required TResult Function(L value) left,
  required TResult Function(R value) right,
}) {
  final _that = this;
  switch (_that) {
    case Left():
      return left(_that.value);
    case Right():
      return right(_that.value);
  }
}