when<TResult extends Object?> method

  1. @optionalTypeArgs
TResult when<TResult extends Object?>()

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?>() {final _that = this;
switch (_that) {
case _:
  throw StateError('Unexpected subclass');

}
}