when<TResult extends Object?> method

@optionalTypeArgs TResult when<TResult extends Object?>(TResult $default(num amount, String label, bool pending))

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?>(TResult Function( num amount,  String label,  bool pending)  $default,) {final _that = this;
switch (_that) {
case _$PaymentItem():
return $default(_that.amount,_that.label,_that.pending);case _:
  throw StateError('Unexpected subclass');

}
}