when<TResult extends Object?> method

  1. @optionalTypeArgs
TResult when<TResult extends Object?>(
  1. TResult $default(
    1. int id,
    2. String purchaseOrder,
    3. String invoiceNumber,
    4. DateTime invoiceDate,
    5. int? itemCount,
    6. int? statusCount,
    )
)

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( int id,  String purchaseOrder,  String invoiceNumber,  DateTime invoiceDate,  int? itemCount,  int? statusCount)  $default,) {final _that = this;
switch (_that) {
case _Order():
return $default(_that.id,_that.purchaseOrder,_that.invoiceNumber,_that.invoiceDate,_that.itemCount,_that.statusCount);case _:
  throw StateError('Unexpected subclass');

}
}