when<TResult extends Object?> method

  1. @optionalTypeArgs
TResult when<TResult extends Object?>(
  1. TResult $default(
    1. bool? regexp,
    2. String? match,
    3. double? 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?>(
  TResult Function(bool? regexp, String? match, double? value) $default,
) {
  final _that = this;
  switch (_that) {
    case _StrategyWeight():
      return $default(_that.regexp, _that.match, _that.value);
    case _:
      throw StateError('Unexpected subclass');
  }
}