whenOrNull<TResult extends Object?> method

  1. @optionalTypeArgs
TResult? whenOrNull<TResult extends Object?>({
  1. TResult? idle()?,
  2. TResult? loading()?,
  3. TResult? error(
    1. Object error
    )?,
  4. TResult? success(
    1. T? value
    )?,
})

A variant of when that fallback to returning null

It is equivalent to doing:

switch (sealedClass) {
  case Subclass(:final field):
    return ...;
  case _:
    return null;
}

Implementation

@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>({TResult? Function()?  idle,TResult? Function()?  loading,TResult? Function( Object error)?  error,TResult? Function( T? value)?  success,}) {final _that = this;
switch (_that) {
case DataStateIdle() when idle != null:
return idle();case DataStateLoading() when loading != null:
return loading();case DataStateError() when error != null:
return error(_that.error);case DataStateSuccess() when success != null:
return success(_that.value);case _:
  return null;

}
}