whenOrNull<TResult extends Object?> method

@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>({ TResult? success(String title, String message)?, TResult? failure(String title, String message)?, TResult? info(String title, String message)?, TResult? warning(String title, String message)?, })

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( String title,  String message)?  success,TResult? Function( String title,  String message)?  failure,TResult? Function( String title,  String message)?  info,TResult? Function( String title,  String message)?  warning,}) {final _that = this;
switch (_that) {
case _Success() when success != null:
return success(_that.title,_that.message);case _Failure() when failure != null:
return failure(_that.title,_that.message);case _Info() when info != null:
return info(_that.title,_that.message);case _Warning() when warning != null:
return warning(_that.title,_that.message);case _:
  return null;

}
}