// sortByValue fetches values and sort UIDList.
func sortByValue(attr string, ul *task.List, scalar types.Scalar, desc bool) error {
values := make([]types.Value, len(ul.Uids))
for i, uid := range ul.Uids {
val, err := fetchValue(uid, attr, scalar)
if err != nil {
return err
}
values[i] = val
}
return scalar.Sort(values, ul, desc)
}
