Question

I have a Request object which contains a list of Approvers. An approver has a name and an approval position.

1. Mathew
2. Mark
3. Luke
4. John

Ultimately, a request will move through this chain, starting at Mathew and ended at John.

I need to be able to re-order these allowing adds and deletes as outlined below.

An approver can be –

Added at a certain position – ie. Add Peter at position 3 in which case the new order would be

1. Mathew
2. Mark
3. Peter
4. Luke
5. John

Delete – ie. Delete Mark in which case the new order is

1. Mathew
2. Luke
3. John

Edited – ie you can change John’s position to 1 in which case the new order is

1. John
2. Mathew
3. Mark
4. Luke

I have come up with a number of solutions, however none of them is particular elegant.

Any help would be much appreciated

Answer 1

How large are the lists likely to be? List<T> is likely to be the easiest representation of the collection, but it means a copy is required every time you insert into or remove from the middle of the list. ‘Editing’ the list basically means a remove/insert.

Iteration is then straightforward.

An alternative might be LinkedList<T> – which makes iteration simple and ‘insert after’, ‘insert before’ and ‘delete’ cheap if you hang onto the LinkedListNode<T> associated with each of your approvers. But it doesn’t make it easy to say ‘this reviewer should now be at position 3’ – you’d have to iterate through to find position 3 first (or 2, anyway). If it’s a case of ‘move this approver after this one’ then it’s ideal.