Fwd: [Dev] [UIDev] Item Collection inclusion/exclusion

[Chih-Chao Lam]

Forwarded reply from Mimi with additional comments from me.

chao

Begin forwarded message:

> From: "Mimi Yin" <mimiyin at aya.yale.edu>
> Date: July 1, 2004 3:58:00 PM PDT
> To: <chao at osafoundation.org>
>
> ===
> Hi,
>
> Answers in-line... Mimi
>
> From: Jed Burgess <jed at osafoundation.org>
>
> Question 1:
>
> If an item already exists in an item collection because it meets the
> rule, and then you call include() passing that item, should the item
> exist in the list twice?  Some possibilities are not changing the
> collection at all when this action is taken, adding it to the
> inclusions list but only reporting the item once when asked for all
> of its members, or reporting the item twice.  From a users
> standpoint you probably only want to report it once (is there a case
> where this isn't true?) and performance would be best if you take
> no action if the item is already included.  However, with that
> scenario some information is lost (the fact that the item was
> manually included) which may or may not be important.
>
> ANSWER: As far as the user knows, the item exists once in the
> collection.
>
chao: Mimi, I think Jed is pointing out the scenario where item A is 
manually added and also part of a query that originally contains item 
A. What if the query no longer contains A, should item A still appear 
in this collection because it was also manually added? My first guess 
is the answer is yes, but it's a good question and merits more 
thinking.

Jed, I agree with you and Mimi that the item should always be displayed 
(or reported) only once to the user for any given collection.

>
>
> Question 2:
>
> How should the exclusion list operate?  If you have an item that is
> in an item collection solely because it was manually included, can
> you just remove it from the inclusion list or do you have to track it
> on an exclusion list.  If you just remove it from the inclusion list
> then it might show up at some later point if it begins to meet the
> rule.  If you keep it on an exclusion list, then that exlusion list can
> grow to an unmanageable size.  In general, there is a distinct
> possibility that our exclusion lists could grow quickly if we aren't
> careful (think removing spam).
>
> ANSWER: For the user, taking an item off the inclusion list should
> be the same as putting it on the exclusion list. It is an explicitly
> removed item, which means that unless they explicitly put it back
> into the collection, it should never show up in that collection again.