Re: [Snap-photo-devel] List<T> vs. Set<T>

[Maciej S. <m.s...@gm...>]

Well, I guess we have two options:

1. Rewrite any code that depends on ordering not to depend on ordering.
2. Rewrite Set<T> to implement IList<T>. It sounds kind of crazy, but
if Set<T> uses two data structures, a List<T> to hold the actual T
items, and a Dictionary<T,int> to hold a mapping from the T items to
positions in the list, we should be able to get it to work without too
big a performance hit. Of course, this raises memory requirements for
the Set<T> by at least 50%. Although if we're really concerned about
memory usage, we should not use a Dictionary<T,bool> internally but
rewrite Set<T> to do its own hashing...

I'll give Option 1 a shot first, once I commit the Trie/SearchTree
business. If that doesn't pan out, we can consider Option 2.

-Maciek

On 7/29/06, Jimmy Do <cri...@gm...> wrote:
> I like the idea, but I'm hesitant because some of the filtering or
> grouping code does rely on ordering so that the pictures show up in
> the right order in the thumbnail view. But it would be nice to use
> Set<T>, so maybe you can give it a try and see if it can be done?
>
> Jimmy
>
> On 7/28/06, Maciej Sakrejda <m.s...@gm...> wrote:
> > So we use List<T>s (or at least IList<T>s) all over the place, where
> > we are implicitly ignoring the occurence of duplicates. Should we
> > maybe move this all to Set<T>s? I've added a lot of stuff to the
> > Set<T> class, and have tested it thoroughly. Maybe we should move to
> > ISet<T>s instead, in case we ever feel like implementing a Set<T>-like
> > class in another way. Either way, though, it seems like it's a bad
> > idea to use IList<T>s where we really mean "IList<T>, but with no
> > duplicates". I guess the major catch is that since Set<T> is
> > implemented on top of a dictionary, and not a list, we lose the
> > ordered property. I don't know if any code actually depended on this.
> > Set<T> does implement ICollection (among other things), so it should
> > be pretty easy to work with, but I thought I'd check with you guys in
> > case there is a good reason to use IList<T> in some place (mostly I'm
> > talking about passing around IList<T>s of IPictureInfos for filtering
> > purposes)...
> >
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