Joaquín M López Muñoz wrote:
De: "David B. Held"
"Jeremy Maitin-Shepard" <jbms@attbi.com> wrote in message news:87u128yr3g.fsf@jbms.ath.cx...
I believe that a library named ``indexed_set,'' which has been proposed and is pending formal review, provides this functionality in addition to supporting multiple indices.
Are you sure it does the same thing? I was under the impression that Joaquin's library lets you define *additional* indexes, but what if you just want to use an existing index, but it is comparable to something other than the key_type?
indexed_set does provide this functionality (multiple indices aside.) See
http://tinyurl.com/2vu5g, section "Special lookup operations". See also http://tinyurl.com/3dyzh, section "Index set operations" for a formal definition of the kind of special lookup operations provided.
And so indexed_set does provide the ability to lookup by a type other than the key_type. Which means that if we compared the various set containers in terms of abilities, flex_set is a special case of indexed_set where the number of indexes == 1.
From what I just read about indexed_set, it seems that the best benefit to using flex_set instead of indexed_set is that flex_set is simpler and smaller.
We can sort set container classes by abilities to get this: std::set < flex_set < indexed_set. We can also sort multiset containers by ability and get this: std::multiset < flex_multiset < indexed_set. Rich Sposato