Joaquín M López Muñoz wrote:

De: "David B. Held"

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"Jeremy Maitin-Shepard" <jbms@attbi.com> wrote in message news:87u128yr3g.fsf@jbms.ath.cx...

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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.

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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