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Herve, On Tuesday 19 November 2002 07:11, Herve Bronnimann wrote: > Dave, Jeremy: one iterator adaptor I needed often (and once again today) > is the projection on the first or second member of a pair. I could make > it using projection_iterator<> and select1st, except that select1st is > an std extension from SGI. I haven't found any other out-of-the-box way > to do this, did I miss something? Not as far as I can see. As a sidenote. From my experience you will run into the projection/transform problem quite frequently. IIRC projection iterators cannot be used on base iterators that don't have real reference types. > > I find them especially useful in connection with map::iterator, since > std::map does not have a value_iterator. I guess that alone provides the > rationale for including such an iterator adaptor, not to mention better > support of std::pair. Actually, I'd like to see a more general solution for all kind of tuple like types. Smth like typedef select_iterator<0, std::map<int>::iterator > key_iterator_t; Btw, templated typedefs anybody ? > > It's simple enough to make two adaptors, so if you don't see anything > wrong with it, I'm proposing the patch for you. I'll even write the > corresponding portion of the documentation if you go ahead with it. > Hope you like it, I like the idea, and yes I do believe there is a real need. There are just some issues to be sorted out. I'd like to postpone this until the new iterator_adaptor version is finished. Thanks Thomas - -- Dipl.-Ing. Thomas Witt Institut fuer Verkehrswesen, Eisenbahnbau und -betrieb, Universitaet Hannover voice: +49(0) 511 762 - 4273, fax: +49(0) 511 762-3001 http://www.ive.uni-hannover.de -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: For info see http://www.gnupg.org iD8DBQE92kr/0ds/gS3XsBoRAquxAJ4yr6ZLp/LRhxjYDyW6bZHrqrpYBgCeO7E+ b7Ebbr85gMKFXrqBFqFMr/E= =u8Oq -----END PGP SIGNATURE----- _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
