Why does inserter need Iterator template parameter
in [C++]
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From: Kris Prad on 16 Feb 2010 02:19 The inserter function (from msdn): template<class Container, class Iterator> insert_iterator<Container> inserter( Container& _Cont, Iterator _It ); It returns an object of insert_iterator. Can't iterator type be obtained from Container type? Something like: template<class Container> insert_iterator<Container> inserter( Container& _Cont, typename Container::iterator _It ); In fact insert_iterator's ctor does this. Kris -- [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ]
From: Daniel Krügler on 16 Feb 2010 07:42 On 16 Feb., 20:19, Kris Prad <krisp...(a)yahoo.co.uk> wrote: > The inserter function (from msdn): > > template<class Container, class Iterator> > insert_iterator<Container> inserter( > Container& _Cont, > Iterator _It > ); > > It returns an object of insert_iterator. This is a perfect match against the C++03 standard. > Can't iterator type be obtained from Container type? > > Something like: > > template<class Container> > insert_iterator<Container> inserter( > Container& _Cont, > typename Container::iterator _It > ); Sure, this is possible. And in retro-perspective the current spec has been recognized as overly generic, see http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#561 > In fact insert_iterator's ctor does this. Correct, and this is actually more evidence for that defect. HTH & Greetings from Bremen, Daniel Kr�gler -- [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ]
From: Pete Becker on 16 Feb 2010 22:40
Pete Becker wrote: > Kris Prad wrote: >> The inserter function (from msdn): >> >> template<class Container, class Iterator> >> insert_iterator<Container> inserter( >> Container& _Cont, >> Iterator _It >> ); >> >> It returns an object of insert_iterator. >> >> Can't iterator type be obtained from Container type? >> > > Of course. > >> Something like: >> >> template<class Container> >> insert_iterator<Container> inserter( >> Container& _Cont, >> typename Container::iterator _It >> ); >> > > If that's all that was needed, that would indeed work. So there's a > strong possibility that there's more going on here than that. To find > out if that's the case, read the documentation. I'm sure that MSDN > provides more than just the declaration... > Whoops, sorry: answered the wrong question. Yes, the type can be obtained from the Container type, and, yes, your rewrite works just fine. -- Pete Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The Standard C++ Library Extensions: a Tutorial and Reference" (www.petebecker.com/tr1book) [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] |