Re: [Boost-users] zip_iterator and sTL algorithms like random_shuffle

This is not standard conform to introduce overloaded functions into std namespace. This posting might answer your question: http://groups.google.com/group/comp.lang.c++.moderated/browse_frm/thread/b39... It is pretty long, but worth reading it all. And that is what Steven means in his previous post, that there is no C++03 standard way to fix it. Greetings, Ovanes On Tue, Mar 31, 2009 at 12:59 PM, Andreas Fabri < andreas.fabri@geometryfactory.com> wrote:

Hi Steven,

Adding a specialization for iter_swap

typedef boost::tuple< std::vector<int>::iterator, std::vector<int>::iterator

...

iterator_tuple;

typedef boost::zip_iterator< iterator_tuple

...

ziterator;

namespace std {

void iter_swap(ziterator a, ziterator b) { std::swap(a->get<0>(), b->get<0>()); std::swap(a->get<1>(), b->get<1>()); }

}

solved the problem for std::random_shuffle.

For std::sort I provide a comparison functor for the tuple. but the compiler (VC8) complains about no match for _Rotate

Any hint would be appreciated.

andreas

C:\Program Files (x86)\Microsoft Visual Studio 8\VC\INCLUDE\algorithm(1719) : error C2665: 'std::_Rotate' : none of the 3 overloads could convert all the argument types C:\Program Files (x86)\Microsoft Visual Studio 8\VC\INCLUDE\algorithm(1649): could be 'void std::_Rotate<_FwdIt>(_FwdIt,_FwdIt,_FwdIt,std::forward_iterator_tag)' with [ _FwdIt=boost::zip_iterator ] C:\Program Files (x86)\Microsoft Visual Studio 8\VC\INCLUDE\algorithm(1666): or 'void std::_Rotate<_FwdIt>(_BidIt,_BidIt,_BidIt,std::bidirectional_iterator_tag)' with [ _FwdIt=boost::zip_iterator, _BidIt=boost::zip_iterator ] C:\Program Files (x86)\Microsoft Visual Studio 8\VC\INCLUDE\algorithm(1709): or 'void std::_Rotate<_FwdIt>(_RanIt,_RanIt,_RanIt,std::random_access_iterator_tag)' with [ _FwdIt=boost::zip_iterator, _RanIt=boost::zip_iterator ] while trying to match the argument list '(boost::zip_iterator<IteratorTuple>, boost::zip_iterator<IteratorTuple>, boost::zip_iterator<IteratorTuple>, boost::detail::iterator_category_with_traversal)' with [ IteratorTuple=iterator_tuple ] and [ IteratorTuple=iterator_tuple ] and [ IteratorTuple=iterator_tuple ] and [ Category=std::input_iterator_tag, Traversal=boost::random_access_traversal_tag ] C:\Program Files (x86)\Microsoft Visual Studio 8\VC\INCLUDE\algorithm(3125) : see reference to function template instantiation 'void std::rotate<_BidIt>(_FwdIt,_FwdIt,_FwdIt)' being compiled with [ _BidIt=boost::zip_iterator, _FwdIt=boost::zip_iterator ] C:\Program Files (x86)\Microsoft Visual Studio 8\VC\INCLUDE\algorithm(3252) : see reference to function template instantiation 'void std::_Insertion_sort<_RanIt,_Pr>(_BidIt,_BidIt,_Pr)' being compiled with [ _RanIt=boost::zip_iterator, _Pr=Compare, _BidIt=boost::zip_iterator ] C:\Program Files (x86)\Microsoft Visual Studio 8\VC\INCLUDE\algorithm(3261) : see reference to function template instantiation 'void std::_Sort<_RanIt,__int64,_Pr>(_RanIt,_RanIt,_Diff,_Pr)' being compiled with [ _RanIt=boost::zip_iterator, _Pr=Compare, _Diff=__int64 ]

Steven Watanabe wrote:

...

AMDG

Andreas Fabri wrote:

...

I have two vectors and want to random_shuffle them the same way using the zip_iterator. I thought the code below would do it, but when I execute it I see that both sequences get screwded up.

What do I wrong?

The problem is that std::iter_swap doesn't work for zip_iterator and there is no standard compliant way to fix it.

In Christ, Steven Watanabe

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