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[qi and lambda] Get wrong reaction of the qi::rule if I use lambda for the action
by boost_mailinglist＠gmx.de 16 Aug '11

16 Aug '11

Hello, if I execute the following example, I get the following output "The bad one The good one a" but I only expected "The good one a". Why does it happens? Boost 1.47.0 was used. #include <boost/config/warning_disable.hpp> #include <boost/spirit/include/qi.hpp> #include <boost/lambda/lambda.hpp> #include <iostream> int main() { using boost::spirit::qi::char_; using boost::spirit::qi::parse; char const *first = "{a}", *last = first + std::strlen(first); parse(first, last, '{' >> char_("a")[std::cout << "The good one " << boost::lambda::_1 << '\n'] | char_("b")[std::cout << "The bad one " << boost::lambda::_1 << '\n'] >> '}'); return 0; }

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boost multithread use all cores in parallel ?
by Jack Bryan 16 Aug '11

16 Aug '11

Hi, How to make sure that a multithreaded C++ program is run by ALL cores on a multicore server to do computing in parallel physically (not logically). I have a multicore server, which has 24 CPUs, each of which has 6 cores. It is Intel Xeon X5650 2.67GHz cpu cores : 6 (support 6 threads) cpu MHz : 1596.000 totally, I have 24 * 6 = 144 cores. I designed a multithreaded C++ program with boost/thread. How to make sure that my program is run by all 144 cores ? Any help is really appreciated. thanks

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iterator_adaptor : const and regular form
by John M. Dlugosz 15 Aug '11

15 Aug '11

I wrote an iterator by deriving from the boost::iterator_adaptor template. Now I need the const_iterator for my collection, too. The instructions for iterator_adaptor are not clear, but the implication is that I should transfer what I read from iterator_facade. So, is using a const type for the Value (the 3rd template argument) all it takes to write a proper const_iterator? (assuming the functions I supply are proper, too) So, I can just write my iterator as a template of T, passing T through as Value to the iterator_adaptor base class, and then instantiate _that_ with my value type and with const value type to make iterator and const_iterator respectively, right? —John

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[Range] Why adaptor stores iterator_range instead of its underlying range?
by TONGARI 15 Aug '11

15 Aug '11

Hi, I've had this question for a long time, but I still haven't seen others asked the same question. I wonder what's the rationale for range adaptor holding an iterator_range, instead of storing the underlying range (by reference when the range is a container) and calculating begin() and end() on the fly. For C++11 code, it's not unusual to store the temporary expression aside and use it more than once. E.g. vector<int> v = {1, 2, 3}; auto view = v | filtered(...); do_something(view); v.push_back(4); // X do_something(view); Above code is broken since 'v''s iterator is invalidated after X. Could anybody shed some light on this matter?

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[Boost.Range][Boost.Iterators] - iterator as pointer
by Christoph Heindl 15 Aug '11

15 Aug '11

Hi folks, I wonder if it is possible to determine if an iterator or a boost.range can be handled like a pointer to contiguous memory using an iterator/range trait? I need to enable functions if the given range is convertible to a c-array like pointer range. Best regards, Christoph

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[geometry] weird define in adapted fusion sequence
by alfC 15 Aug '11

15 Aug '11

Hi, Trying (again) to use Boost.Geometry with coordinates with Boost.Units (BTW, what is the status of the compatibility between geometry and units?) I found the following macro definition in boost/ geometry/geometries/adapted/boost_fusion.hpp // Convenience registration macro to bind a Fusion sequence to a CS #define BOOST_GEOMETRY_REGISTER_BOOST_FUSION_CS(CoordinateSystem) \ namespace boost { namespace geometry { namespace traits { \ template <typename Sequence> \ struct coordinate_system \ < \ Sequence, \ typename boost::enable_if \ < \ fusion_adapt_detail::is_fusion_sequence<Sequence> \ >::type \ > \ { typedef cs::cartesian type; }; \ }}} Unless I am missing something, the definition of the macro does not depend on the parameter "CoordinateSystem" !. To make the situation even more confusing the manual's example (http://www.boost.org/doc/ libs/1_47_0/libs/geometry/doc/html/geometry/reference/adapted/ boost_fusion.html) uses the struct as the parameter and not the coordinate system ! Unless I am wrong the last lines of the definition of BOOST_GEOMETRY_REGISTER_BOOST_FUSION_CS should be: { typedef CoordinateSystem type; }; \ }}} and the manual should be updated accordingly. E.g. the example should read BOOST_FUSION_ADAPT_STRUCT(sample_point, (double, x) (double, y) (double, z)) BOOST_GEOMETRY_REGISTER_BOOST_FUSION_CS(cs::cartesian) Am I missing something? Thanks, Alfredo

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Problem building boost\optional\optional.hpp in VS2010
by Pally Sandher 15 Aug '11

15 Aug '11

Hi, We've been using boost v1.36 in Visual Studio 2005 for a few years now. I'm attempting to upgrade our projects & solutions to build in Visual Studio 2010 & thus I've upgraded to boost 1.47.0. However I'm getting an error when trying to compile a project which uses some boost functions Full text of the error message is as follows: 1> ASIMNET.CPP 1>c:\code\inc\boost\optional\optional.hpp(346): error C2061: syntax error : identifier 'm_storage' 1> c:\code\inc\boost\optional\optional.hpp(345) : while compiling class template member function 'void boost::optional_detail::optional_base<T>::construct(const std::locale &)' 1> with 1> [ 1> T=boost::io::detail::locale_t 1> ] 1> c:\code\inc\boost\optional\optional.hpp(500) : see reference to class template instantiation 'boost::optional_detail::optional_base<T>' being compiled 1> with 1> [ 1> T=boost::io::detail::locale_t 1> ] 1> c:\code\inc\boost\format\internals.hpp(56) : see reference to class template instantiation 'boost::optional<T>' being compiled 1> with 1> [ 1> T=boost::io::detail::locale_t 1> ] 1> c:\code\inc\boost\format\internals.hpp(57) : see reference to class template instantiation 'boost::io::detail::stream_format_state<Ch,Tr>' being compiled 1> 1>Build FAILED. 1> The only references to boost in ASIMNET.CPP are as follows: #include <boost/math/special_functions/round.hpp> translation[X] = boost::math::round( (translation[X]/TILEWIDTH) ) * TILEWIDTH; translation[Y] = boost::math::round( (translation[Y]/TILEWIDTH) ) * TILEWIDTH; Any help will be most appreciated. Thanks, Palbinder Sandher Software Deployment Engineer T: +44 (0) 141 945 8500 F: +44 (0) 141 945 8501 http://www.iesve.com **Design, Simulate + Innovate with the <Virtual Environment>** Integrated Environmental Solutions Limited. Registered in Scotland No. SC151456 Registered Office - Helix Building, West Of Scotland Science Park, Glasgow G20 0SP Email Disclaimer

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boost.clang -- linq like operations in C++
by Julien Nitard 15 Aug '11

15 Aug '11

Hi All, Some (rather long) time ago there were some talks and some code written about LINQ-like feature for C++, notably one named boost.qlang. Were there any followups ? Is there any equivalent in other libraries ? The original thread: http://boost.2283326.n4.nabble.com/C-LINQ-is-cool-What-about-boost-qlang-td… Thanks for any help, Julien

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boost timer
by Kraus Philipp 15 Aug '11

15 Aug '11

Hello, I would like to calculate the runtime of my algorithms. I have written a MPI based algorithms and must determine the duration of the algorithm on each CPU. I would like to show the really duration, which is based on Amdahls law, so I need a "exactly" timer. Can I use the Boost Timer / Boost MPI Timer to calculate the duration between start and end of my algorithm? On large datasets I think the timer is a good choice. Is the resolution of the timer object just enough for small amounts of data? I would like to do this: timer t; run_algorithm; std::cout << t.elapsed << std::endl; Is a timer object a good choice to determine runtime structure or do you a better structure? Thanks Phil

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Compiler warnings when compiling property_tree v1.47.0
by Bill Moo 15 Aug '11

15 Aug '11

Hello Users, I am using the Intel compiler v12.0.1029.2010 on Windows 7 x64 and when compiling the property_tree (v1.47.0) I get lots of warnings reported: infoStruct.cpp ..\..\Includes\boost/mpl/aux_/has_begin.hpp(20): warning #2586: 'test' : decorated name length exceeded, name was truncated BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(has_begin, begin, true) This is one of many similar warnings generated and I was wondering if anyone could shed some light on how this can be solved. The code compiles of course and the library builds but I'd rather not have them at all. I would appreciate your comments on this thanks. -- Bill

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