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[boost-users][tuple] Tuple::get<0> as std::mem_fun_ref
by Miklós Tóth 30 Aug '13

30 Aug '13

Hi! I have a problem with std::mem_fun_ref and boost::tuple. Here is my code: I have small LevelSetter class. It makes a level vector indexed by a transform_iterator value. template <typename LevelType> class LevelSetter { private: int nmb_of_elements; public: LevelSetter(int nmb_of_elements_) : nmb_of_elements(nmb_of_elements_) {} template <typename TrRange> std::vector<LevelType> set(TrRange range) { typedef typename TrRange::first_type TrIter; std::vector<LevelType> levels(nmb_of_elements); for (TrIter it = range.first; it != range.second; ++it) { levels[*it] = 0.0; } // much more complicated code return levels; } }; Let's call it: class MemFunRefTest { private: typedef float Scalar; typedef boost::tuple<int, Scalar> Tuple; typedef std::vector<Tuple> Fwd; typedef Fwd::iterator FwdIter; typedef std::pair<FwdIter, FwdIter> FwdRange; Fwd elements; public: MemFunRefTest() { elements.push_back(Tuple(0, 400.0)); elements.push_back(Tuple(1, 120.0)); elements.push_back(Tuple(2, 150.0)); } void fun() { FwdRange element_range = std::make_pair(elements.begin(), elements.end()); LevelSetter<Scalar> setter(elements.size()); setter.set(std::make_pair( boost::make_transform_iterator( element_range.first, std::mem_fun_ref(&Tuple::get<0>) ), boost::make_transform_iterator( element_range.second, std::mem_fun_ref(&Tuple::get<0>) ) ) ); } }; When I try to compile i get: error: call of overloaded 'mem_fun_ref(<unresolved overloaded function type>)' is ambiguous candidates are: c:\mingw-4.6\bin\..\lib\gcc\i686-pc-mingw32\4.6.1\..\..\..\..\include\c++\4.6.1\bits\stl_function.h:697: std::mem_fun_ref_t<_Ret, _Tp> std::mem_fun_ref(_Ret (_Tp::*)()) [with _Ret = int&, _Tp = boost::tuples::cons<int, boost::tuples::cons<float, boost::tuples::null_type> >] c:\mingw-4.6\bin\..\lib\gcc\i686-pc-mingw32\4.6.1\..\..\..\..\include\c++\4.6.1\bits\stl_function.h:702: std::const_mem_fun_ref_t<_Ret, _Tp> std::mem_fun_ref(_Ret (_Tp::*)()const) [with _Ret = const int&, _Tp = boost::tuples::cons<int, boost::tuples::cons<float, boost::tuples::null_type> >] What am I missing? Thanks, Miklos

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[typeof] registering class templates whose NTTPs depend on other TPs
by Cromwell Enage 29 Aug '13

29 Aug '13

Hi, all. Using Boost.Typeof, how would I register the following class template? ['' template <typename foo, foo bar> struct baz { }; ''] Any help would be appreciated. Cromwell D. Enage

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CUDA and Boost
by Víctor Felipe 29 Aug '13

29 Aug '13

Hey guys! I have been using Boost inside a Visual C++ CUDA project. I'm using "regex.hpp" inside a ".cu" file and it works fine including it this way: "#include < boost / regex.hpp >". Now, I need to use "abs.hpp", which I'm including this way: "#include < boost / ratio / detail / mpl / abs.hpp >" and it fails while compiling. I'm using Windows 8 64-bits, Visual Studio 2012, Boost 1.53.0 and CUDA 5.5. I get this error only by putting this in my code: "#include < boost / ratio / detail / mpl / abs.hpp >" without using more instructions related with Boost. I have several ".cpp" and ".cu" files in my project. If I put that include in a ".cpp" file, it compiles fine. If I put that include in a ".cu", this error appear: 1>C:\Program Files (x86)\Microsoft Visual Studio 11.0\VC\include\boost/ratio/detail/mpl/abs.hpp(68): error C2675: unary '-' : 'T' does not define this operator or a conversion to a type acceptable to the predefined operator Thanks for any help you can provide and sorry for my English, it's not my native language!

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boost asio with scatter gather list and udp ....
by jean-luc malet 29 Aug '13

29 Aug '13

Hi! I'm new to boost, so I don't understand everything, be kind please ;) I'm working on a piece of code that use boost::asio with a ba::ip::udp::socket the code is sending data using 2 buffers stored in a boost::array my work is to write the receiver and my question is : how many udp packets will be sent? 1? 2? if multiple packets are sent, how does boost::asio will re-order them on reception? if one packet is sent, and if on reception I use another scatter gather list as above (but with mutable buffers) how does boost know the size of the 2 buffers? thanks and regards MALET Jean-Luc >

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[posix_time] ARM clock scaling issue
by Michael Powell 28 Aug '13

28 Aug '13

Hello, I am using the posix_time ptime interface to gauge clock times, universal time (Utc), and do date/time math, subtracting for durations type thing. What I am finding is that the accuracy seems to be fast. By how much I don't know, whether that's by a factor of what, or what not, I do not know. We are encountering this on an ARM platform. Has anyone else experience this? If so what can we do to workaround it? Assuming we stick with the Boost API to comprehend date/time, duration, our stopwatch abstraction, elapsed-timer, and so on. Thank you... Regards, Michael Powell

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Meta State Machine, wayward transition
by Archie Campbell 28 Aug '13

28 Aug '13

Hello, I have a simple state machine, that uses only standard rows and no internal transitions, to which I am sending events that are clearly in the transition table for the state that the machine is in, yet the no_transition handler is running for this particular event. I have not yet been able to discover any reasons for a compiling transition table to fail to process an event that is listed in the row against the source state. Have I missed something fundamental? Regards, Archie

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Interprocess : multithreading of the mapping
by Oodini 27 Aug '13

27 Aug '13

Hello, I have several shared memory regions to map in my client process. May I experience troubles if use multithreading to do this operation ? (http://www.boost.org/doc/libs/1_54_0/doc/html/interprocess/sharedmemorybetw…) I have a good reason to do that. Thanks !

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Interoperability of multiple boost versions.
by Wilfried Kirschenmann 26 Aug '13

26 Aug '13

Hi all, I'm currently working on a large software project having an unchangeable dependency on boost 1.33, but I would like to use functionality from a more up-to-date version of the library (say 1.54). Can it be done? If so, how ? One of the things we aim to achieve is use the std::hash and unoredered_map from boost 1.54, while also using othe containers from boost 1.33. Since boost if mostly header only and template-based, using an intermediary interface doesn't work well. Any ideas ? Are we better off using another library instead of boost to avoid conflicts ? Help appreciated, thanks. Kind regards, Wilfried K. ----- Cordialement, Wilfried Kirschenmann "Ma femme, si elle croit que je vis, croit que je marche. Les camarades croient que je marche. Ils ont tous confiance en moi. Et je suis un salaud si je ne marche pas."* *Guillaumet (1902 - 1940) cité dans *Terre des Hommes* par Antoine de Saint-Exupéry (1900 - 1944)

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[geometry] problems with the ring concept
by Lepere Renaud 25 Aug '13

25 Aug '13

I have an existing geometric structure, and i try to make it usable with boost geometry. I read the documentation for a similar problem but i did not successhttp://www.boost.org/doc/libs/1_54_0/libs/geometry/doc/html/geometry… My Ring structure is very simple : typedef std::vector< Point > Points; struct Ring { Points points; }; void f() { boost::geometry::concept::check< Geom::Ring >(); } show failure since apparently my range does not support a clear() method correctly. however i think i implemented correctly the range adaption namespace boost/geometry/traints template<> struct tag< Geom::Ring > { typedef ring_tag type; }; namespace Geom inline Geom::Points::iterator range_begin(Ring & ring) { return ring.points.begin(); } inline Geom::Points::iterator range_end(Ring & ring) { return ring.points.end(); } inline Geom::Points::const_iterator range_begin(const Ring & ring) { return ring.points.begin(); } inline Geom::Points::const_iterator range_end(const Ring & ring) { return ring.points.end(); } and in namespace boost template <> struct range_mutable_iterator< Geom::Ring > { typedef Geom::Points::iterator type; }; // i tried also with range_iterator template<> struct range_const_iterator< Geom::Ring > { typedef Geom::Points::const_iterator type; }; I am a bit lost. Did i missed something obvious ? Thanks, Renaud

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[logging] operator<< not called if logger initialized by init_from_settings()
by Eric Prud'hommeaux 25 Aug '13

25 Aug '13

Following the standard recipe for a severity logger, I failed to get a logger configured by parsing a settings file to property invoke the operator<< for the severity. I tested by creating two logs, one by parsing and one by explicit construction (attached). Below, the former (starting with "parse: ") does not call the operator<< while the latter (staring with (const: ") does: [[ parse: : <> normal 1 severity_enum.cpp:25: operator<<(0x164dce0, 0) const: : <normal> normal 1 parse: : <> criticial 2 severity_enum.cpp:25: operator<<(0x164dce0, 1) const: : <critical> criticial 2 ]] It also doesn't matter whether the explicitly constructed logger is before the parsed logger: [[ severity_enum.cpp:25: operator<<(0x20b5d40, 0) const: : <normal> normal 1 parse: : <> normal 1 severity_enum.cpp:25: operator<<(0x20b5d40, 1) const: : <critical> criticial 2 parse: : <> criticial 2 ]] I've also tested this with a severity_channel logger with the same result. typedef unsigned int severity_level; (and some #defines) shows that the specialized operator<<(..., severity_level) isn't called at all, but at least the std:: one prints integers: [[ parse: : <0> normal 1 const: : <0> normal 1 parse: : <1> criticial 2 const: : <1> criticial 2 ]] I haven't worked out how to construct a settings object directly (as opposed to using the setting parser). I guess that's the next test. -- -ericP

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