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Boost, MinGW and SjLj
by Archie Campbell 26 Apr '13

26 Apr '13

Hi, I have compiled boost_1_53_0 using bjam on windows with MinGW (gcc-4.6.3). I am using CodeBlocks for IDE and have successfully linked against Qt5. Attempting to link against libboost_serialization produces undefined references to things like sjlj_unwind and archive_exception. What's going wrong? Do I need to flag the compiler to change exception strategy? Thanks in advance. Archie

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Using C++ class with namespace in C
by Somostetoi Kilato 26 Apr '13

26 Apr '13

Hi, maybe it is not the best place to ask but at this moment I have no other idea where to go. This question is just a preamble for all the comming, BOOST related, questions of mine. So, I have a C++ class, the Apple, at the moment in the std namespace: class Apple { public: Apple(); void eat_an_apple(int p_bites); private: int bites; // number of bites to eat an apple }; I have a C application, an apple picker, first the header: typedef void CApple; #ifdef __cplusplus extern "C" { #endif CApple* pick_an_apple(); void eat_an_apple(const CApple *p_the_apple, int p_bites); void wash_your_hands(CApple *p_the_apple); #ifdef __cplusplus } // extern "C" #endif and the code, too: #include <stdio.h> #include "ApplePicker.hh" int main() { CApple *the_apple = NULL; the_apple = pick_an_apple(); eat_an_apple(the_apple, 9); wash_your_hands(the_apple); the_apple = NULL; return 0; } My question is, if I want to move my Apple class in a custom namespace, garden, how must I modify my C header and code file? Thank you and all the best, Kilato Somostetoi

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Is weak_ptr lock method thread safe?
by Andrea Galeazzi 25 Apr '13

25 Apr '13

I googled this question but, although there are many discussions about it, I didn't find a clear answer. Can I assume the following piece of code to be thread safe? shared_ptr<T> p1(new XXX); //Main thread weak_ptr<T> wp(sp); //Main thread //Then I run two threads: A and B p1.reset(); //thread A shared_ptr<T> p2 = wp.lock(); // thread B In other words, is lock method atomic in respect to deference of the shared point? -- korg Firma *KORG ITALY SPA* *Via Cagiata, 85 -- 60027 Osimo (AN) - ITALY* *Ph. +39 071 727161 -Fax +39 071 7231228* *P.IVA e Cod. fiscale IT01460580424* *Soggetta al controllo della Società KORG Inc. - Giappone* *Reg. Imprese di n. 212056/1996 del 23/12/96* *REA di Ancona al n. 133105 del 06/12/96* *Capitale sociale Euro 814.253,16 i.v.* Ai sensi del D.Lgs. 30 giugno 2003, n. 196, "Codice in materia di protezione dei dati personali" si precisa che le informazioni contenute nel messaggio sono riservate e destinate esclusivamente alla persona od organizzazione sopra indicata. A chi legge il presente avviso - se non è l'effettivo destinatario, o un dipendente, o la persona responsabile della consegna del messaggio - si notifica che sono proibite copie, distribuzione o divulgazione di quanto in esso contenuto (C.P. 616). Se questo messaggio Vi è pervenuto per errore, Vi preghiamo di informarci immediatamente, di non leggerlo e di distruggerlo. Grazie. /According to Legislative Decree n. 196 of 30 June 2003 about "Personal Data Protection Code" we point out that the information contained in this message may be privileged and confidential and is intended only for the use of the individual entity named above. If the reader of this message is not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this message is strictly prohibited. If you have received this message in error, please notify us immediately and destroy the original message. //Thank you./

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regex instantiation crashes at program exit
by Gianfranco Zuliani 24 Apr '13

24 Apr '13

Hi, I get a crash when trying to instantiate a boost::regex during program shutdown. I've boiled down the code to this: #include <boost/regex.hpp> #include <boost/thread.hpp> struct Object { ~Object() { boost::regex param("a"); } static Object& Instantiate() { static boost::thread_specific_ptr<Object> theObject; if (theObject.get() == 0) theObject.reset(new Object); return *theObject; } }; int main() { Object::Instantiate(); boost::regex param("a"); return 0; } Program exists fine if I comment out the boost::regex instantiation in main. I'm using Boost v. 1.42, Visual Studio 2008 Pro on Windows 7 SP1 64 bit. Test program is 64 bit too. TIA, Gianfranco

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[TypeTraits] Using has_call
by Robert Jones 24 Apr '13

24 Apr '13

Hi Folks I know has_call is not yet part of Boost, but using the implementation from https://github.com/jamboree/boost.has_call with this code #include "boost/type_traits/has_call.hpp" #include <cassert> template<typename Sig, typename F> bool HasCall(F const&) { return boost::has_call<F, Sig>::value; } void DefaultVal(int) {} int main() { assert(HasCall<boost::dont_care(int)>(DefaultVal)); } fails to compile for me, with a template instantiation ambiguity error. Seems the error is triggered by the use of boost::dont_care. Any ideas? Thx, Rob.

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[FunctionTypes] Testing for a general callable type.
by Robert Jones 24 Apr '13

24 Apr '13

Hi All Is there anything in Boost to help me test for a general type being callable with a specific signature? I've found Boost.FuncionTypes, which seems to be confined to *builtin* callable types, but has made me aware that all the const/volatile/reference variations might make a general test more complicated than I first thought. Any pointers much appreciated. Thx, Rob.

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[units] how to use scaled_base_unit?
by Olaf Peter 24 Apr '13

24 Apr '13

Hi, at this time I start to understand boost.units. Following the doc http://www.boost.org/doc/libs/1_53_0/doc/html/boost_units/Units.html#boost_… scaled_units are useful. But I didn't found use cases in the test or examples. E.g. https://svn.boost.org/svn/boost/trunk/libs/units/test/test_output.cpp show how to typedef this, but no usage. I try to map metric/si and imperial/us length to an intrinsic length using integer scale factors to avoid double representation uncertainly. Using BOOST_UNITS_DEFINE_CONVERSION_FACTOR I can convert meter and inch to the intrinsic length. But what about mm/um and thou/mil etc? For this I did consider scaled_base_unit. I like to convert between all of them. Since the dimensions are constant, no runtime conversation are required (as the dollar/euro example it shows). Later area calculations based on the intrinsic length are required, convertible also to metric/si and imperial systems. Thanks, Olaf

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boost interprocess linking problems under windows
by Jonathon Love 24 Apr '13

24 Apr '13

hi, i'm having difficulty compiling my program which uses boost::interprocess under windows. it compiles successfully under OS X. ./debug\enginesync.o: In function `ZN5boost12interprocess6winapi16co_uninitializerD1Ev': C:/progra~1/boost/boost_1_53_0/boost/interprocess/detail/win32_api.hpp:1651: undefined reference to `_imp__CoUninitialize@0' ./debug\enginesync.o: In function `ZN5boost12interprocess6winapi23get_wmi_class_attributeERSbIwSt11char_traitsIwESaIwEEPKwS8_': C:/progra~1/boost/boost_1_53_0/boost/interprocess/detail/win32_api.hpp:1673: undefined reference to `_imp__CoInitializeEx@8' Makefile.Debug:148: recipe for target '..\JASPDesktop.exe' failed C:/progra~1/boost/boost_1_53_0/boost/interprocess/detail/win32_api.hpp:1690: undefined reference to `_imp__CoInitializeSecurity@36' C:/progra~1/boost/boost_1_53_0/boost/interprocess/detail/win32_api.hpp:1700: undefined reference to `_imp__CoCreateInstance@20' C:/progra~1/boost/boost_1_53_0/boost/interprocess/detail/win32_api.hpp:1731: undefined reference to `_imp__CoSetProxyBlanket@32' C:/progra~1/boost/boost_1_53_0/boost/interprocess/detail/win32_api.hpp:1774: undefined reference to `_imp__VariantClear@4' collect2.exe: error: ld returned 1 exit status mingw32-make[2]: *** [..\JASPDesktop.exe] Error 1 i'm using mingw32 gcc 4.7, boost 1.53, under windows xp 32 bit. any assistance would be appreciated. with thanks

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Cpp_int and cpp_dec_float conversion
by Alessandro Tagliapietra 24 Apr '13

24 Apr '13

Hello, is there a way to convert from cpp_int to cpp_dec_float and viceversa? Since I've to use the modulus between two cpp_dec_float which I know they're integers but I need sqrt before and trying to run % with them gives: /usr/local/include/boost/multiprecision/number.hpp: In member function > ‘void boost::multiprecision::number<Backend, > ExpressionTemplates>::do_assign(const Exp&, const > boost::multiprecision::detail::modulus_immediates&) [with Exp = > boost::multiprecision::detail::expression<boost::multiprecision::detail::modulus_immediates, > boost::multiprecision::number<boost::multiprecision::backends::cpp_dec_float<100u, > int, void>, et_on>, > boost::multiprecision::number<boost::multiprecision::backends::cpp_dec_float<100u, > int, void>, et_on>, void, void>, Backend = > boost::multiprecision::backends::cpp_dec_float<100u, int, void>, > boost::multiprecision::expression_template_option ExpressionTemplates = > et_on]’: > /usr/local/include/boost/multiprecision/number.hpp:680: instantiated > from ‘void boost::multiprecision::number<Backend, > ExpressionTemplates>::do_assign(const > boost::multiprecision::detail::expression<tag, Arg1, Arg2, Arg3, Arg4>&, > const mpl_::true_&) [with tag = > boost::multiprecision::detail::modulus_immediates, Arg1 = > boost::multiprecision::number<boost::multiprecision::backends::cpp_dec_float<100u, > int, void>, et_on>, Arg2 = > boost::multiprecision::number<boost::multiprecision::backends::cpp_dec_float<100u, > int, void>, et_on>, Arg3 = void, Arg4 = void, Backend = > boost::multiprecision::backends::cpp_dec_float<100u, int, void>, > boost::multiprecision::expression_template_option ExpressionTemplates = > et_on]’ > /usr/local/include/boost/multiprecision/number.hpp:134: instantiated > from ‘typename boost::enable_if<boost::is_convertible<typename > boost::multiprecision::detail::expression<tag, Arg1, Arg2, Arg3, > Arg4>::result_type, boost::multiprecision::number<Backend, > ExpressionTemplates> >, boost::multiprecision::number<Backend, > ExpressionTemplates>&>::type boost::multiprecision::number<Backend, > ExpressionTemplates>::operator=(const > boost::multiprecision::detail::expression<tag, Arg1, Arg2, Arg3, Arg4>&) > [with tag = boost::multiprecision::detail::modulus_immediates, Arg1 = > boost::multiprecision::number<boost::multiprecision::backends::cpp_dec_float<100u, > int, void>, et_on>, Arg2 = > boost::multiprecision::number<boost::multiprecision::backends::cpp_dec_float<100u, > int, void>, et_on>, Arg3 = void, Arg4 = void, Backend = > boost::multiprecision::backends::cpp_dec_float<100u, int, void>, > boost::multiprecision::expression_template_option ExpressionTemplates = > et_on]’ > /usr/local/include/boost/multiprecision/number.hpp:181: instantiated > from ‘boost::multiprecision::number<Backend, > ExpressionTemplates>::number(const > boost::multiprecision::detail::expression<tag, Arg1, Arg2, Arg3, Arg4>&, > typename boost::enable_if_c<boost::is_convertible<typename > boost::multiprecision::detail::expression<tag, Arg1, Arg2, Arg3, > Arg4>::result_type,boost::multiprecision::number<Backend, > ExpressionTemplates> >::value, void>::type*) [with tag = > boost::multiprecision::detail::modulus_immediates, Arg1 = > boost::multiprecision::number<boost::multiprecision::backends::cpp_dec_float<100u, > int, void>, et_on>, Arg2 = > boost::multiprecision::number<boost::multiprecision::backends::cpp_dec_float<100u, > int, void>, et_on>, Arg3 = void, Arg4 = void, Backend = > boost::multiprecision::backends::cpp_dec_float<100u, int, void>, > boost::multiprecision::expression_template_option ExpressionTemplates = > et_on]’ > test.cpp:20: instantiated from here > /usr/local/include/boost/multiprecision/number.hpp:912: error: invalid > application of ‘sizeof’ to incomplete type > ‘boost::STATIC_ASSERTION_FAILURE<false>’ Thanks in advance Best Regards

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HOWTO: Connect Boost Signals & Slots to Qt Signals & Slots
by John Adamson 24 Apr '13

24 Apr '13

Hello everyone, Please find the first in a series of articles here: http://www.oxforddynamics.com/articles/connect_qt_and_boost_signals_and_slo… I hope it will be of use! Moderators: is this type of post is acceptable or not? Please let me know if it isn't and I won't post Boost related HOWTOs here again. Kind Regards, John

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