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undefined reference to `boost::log::v2_mt_posix::...
by Antonis Polykratis 01 Oct '18

01 Oct '18

Hello I face this error and I cannot figure out a fix. I use bjam to build the application code, and inside site-config file, I have also the following a section where I define BOOST_ALL_DYN_LINK: ''' using gcc : : : where I have defined <define> BOOST_ALL_DYN_LINK ''' I have build boost libraries with the following command: sudo bjam toolset=gcc --with-system --with-thread --with-timer --with-chrono --with-filesystem --with-program_options --with-timer *--with-log* --with-program_options --with-date_time --with-math --with-serialization --with-regex --with-chrono --with-atomic runtime-link=shared define=*BOOST_ALL_DYN_LINK* --prefix=/opt/boost_shared install | tee output.txt I also changed some files (macro definitions and jam files) because I had an error that system and filesystem are configured to be compiled both as static and shared. I compiled them as shared. When I build the application code, I have plenty of `boost::log::v2_mt_posix::...` error messages. Could you give me some guide why this problem exist? Thanks, Antonis

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error: ‘class boost::mutex’ has no member named ‘try_lock_for’
by Antonis Polykratis 28 Sep '18

28 Sep '18

Hi, I face this error, in linux, does this indicates that I have not build the library correctly? the error is in that line: boost/thread/lock_types.hpp:162:45 #ifdef BOOST_THREAD_USES_CHRONO template <class Clock, class Duration> unique_lock(Mutex& mtx, const chrono::time_point<Clock, Duration>& t) : m(&mtx), is_locked(mtx.try_lock_until(t)) { } template <class Rep, class Period> unique_lock(Mutex& mtx, const chrono::duration<Rep, Period>& d) : m(&mtx), is_locked(mtx.try_lock_for(d)) <--- here is the error { } #endif Thanks, Antonis

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Boost.Units Example: Convert between nautical mile and imperial foot
by Carel Combrink 27 Sep '18

27 Sep '18

Hi, I am trying to use Boost.Units to convert between different units. I have implemented the example code for the "Radar Beam Height" [1] section but trying to convert between nautical mile and imperial foot result in a compiler error: I have: typedef boost::units::quantity<boost::units::si::length> Meters; typedef boost::units::quantity<imperial::length> Feet; typedef boost::units::quantity<nautical::length> NMiles; double func() { // Working const Meters si1(300.0*nautical::miles); const Meters si2(300.0*imperial::feet); const Feet feet1(300.0*imperial::feet); const Feet feet2(300.0*boost::units::si::meters); const NMiles mile1(300.0*nautical::miles); const NMiles mile2(300.0*boost::units::si::meters); // BROKEN const Feet feet3(300.0*nautical::miles); const NMiles mile3(300.0*imperial::feet); } The first few works, converting between meters and the new units, but converting between the two does not work. To see the issue see the code on Compiler Explorer here: https://gcc.godbolt.org/z/MpvuMy How can I get this working? [1] https://www.boost.org/doc/libs/1_68_0/doc/html/boost_units/Examples.html#bo… Regards,

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Serialization with BOOST _CLASS_EXPORT_KEY() is not the same as registert_type<>()
by Kosby, Ray B. (GSFC-428.0)[COLUMBUS TECHNOLOGIES AND SERVICES INC] 25 Sep '18

25 Sep '18

Hi, I’m trying to serialize a derived object with polymorphism into a file and deserialize to a base class pointer. This works when I use the register_type function but not the BOOST_CLASS_EXPORT_KEY() and BOOST_CLASS_IMPLEMENT() macros. I need to use the macros since I am using shared libraries. Here is a sample of code to demonstrate the problem. When run it gets a unregistered class exception. I’m using RHEL 7.4 with Boost 1.53. cat testera.h #ifndef testera_h #define testera_h #include <boost/serialization/serialization.hpp> #include <boost/archive/polymorphic_oarchive.hpp> #include <boost/archive/polymorphic_iarchive.hpp> #include <boost/serialization/export.hpp> #include <boost/serialization/string.hpp> class A { private: friend class boost::serialization::access; template< class Arch > void serialize( Arch &ar, const unsigned int ver ); public: A(); virtual ~A() {} void setStr( const std::string &s ); std::string getStr(); protected: std::string myStr; }; BOOST_CLASS_EXPORT_KEY(A) #endif boost_ptr> cat testera.C #include "testera.h" BOOST_CLASS_EXPORT_IMPLEMENT(A) template void A::serialize<boost::archive::polymorphic_oarchive>( boost::archive::polymorphic_oarchive &ar, const unsigned int ver ); template void A::serialize<boost::archive::polymorphic_iarchive>( boost::archive::polymorphic_iarchive &ar, const unsigned int ver ); A::A() : myStr( "a" ) { } void A::setStr( const std::string &s ) { myStr = s; } std::string A::getStr() { return myStr; } template<class Arch> void A::serialize( Arch &ar, const unsigned int ver ) { ar & myStr; } boost_ptr> cat testerb.h #ifndef testerb_h #define testerb_h #include "testera.h" class B : public A { private: friend class boost::serialization::access; template< class Arch > void serialize( Arch &ar, const unsigned int ver ); public: B(); virtual ~B() {} void set( const int i ); int get(); protected: int myI; }; BOOST_CLASS_EXPORT_KEY(B) #endif boost_ptr> cat testerb.C #include "testerb.h" BOOST_CLASS_EXPORT_IMPLEMENT(B) template void B::serialize<boost::archive::polymorphic_oarchive>( boost::archive::polymorphic_oarchive &ar, const unsigned int ver ); template void B::serialize<boost::archive::polymorphic_iarchive>( boost::archive::polymorphic_iarchive &ar, const unsigned int ver ); B::B(): myI( 1 ) { myStr = "b"; } void B::set( const int i ) { myI = i; } int B::get() { return myI; } template< class Arch > void B::serialize( Arch &ar, const unsigned int ver ) { // boost::serialization::void_cast_register< B, A >( static_cast< B *>( NULL ), static_cast< A * >( NULL ) ); ar & boost::serialization::base_object<A>( *this ); ar & myI; } int main( int argc, char *argv[] ) { int ret = 0; B obj; B obj2; obj.set( 2 ); A *ptr = NULL; B *bptr = NULL; bptr = &obj; ptr = &obj; if( argc > 1 ) { std::string fl = argv[ 1 ]; { std::ofstream ofl( fl.c_str() ); boost::archive::polymorphic_text_oarchive toar( ofl ); boost::archive::polymorphic_oarchive *oar = &toar; /* oar->register_type(static_cast<A *>(NULL)); oar->register_type(static_cast<B *>(NULL)); */ try { *oar & obj; // *oar & ptr; } catch( std::exception &e ) { std::cerr << "Error: archive from B to file " << fl << " - " << e.what() << std::endl; ret = 1; } } if( ! ret ) { ptr = NULL; bptr = NULL; { std::ifstream ifl( fl.c_str() ); boost::archive::polymorphic_text_iarchive tiar( ifl ); boost::archive::polymorphic_iarchive *iar = &tiar; /* iar->register_type(static_cast<A *>(NULL)); iar->register_type(static_cast<B *>(NULL)); */ try { *iar & ptr; // *iar & bptr; } catch( std::exception &e ) { std::cerr << "Error: archive from file " << fl << " to B * - " << e.what() << std::endl; ret = 1; } } if( ! ret ) { // std::cout << bptr->get() << std::endl; std::cout << static_cast<B*>( ptr )->get() << std::endl; } } } return ret; } testera and testerb are compiled into a shared library with this: boost_ptr> cat Makefile_lib CXXFLAGS = -c -ggdb3 -fPIC -funswitch-loops -fgcse-after-reload -std=c++11 LDFLAGS = -std=c++11 -lboost_serialization -lboost_thread -lboost_system -lboost_filesystem OBJLOC = obj OBJS = $(OBJLOC)/testera.o \ $(OBJLOC)/testerb.o LIBRARY_NAME = libtester.so libs:$(LIBRARY_NAME) $(LIBRARY_NAME): $(OBJS) ${CXX} -shared -o $@ $(OBJS) $(OBJLOC)/%.o: ./%.C $(CXX) $(CXXFLAGS) ./$*.C -o $(OBJLOC)/$*.o tester_mn is compiled into the executable with this: boost_ptr> cat Makefile_mn CXXFLAGS = -ggdb3 -funswitch-loops -fgcse-after-reload -std=c++11 LDFLAGS = -lboost_serialization -lboost_thread -lboost_system -lboost_filesystem -L. -ltester tester_mn: tester_mn.o ${CXX} $(CXXFLAGS) $(LDFLAGS) tester_mn.C -o $@ If I were to comment out the BOOST macros and uncomment the register_type() functions from tester_mn.C everything works. Is there a way to get the macros to work? -- Ray Kosby Software Engineer Columbus Technologies and Services, Inc www.columbususa.com<http://www.columbususa.com> Office - (301) 286-5095, fax - (301) 286-7475 NASA Goddard Space Flight Center, MS 452.1 Bldg 13 Rm 141 8800 Greenbelt Rd Greenbelt, MD 20771 USA

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Re: [Boost-users] [Boost.Beast] Libraries augmenting Boost.Beast
by Damian Jarek 24 Sep '18

24 Sep '18

Hi Sean, I've been recently working on a library that is supposed to abstract some of the platform-specific aspects of TLS peer verification (e.g. accessing the OS cert store) and obtaining the system proxy information. The project is in its early stages but is actively being worked on (https://github.com/djarek/ netutils). Another library you might be interested in, though still fairly experimental is Foxy (https://github.com/LeonineKing1199/f3) which abstracts away HTTP session management. Best Regards, Damian Jarek

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Formal Review of Proposed Boost.Histogram Library is HALFWAY through
by Mateusz Loskot 22 Sep '18

22 Sep '18

Dear Boost Community, We've reach half-way through the formal review of Hans Dembinski's Histogram library. The review lasts until the end of September 26th. If you are interested in applications for mathematics, statistics graphics, image analysis, and such, or in the Histogram library itself, please consider reviewing the Histogram library by the end of September 26th. Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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[filesystem] Library maintainers needed
by Beman Dawes 22 Sep '18

22 Sep '18

I'm retiring, so Boost.Filesystem needs one or more maintainers. This is a high complexity library, further complicated by (1) requiring both Windows and non-Windows implementation code and (2) needing a major upgrade for compatibility with the new standard library version shipped in C++17. Furthermore, there are constant Pull Requests and Issues that arise, and these almost invariably take a lot of time for the maintainer to process. My personal opinion is that Boost should deprecate the Boost library in favor of the standard library implementations, and do only minimal maintenance for several years until most users have migrated to C++17 or later. But that's up to the new maintainers to decide. Thanks, --Beman

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[endian] Library maintainer needed
by Beman Dawes 22 Sep '18

22 Sep '18

I'm retiring, so Boost.Endian needs a maintainer. This is a low/medium complexity library that requires only minor effort to maintain. --Beman

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[timer] Library maintainer needed
by Beman Dawes 22 Sep '18

22 Sep '18

I'm retiring, so Boost.Timer needs a maintainer. This is a simple low complexity library, and requires little effort to effort to maintain. --Beman

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undefined reference to `boost::system::detail::generic_category_ncx()'
by Antonis Polykratis 20 Sep '18

20 Sep '18

Hello all, I am new to boost. I try to use some boost files in my program, but I have trouble with some of them. For example compiling the following program #include <boost/log/expressions/formatters/date_time.hpp> int main() { return 0; } with the command g++ -std=c++11 test.cpp -o main -I/home/user101/boost/ -L/home/user101/boost I have a message like the following /tmp/ccm6UOud.o: In function `boost::system::generic_category()': test.cpp:(.text._ZN5boost6system16generic_categoryEv[_ZN5boost6system16generic_c ategoryEv]+0x5): undefined reference to `boost::system::detail::generic_category _ncx()' I also tried to append -lboost_system in the command, but I take back the following message: /usr/bin/ld: cannot find -lboost_system collect2: error: ld returned 1 exit status Could you please guide me with that? I use boost_1_67 if that makes any difference (which I do not think so). Thanks, Antonis

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