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eval_if fails - problem for C++ guru
by Robert Ramey 07 Jun '15

07 Jun '15

I've been having a very difficult time with a problem illustrated by the following program: It looks like the eval_if in line 51 isn't working correctly. That is, the metafuction get_promotion_policy is being invoked when both types are not safe types. I've been working on this for two days and can't see what's going on. Any help from a TMP genious would be much appreciated. #include <type_traits> #include <boost/mpl/and.hpp> #include <boost/mpl/or.hpp> #include <boost/mpl/if.hpp> #include <boost/mpl/eval_if.hpp> #include <boost/mpl/identity.hpp> struct safe_tag {}; template<class T, class P = void> struct safe : public safe_tag { T m_t; typedef P PromotionPolicy; }; template<class T> struct is_safe : public //std::is_arithmetic<T> std::is_base_of<safe_tag, T> {}; template<class T, class U> struct common_policies { static_assert( boost::mpl::or_< is_safe<T>, is_safe<U> >::value, "at least one type must be a safe type" ); template<typename Z> struct get_promotion_policy { static_assert( is_safe<Z>::value, "only safe types have promotion policies" ); typedef typename Z::PromotionPolicy type; }; // if both types are safe, the policies have to be the same! static_assert( boost::mpl::eval_if< boost::mpl::and_< is_safe<T>, is_safe<U> >, typename std::is_same< typename get_promotion_policy<T>::type, typename get_promotion_policy<U>::type >::type, boost::mpl::identity<boost::mpl::true_> >::type::value, "if both types are safe, the policies have to be the same!" ); // now we've verified that there is no conflict between policies // return the one from the first safe type typedef typename boost::mpl::if_< is_safe<T>, T, typename boost::mpl::if_< is_safe<U>, U, // boost::mpl::void_ >::type >::type safe_type; typedef typename get_promotion_policy<safe_type>::type promotion_policy; }; common_policies<int, safe<int> > t; int main(){ return 0; }

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boost::tuple in std::map
by Uthpal Urubail 06 Jun '15

06 Jun '15

Experts, I am using boost::tuple as key in std::map. I would like to write my own comparison method (considering tolerance in comparison) The default comparison defined in tuple_comparison.hpp is of no use to me. Any help in this is highly appreciated. Regards, UJ

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[Log] Failed to compile applications with Boost.Log
by lin li 05 Jun '15

05 Jun '15

Hi, guys. I am trying to to compile the tutorial code from Boost.Log with the trivial logger. But it fails with the error: "‘boost::log::v2s_mt_posix::trivial::boost’ has not been declared" OS: OracleLinux 6.6 G++: 4.4.7 Boost: 1.57 I have googled a lot about it, but it seems that all answers are related to some linking error, but this one is different. It seems that it does not even find the declaration in the first place. Anyone has similar experience?

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Re: [Boost-users] Serialization] Non-default constructor and static data members
by Mccall, Kurt E. (JSC-EG411) 04 Jun '15

04 Jun '15

Robert, thanks for the reply -- I won't attempt to serialize the static const members. Also, it looks like if the members is static but not const and defined outside of the class, the linker finds it just fine, when it is referenced in save_construct_data(). Kurt > >I'm not so sure about that. There no need to serialize the static const >values since they are fixed and initialized before the first instance is >constructed. > >It has always been that static variables had to be explicitly >initialized outside the class. As in > >const int A::var1 = 1; // no longer necessary >const int A::var2 = 2; > >But I guess C++11 changed that. > >Robert Ramey >_______________________________________________ >Boost-users mailing list >Boost-users(a)lists.boost.org >http://lists.boost.org/mailman/listinfo.cgi/boost-users

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[Serialization] Non-default constructor and static data members
by Mccall, Kurt E. (JSC-EG411) 04 Jun '15

04 Jun '15

I'm trying to serialize a class with a non-default constructor and static const data members, so I have to override boost::serialization::save_construct_data() and load_construct_data(). I am getting a linking error:the static members referred to in save_construct_data() cannot be found ("undefined reference"). #include <boost/archive/tmpdir.hpp> #include <boost/archive/xml_iarchive.hpp> #include <boost/archive/xml_oarchive.hpp> // forward declarations class A; namespace boost { namespace serialization { template<class Archive> inline void save_construct_data(Archive &ar, const A *t, const unsigned int file_version); } } class A { friend class boost::serialization::access; // friend function (omitting load_construct_data() for brevity) template<class Archive> friend void save_construct_data(Archive &ar, const A *t, const unsigned int file_version); public: static const int var1 = 1; static const int var2 = 2; template<class Archive> void serialize(Archive & ar, const unsigned int file_version) { // do nothing }; } // overridden Boost function namespace boost { namespace serialization { template<class Archive> inline void save_construct_data( Archive &ar, const A *t, const unsigned int file_version) { // link errors happen at both of these two lines ("undefined reference" of var1, var2). ar << boost::serialization::make_nvp("var1", ::A::var1); ar << boost::serialization::make_nvp("var2", t->var2); }; }} // namespace… This puzzles me since I thought that static members have external linkage. This question seems to be more about namespaces than it is about Boost::Serialization, but I post here because some Serialization user must have run into it. Thanks, Kurt

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boost multi_index_container with composite_key iterator
by Uthpal Urubail 04 Jun '15

04 Jun '15

Experts, Is there a better approach to iterator over boost multiindex composite key? The issue with the below approach is, the same key is appearing multiple times. typedef multi_index_container loadTable_Def; loadTable_Def pb; //! for(loadTable_Def::iterator i=pb.begin(),i_end=pb.end();i!=i_end; ) { // Get the range of the current key loadTable_Def::iterator iter_next=pb.upper_bound(pb.key_extractor()(*i)); do { loadTable_Def::iterator it1,it2; boost::tie(it1,it2) = pb.equal_range(boost::make_tuple(<passing multiple key >)); while(it1 != it2) { //std::cout<<"print values"<<" ,"; ++it1; } } while(++i!=iter_next); } Regards, UJ

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threads and async questions and asnwers
by Victor Yankee 03 Jun '15

03 Jun '15

Hello List, I have a thread with a class and its method that raises a "question" signal and needs to wait with a timeout for an "answer" signal. There are several worker threads, some of which may be connected to the question signal. The answer signal will be raised by a worker thread only if it knows the answer; it is possible that no worker thread knows the answer so no answer signal will be raised (hence need for timeout). The question thread cannot know which worker thread to ask. What is a good way to achieve this using boost 1.58 and/or C++11? I am using g++ 4.9 on 64bit ubuntu 14.04. Thanks, Vic

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[Test]
by Merrill Cornish 02 Jun '15

02 Jun '15

I'm get a SIGEGV segmentation fault /only/ when trying to register a test manually. Everything works just fine if I use auto registration. All compiles and links in both cases are without error. I know almost nothing about using gdb, but I was able to see the segment violation message shown below. I'm running Boost 1.58.0; Windows 7.1 64-bit; MinGW 4.9.2 64-bit; Eclipse Luna; CDT 8.6.0 In my TestMain.cpp #define BOOST_TEST_ALTERNATIVE_INIT_API #define BOOST_TEST_NO_MAIN #include "boost/test/unit_test.hpp" extern void Operand_Default_Constructor_Test(); bool init_unit_test() { framework::master_test_suite().p_name.value = "DiGSE Master Test"; framework::master_test_suite().add(BOOST_TEST_CASE(&Operand_Default_Constructor_Test)); return true; } int main(int argc, char* argv[]) { return boost::unit_test::unit_test_main(&init_unit_test, argc, argv); } It compiles and links without error. However, executing it gives this SIGEGV fault: Program received signal SIGSEGV, Segmentation fault. 0x000000006b405a12 in boost::unit_test::framework::get (id=1, t=boost::unit_test::tut_suite) at ./boost/test/impl/framework.ipp:388 388 if( (res->p_type & t) == 0 ) The failing snippet is part of a test that would throw internal_error(), but the if test itself seems to fail. if( (res->p_type & t) == 0 ) throw internal_error( "Invalid test unit type" ); If the Operand_Default_Constructor_Test test is changed from void Operand_Default_Constructor_Test() to BOOST_AUTO_TEST_CASE(Operand_Default_Constructor_Test) and the contents of init_unit_test() are removed, it works just fine with automatic registration. And the automatic registration is certainly the easiest way; but I was holding out hope for being able to specify test ordering. Merrill Cornish

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boost::posix_time::time_period and boost::serialization
by Lakin Wecker 01 Jun '15

01 Jun '15

I'm having some issues getting the following example to compile in g++4.9, or clang 3.6, using boost 1.58.0 I'm not quite experienced enough with boost or c++ to be certain, but it appears that the vector serialization is done in such a way that it doesn't pick up the load_construct_data for time_period from boost/date_time/posix_time/time_serialize.hpp Is the fix simply to do my own vector serialization a situation like this? Or is there another fix? Thank in advance, Lakin $ cat test.cpp #include <boost/date_time/posix_time/time_serialize.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/date_time/posix_time/posix_time_types.hpp> #include <boost/serialization/vector.hpp> #include <vector> #include <sstream> class test { public: friend class boost::serialization::access; std::vector<boost::posix_time::time_period> m_vec; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & m_vec; } }; int main(int argc, char *argv[]) { test a; std::ostringstream os; boost::archive::text_oarchive oa(os); oa << a; std::istringstream is(os.str()); boost::archive::text_iarchive ia(is); ia >> a; std::cout << os.str() << std::endl; return 0; } $ g++ -std=c++14 test.cpp -I deps/boost_1_58_0 In file included from /usr/include/c++/4.9/memory:64:0, from deps/boost_1_58_0/boost/config/no_tr1/memory.hpp:21, from deps/boost_1_58_0/boost/smart_ptr/shared_ptr.hpp:23, from deps/boost_1_58_0/boost/shared_ptr.hpp:17, from deps/boost_1_58_0/boost/date_time/gregorian/greg_month.hpp:14, from deps/boost_1_58_0/boost/date_time/gregorian/greg_ymd.hpp:16, from deps/boost_1_58_0/boost/date_time/gregorian/greg_calendar.hpp:16, from deps/boost_1_58_0/boost/date_time/gregorian/gregorian_types.hpp:19, from deps/boost_1_58_0/boost/date_time/posix_time/posix_time_config.hpp:18, from deps/boost_1_58_0/boost/date_time/posix_time/posix_time_system.hpp:13, from deps/boost_1_58_0/boost/date_time/posix_time/ptime.hpp:12, from deps/boost_1_58_0/boost/date_time/posix_time/posix_time.hpp:15, from deps/boost_1_58_0/boost/date_time/posix_time/time_serialize.hpp:12, from test.cpp:1: /usr/include/c++/4.9/bits/stl_construct.h: In instantiation of ‘void std::_Construct(_T1*, _Args&& ...) [with _T1 = boost::date_time::period<boost::posix_time::ptime, boost::posix_time::time_duration>; _Args = {}]’: /usr/include/c++/4.9/bits/stl_uninitialized.h:516:43: required from ‘static void std::__uninitialized_default_n_1<_TrivialValueType>::__uninit_default_n(_ForwardIterator, _Size) [with _ForwardIterator = boost::date_time::period<boost::posix_time::ptime, boost::posix_time::time_duration>*; _Size = long unsigned int; bool _TrivialValueType = false]’ /usr/include/c++/4.9/bits/stl_uninitialized.h:571:33: required from ‘void std::__uninitialized_default_n(_ForwardIterator, _Size) [with _ForwardIterator = boost::date_time::period<boost::posix_time::ptime, boost::posix_time::time_duration>*; _Size = long unsigned int]’ /usr/include/c++/4.9/bits/stl_uninitialized.h:632:50: required from ‘void std::__uninitialized_default_n_a(_ForwardIterator, _Size, std::allocator<_Tp>&) [with _ForwardIterator = boost::date_time::period<boost::posix_time::ptime, boost::posix_time::time_duration>*; _Size = long unsigned int; _Tp = boost::date_time::period<boost::posix_time::ptime, boost::posix_time::time_duration>]’ /usr/include/c++/4.9/bits/vector.tcc:549:39: required from ‘void std::vector<_Tp, _Alloc>::_M_default_append(std::vector<_Tp, _Alloc>::size_type) [with _Tp = boost::date_time::period<boost::posix_time::ptime, boost::posix_time::time_duration>; _Alloc = std::allocator<boost::date_time::period<boost::posix_time::ptime, boost::posix_time::time_duration> >; std::vector<_Tp, _Alloc>::size_type = long unsigned int]’ /usr/include/c++/4.9/bits/stl_vector.h:676:41: required from ‘void std::vector<_Tp, _Alloc>::resize(std::vector<_Tp, _Alloc>::size_type) [with _Tp = boost::date_time::period<boost::posix_time::ptime, boost::posix_time::time_duration>; _Alloc = std::allocator<boost::date_time::period<boost::posix_time::ptime, boost::posix_time::time_duration> >; std::vector<_Tp, _Alloc>::size_type = long unsigned int]’ deps/boost_1_58_0/boost/serialization/vector.hpp:90:9: [ skipping 24 instantiation contexts, use -ftemplate-backtrace-limit=0 to disable ] deps/boost_1_58_0/boost/archive/detail/iserializer.hpp:618:24: required from ‘void boost::archive::load(Archive&, T&) [with Archive = boost::archive::text_iarchive; T = test]’ deps/boost_1_58_0/boost/archive/detail/common_iarchive.hpp:66:40: required from ‘void boost::archive::detail::common_iarchive<Archive>::load_override(T&, int) [with T = test; Archive = boost::archive::text_iarchive]’ deps/boost_1_58_0/boost/archive/basic_text_iarchive.hpp:71:9: required from ‘void boost::archive::basic_text_iarchive<Archive>::load_override(T&, int) [with T = test; Archive = boost::archive::text_iarchive]’ deps/boost_1_58_0/boost/archive/text_iarchive.hpp:92:57: required from ‘void boost::archive::text_iarchive_impl<Archive>::load_override(T&, int) [with T = test; Archive = boost::archive::text_iarchive]’ deps/boost_1_58_0/boost/archive/detail/interface_iarchive.hpp:60:9: required from ‘Archive& boost::archive::detail::interface_iarchive<Archive>::operator>>(T&) [with T = test; Archive = boost::archive::text_iarchive]’ test.cpp:36:11: required from here /usr/include/c++/4.9/bits/stl_construct.h:75:7: error: no matching function for call to ‘boost::date_time::period<boost::posix_time::ptime, boost::posix_time::time_duration>::period()’ { ::new(static_cast<void*>(__p)) _T1(std::forward<_Args>(__args)...); } ^ /usr/include/c++/4.9/bits/stl_construct.h:75:7: note: candidates are: In file included from deps/boost_1_58_0/boost/date_time/gregorian/gregorian_types.hpp:18:0, from deps/boost_1_58_0/boost/date_time/posix_time/posix_time_config.hpp:18, from deps/boost_1_58_0/boost/date_time/posix_time/posix_time_system.hpp:13, from deps/boost_1_58_0/boost/date_time/posix_time/ptime.hpp:12, from deps/boost_1_58_0/boost/date_time/posix_time/posix_time.hpp:15, from deps/boost_1_58_0/boost/date_time/posix_time/time_serialize.hpp:12, from test.cpp:1: deps/boost_1_58_0/boost/date_time/period.hpp:101:3: note: boost::date_time::period<point_rep, duration_rep>::period(point_rep, duration_rep) [with point_rep = boost::posix_time::ptime; duration_rep = boost::posix_time::time_duration] period<point_rep,duration_rep>::period(point_rep first_point, duration_rep len) : ^ deps/boost_1_58_0/boost/date_time/period.hpp:101:3: note: candidate expects 2 arguments, 0 provided deps/boost_1_58_0/boost/date_time/period.hpp:90:3: note: boost::date_time::period<point_rep, duration_rep>::period(point_rep, point_rep) [with point_rep = boost::posix_time::ptime; duration_rep = boost::posix_time::time_duration] period<point_rep,duration_rep>::period(point_rep first_point, ^ deps/boost_1_58_0/boost/date_time/period.hpp:90:3: note: candidate expects 2 arguments, 0 provided deps/boost_1_58_0/boost/date_time/period.hpp:51:9: note: constexpr boost::date_time::period<boost::posix_time::ptime, boost::posix_time::time_duration>::period(const boost::date_time::period<boost::posix_time::ptime, boost::posix_time::time_duration>&) class period : private ^ deps/boost_1_58_0/boost/date_time/period.hpp:51:9: note: candidate expects 1 argument, 0 provided deps/boost_1_58_0/boost/date_time/period.hpp:51:9: note: constexpr boost::date_time::period<boost::posix_time::ptime, boost::posix_time::time_duration>::period(boost::date_time::period<boost::posix_time::ptime, boost::posix_time::time_duration>&&) deps/boost_1_58_0/boost/date_time/period.hpp:51:9: note: candidate expects 1 argument, 0 provided

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Re: [Boost-users] [MSM] Boost.MSM: statemachine to transition on templatized event-type
by Christophe Henry 01 Jun '15

01 Jun '15

Hi, > having tested Boost.MSM, I'm pretty happy with it. :) >It's interesting, in that it seems to handle all states in a static table. >No "new" operator etc. It's much faster without dynamic allocation. <snip> g_row<StateInitial, EventT, StateEven, &Machine_<EventT>::guardToEven>, >Unfortunately >gcc gives this error: >d.cpp:119:5: error: ‘g_row’ was not declared in this scope > g_row<StateInitial, EventT, StateEven, &Machine_<EventT>::guardToEven>, Short answer. Try: typename Machine_<EventT>::template g_row<StateFloat, EventT, StateFloat, &Machine_<EventT>::guardToFloat> Long answer: g_row is a type of state_machine_def and as your fsm is a template, it becomes a dependent type (=> typename) and a template one even (=> template). C++ is sometimes really annoying :( Longer answer. Give up this front-end, it's deprecated anyway. A better solution will be: #include <boost/msm/front/functor_row.hpp> using namespace boost::msm::front; struct GuardToOdd { template <class EVT,class FSM,class SourceState,class TargetState> bool operator()(EVT const& num,FSM& ,SourceState& ,TargetState& ) { const long long x = static_cast<long long>(num.getNum()); return ((x == num.getNum()) // is Integral type && ((x % 2) != 0)); } }; Row< StateFloat, EventT, StateOdd, none, GuardToOdd> HTH, Christophe

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