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[Thread] why isn't it possible to acquire 2 different upgrade_lock from 2 different threads?
by Elad Moshe 30 Mar '14

30 Mar '14

Hi, this is my first post here so please bare with me :) . I recently used upgrade_lock to try access a shared resource from 2 different threads. I noticed that once the first thread acquired its upgrade_lock the second thread was blacked until the first thread unlock it. can someone please explain me the logic behind this behavior? isn't an upgrade lock just a shared_lock that can be upgraded to unique_lock? why not let both threads acquire it just like shared_lock until, and if, they decide to upgrade it to unique_lock? Thanks a lot, Elad.

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cross compiling boost python (64->32bits)
by Stéphane ANCELOT 30 Mar '14

30 Mar '14

Hi, I need to compile boost python from my linux system. the host system is a 64bits , and the target a 32 bit one. when I try using it on the target system, I have this message, ImportError: ./libboost_python.so.1.55.0: undefined symbol: Py_InitModule4_64 So, I suppose it is not compiled for 32bits system . I have tried many things, what is the right way to compile a 32 bits boost python lib, from a linux 64 bits system ? Regards, Steph

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cygwin 64 boost install
by jfrm.maurel＠gmail.com 29 Mar '14

29 Mar '14

Hi, Trying to install boost 1_54 (I had the same problem with 1.55) on my laptop Windows 7 (64bits RAM 6 Go), I have following failure (details in attached file): common.mkdir bin.v2/libs/context/build common.mkdir bin.v2/libs/context/build/gcc-4.8.2 common.mkdir bin.v2/libs/context/build/gcc-4.8.2/release common.mkdir bin.v2/libs/context/build/gcc-4.8.2/release/address-model-64 common.mkdir bin.v2/libs/context/build/gcc-4.8.2/release/address-model-64/link-static common.mkdir bin.v2/libs/context/build/gcc-4.8.2/release/address-model-64/link-static/asm gcc.compile.asm bin.v2/libs/context/build/gcc-4.8.2/release/address-model-64/link-static/asm/make_x86_64_sysv_elf_gas.o libs/context/src/asm/make_x86_64_sysv_elf_gas.S: Messages de l'assembleur: libs/context/src/asm/make_x86_64_sysv_elf_gas.S:43: Avertissement: .type pseudo opérateur utilisé à l'extérieur de .def/.endef ignoré. libs/context/src/asm/make_x86_64_sysv_elf_gas.S:43: Erreur: rebut à la fin de la ligne, premier caractère non reconnu est « m » libs/context/src/asm/make_x86_64_sysv_elf_gas.S:73: Avertissement: .size pseudo opérateur utilisé à l'extérieur de .def/.endef ignoré. libs/context/src/asm/make_x86_64_sysv_elf_gas.S:73: Erreur: rebut à la fin de la ligne, premier caractère non reconnu est « m » "g++" -x assembler-with-cpp -O3 -finline-functions -Wno-inline -Wall -m64 -DBOOST_ALL_NO_LIB=1 -DNDEBUG -I"." -c -o "bin.v2/libs/context/build/gcc-4.8.2/release/address-model-64/link-static/asm/make_x86_64_sysv_elf_gas.o" "libs/context/src/asm/make_x86_64_sysv_elf_gas.S" ...failed gcc.compile.asm bin.v2/libs/context/build/gcc-4.8.2/release/address-model-64/link-static/asm/make_x86_64_sysv_elf_gas.o... gcc.compile.asm bin.v2/libs/context/build/gcc-4.8.2/release/address-model-64/link-static/asm/jump_x86_64_sysv_elf_gas.o The process I followed after fresh cygwin 64 install: tar --bzip2 -xf boost_1_54_0.tar.bz2 cd boost_1_54_0/ ./bootstrap.sh #./b2 -j8 --prefix=$PWD --libdir=$PWD/lib64 --layout=tagged link=static threading=multi,single install || echo FAILURE ./b2 --prefix=$PWD --libdir=$PWD/lib64 --layout=tagged link=static threading=single address-model=64 install >build.log Could you please tell me what I am doing wrong ? I have read https://groups.google.com/forum/#!msg/boost-devel-archive/vqK2MXdmUZ0/cvhmd… but don't know if this is related. Regards -- Jean-François MAUREL PIMECA http://www.pimeca.com

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[BOOST Users] serialize a pointer
by Andy Sardina 29 Mar '14

29 Mar '14

Hello, I would like to just serialize a pointer value. I have understood that boost save the pointer value, and serialize the object it points. How can I do?

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[serialization] serialization of an ifstream/ofstream class member
by Pablo Madoery 28 Mar '14

28 Mar '14

Hi. Do You know if there is a way to serialize an ifstream/ofstream class member. I have this class for example class Object { public: Object(); Object(string name); virtual ~Object(); string getName() const; private: string name_; ifstream file_; friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & name_; ar & file_; } }; when I try to serialize it throw compilation error : error: 'struct std::basic_ifstream<char>' has no member named 'serialize'. Is there a specific header i must include ?

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[serialization] of nested stl containers
by Pablo Madoery 27 Mar '14

27 Mar '14

I have the following code: #include <list> #include <utility> #include <vector> #include <string> #include <fstream> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/access.hpp> #include <boost/serialization/string.hpp> #include <boost/serialization/vector.hpp> #include <boost/serialization/utility.hpp> #include <boost/serialization/map.hpp> #include <boost/serialization/base_object.hpp> using namespace std; int main() { list< pair<string, string> > stlStr; pair<string, string> par1("aaa", "bbb"); stlStr.push_back(make_pair("key", par1)); std::ofstream ofs("filename"); { boost::archive::text_oarchive serial(ofs); serial << stlStr; } std::ifstream ifs("filename"); boost::archive::text_iarchive serial2(ifs); list<pair<string, string> > lst; serial2 >> lst; return 0; } that throw the following compilation error: error: 'class std::list<std::pair<std::basic_string<char>, std::basic_string<char> > >' has no member named 'serialize'. I'd like to know if I have to manually implement the serialization of this nested list. Because for example I haven't problems with maps that have inside a pair : map<string, pair<string, string> >. Thanks !

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boost::future and when_all => compile error "call to deleted constructor"
by Tobias Oberstein 26 Mar '14

26 Mar '14

Hello, I am trying to use boost::future with continuations, in particular when_all/when_any. I am using Boost trunk from GitHub (since only that has when_all etc). This is what I want to compile: === #include <iostream> #define BOOST_THREAD_PROVIDES_FUTURE #define BOOST_THREAD_PROVIDES_FUTURE_CONTINUATION #define BOOST_THREAD_PROVIDES_FUTURE_WHEN_ALL_WHEN_ANY #include <boost/thread/future.hpp> using namespace boost; int main() { future<int> f1 = async([]() { return 1; }); future<int> f2 = async([]() { return 2; }); auto f3 = when_all(f1, f2); f3.then([](decltype(f3)) { std::cout << "done" << std::endl; }); f3.get(); } === https://gist.github.com/oberstet/9783359 This bails out with /usr/include/c++/v1/memory:1685:31: error: call to deleted constructor of 'boost::future<int>' https://gist.github.com/oberstet/9783364 Am I doing it wrong? Thanks! /Tobias

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[msm] handle errors and no_transition
by Sam Fisher 25 Mar '14

25 Mar '14

Hi, I have root fsm which has a sub-fsm. In the sub-fsm there are some useful actions that can throw exceptions. For that case any fsm has its own exception handler that translates exception into a generic error event: template <typename Event, typename OtherFSM> void exception_caught(Event&, OtherFSM& fsm, std::exception& e) { fsm.process_event(error()); } I faced a strange problem: if an exception occurs, the sub successfully goes to Error state, the root has no_transition I use boost 1.55 and VS2013 there are transition tables: Sub: Error & Finish - exit points A_Exception action generates exception typedef ::boost::mpl::vector<Empty, AllOk> initial_state; struct /*sub*/ transition_table : public ::boost::mpl::vector < // Start Event Next Action Guard // +----------------+---------------+------------------+----------------------+--------------------------+ Row < Empty , none , Waiting , none , none >, Row < Waiting , process , Process , A_Exception , none >, Row < Process , none , Finish , none , none >, // +----------------+---------------+------------------+----------------------+--------------------------+ Row < AllOk , error , Error , none , none > // +----------------+---------------+------------------+----------------------+--------------------------+ > {}; Root: struct S { typedef SubFsm::exit_pt<SubFsm_::Error> Error; typedef SubFsm::exit_pt<SubFsm_::Finish> Finish; }; struct /*root*/ transition_table : public ::boost::mpl::vector < // Start Event Next Action Guard // +----------------+---------------+------------------+----------------------+--------------------------+ Row < Empty , init , Initial , none , none >, Row < Initial , sub , SubFsm , none , none >, // +----------------+---------------+------------------+----------------------+--------------------------+ Row < S::Error , error , Error , none , none >, Row < S::Finish , none , Initial , none , none > // +----------------+---------------+------------------+----------------------+--------------------------+ > {}; the control flow: Root root; root.start(); root.process_event(init()); root.process_event(sub()); root.process_event(process()); output log: =============> start Root_::InitEvent: Enter to Root_ state. Root_::InitEvent: Enter to Root_::Empty state. =============> init Exit from Root_::Empty state. init: Enter to Root_::Initial state. =============> sub Exit from Root_::Initial state. sub: Enter to Root_::SubFsm_ state. sub: Enter to SubFsm_::Empty state. sub: Enter to SubFsm_::AllOk state. Exit from SubFsm_::Empty state. front::none: Enter to SubFsm_::Waiting state. =============> process Exit from SubFsm_::Waiting state. SubFsm_::A_Exception() State machine produces an exception on event process Current state: SubFsm_::Waiting Message: A_Process exception Exit from SubFsm_::AllOk state. error: Enter to SubFsm_::Error state. No transition from state Root_::SubFsm_ on event process Exit from SubFsm_::Waiting state. Exit from SubFsm_::Error state. Exit from Root_::SubFsm_ state. error: Enter to Root_::Error state. A I understood, after exception comes, the "process" event now in kind of "unhandled" state. So it rises up to the root fsm that doesn't have any suitable transition How to make the root or sub to "forget" about unhandled event?

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'Hashable' concept for type erasure
by Samuel Christie 25 Mar '14

25 Mar '14

Hello, I've been trying to add a 'hashable' concept to one of my type erasure requirements, but I haven't been getting anywhere and I still don't understand the voluminous error messages enough to make any progress. Here's approximately what I tried so far: namespace mpl = boost::mpl; namespace te = boost::type_erasure; template<class T> struct hashable { static size_t apply(const T& obj) { return std::hash<T>()(obj); } }; namespace std { template<> class hash<t>{ public : size_t operator()(const test &t ) const { return te::call(hashable<test>(), t); } }; }; typedef mpl::vector< ... hashable<te::_self>, ... > requirements typedef any<requirements> test; namespace std { template<> class hash<test>{ public : size_t operator()(const test&h ) const { return te::call(hashable<test>(), h); } }; }; I also tried something else, similar to the following: template<class C> struct hashable { static std::size_t apply(const C& c) { return c.hash(); } }; namespace boost { namespace type_erasure { template<class C, class Base> struct concept_interface<hashable<C>, Base, C> : Base { std::size_t hash() const { return call(hashable<C>(), *this); } }; } } // ... similar requirements / typedef as above namespace std { template<> class hash<test>{ public : size_t operator()(const test &t ) const { return t.hash(); } }; }; The first one is probably just wrong, and for the second one I'm getting some failed assertions when I try to use it with an implementation of hash that is: size_t hash() const { //coord is a member std::vector<int> return boost::hash_range(coord.begin(), coord.end()); } Any help would be most useful. -sc

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[ANN] CppCon 2014 Call for Submissions
by Boris Kolpackov 25 Mar '14

25 Mar '14

Hi, CppCon is the annual, week-long face-to-face gathering for the entire C++ community. The conference is organized by the C++ community for the community and so we invite you to present. Have you learned something interesting about C++, maybe a new technique possible in C++11? Or perhaps you have implemented something cool related to C++, maybe a new C++ library? If so, consider sharing it with other C++ enthusiasts by giving a talk at CppCon 2014. Submissions deadline is May 15 with decisions sent by June 13. For topic ideas, possible formats, and submission instructions, see the Submissions page: http://cppcon.org/submissions/ Hope to hear you speak! Boris

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