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[multiprecision] noexcept() usage in gmp int
by Francesco Biscani 16 Jun '13

16 Jun '13

Hello, I was trying out the new multiprecision library (kudos!), and I ran into a problem. In order to make certain guarantees in my code regarding exception safety, I am mandating that types being used in generic containers are marked noexcept() for certain basic operations (namely, destruction and move operations). It seems like this is generally guaranteed in the multiprecision library (tried with cpp_int and the mpfr adaptor), with the important exception of the gmp integer class. A glance at the headers reveals that (gmp.hpp): // // Within this file, the only functions we mark as noexcept are those that manipulate // (but don't create) an mpf_t. All other types may allocate at pretty much any time // via a user-supplied allocator, and therefore throw. // Additionally, browsing the gmp documentation yields this snippet ( http://gmplib.org/manual/Custom-Allocation.html) """ There's currently no defined way for the allocation functions to recover from an error such as out of memory, they must terminate program execution. A longjmp or throwing a C++ exception will have undefined results. This may change in the future. """ Would it be possible then for the mp library authors to consider adding basic noexcept() guarantees to the gmp adaptor class in future versions? Cheers and thanks for the great library, Francesco.

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Building a large graph using Parallel Boost Graph Library
by William Shipman 15 Jun '13

15 Jun '13

Hi all, I'm working with a graph that has about 16 million vertices and 320 million edges. Currently, I'm using graph-tool in Python but building the graph is far too slow. Before I start porting to C++ I starting reading up on the Parallel Boost Graph Library. From the examples in the documentation, it seems that one must build the graph on one node in the cluster, then call synchronize to send that graph to all nodes. Is there a way to build parts of the graph on each node and then synchronize those parts? Some background: the graph actually comes from a CT scan. The vertices are voxels, the edges are relationships between adjacent voxels. At the moment I'm working on a very small test volume - 256^3 voxels - but later volumes will have billions of vertices and edges. Thanks for the help.

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Regarding boost interval library package.
by Pranjal vyas 15 Jun '13

15 Jun '13

Hello, I have written a program in boost which simply calculates the exponent in an interval, but for some interval inputs it is giving the wrong output such as for [1,3] or [-1,3]...but for some values it is giving correct o/p such as [1,9]. Please help in solving this query. The program is appended below.... ********************************************************************************************************************************************************* #include </boost/numeric/interval.hpp> #include <vector> #include <algorithm> #include <utility> #include <iostream> #include <iomanip> #include <math.h> using namespace boost; using namespace numeric; using namespace interval_lib; template<class T, class Policies> std::ostream &operator<<(std::ostream &os, const boost::numeric::interval<T, Policies> &x) { os << "[" << x.lower() << ", " << x.upper() << "]"; return os; } int main() { typedef interval<double,policies<save_state<rounded_transc_opp<double> >,checking_base<double> > > I; //typedef interval<double> I; I a(1,3.2); std::cout << exp(a) << std::endl; } ********************************************************************************************************************************************************** Thanks in Advance. Regards, PV

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http://www.boost.org/doc/libs/1_53_0/libs/serialization/example/demo.cpp does not work properly when using polymorphic xml archive
by Fadhel 14 Jun '13

14 Jun '13

Hi all, I used http://www.boost.org/doc/libs/1_53_0/libs/serialization/example/demo.cpp file as a first introduction to boost serialization. I would like to use polymorphic archives with XML serilialization format (to avoid having the templatized version). I edited this example and run it. Writing the data has worked fine -- except for the base_class serialization which needed an nvp -- but reading it causes a memory/segmentation fault problem. The same error happens with a binary archive. Using a text archive works fine. I'm new to boost serialization and debugging the code did not help me a lot. Is there anything specific to the serialization of base classes or abstract classes with the polymorphic XML format which needs to be handled? Or is this related to the serialization of pointers to the base class. Thanks for your help. Best Regards, Fadhel BA Here is the code I'm using: ( I removed some comments to make the code shorter) /////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8 // demo.cpp #include <cstddef> // NULL #include <iomanip> #include <iostream> #include <fstream> #include <string> #include <boost/archive/polymorphic_iarchive.hpp> #include <boost/archive/polymorphic_oarchive.hpp> #include <boost/archive/polymorphic_xml_iarchive.hpp> #include <boost/archive/polymorphic_xml_oarchive.hpp> #include <boost/archive/polymorphic_binary_iarchive.hpp> #include <boost/archive/polymorphic_binary_oarchive.hpp> #include <boost/archive/polymorphic_text_iarchive.hpp> #include <boost/archive/polymorphic_text_oarchive.hpp> #include <boost/serialization/base_object.hpp> #include <boost/serialization/utility.hpp> #include <boost/serialization/list.hpp> #include <boost/serialization/assume_abstract.hpp> #include <boost/serialization/nvp.hpp> ///////////////////////////////////////////////////////////// // gps coordinate // // llustrates serialization for a simple type // class gps_position { friend std::ostream & operator<<(std::ostream &os, const gps_position &gp); friend class boost::serialization::access; int degrees; int minutes; float seconds; void serialize(boost::archive::polymorphic_oarchive &ar, const unsigned int /* file_version */) const { ar << BOOST_SERIALIZATION_NVP(degrees); ar << BOOST_SERIALIZATION_NVP(minutes); ar << BOOST_SERIALIZATION_NVP(seconds); } void serialize(boost::archive::polymorphic_iarchive &ar, const unsigned int /* file_version */) { ar >> BOOST_SERIALIZATION_NVP(degrees); ar >> BOOST_SERIALIZATION_NVP(minutes); ar >> BOOST_SERIALIZATION_NVP(seconds); } public: // every serializable class needs a constructor gps_position(){}; gps_position(int _d, int _m, float _s) : degrees(_d), minutes(_m), seconds(_s) {} }; std::ostream & operator<<(std::ostream &os, const gps_position &gp) { return os << ' ' << gp.degrees << (unsigned char)186 << gp.minutes << '\'' << gp.seconds << '"'; } ///////////////////////////////////////////////////////////// // One bus stop // // illustrates serialization of serializable members // class bus_stop { friend class boost::serialization::access; friend std::ostream & operator<<(std::ostream &os, const bus_stop &gp); virtual std::string description() const = 0; gps_position latitude; gps_position longitude; void serialize(boost::archive::polymorphic_oarchive &ar, const unsigned int version) const { ar << BOOST_SERIALIZATION_NVP(latitude); ar << BOOST_SERIALIZATION_NVP(longitude); } void serialize(boost::archive::polymorphic_iarchive &ar, const unsigned int version) { ar >> BOOST_SERIALIZATION_NVP(latitude); ar >> BOOST_SERIALIZATION_NVP(longitude); } protected: bus_stop(const gps_position & _lat, const gps_position & _long) : latitude(_lat), longitude(_long) {} public: bus_stop(){} virtual ~bus_stop(){} }; BOOST_SERIALIZATION_ASSUME_ABSTRACT(bus_stop) std::ostream & operator<<(std::ostream &os, const bus_stop &bs) { return os << bs.latitude << bs.longitude << ' ' << bs.description(); } ///////////////////////////////////////////////////////////// // Several kinds of bus stops // // illustrates serialization of derived types // class bus_stop_corner : public bus_stop { friend class boost::serialization::access; std::string street1; std::string street2; virtual std::string description() const { return street1 + " and " + street2; } void serialize(boost::archive::polymorphic_oarchive &ar, const unsigned int version) const { // save/load base class information ar << boost::serialization::make_nvp("base", boost::serialization::base_object<bus_stop>(*this)); ar << BOOST_SERIALIZATION_NVP(street1); ar << BOOST_SERIALIZATION_NVP(street2);; } void serialize(boost::archive::polymorphic_iarchive &ar, const unsigned int version) { // save/load base class information ar >> boost::serialization::make_nvp("base", boost::serialization::base_object<bus_stop>(*this)); ar >> BOOST_SERIALIZATION_NVP(street1); ar >> BOOST_SERIALIZATION_NVP(street2); } public: bus_stop_corner(){} bus_stop_corner(const gps_position & _lat, const gps_position & _long, const std::string & _s1, const std::string & _s2 ) : bus_stop(_lat, _long), street1(_s1), street2(_s2) { } }; class bus_stop_destination : public bus_stop { friend class boost::serialization::access; std::string name; virtual std::string description() const { return name; } void serialize(boost::archive::polymorphic_oarchive &ar, const unsigned int version) const { ar << boost::serialization::make_nvp("base", boost::serialization::base_object<bus_stop>(*this)); ar << BOOST_SERIALIZATION_NVP(name); } void serialize(boost::archive::polymorphic_iarchive &ar, const unsigned int version) { ar >> boost::serialization::make_nvp("base", boost::serialization::base_object<bus_stop>(*this)); ar >> BOOST_SERIALIZATION_NVP(name); } public: bus_stop_destination(){} bus_stop_destination( const gps_position & _lat, const gps_position & _long, const std::string & _name ) : bus_stop(_lat, _long), name(_name) { } }; ///////////////////////////////////////////////////////////// // a bus route is a collection of bus stops // // illustrates serialization of STL collection templates. // // illustrates serialzation of polymorphic pointer (bus stop *); // class bus_route { friend class boost::serialization::access; friend std::ostream & operator<<(std::ostream &os, const bus_route &br); typedef bus_stop * bus_stop_pointer; std::list<bus_stop_pointer> stops; void serialize(boost::archive::polymorphic_oarchive &ar, const unsigned int version) const { // in this program, these classes are never serialized directly but rather // through a pointer to the base class bus_stop. So we need a way to be // sure that the archive contains information about these derived classes. //ar.template register_type<bus_stop_corner>(); ar.register_type(static_cast<bus_stop_corner *>(NULL)); //ar.template register_type<bus_stop_destination>(); ar.register_type(static_cast<bus_stop_destination *>(NULL)); // serialization of stl collections is already defined // in the header ar << BOOST_SERIALIZATION_NVP(stops); } void serialize(boost::archive::polymorphic_iarchive &ar, const unsigned int version) { ar.register_type(static_cast<bus_stop_corner *>(NULL)); ar.register_type(static_cast<bus_stop_destination *>(NULL)); // in the header ar >> BOOST_SERIALIZATION_NVP(stops); } public: bus_route(){} void append(bus_stop *_bs) { stops.insert(stops.end(), _bs); } }; std::ostream & operator<<(std::ostream &os, const bus_route &br) { std::list<bus_stop *>::const_iterator it; // note: we're displaying the pointer to permit verification // that duplicated pointers are properly restored. for(it = br.stops.begin(); it != br.stops.end(); it++){ os << '\n' << std::hex << "0x" << *it << std::dec << ' ' << **it; } return os; } ///////////////////////////////////////////////////////////// // a bus schedule is a collection of routes each with a starting time class bus_schedule { public: // note: this structure was made public. because the friend declarations // didn't seem to work as expected. struct trip_info { void serialize(boost::archive::polymorphic_oarchive &ar, const unsigned int file_version) const { // in versions 2 or later if(file_version >= 2) // read the drivers name ar << BOOST_SERIALIZATION_NVP(driver); // all versions have the follwing info ar << BOOST_SERIALIZATION_NVP(hour); ar << BOOST_SERIALIZATION_NVP(minute); } void serialize(boost::archive::polymorphic_iarchive &ar, const unsigned int file_version) { // in versions 2 or later if(file_version >= 2) // read the drivers name ar >> BOOST_SERIALIZATION_NVP(driver); // all versions have the follwing info ar >> BOOST_SERIALIZATION_NVP(hour); ar >> BOOST_SERIALIZATION_NVP(minute); } // starting time int hour; int minute; // only after system shipped was the driver's name added to the class std::string driver; trip_info(){} trip_info(int _h, int _m, const std::string &_d) : hour(_h), minute(_m), driver(_d) {} }; private: friend class boost::serialization::access; friend std::ostream & operator<<(std::ostream &os, const bus_schedule &bs); friend std::ostream & operator<<(std::ostream &os, const bus_schedule::trip_info &ti); std::list<std::pair<trip_info, bus_route *> > schedule; void serialize(boost::archive::polymorphic_oarchive &ar, const unsigned int version) const { ar << BOOST_SERIALIZATION_NVP(schedule); } void serialize(boost::archive::polymorphic_iarchive &ar, const unsigned int version) { ar >> BOOST_SERIALIZATION_NVP(schedule); } public: void append(const std::string &_d, int _h, int _m, bus_route *_br) { schedule.insert(schedule.end(), std::make_pair(trip_info(_h, _m, _d), _br)); } bus_schedule(){} }; BOOST_CLASS_VERSION(bus_schedule, 2) std::ostream & operator<<(std::ostream &os, const bus_schedule::trip_info &ti) { return os << '\n' << ti.hour << ':' << ti.minute << ' ' << ti.driver << ' '; } std::ostream & operator<<(std::ostream &os, const bus_schedule &bs) { std::list<std::pair<bus_schedule::trip_info, bus_route *> >::const_iterator it; for(it = bs.schedule.begin(); it != bs.schedule.end(); it++){ os << it->first << *(it->second); } return os; } void save_schedule(const bus_schedule &s, const char * filename){ // make an archive std::ofstream ofs(filename); boost::archive::polymorphic_xml_oarchive oa(ofs); oa << s; } void restore_schedule(bus_schedule &s, const char * filename) { // open the archive std::ifstream ifs(filename); boost::archive::polymorphic_xml_iarchive ia(ifs); // restore the schedule from the archive ia >> s; } int main(int argc, char *argv[]) { // make the schedule bus_schedule original_schedule; // fill in the data // make a few stops bus_stop *bs0 = new bus_stop_corner( gps_position(34, 135, 52.560f), gps_position(134, 22, 78.30f), "24th Street", "10th Avenue" ); bus_stop *bs1 = new bus_stop_corner( gps_position(35, 137, 23.456f), gps_position(133, 35, 54.12f), "State street", "Cathedral Vista Lane" ); bus_stop *bs2 = new bus_stop_destination( gps_position(35, 136, 15.456f), gps_position(133, 32, 15.300f), "White House" ); bus_stop *bs3 = new bus_stop_destination( gps_position(35, 134, 48.789f), gps_position(133, 32, 16.230f), "Lincoln Memorial" ); // make a routes bus_route route0; route0.append(bs0); route0.append(bs1); route0.append(bs2); // add trips to schedule original_schedule.append("bob", 6, 24, &route0); original_schedule.append("bob", 9, 57, &route0); original_schedule.append("alice", 11, 02, &route0); // make aother routes bus_route route1; route1.append(bs3); route1.append(bs2); route1.append(bs1); // add trips to schedule original_schedule.append("ted", 7, 17, &route1); original_schedule.append("ted", 9, 38, &route1); original_schedule.append("alice", 11, 47, &route1); // display the complete schedule std::cout << "original schedule"; std::cout << original_schedule; std::string filename("C:/Dev/XML"); filename += "/demofile.xml"; // save the schedule save_schedule(original_schedule, filename.c_str()); // ... some time later // make a new schedule bus_schedule new_schedule; std::cout << "\n\nstarting restored schedule"; restore_schedule(new_schedule, filename.c_str()); // and display std::cout << "\nrestored schedule"; std::cout << new_schedule; // should be the same as the old one. (except for the pointer values) delete bs0; delete bs1; delete bs2; delete bs3; return 0; }

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Boost 32-64
by Dave Dyer 14 Jun '13

14 Jun '13

This is sort of a final report to thank the list for several good pieces of advice. I'm just completing a project which uses boost libraries to assist a project which uses shared memory to communicate between a 64 bit process and a separate 32 bit Application. Trying to use the managed version of shared memory proved to be too unreliable. Doing so is advertized as "experimental" and it proved not ready for prime time. I succeeded by using only the very simplest, unmanaged versions of boost shared memory and managing my own memory, very carefully, to be sure the shared structures were identical on the 32 and 64 bit sides of the divide.

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[unordered] order in container
by gast128 14 Jun '13

14 Jun '13

Hello all, although it's called 'unordered_set', it surprised me that an unordered container could have a different ordering although its contents are the same: void f() { boost::unordered_set<int> uset1; uset1.insert(10); uset1.insert(9); uset1.insert(8); boost::unordered_set<int> uset2; uset2.insert(8); uset2.insert(9); uset2.insert(10); //uset1: 8, 9, 10 //uset2: 10, 9, 8 bool b = uset1 == uset2; //ok, they are the same } Maybe it is somewhere in the documentation, otherwise maybe add a documentation note.

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[accumulator] compiler error with quantil
by Philipp Kraus 14 Jun '13

14 Jun '13

Hello, I try to create a complex accumulator. I would like to use an accumulator for a box plot with the whisker data ( http://en.wikipedia.org/wiki/Box_plot ). My typedef shows at the momen like this: typedef boost::accumulators::accumulator_set<double, boost::accumulators::stats< boost::accumulators::tag::count, boost::accumulators::tag::sum, //boost::accumulators::tag::median, boost::accumulators::tag::mean, boost::accumulators::tag::variance, boost::accumulators::tag::min, boost::accumulators::tag::max, boost::accumulators::tag::extended_p_square > > Accumulator; I would like to create the 25% & 75% quantil and replace the median with the 50% quantil, so I have defined the ctor accumulator call like this: boost::array<double, 3> probs = {0.25, 0.5, 0.75}; m_times[p_name] = Accumulator( boost::accumulators::extended_p_square_probabilities = probs ); (the median is disabled and m_times is a std::map<std::string, Accumulator>). At this point I get a compiler errors: /Developer/opt/Boost/1.53.0/include/boost/accumulators/statistics/extended_p_square.hpp: In constructor 'boost::accumulators::impl::extended_p_square_impl<Sample>::extended_p_square_impl(const Args&) [with Args = boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<boost::accumulators::tag::accumulator, boost::accumulators::accumulator_set<double, boost::accumulators::stats<boost::accumulators::tag::count, boost::accumulators::tag::sum, boost::accumulators::tag::mean, boost::accumulators::tag::variance, boost::accumulators::tag::min, boost::accumulators::tag::max, boost::accumulators::tag::extended_p_square, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, void> >, boost::parameter::aux::empty_arg_list>, Sample = double]': /Developer/opt/Boost/1.53.0/include/boost/accumulators/framework/depends_on.hpp:319: instantiated from 'boost::accumulators::detail::accumulator_wrapper<Accumulator, Feature>::accumulator_wrapper(const Args&) [with Args = boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<boost::accumulators::tag::accumulator, boost::accumulators::accumulator_set<double, boost::accumulators::stats<boost::accumulators::tag::count, boost::accumulators::tag::sum, boost::accumulators::tag::mean, boost::accumulators::tag::variance, boost::accumulators::tag::min, boost::accumulators::tag::max, boost::accumulators::tag::extended_p_square, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, void> >, boost::parameter::aux::empty_arg_list>, Accumulator = boost::accumulators::impl::extended_p_square_impl<double>, Feature = boost::accumulators::tag::extended_p_square]' .... I need one accumulator for all the data. I'm using Boost 1.53. How can I create working code? Thanks for help Phil

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Any debugging tips for Boost Interprocess shared memory crashes?
by Warren Postma 14 Jun '13

14 Jun '13

I am a newly humbled mediocre C++ programmer, who is completely unable to figure out why Boost interprocess shared memory classes frequently freeze or crash both at creation and deletion of the manager objects, both with the persistent and the windows-only non persistent versions of the classes. Do you ever debug things and it all just gets worse and worse the longer you try to fix it? http://stackoverflow.com/questions/17100597/does-boostinterprocesswindows-s… Today I am getting crashes in the boost shared memory manager object destructor, or deadlocks in WMI calls. It's in Boost 1.53, on Visual C++ 2008, and involves DLLs. I am unable to reproduce the insanity at a top level EXE demo, and I tried to build a exe-loads DLL1, which loads DLL2, which creates boost objects, which fail when you destroy them, but I am unable to extricate it from my project. So it could be one of the lovely compiler or linker or project settings in my Visual C++ project, something about Multithreaded Debug DLL and MFC and ATL and all the billion varieties of weird RTL and heap bugs that lurk in Visual C++ runtime libraries. I am not blaming boost, but I am at wits end here. I have about 80 hours into debugging this and it's only getting worse the more I look at it. After this I promise to go away, perhaps drink myself silly, and never ever again try to use C++ or boost. Or Windows. Because for all I know this could be a windows SxS issue with Visual Studio 2008 and its lovely assortment of DLLs and runtime SxS insanity. Warren

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boost 1.49.0 on Redhat 5.2 link issues
by Stefan Schwarzer 13 Jun '13

13 Jun '13

Dear everybody, we need to backport boost 1.49.0 to Redhat 5.2. b2 ; b2 install --prefix=/usr/local succeeds and installs libraries and headers in /usr/local as requested (g++ 4.1.2-42, 32 bit PAE kernel). However, we have a problem even linking a mostly trivial example: #include <boost/filesystem.hpp> int main () { copy_file(boost::filesystem::path("atest"), boost::filesystem::path("btest")); } $ g++ testBoost.cpp -lboost_filesystem -lboost_system /tmp/cc10doAS.o: In function `boost::filesystem3::copy_file(boost::filesystem3::path const&, boost::filesystem3::path const&)': testBoost.cpp: (.text._ZN5boost11filesystem39copy_fileERKNS0_4pathES3_[boost::filesystem3::copy_file(boost::filesystem3::path const&, boost::filesystem3::path const&)]+0x24): undefined reference to `boost::filesystem3::detail::copy_file(boost::filesystem3::path const&, boost::filesystem3::path const&, boost::filesystem3::copy_option::enum_type, boost::system::error_code*)' collect2: ld returned 1 exit status The symbol is present in /usr/local/lib/libboost_filesystem and ldconfig does know about its location (see below). Also, trying to link statically or adding -pthread does not change the situation. We are desperate for advice... Roald and Stefan. $ nm -C /usr/local/lib/libboost_filesystem.so | grep 'boost::filesystem3::detail::copy_file' 00010ae0 T boost::filesystem3::detail::copy_file(boost::filesystem3::path const&, boost::filesystem3::path const&, boost::filesystem3::copy_option::enum_type, boost::system::error_code*) $ cat /etc/ld.so.conf include ld.so.conf.d/*.conf /usr/local/lib

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boost::thread::attributes reference overload?
by Anthony Foiani 13 Jun '13

13 Jun '13

Greetings. I have a class that wraps a boost::thread object, and I would like to specify certain thread attributes at construction time. My first attempt looked basically like this: struct my_thread { static boost::thread::attributes getThreadAttr() { boost::thread::attributes attrs; attrs.set_stack_size( 256 * 1024 ); return attrs; } my_thread( Runnable func ) : thread_( getThreadAttr(), func ) {} boost::thread thread_; }; But that fails: g++ -std=c++0x -o thread-attr thread-attr.cpp \ -lboost_thread-mt -lboost_system -pthread ... /usr/include/boost/thread/detail/thread.hpp:191:9: note: \ template argument deduction/substitution failed: thread-attr.cpp:48:42: note: cannot convert ‘my_thread::getThreadAttr()()’ (type \ ‘boost::thread::attributes {aka boost::thread_attributes}’) to type ‘boost::thread::attributes& {aka boost::thread_attributes&}’ Replacing 'getThreadAttr' with a method that returns a non-const reference to internal static variables allows the program to compile and run successfully: static boost::thread::attributes & getThreadAttr() { static boost::thread::attributes attrs; static bool init = false; if ( ! init ) { attrs.set_stack_size( 256 * 1024 ); init = true; } return attrs; } The full program, with Linux compile lines, can be found at the bottom of this message and also at: http://foiani.home.dyndns.org/~tony/boost/thread-attr.cpp I did find a closely-related question on StackOverflow: http://stackoverflow.com/questions/13868619 Where Vicente replied (http://stackoverflow.com/a/13894968/784478) The needed overload template <class F, class Arg, class ...Args> thread(attributes const& attrs, F&& f, Arg&& arg, Args&&... args) is defined only if the compiler supports variadic templates and rvalue references. This could explain your problem. I guess the documentation could be improved to signal this clearly. Please could you create a Trac ticket to follow this issue? However, the compiler I'm using (g++ 4.7.2) has supported both of these features for years. According to this page: http://gcc.gnu.org/projects/cxx0x.html g++ has supported both of these features since 4.3. Josef_K (on freenode IRC #boost channel) was kind enough to try the sample code in their own environment, and they encountered the same errors on both g++ 4.8.1 and clang 3.4. The most likely explanation is that I'm doing something stupid. If anyone has the time to hit me with the clue-by-four, I would appreciate it. There is the possibility that Boost.Thread v4 fixes this (I'm on 1_51_0, which is Boost.Thread v3.0.1). I'd rather not try to transition libraries at this point, but if it has been fixed, confirmation would be welcome. For now, I'll most likely implement the "return reference to internal static" method in my project. It's a bit racy, but since I do all my thread creation through this one routine, I should be able to manage it. Anyway. I'm left feeling that there is a gap somewhere; whether it's in my understanding, in the older version of Boost.Threads, in compiler support / quirks, or elsewhere, I don't know. Regardless, thanks for the excellent library, and happy hacking! Best regards, Anthony Foiani Sample program follows: ======================================================================== // this should work: // g++ -std=c++0x -o thread-attr thread-attr.cpp -lboost_thread-mt -lboost_system -pthread // // this explodes: // g++ -std=c++0x -o thread-attr thread-attr.cpp -DRVALUE_REFERENCE_DOOM -lboost_thread-mt -lboost_system -pthread #include <iostream> #include <boost/function.hpp> #include <boost/thread.hpp> typedef boost::function< void ( void ) > Runnable; struct my_thread { #ifdef RVALUE_REFERENCE_DOOM // this doesn't work. static boost::thread::attributes getThreadAttr() { boost::thread::attributes attrs; attrs.set_stack_size( 256 * 1024 ); return attrs; } #else // this does work, but needs more structure before it can be // considered safe. static boost::thread::attributes & getThreadAttr() { static boost::thread::attributes attrs; static bool init = false; if ( ! init ) { attrs.set_stack_size( 256 * 1024 ); init = true; } return attrs; } #endif my_thread( Runnable func ) : thread_( getThreadAttr(), func ) {} void join() { thread_.join(); } boost::thread thread_; }; void foo() { std::cout << "foo!" << std::endl; } int main( int argc, char * argv [] ) { my_thread t( foo ); t.join(); return 0; }

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