February 2007 - Boost-users - lists.preview.boost.org

Boost.Thread contained within a class?
by Joshua ChaitinPollak 07 Feb '07

07 Feb '07

Hello, I have a question about Boost.Thread. I am trying to create a class which upon instantiation creates a thread based upon itself, and then on destruction, stops the thread and cleans up after itself. A simple example is below. Is this possible, and if not, what alternatives do I have? The reason for this is to create a single external API (actually defined in a base class), and still have a background thread (hidden from the API) which can share that object's internal member variables. I'm looking to do something like this: class my_handler { public: boost::thread* background_thread; my_hander() : background_thread(NULL) { background_thread(*this); } ~my_hander() { if (background_thread != NULL) { running = false; background_thread.join(); } operator()() { while(running) { // do something } } }; -Thanks, Josh -- Joshua ChaitinPollak Software Engineer Kiva Systems

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[thread_safe_signals] postconstructors and predestructors
by Frank Mori Hess 07 Feb '07

07 Feb '07

> Actually, I've realized there's no reason it has to be tied so closely to > enable_shared_from_this. There could be a completely independent base > class called boost::postconstructible which is treated similarly to > enable_shared_from_this in shared_ptr.hpp. Similarly, there could be a > boost::predestructible base class that gets its hook called before the > shared_ptr deletes its pointer (perhaps only in the default deleter). I > believe the hooks would compile to nothing if the shared_ptr isn't > holding a pointer derived from one of these classes, just like (I assume) > they do for enable_shared_from_this. > > > I think you're better off writing a specialized smart pointer if you > > want that kind of functionality. > > I'm no so keen on a specialized smart pointer, for reasons that you've > already brought up earlier. But I suppose that's what I'll do if it comes > to it. It shouldn't be too bad to come up with a new name and do a search > and replace on shared_ptr.hpp. > > My point is, enable_shared_from_this was deemed important enough for > special hooks to be put into shared_ptr.hpp for it. So there is > precedent. And postconstructors/predestructors aren't peculiar ideas that > I just came up with myself. I'm sure they could be useful in other > contexts. > Now I realize I don't need any changes to shared_ptr at all, I can do it all in a wrapper function inserted between the raw pointer and shared_ptr. I can't think of a name, so call it ptr_wrapper(): shared_ptr<MyClass>(signalslib::ptr_wrapper(new MyClass)); ptr_wrapper would call postconstruct() if its input pointer is derived from postconstructible, and return a shared_ptr. The deleter for the returned shared pointer would be (by default) customized to call the predestructor if the input pointer is derived from predestructible. A custom deleter could be accepted as a second argument to ptr_wrapper. -- Frank

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[Serialization] Undefined reference to... (header or compilation problem)
by misha＠gildia.pl 07 Feb '07

07 Feb '07

Hello, I wonder if anyone could help me with my problem. I'm trying to serialize my project's data. Beeing new to the boost libs I started with simple tutorial example. Today is the 3rd day I'm unable to launch a serialization of an object of the simpliest Vertex class containing 2 double values. The errors I get follow this patern: [mack/.../]$ g++ -Wall -o main test3.cpp /tmp/ccQkfdAS.o (.gnu.linkonce.t._ZN5boost7archive18text_oarchive_implINS0_13text_oarchiveEED2Ev+0x31): In function `boost::archive::text_oarchive_impl<boost::archive::text_oarchive>::~text_oarchive_impl()': : undefined reference to `boost::archive::basic_text_oprimitive<std::basic_ostream<char, std::char_traits<char> > >::~basic_text_oprimitive()' The problem is in line : boost::archive::text_oarchive oa (ofs); Any ideas? IMHO it's either compilation issue ( should I include any additional libs to cmd line?) or header order/lacking. To be sure I didn't miss anything else let me include the whole code: //CODE #include <iostream> #include <vector> #include <functional> #include <algorithm> #include <fstream> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/vector.hpp> //using namespace std; //using namespace boost::serialization; class Vertex { private: friend class boost::serialization::access; public: double x; double y; Vertex() {} // Serialization requires a default constructor Vertex(double newX, double newY) : x(newX), y(newY) {} double getX() const { return x; } double getY() const { return y; } void dump() { std::cout << x << " " << y << std::endl; } }; BOOST_IS_ABSTRACT(Vertex) namespace boost { namespace archive { template<class Archive> void serialize(Archive & ar, Vertex & vtx, const unsigned int version) { ar & vtx.x; ar & vtx.y; } } // namespace serialization } // namespace boost int main() { Vertex v1(1.5, 2.5); std::ofstream ofs("myfile.vtx"); boost::archive::text_oarchive oa(ofs); oa << v1; ofs.close(); return 0; } // END CODE I use g++ (GCC) 3.4.4 20050721 (Red Hat 3.4.4-2) Fedora Core Boost ver. 1.32 Thanks in advance for any feedback. Regards Misha

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Error from boost
by gopal.reddy＠wipro.com 07 Feb '07

07 Feb '07

Hi All , I am using boost in Opendiameter code using boost libraray, but i am not running into problems! Details: Tool(compiler) : MSVC60 OS : Windows XP Boost Library Version: boost_1_33_1 Error : :\projects\diameter\opendiameter-1.0.7-h\include\framework.h(255) : error C2352: 'boost::shared_ptr<class AAA_GroupedJob>::get' : illegal call of non-static member function d:\projects\diameter\supporting softwares\boost_1_33_1\boost\shared_ptr.hpp(257) : see declaration of 'get' d:\projects\diameter\opendiameter-1.0.7-h\include\framework.h(255) : while compiling class-template member function 'class AAA_GroupedJob &__thiscall AAA_JobHandle<class AAA_GroupedJob>::Job(void)' memory_manager.cxx How it is used in framework.cpp (file) : template <class JOB> class AAA_JobHandle : public boost::shared_ptr<JOB> { public: AAA_JobHandle(JOB* job) : boost::shared_ptr<JOB>(job, AAA_JobDeleter()) {} JOB& Job() { return (JOB&)*boost::shared_ptr<JOB>::get(); } }; I seem to be doing some thing wrong with the above. Any help on how to go about resolving the problem would be appreciated! Thanks, Gopal The information contained in this electronic message and any attachments to this message are intended for the exclusive use of the addressee(s) and may contain proprietary, confidential or privileged information. If you are not the intended recipient, you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately and destroy all copies of this message and any attachments. WARNING: Computer viruses can be transmitted via email. The recipient should check this email and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this email. www.wipro.com

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Re: [Boost-users] [statechart] : asynchronous_state_machine - access member functions
by Oliver.Kowalke＠qimonda.com 07 Feb '07

07 Feb '07

Hi Andreas, Your solution will not work in my application. I use an io-framework which has some requirements that could not be fullfilled with the creation process of an asynchronous_state_machine. asynchronous_state_machine is derived from state_machine - does this mean that asynchronous_state_machine provides only a thread-safe access to state_machine (acts as a wrapper)? In my application I've three event sources (io-device, UNIX-signal handler, trigger which periodically produces events). Each event source runs in ist own thread. I could use a state_machine and synchronize the insertion of events (process_event() function) via a mutex. Would asynchronous_state-machine provide a preformance benfit in this case? Would it be an adequat solution to queue the events from the three event sources in a thread-safe queue (producer-consumer pattern)? The threads providing events act as producer threads) and should not be blocked and the processing of the events (calling state_machine::process_event()) will be done snychronous (maybe by one consumer thread). Regards,Oliver

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Problem Using Bjam V2
by Wu Yinghui, Freddie 07 Feb '07

07 Feb '07

Hi all, I've been using bjam v1 in 1.33 to build my Boost, and everything went smoothly. I tried lately to grab the latest Boost from CVS in order to preview its upcoming feature, but I faced problems building it using the new bjam v2. My system: Windows XP Pro SP2 Compiler: MSVC 7.1 First of all, I'd like to build Boost with STLport 5.1.0 (the latest STLport release). In the old bjam, I could use the vc_7_1-stlport toolset to activate STLport. In the new bjam, I found that the <stdlib> option was always set to "native" when I run bjam with --debug-building. (I've enabled "using stlport" in user-config.jam".) So how do I activate STLport? Secondly, I downloaded Zlib and Libbz2 source and wanted to build Boost.IOStream with zip and bzip2 support. In the old bjam, I could set ZLIB_INCLUDE, etc. environment variables and then Boost will find the necessary headers and libraries. In the new bjam, I always get an error complaining zlib.h not found even though I've already set the environment variables properly. How do I go about doing this? Lastly, due to our project requirements, I need to provide some customized compiler options when building Boost. In the old bjam, I could use -sBUILD=<cxx-flags>option to do so. But these flags doesn't seem effective with the new bjam (I don't see them when using -d+2 to check the compiler parameters). So how do I go about doing this? Thanks, Freddie -- Wu Yinghui, Freddie Senior Software Engineer Advanced Technology Research and Development Group Volume Interactions Pte Ltd 1 Kim Seng Promenade #12-01 Great World City East Tower Singapore 237994 Tel: +65 62226962 (Ext 216) Fax: +65 62226215 Email: yhwu(a)volumeinteractions.com URL: http://www.volumeinteractions.com http://www.dextroscope.com Important: This message is intended for the recipient(s) addressed above. It contains privileged and confidential information. If you are not the intended recipient, please notify the sender immediately by replying to this message and then delete it from your system. You must not read, copy, use, or disseminate this communication in any form. Thank you.

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get time in different zone
by Fred J. 07 Feb '07

07 Feb '07

Dear all. I am trying to get New York time in time_t epoch now. my PC is set to Sydney time. please help thanks here is my effort fro the last 4 hours. #include <fstream> #include <ios> #include <iostream> #include <string> #include "boost/date_time/local_time/local_time.hpp" #include "boost/date_time/posix_time/posix_time.hpp" #include "boost/date_time/local_time_adjustor.hpp" #include "boost/date_time/c_local_time_adjustor.hpp" using namespace std; int main(){ using namespace boost::gregorian; using namespace boost::local_time; using namespace boost::posix_time; // now time is ptime now = second_clock::local_time(); // current PC time cout << "Your computer time is: " << now << endl; // typedef boost::date_time::c_local_adjustor<ptime> local_adj; // // create a sydney time // ptime sydtime(date(2007,02,07), hours(12)+minutes(9)+seconds(32)); // cout << "Sydney local time is: " << to_simple_string( sydtime ) << endl; // load time zone conversion date form file tz_database tz_db; tz_db.load_from_file("../date_time_zonespec.csv"); time_zone_ptr nyc_tz = tz_db.time_zone_from_region("America/New_York"); time_zone_ptr syd_tz = tz_db.time_zone_from_region("Australia/Sydney"); // create a sydney time from date and time_duration date in_date(2007,02,07); time_duration td(12,25,32); local_date_time sydtime(in_date, td, syd_tz, local_date_time::NOT_DATE_TIME_ON_ERROR); cout << "Sydney time is: " << sydtime << endl; cout << "in UTC it is: " << sydtime.utc_time() << endl; // // convrt sydney to utc // ptime syd_t_utc = local_adj::local_to_utc( sydtime ); // cout << "UTC time is: " << to_simple_string( syd_t_utc ) << endl; // // conver it to new york // time_zone_ptr nyc_tz = tz_db.time_zone_from_region("America/New_York"); // ptime nytime = nyc_tz::utc_to_local( nyc_tz ); // cout << "New York local time is: " << to_simple_string( nyctime ) << endl; } --------------------------------- Any questions? Get answers on any topic at Yahoo! Answers. Try it now.

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Undefined symbol
by Jojy Varghese 07 Feb '07

07 Feb '07

Hi all I am getting a link error while running my application that uses boost regex library. Here is the error message: undefined symbol: _ZN5boost9re_detail12perl_matcherIPKcN4_STL9allocatorINS_9sub_matchIS3_E EEENS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEE14construct_initERKNS_ 11basic_regexIcSC_EENS_15regex_constants12_match_flagsE Any help is appreciated. thanks in advance Jojy

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[boost::fusion] set_c or vector_c in fusion?
by Ovanes Markarian 07 Feb '07

07 Feb '07

Hello all! Does someone know if the fusion library has some analog to mpl::sec_c or mpl::vector_c? Or is there any way to pass mpl::set_c as a template parameter to fusion::set class? Thanks a lot, Ovanes

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Re: [Boost-users] [date_time] timezone rules for different years
by Stephen Turner 06 Feb '07

06 Feb '07

> -----Original Message----- > From: Stephen Turner [mailto:sturner@clicktracks.com] > Sent: 22 December 2006 16:39 > To: 'boost-users(a)lists.boost.org' > Subject: [date_time] timezone rules for different years > > For my application, I need to be able to get the local time > of any UTC time in the last five years in any location. > > As far as I can see, the date_time library doesn't provide > this. The documentation says that date_time_zonespec.csv is > "based on data found in the zoneinfo datebase", but whereas > the zoneinfo database contains historical information about > daylight saving time changes, date_time_zonespec.csv only > seems to allow you to specify a single rule for each > timezone. And I can't find another mechanism to do it. > > Am I missing something, or is this capability not present? > And if not, is there any plan to add it? Or a workaround? I > anticipate that this will become more of a problem when the > rules for the U.S. change by several weeks next year. > I'm not sure whether this one got lost in the holiday break, or whether there's nobody who's familiar with the internals of this library on this list, but let me try again. I've been trying to work out how to add the capability to have different timezone rules in different years to the library. It seems to me it's not too hard (although I'm nervous of making such a judgement in code I'm not familiar with). I think all that's needed is: 1) In class custom_time_zone, the rules should depend on y, rather than there just being one set of rules. 2) The date_time_zonespec.csv file would have to have extra columns for years a rule applied to. tz_db_base::parse_string would have to parse them, and instead of creating a new timezone for each line, add the rule to the appropriate timezone if it had already been seen once. Is there anything else that would need to be done? Actually, I think the hardest part would be populating the date_time_zonespec.csv file. Is there already a program to generate that file from the zoneinfo files, or was it done semi-by-hand? Thanks, -- Stephen Turner, Cambridge, UK http://homepage.ntlworld.com/adelie/stephen/ "The internet is a reflection of our society. If we do not like what we see, the problem is not to fix the mirror, we have to fix society." (Vint Cerf)

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