August 2007 - Boost-users - lists.boost.org

[statechart] using events for passing information
by "Christian Bähnisch" 17 Aug '07

17 Aug '07

Hello, I wonder if it is possible to use events for passing in data to states. I even cannot find some hints in the statechart documentation how to determine in some state which event caused a transistion to the this state! regards, chris -- Der GMX SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen! Ideal für Modem und ISDN: http://www.gmx.net/de/go/smartsurfer

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Passing user defined visitor for breadth_first_search
by Sourabh 17 Aug '07

17 Aug '07

Hi, I am using the boost graph (adjacency_list) and want to perform BFS on that. I am constructing the graph, passing VertexProperty as a structure (bundled_properties). When I try to modify the structure in my own bfs visitior (in the overriden function discover_vertex), the compiler says the structure (representing the vertex property) is readonly. I had to switch to const_cast of that structure, but it is not elegant. Can anyone help me through this? Regards, Sourabh

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Boost.Test Documentation
by James Hamlin 17 Aug '07

17 Aug '07

Hi, I've begun using Boost.Test to construct test suites for a project, and it looks like it does a great job and is full of nice features (I really like the auto unit tests). But I have a big complaint: the documentation is pretty poor. I had a hard time getting a simple example off the ground, because it wasn't clear that I had to link to parts of the library. This was a surprise since most of Boost is templated and so is available entirely through the headers. I had to dig a bit to find the comment about the header that includes the main() code and other concrete functions. In addition, many of the examples are missing, and some of those that are available require the linking I mentioned but fail to note this, adding to my initial confusion. Lastly, the English grammar is very rough in parts, and while I understand that English may not be the primary language of the author, it can be a big hurdle to get started using the library when one has to grapple with the documentation to understand the intentions of the author. I don't mean to rant - the library is great, and I've already found it useful - but I'd love to get more out of it, and clean, clear, and thorough documentation will get me and others started with much less head scratching and frustration.<boost-test%20at%20emailaccount%20dot%20com%20%28please%20unobscure%29> Sincerely, James Hamlin Postscript: This is Boost-users, but I assume Gennadiy Rozental or somebody else with the knowledge and ability to update the documentation will see this message.

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[multi_array]BOOST_NO_SFINAE Warnings
by Mark Ruzon 16 Aug '07

16 Aug '07

I recently upgraded to 1.34.1, gcc 3.4.6, and certain new changes in multi_array don't make sense to me: In view.hpp: template <class BaseList> #ifdef BOOST_NO_SFINAE void #else typename disable_if<typename boost::is_integral<BaseList>::type,void >::type #endif reindex(const BaseList& values) { boost::function_requires< detail::multi_array::CollectionConcept<BaseList> >(); boost::detail::multi_array:: copy_n(values.begin(),num_dimensions(),index_base_list_.begin()); origin_offset_ = this->calculate_indexing_offset(stride_list_,index_base_list_); } multi_array_ref.hpp has a similar function except for the last function call. Both give me warnings because BOOST_NO_SFINAE is not defined, and so reindex has a non-void return type but does not actually return anything. I can get rid of it by #defining this constant, but it seems like a bug in the code. Will someone more knowledgeable shed some light on this, please? Do I need to #define BOOST_NO_SFINAE? Thanks, Mark Ruzon P.S. Apologies if this is the second post asking this question.

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[iostreams] file sink/source and wide char paths?
by Michael Ellery 16 Aug '07

16 Aug '07

it looks like the file_sink and file_source classes in iostreams take std::string for the file path. Was this intentional? I'm not sure what the consensus is on wide char file system paths, but it seems like they are supported by the filesystem package, for instance. Should I just convert my wide char paths to narrow char when it comes to using them with file_sink/file_source -- or is there a better way? Thanks, Mike Ellery

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Unregistered Class Exception - Boost Serialization
by Jason Gorski 16 Aug '07

16 Aug '07

Hello, I have been using the Boost Serialization libraries on a project of mine and so far they have worked very well. However, I have been unable to properly load derived objects using a base class pointer. The following code generates an unregistered class exception: #include <iostream> #include <sstream> #include <iomanip> #include <string> #include <sstream> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/export.hpp> class Base_Class { public: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { // empty } virtual void print()=0; }; class Derived_Class: public Base_Class { public: int i1; int i2; int i3; friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & boost::serialization::base_object<Base_Class>(*this); ar & i1; ar & i2; ar & i3; } void print(){ std::cout << "i am a derived class object" << std::endl; } }; BOOST_CLASS_EXPORT(Derived_Class) /***************************************** Main *****************************************/ int main() { Derived_Class derived_send; derived_send.i1=12; derived_send.i2=13; derived_send.i3=14; Base_Class * base_ptr; Derived_Class * derived_recv; // save derived class std::ostringstream output_stream; boost::archive::text_oarchive output_archive( output_stream ); output_archive & derived_send; // load using base class ptr std::istringstream input_stream( output_stream.str() ); boost::archive::text_iarchive input_archive( input_stream ); input_archive & base_ptr; derived_recv = (Derived_Class*) base_ptr; derived_recv->print(); } From reading the documentation, it seems as if this should work fine. Am I missing something? Thanks in advance, Jason -- Jason Gorski Research Engineer Oasis Advanced Engineering, Inc. (248)373-9800 x 269 gorski(a)OasisAdvancedEngineering.com

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asio example compile error
by ope 16 Aug '07

16 Aug '07

Hi, I try to compile the asio example at http://asio.sourceforge.net/boost_asio_0_3_7/libs/asio/doc/tutorial/tuttime… using boost 1.34.0 with latest sf.com release of boost_asio in directory extra/boost and lib_system of asio is in directory build/lib. The error attached occoured. What did I wrong? All headers seems to be found. Thanks, Olaf $ g++ asio.cpp -o asio -I /usr/local/include/ -I extra/boost/ -L build/lib/ -static -lboost_system-gcc41-mt-0_1 extra/boost/boost/asio/detail/bind_handler.hpp: In member function »void boost::asio::detail::binder1<Handler, Arg1>::operator()() [with Handler = void (*)(const boost::asio::error&), Arg1 = boost::system::error_code]«: extra/boost/boost/asio/handler_invoke_hook.hpp:63: instantiated from »void boost::asio::asio_handler_invoke(Function, ...) [with Function = boost::asio::detail::binder1<void (*)(const boost::asio::error&), boost::system::error_code>]« extra/boost/boost/asio/detail/handler_invoke_helpers.hpp:39: instantiated from »void asio_handler_invoke_helpers::invoke(const Function&, Context*) [with Function = boost::asio::detail::binder1<void (*)(const boost::asio::error&), boost::system::error_code>, Context = void (*)(const boost::asio::error&)]« extra/boost/boost/asio/detail/bind_handler.hpp:72: instantiated from »void boost::asio::detail::asio_handler_invoke(const Function&, boost::asio::detail::binder1<Handler, Arg1>*) [with Function = boost::asio::detail::binder1<void (*)(const boost::asio::error&), boost::system::error_code>, Handler = void (*)(const boost::asio::error&), Arg1 = boost::system::error_code]« extra/boost/boost/asio/detail/handler_invoke_helpers.hpp:39: instantiated from »void asio_handler_invoke_helpers::invoke(const Function&, Context*) [with Function = boost::asio::detail::binder1<void (*)(const boost::asio::error&), boost::system::error_code>, Context = boost::asio::detail::binder1<void (*)(const boost::asio::error&), boost::system::error_code>]« extra/boost/boost/asio/detail/task_io_service.hpp:412: instantiated from »static void boost::asio::detail::task_io_service<Task>::handler_wrapper<Handler>::do_call(boost::asio::detail::task_io_service<Task>::handler_base*) [with Handler = boost::asio::detail::binder1<void (*)(const boost::asio::error&), boost::system::error_code>, Task = boost::asio::detail::epoll_reactor<false>]« extra/boost/boost/asio/detail/task_io_service.hpp:392: instantiated from »boost::asio::detail::task_io_service<Task>::handler_wrapper<Handler>::handler_wrapper(Handler) [with Handler = boost::asio::detail::binder1<void (*)(const boost::asio::error&), boost::system::error_code>, Task = boost::asio::detail::epoll_reactor<false>]« extra/boost/boost/asio/detail/handler_alloc_helpers.hpp:138: instantiated from »boost::asio::detail::handler_ptr<Alloc_Traits>::handler_ptr(boost::asio::detail::raw_handler_ptr<Alloc_Traits>&, Arg1&) [with Arg1 = boost::asio::detail::binder1<void (*)(const boost::asio::error&), boost::system::error_code>, Alloc_Traits = boost::asio::detail::handler_alloc_traits<boost::asio::detail::binder1<void (*)(const boost::asio::error&), boost::system::error_code>, boost::asio::detail::task_io_service<boost::asio::detail::epoll_reactor<false> >::handler_wrapper<boost::asio::detail::binder1<void (*)(const boost::asio::error&), boost::system::error_code> > >]« extra/boost/boost/asio/detail/task_io_service.hpp:180: instantiated from »void boost::asio::detail::task_io_service<Task>::post(Handler) [with Handler = boost::asio::detail::binder1<void (*)(const boost::asio::error&), boost::system::error_code>, Task = boost::asio::detail::epoll_reactor<false>]« extra/boost/boost/asio/impl/io_service.ipp:125: instantiated from »void boost::asio::io_service::post(Handler) [with CompletionHandler = boost::asio::detail::binder1<void (*)(const boost::asio::error&), boost::system::error_code>]« extra/boost/boost/asio/detail/deadline_timer_service.hpp:169: instantiated from »void boost::asio::detail::deadline_timer_service<Time_Traits, Timer_Scheduler>::wait_handler<Handler>::operator()(const boost::system::error_code&) [with Handler = void (*)(const boost::asio::error&), Time_Traits = boost::asio::time_traits<boost::posix_time::ptime>, Timer_Scheduler = boost::asio::detail::epoll_reactor<false>]« extra/boost/boost/asio/detail/timer_queue.hpp:243: instantiated from »static void boost::asio::detail::timer_queue<Time_Traits>::timer<Handler>::invoke_handler(boost::asio::detail::timer_queue<Time_Traits>::timer_base*, const boost::system::error_code&) [with Handler = boost::asio::detail::deadline_timer_service<boost::asio::time_traits<boost::posix_time::ptime>, boost::asio::detail::epoll_reactor<false> >::wait_handler<void (*)(const boost::asio::error&)>, Time_Traits = boost::asio::time_traits<boost::posix_time::ptime>]« extra/boost/boost/asio/detail/timer_queue.hpp:234: instantiated from »boost::asio::detail::timer_queue<Time_Traits>::timer<Handler>::timer(const typename Time_Traits::time_type&, Handler, void*) [with Handler = boost::asio::detail::deadline_timer_service<boost::asio::time_traits<boost::posix_time::ptime>, boost::asio::detail::epoll_reactor<false> >::wait_handler<void (*)(const boost::asio::error&)>, Time_Traits = boost::asio::time_traits<boost::posix_time::ptime>]« extra/boost/boost/asio/detail/timer_queue.hpp:68: instantiated from »bool boost::asio::detail::timer_queue<Time_Traits>::enqueue_timer(const typename Time_Traits::time_type&, Handler, void*) [with Handler = boost::asio::detail::deadline_timer_service<boost::asio::time_traits<boost::posix_time::ptime>, boost::asio::detail::epoll_reactor<false> >::wait_handler<void (*)(const boost::asio::error&)>, Time_Traits = boost::asio::time_traits<boost::posix_time::ptime>]« extra/boost/boost/asio/detail/epoll_reactor.hpp:325: instantiated from »void boost::asio::detail::epoll_reactor<Own_Thread>::schedule_timer(boost::asio::detail::timer_queue<Time_Traits>&, const typename Time_Traits::time_type&, Handler, void*) [with Time_Traits = boost::asio::time_traits<boost::posix_time::ptime>, Handler = boost::asio::detail::deadline_timer_service<boost::asio::time_traits<boost::posix_time::ptime>, boost::asio::detail::epoll_reactor<false> >::wait_handler<void (*)(const boost::asio::error&)>, bool Own_Thread = false]« extra/boost/boost/asio/detail/deadline_timer_service.hpp:183: instantiated from »void boost::asio::detail::deadline_timer_service<Time_Traits, Timer_Scheduler>::async_wait(boost::asio::detail::deadline_timer_service<Time_Traits, Timer_Scheduler>::implementation_type&, Handler) [with Handler = void (*)(const boost::asio::error&), Time_Traits = boost::asio::time_traits<boost::posix_time::ptime>, Timer_Scheduler = boost::asio::detail::epoll_reactor<false>]« extra/boost/boost/asio/deadline_timer_service.hpp:153: instantiated from »void boost::asio::deadline_timer_service<TimeType, TimeTraits>::async_wait(typename boost::asio::detail::deadline_timer_service<TimeTraits, boost::asio::detail::epoll_reactor<false> >::implementation_type&, WaitHandler) [with WaitHandler = void (*)(const boost::asio::error&), TimeType = boost::posix_time::ptime, TimeTraits = boost::asio::time_traits<boost::posix_time::ptime>]« extra/boost/boost/asio/basic_deadline_timer.hpp:374: instantiated from »void boost::asio::basic_deadline_timer<Time, TimeTraits, TimerService>::async_wait(WaitHandler) [with WaitHandler = void (*)(const boost::asio::error&), Time = boost::posix_time::ptime, TimeTraits = boost::asio::time_traits<boost::posix_time::ptime>, TimerService = boost::asio::deadline_timer_service<boost::posix_time::ptime, boost::asio::time_traits<boost::posix_time::ptime> >]« asio.cpp:15: instantiated from here extra/boost/boost/asio/detail/bind_handler.hpp:39: Fehler: ungültige Initialisierung einer Referenz des Typs »const boost::asio::error&« von Ausdruck des Typs »boost::system::error_code«

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[Announcement] Boost joins the Software Freedom Conservancy
by Beman Dawes 16 Aug '07

16 Aug '07

Effective August 10th, 2007, Boost became a member project of the Software Freedom Conservancy, http://conservancy.softwarefreedom.org. This means that Boost is now part of a legal entity under US law, and tax-exempt under section 501(c)(3) of the US tax regulations. Although this doesn't have much short-term effect, it lets us move forward with BoostCon 2008 planning with less administrative delay. Long-term, being part of a non-profit organization allows Boost to continue to grow and prosper, and to raise money if that becomes useful. After considering the option of starting our own foundation (a huge amount of work), the Boost moderators decided that joining the Software Freedom Conservancy was a better option. The SFC provides the same legal abilities of a foundation at NO cost to the Boost project. It also minimizes the amount of legal and administrative hassles for project members -- allowing us to stay focused on technical matters rather than tax law. In addition, we are free to leave the SFC and create our own foundation at a later time if we decide that the SFC is not serving us well. Boost is not alone -- some other well known open source projects have also joined the SFC (eg: Samba, Wine). For those interested in the details, see a copy of the legal agreement at svn.boost.org/svn/boost/trunk/more/BoostSponsorshipAgreement.pdf I signed for Boost, since I was the founder and am the owner of the boost.org domain name. Dave Abrahams gets the credit for working out the details of the SFC agreement, with the help of the other moderators. --Beman

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Boost Serialization tracking issues
by gast128 16 Aug '07

16 Aug '07

Dear all, I was trying to use the Boost Serialization library again, but I ran into a problem which cost me a full day. The Boost Serialization library is a very handy library, but often when I use it I run into problems which cost me days. This time I try to serialize just 'track_never' objects. First of all the compiler firewall which is built in the library does not work when using the nvp macro: void Foo() { boost::archive::xml_oarchive oa(...) SomeStruct s; oa << s; // compile time error oa << BOOST_SERIALIZATION_NVP(s); //ok } But this wasn't the real problem. I was looping to serialize non tracking objects: void Bla() { boost::archive::xml_oarchive oa(...) for (int i = 0; i < 1000; ++i) { const SomeStruct s; oa << s; } } However the library did track them by pointer due to a previous request to serialize a pointer. It decides this on a call to 'basic_serializer::serialized_as_pointer' deep in the library. struct SomeStructHolder { SomeStructHolder() : m_p(NULL){} template <class Archive> void serialize(Archive& ar, const unsigned int /*version*/) { ar & BOOST_SERIALIZATION_NVP(m_p); } const SomeStruct* m_p; }; somewhere else: void Bla() { boost::archive::xml_oarchive oa(...) const SomeStructHolder holder; oa << holder; } So this is again an unexpected property of the library. Maybe the ambition for automatic object tracking is too high, and specify it explicitly per class / per archiving operation would be more work for the user, but also clearer. And still the original problem was too find out if Boost Serialization could also be used on a per demand loading of (value-)objects: in my problem the final storage can be potential bigger than computer memory, so I was wondering if objects could be loaded on demand (instead of all in once). wkr, me

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ScopeExit Review Reminder
by Jody Hagins 16 Aug '07

16 Aug '07

We have received only a few reviews so far. The review ends in less than a week, so time is running short. Thanks! >From the original announcement... The review period for Scope Exit Time Series, submitted by Alexander Nasonov, runs from Monday, August 13 until Wednesday, August 22. >From the documentation: Nowadays, every C++ developer is familiar with RAII technique. It binds resource acquisition and release to initialization and destruction of a variable that holds the resource. But there are times when writing a special class for such variable is not worth the effort. This is when ScopeExit macro comes into play. You put resource acquisition directly in your code and next to it you write a code that releases the resource. Note that ScopeExit uses PP macros and relies on Boost.Typeof. The latest version can is here: http://boost-consulting.com/vault/index.php?action=downloadfile&filename=sc… It's available also at http://tinyurl.com/2z6qg2 Online documentation is here: http://194.6.223.221/~nasonov/scope_exit-0.04/libs/scope_exit/doc/html/inde… >From the review guidelines here: http://boost.org/more/formal_review_process.htm ... Boost mailing list members are encouraged to submit Formal Review comments: * Publicly on the mailing list. * Privately to the Review Manager. Private comments to a library submitter may be helpful to her or him, but won't help the Review Manager reach a decision, so the other forms are preferred. What to include in Review Comments Your comments may be brief or lengthy, but basically the Review Manager needs your evaluation of the library. If you identify problems along the way, please note if they are minor, serious, or showstoppers. Here are some questions you might want to answer in your review: * What is your evaluation of the design? * What is your evaluation of the implementation? * What is your evaluation of the documentation? * What is your evaluation of the potential usefulness of the library? * Did you try to use the library? With what compiler? Did you have any problems? * How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? * Are you knowledgeable about the problem domain? And finally, every review should answer this question: * Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. Thanks in advance to every for your participation in this review.

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