July 2009 - Boost-users - lists.boost.org

Boost StateChart and Template parameters
by Etienne Philip Pretorius 27 Jul '09

27 Jul '09

Hello List, I would like to have a templated parse function within each of my states. Unfortunatly I am unable to successfully create a version that compiles, perhaps if someone could show how to get it to work. Here is the code: namespace xml { class prolog; template<typename T> class Entity { public: virtual boost::regex regex() const = 0; virtual void parse(T,T) = 0; }; class document : public boost::statechart::state_machine< document, prolog > { public: virtual ~document( ) {}; private: friend class prolog; static boost::regex character, white_space, name_start_character, name_character, name, names, nmtoken, nmtokens, comment, process_instruction_target, process_instruction, CDATA, equal, version_info, encoding_name, encoding_declaration, standalone_document_declaration, xml_declaration, prolog; protected: document( ) { initiate(); }; template<typename T> boost::regex regex( ) const { return state_cast<const Entity<T>&>().regex(); }; template<typename T> void parse( T begin, T end ) { return state_cast<const Entity<T>&>().parse(begin,end); } }; class prolog : public Entity ///<-----needs argument here but compains the 'prolog' is NOT a template , public boost::statechart::simple_state< prolog, document > { public: prolog( ) {}; ~prolog( ) {}; virtual boost::regex regex( ) const { return document::prolog;//FIXME...match element aswell }; virtual void parse( T begin, T end ) { }; private: protected: }; }; Any help on this will be appreciated. Thank you all. Etienne

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Database Template Libraries
by Etienne Philip Pretorius 27 Jul '09

27 Jul '09

Hello list, Just a quick question, are there boost libraries that are similar to this: http://dtemplatelib.sourceforge.net/ If not are there any plans for a generic boost database template library? Just Wandering. Etienne

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boost.datetime query
by Sean Farrow 27 Jul '09

27 Jul '09

Hi: I am working on a project whereby I need the date in the format yyyy-mm-dd (iso format). Am I write in thinking that the boost::Gregorian::to_Iso_string function will do this for me given a date as it's argument? I seem to have some discrepancies between the Embarcadero c++ 2009 implementation of that function and what I think should be happening having used the ms vc++ built version. Any help appreciated. Sean.

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test boost::try_mutex is locked or not
by Boost lzw 26 Jul '09

26 Jul '09

Hi everyone, I just did not find the right member function for it. Can anyone point out the correct function I should use? Thanks. CODE: ----------- boost::try_mutex resourceX; boost::try_mutex::scoped_lock lockX(resourceX); ... if(lockX.locked() == false) // compilation error do sth. ----------- The compiler complains that locked() is not a member function of boost::try_mutex Cheers, Robert

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Number of cores
by Ruediger Berlich 26 Jul '09

26 Jul '09

Hi there, is there a possibility in Boost to find out the number of processor(-core)s on a local system in a platform-independent way ? I'd like to start a corresponding number of threads. Thanks and Best Regards, Ruediger

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problem with boost::phoenix::lambda
by Kim Kuen Tang 25 Jul '09

25 Jul '09

Hi all, the following code double abc=lambda(_a=*ref(it)++)[_a*2.0]()(); // here 'it' is an //iterator produces the error C2440: 'initializing' : cannot convert from 'boost::phoenix::detail::error_expecting_arguments' to 'double' which should not be. The two lines of code let(_a=*ref(it)++)[_a*2.0](); //or lambda(_a=*ref(it)++)[_a*2.0*arg1]()( val); compile fine. Perhaps someone has an answer to this error? ( I use boost trunk version and msvc 2008) To reproduce the errors just compile the code below. Best regards Kim Tang # include <algorithm> # include <vector> # include <boost/spirit/include/phoenix.hpp> using namespace boost::phoenix; using namespace boost::phoenix::arg_names; using namespace boost::phoenix::local_names; int main() { std::vector<double> u(11,1.0); std::vector<double> w(11,2.0); std::vector<double>::const_iterator it=w.begin(); //boost::phoenix::generate(ref(u) // ,lambda(_a=*ref(it)++)[_a*2.0 ] //)(); double abc=lambda(_a=*ref(it)++)[_a*2.0]()(); return 0; }

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Problem in running blocking_udp_echo_client on MacOSX
by n179911 25 Jul '09

25 Jul '09

I am trying to run blocking_udp_echo_client on MacOS X http://www.boost.org/doc/libs/1_35_0/doc/html/boost_asio/example/echo/block… I run it with argument 'localhost 9000' But the program crashes and this is the line in the source which crashes: udp::socket s(io_service, udp::endpoint(udp::v4(), 0)); this is the stack trace: #0 0x918c3e42 in __kill #1 0x918c3e34 in kill$UNIX2003 #2 0x9193623a in raise #3 0x91942679 in abort #4 0x940d96f9 in __gnu_debug::_Error_formatter::_M_error #5 0x0000e76e in __gnu_debug::_Safe_iterator<__gnu_norm::_List_iterator<std::pair<int, boost::asio::detail::reactor_op_queue<int>::op_base*> >, __gnu_debug_def::list<std::pair<int, boost::asio::detail::reactor_op_queue<int>::op_base*>, std::allocator<std::pair<int, boost::asio::detail::reactor_op_queue<int>::op_base*> > > >::_Safe_iterator at safe_iterator.h:124 #6 0x00014729 in boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type::bucket_type at hash_map.hpp:277 #7 0x00019e97 in std::_Construct<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type, boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type> at stl_construct.h:81 #8 0x0001a457 in std::__uninitialized_fill_n_aux<__gnu_cxx::__normal_iterator<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type*, __gnu_norm::vector<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type, std::allocator<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type> > >, unsigned long, boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type> at stl_uninitialized.h:194 #9 0x0001a4e1 in std::uninitialized_fill_n<__gnu_cxx::__normal_iterator<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type*, __gnu_norm::vector<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type, std::allocator<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type> > >, unsigned long, boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type> at stl_uninitialized.h:218 #10 0x0001a509 in std::__uninitialized_fill_n_a<__gnu_cxx::__normal_iterator<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type*, __gnu_norm::vector<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type, std::allocator<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type> > >, unsigned long, boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type, boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type> at stl_uninitialized.h:310 #11 0x0001aa34 in __gnu_norm::vector<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type, std::allocator<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type> >::_M_fill_insert at vector.tcc:365 #12 0x0001acda in __gnu_norm::vector<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type, std::allocator<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type> >::insert at stl_vector.h:658 #13 0x0001ad81 in __gnu_norm::vector<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type, std::allocator<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type> >::resize at stl_vector.h:427 #14 0x0001ae3a in __gnu_debug_def::vector<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type, std::allocator<boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::bucket_type> >::resize at vector:169 #15 0x0001b7be in boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::rehash at hash_map.hpp:221 #16 0x0001bbeb in boost::asio::detail::hash_map<int, boost::asio::detail::reactor_op_queue<int>::op_base*>::hash_map at hash_map.hpp:67 #17 0x0001bc74 in boost::asio::detail::reactor_op_queue<int>::reactor_op_queue at reactor_op_queue.hpp:42 #18 0x0001bd24 in boost::asio::detail::kqueue_reactor<false>::kqueue_reactor at kqueue_reactor.hpp:86 #19 0x0001c000 in boost::asio::detail::service_registry::use_service<boost::asio::detail::kqueue_reactor<false> > at service_registry.hpp:109 #20 0x0001c14d in boost::asio::use_service<boost::asio::detail::kqueue_reactor<false> > at io_service.ipp:195 #21 0x0001c26d in boost::asio::detail::reactive_socket_service<boost::asio::ip::udp, boost::asio::detail::kqueue_reactor<false> >::reactive_socket_service at reactive_socket_service.hpp:111 #22 0x0001c344 in boost::asio::detail::service_registry::use_service<boost::asio::detail::reactive_socket_service<boost::asio::ip::udp, boost::asio::detail::kqueue_reactor<false> > > at service_registry.hpp:109 #23 0x0001c491 in boost::asio::use_service<boost::asio::detail::reactive_socket_service<boost::asio::ip::udp, boost::asio::detail::kqueue_reactor<false> > > at io_service.ipp:195 #24 0x0001c4d5 in boost::asio::datagram_socket_service<boost::asio::ip::udp>::datagram_socket_service at datagram_socket_service.hpp:95 #25 0x0001c59e in boost::asio::detail::service_registry::use_service<boost::asio::datagram_socket_service<boost::asio::ip::udp> > at service_registry.hpp:109 #26 0x0001c6eb in boost::asio::use_service<boost::asio::datagram_socket_service<boost::asio::ip::udp> > at io_service.ipp:195 #27 0x0001c711 in boost::asio::basic_io_object<boost::asio::datagram_socket_service<boost::asio::ip::udp> >::basic_io_object at basic_io_object.hpp:72 #28 0x0001c783 in boost::asio::basic_socket<boost::asio::ip::udp, boost::asio::datagram_socket_service<boost::asio::ip::udp> >::basic_socket at basic_socket.hpp:108 #29 0x0001c865 in boost::asio::basic_datagram_socket<boost::asio::ip::udp, boost::asio::datagram_socket_service<boost::asio::ip::udp> >::basic_datagram_socket at basic_datagram_socket.hpp:107 #30 0x000027bc in main at main.cpp:32 This is the gdb output: (gdb) continue /Developer/SDKs/MacOSX10.5.sdk/usr/include/c++/4.0.0/debug/safe_iterator.h:127: error: attempt to copy-construct an iterator from a singular iterator. Objects involved in the operation: iterator "this" @ 0x0x100420 { type = N11__gnu_debug14_Safe_iteratorIN10__gnu_norm14_List_iteratorISt4pairIiPN5boost4asio6detail16reactor_op_queueIiE7op_baseEEEEN15__gnu_debug_def4listISB_SaISB_EEEEE (mutable iterator); state = singular; } iterator "other" @ 0x0xbfffe8a4 { type = N11__gnu_debug14_Safe_iteratorIN10__gnu_norm14_List_iteratorISt4pairIiPN5boost4asio6detail16reactor_op_queueIiE7op_baseEEEEN15__gnu_debug_def4listISB_SaISB_EEEEE (mutable iterator); state = singular; } Program received signal: “SIGABRT”. (gdb) continue Program received signal: “?”. Does someone has any idea why this example does not work on mac osx? Thank you.

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Using boost library on MacOSx
by n179911 25 Jul '09

25 Jul '09

Hi, I have install boost library using this: $ sudo port install boost It seems download and compile fine on my local machine. But then i tried to compile a simple echo client example from http://www.boost.org/doc/libs/1_35_0/doc/html/boost_asio/examples.html I get a bunch of compiler errors. I am using "g++ -o block_client blocking_udp_echo_client.cpp " Here are some of the errors: $ g++ -o block_client blocking_udp_echo_client.cpp blocking_udp_echo_client.cpp:68:10: error: #include expects "FILENAME" or <FILENAME> blocking_udp_echo_client.cpp:69:10: error: #include expects "FILENAME" or <FILENAME> blocking_udp_echo_client.cpp:70:10: error: #include expects "FILENAME" or <FILENAME> blocking_udp_echo_client.cpp:71:10: error: #include expects "FILENAME" or <FILENAME> blocking_udp_echo_client.cpp:83: error: stray ‘\’ in program blocking_udp_echo_client.cpp:108: error: stray ‘\’ in program blocking_udp_echo_client.cpp:112: error: stray ‘\’ in program Thank you for any help.

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A lambda and boost function problem. Can any one with kindness help me?
by fmingu 25 Jul '09

25 Jul '09

I am using Dev-C++ 4.9.8.0 and lambda expression. I builded a class and put it into a dll made by myself. The dll will be used by else's programs which contain the functions that I do not know. All I know is just the function type.So I used the boost function library. ............ class classA{ ................. public: boost::function<double (const int& )> theunknownfunc; ........................ and a member function in classA used such function: double classA::function1( int& q, const int& n){ double result=0.0; int loopvalue=1, totaltime=thenumbern; int innern=1; ( for_loop(var(loopvalue)=1,var(loopvalue)<=var(totaltime),++var(loopvalue), (var(result)+= ( bind(&classA::theunknownfunc,this,_2)*bind(&classA::function2,this,_1,_2)), ++_2,_2%=_1))) (q,innern); return result; } ................. but the complier told me that: instantiated from `RET boost::lambda::lambda_functor_base<boost::lambda::forloop_action, Args>::call(A&, B&, C&, Env&) const [with RET = void, A = int, B = int, C = const boost::tuples::null_type,<............. instantiated from `T::sig<boost::tuples::tuple<A&, B&, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, .............. instantiated from here The user do not want to read the source code of mine since it is built with many lambda expressions. He just want to use the dll. And I do not know how to solve it by using boost function library. Can anyone with kindness help me?

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[filesystem] Strange seg.faults of boost::filesystem under ElectricFence
by Pavel Shevaev 25 Jul '09

25 Jul '09

Folks, I'm trying to spot a memory corruption error in my application using ElectricFence[1] and I'm facing really weird segfaults in boost::filesystem. I don't really believe it is boost::filesystem which causes a seg.fault but rather my improper usage of ElectricFence. Here is the most interesting part of the core dump: #0 0x00007f2b4aa1c517 in kill () from /lib/libc.so.6 #1 0x000000000048f46b in on_signal (s=4) at main.cpp:180 #2 <signal handler called> #3 0x00007f2b4aa1c517 in kill () from /lib/libc.so.6 #4 0x00007f2b4b4e746f in ?? () from /usr/lib/libefence.so.0 #5 0x00007f2b4b4e8290 in _eff_deallocate () from /usr/lib/libefence.so.0 #6 0x00007f2b4b4e884e in _eff_allocate () from /usr/lib/libefence.so.0 #7 0x00007f2b4b4e7288 in operator new () from /usr/lib/libefence.so.0 #8 0x00007f2b4b27d711 in std::string::_Rep::_S_create () from /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.3/libstdc++.so.6 #9 0x00007f2b4b27e0d5 in ?? () from /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.3/libstdc++.so.6 #10 0x00007f2b4b27e213 in std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string () from /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.3/libstdc++.so.6 #11 0x00007f2b4cbaa81e in boost::filesystem::detail::dir_itr_first () from /home/game/hg/master_49100/shared/scripts/../lib/boost/build/lib/libboost_filesystem-mt.so Basically the following line in my app cases the seg.fault: boost::filesystem::directory_iterator dir_iter(path); Inspecting path variable under gdb shows it's ok and actuall directory exists. Here is some information about my application: * built with gcc-4.3.3 * runs under linux-2.6.29-gentoo * uses boost-1.35 * boost is built with options: ./bjam link=shared --build-type=minimal --layout=system --toolset=gcc * ElectricFence built from gentoo package efence-2.4.13-r1 The question is whether there are any special boost build options which should be used with ElectricFence. Thanks in advance. [1]http://www.pf-lug.de/projekte/haya/efence.php -- Best regards, Pavel

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