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BGL: get(p, g, x) and get(get(p, g), x)
by Shaun Jackman 11 May '12

11 May '12

Hi, I’ve implemented a graph that’s quite similar to adjacency_list. get(get(vertex_index, g), u) works as expected, but get(vertex_index, g, u) does not work. Is their a default implementation in boost/graph somewhere that translates the latter call to the first, or does my graph have to implement the following function? template <typename Tag, typename Key> typename property_map_value<MyGraph, Tag>::type get(Tag tag, const MyGraph& g, Key key) { return get(get(tag, g), key); } When I include this implementation, the get(tag, g, u) call works as expected. Cheers, Shaun

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multiprecision (/sandbox/big_number/) - pow function
by Ryan Lichtenwalter 11 May '12

11 May '12

I am using the multiprecision library from /sandbox/big_number compiling with boost 1.49.0. Specifically, I am using cpp_int. I can successfully compile and run the following example: #include <boost/multiprecision/cpp_int.hpp> using namespace boost::multiprecision; cpp_int u = 1; for(unsigned i = 1; i <= 100; ++i) u *= i; std::cout << u << std::endl; // prints 100! which I obtained from: https://svn.boost.org/svn/boost/sandbox/big_number/libs/multiprecision/doc/… When I add the following code: cpp_int x; x = pow( u, 2 ); I receive the following compiler error (g++ 4.1.2): ./boost/boost/multiprecision/detail/functions/pow.hpp: In function ‘void boost::multiprecision::default_ops::eval_pow(T&, const T&, const U&) [with T = boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, U = int]’: ./boost/boost/multiprecision/detail/default_ops.hpp:1250: instantiated from ‘void boost::multiprecision::detail::pow_funct<Backend>::operator()(Backend&, const Backend&, const Arithmetic&) const [with Arithmetic = int, Backend = boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >]’ ./boost/boost/multiprecision/mp_number.hpp:1089: instantiated from ‘void boost::multiprecision::mp_number<Backend, ExpressionTemplates>::do_assign_function_2(const F&, const Exp1&, const Exp2&, const boost::multiprecision::detail::terminal&, const boost::multiprecision::detail::terminal&) [with F = boost::multiprecision::detail::pow_funct<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> > >, Exp1 = boost::multiprecision::detail::mp_exp<boost::multiprecision::detail::terminal, boost::multiprecision::mp_number<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, true>, void, void>, Exp2 = boost::multiprecision::detail::mp_exp<boost::multiprecision::detail::terminal, int, void, void>, Backend = boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, bool ExpressionTemplates = true]’ ./boost/boost/multiprecision/mp_number.hpp:1084: instantiated from ‘void boost::multiprecision::mp_number<Backend, ExpressionTemplates>::do_assign_function(const Exp&, const mpl_::int_<3>&) [with Exp = boost::multiprecision::detail::mp_exp<boost::multiprecision::detail::function, boost::multiprecision::detail::pow_funct<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> > >, boost::multiprecision::mp_number<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, true>, int>, Backend = boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, bool ExpressionTemplates = true]’ ./boost/boost/multiprecision/mp_number.hpp:973: instantiated from ‘void boost::multiprecision::mp_number<Backend, ExpressionTemplates>::do_assign(const Exp&, const boost::multiprecision::detail::function&) [with Exp = boost::multiprecision::detail::mp_exp<boost::multiprecision::detail::function, boost::multiprecision::detail::pow_funct<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> > >, boost::multiprecision::mp_number<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, true>, int>, Backend = boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, bool ExpressionTemplates = true]’ ./boost/boost/multiprecision/mp_number.hpp:570: instantiated from ‘void boost::multiprecision::mp_number<Backend, ExpressionTemplates>::do_assign(const boost::multiprecision::detail::mp_exp<tag, Arg1, Arg2, Arg3>&, const mpl_::true_&) [with tag = boost::multiprecision::detail::function, Arg1 = boost::multiprecision::detail::pow_funct<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> > >, Arg2 = boost::multiprecision::mp_number<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, true>, Arg3 = int, Backend = boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, bool ExpressionTemplates = true]’ ./boost/boost/multiprecision/mp_number.hpp:95: instantiated from ‘boost::multiprecision::mp_number<Backend, ExpressionTemplates>& boost::multiprecision::mp_number<Backend, ExpressionTemplates>::operator=(const boost::multiprecision::detail::mp_exp<tag, Arg1, Arg2, Arg3>&) [with tag = boost::multiprecision::detail::function, Arg1 = boost::multiprecision::detail::pow_funct<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> > >, Arg2 = boost::multiprecision::mp_number<boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, true>, Arg3 = int, Backend = boost::multiprecision::backends::cpp_int_backend<0u, true, std::allocator<unsigned int> >, bool ExpressionTemplates = true]’ vcp_translator_test.cpp:24: instantiated from here ./boost/boost/multiprecision/detail/functions/pow.hpp:89: error: invalid application of ‘sizeof’ to incomplete type ‘boost::STATIC_ASSERTION_FAILURE<false>’ Different invocations of pow with the arbitrary precision argument as the base, exponent, or both yield different compiler errors, but all of them seem to be broken. Am I doing something wrong? Is there some other fast way to achieve exponentiation with this library? Thanks, Ryan

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Interval Timers - Boost 1.49.0
by asif saeed 11 May '12

11 May '12

Hi, >From 1.49.0 release notes: "ASIO : Added a new class template basic_waitable_timer based around the C++11 clock type requirements. It may be used with the clocks from the C++11 <chrono> library facility or, if those are not available, Boost.Chrono. The typedefs high_resolution_timer, steady_timer and system_timer may be used to create timer objects for the standard clock types". I haven't yet looked into these facilities much - I only want to know if I can use any one or more of these facilities to create a periodic interval timer that could call my callback after every, say, 10 milliseconds. Has this been incorporated? Someone in an earlier thread said that ASIO deadline timer could be used but that doesn't work if system clock gets modified by the code itself. I look forward to receiving your feedback on this. -Asif

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[BGL] remove all children of a given vertex in a directed graph
by NsPx 11 May '12

11 May '12

Hi all, I would like to delete a vertex and all its children vertices in a directed graph. For example, 0 <-- 1 1 <-- 2 1 <-- 3 3 <-- 5 0 <-- 4 Removing 1 will remove 2, 3, 5 too. I have read the doc which explains how to remove all vertices from a graph but for my case it's a little more complicated and I can't find a clean way to do it. Thanks by advance for helping me. Here is what I planned to do but it isn't working : ### typedef adjacency_list<boost::vecS, boost::vecS, boost::bidirectionalS, vertex_info> Graph; typedef Graph::vertex_descriptor vertexGraph; Graph* myGraph; //given graph vertexGraph vpos; //given vertex vector<vertexGraph> vertsLvl, allChildren; vector<vertexGraph>::iterator it, ite; vertsLvl.push_back(vpos); while( !vertsLvl.empty() ) { vector<vertexGraph> tmp; // all children of the vertsLvl's vertices for( it=vertsLvl.begin(), ite=vertsLvl.end(); it!=ite; ++it) { vector<vertexGraph> children; this->getChildren(*it, children); allChildren.insert( allChildren.end(), children.begin(), children.end()); tmp.insert( tmp.end(), children.begin(), children.end()); // remove edges between vertices from vertsLvl and their children clear_in_edges(*it, *myGraph); } vertsLvl = tmp; } // remove all children and the given vertex : doesn't work for( it=allChildren.begin(), ite=allChildren.end(); it!=ite; ++it) { remove_vertex(*it, *myGraph); } ###

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The callback of the timer inside a thread is not called
by mozdemir 11 May '12

11 May '12

Hi, I am trying to make the attached code run but no luck. I use the compiler, gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3. I tried all combinations. The timer callback, handle_timeout is never called. The weird thing is that the similar code in windows using msvc works fine. Could anybody help me out to figure out the issue in the code below? Thanks a lot in advance, mustafa ============================================================ #include <boost/asio.hpp> #include <boost/thread.hpp> #include <boost/date_time.hpp> #include <boost/date_time/gregorian/gregorian.hpp> #include <ctime> #include <iostream> struct time_t_traits { // The time type. typedef std::time_t time_type; // The duration type. struct duration_type { duration_type() : value(0) {} duration_type(std::time_t v) : value(v) {} std::time_t value; }; // Get the current time. static time_type now() { return std::time(0); } // Add a duration to a time. static time_type add(const time_type& t, const duration_type& d) { return t + d.value; } // Subtract one time from another. static duration_type subtract(const time_type& t1, const time_type& t2) { return duration_type(t1 - t2); } // Test whether one time is less than another. static bool less_than(const time_type& t1, const time_type& t2) { return t1 < t2; } // Convert to POSIX duration type. static boost::posix_time::time_duration to_posix_duration( const duration_type& d) { return boost::posix_time::seconds(d.value); } }; typedef boost::asio::basic_deadline_timer< std::time_t, time_t_traits> time_t_timer; void handle_timeout(const boost::system::error_code&) { std::cout << "handle_timeout\n"; } boost::asio::io_service io_service; void workerFunc() { using namespace boost::gregorian; boost::posix_time::seconds workTime(8); std::cout << "Worker: running" << std::endl; try { boost::asio::strand io_strand(io_service); time_t_timer timer(io_service); timer.expires_from_now(5); std::cout << "Starting synchronous wait\n"; timer.wait(); std::cout << "Finished synchronous wait\n"; timer.expires_from_now(5); std::cout << "Starting asynchronous wait\n"; // timer.async_wait(&handle_timeout); // timer.async_wait(&handle_timeout); // std::cout << "current UTC time is '" << to_simple_string(microsec_clock::universal_time()) << "'" << std::endl; // std::cout << "current local time is '" << to_simple_string(microsec_clock::local_time()) << "'" << std::endl; std::cout << "timer is set to expire at '" << timer.expires_at() << "'" << std::endl; timer.async_wait(io_strand.wrap(&handle_timeout)); std::cout << "Finished asynchronous wait\n"; } catch (std::exception& e) { std::cout << "Exception: " << e.what() << "\n"; } // Pretend to do something useful... boost::this_thread::sleep(workTime); std::cout << "Worker: finished" << std::endl; while(true) { boost::this_thread::sleep(boost::posix_time::seconds(1)); } } int main(int argc, char* argv[]) { std::cout << "main: startup" << std::endl; boost::thread thrd_io(boost::bind(&boost::asio::io_service::run, &io_service)); std::cout << "main: after thrd_io" << std::endl; boost::thread workerThread(workerFunc); std::cout << "main: after workerThread" << std::endl; // std::cout << "main: waiting for thread" << std::endl; while ( true ) { try { // io_service.poll(); io_service.run(); // boost::this_thread::sleep(boost::posix_time::milliseconds( 20 )); } catch (const boost::thread_interrupted&) { // Thread interruption request received, break the loop std::cout << "[" << boost::this_thread::get_id() << "] WorkerThread Thread interrupted. Exiting thread."; break; } catch ( std::exception & ex ) { std::cout << "[" << boost::this_thread::get_id() << "] Exception: " << ex.what(); } } workerThread.join(); std::cout << "main: done" << std::endl; return 0; } ===================================================== this is the output when the exe file is run. You don't see this line: "handle_timeout" ===================================================== $./timer main: startup main: after workerThread main: after thrd_io Worker: running Starting synchronous wait Finished synchronous wait Starting asynchronous wait timer is set to expire at '1336627143' Finished asynchronous wait Worker: finished -- View this message in context: http://boost.2283326.n4.nabble.com/The-callback-of-the-timer-inside-a-threa… Sent from the Boost - Users mailing list archive at Nabble.com.

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How can i install 32bit libboost lib on Debian6-64bit platform
by clive 11 May '12

11 May '12

Hi,all friends I build my project on Debian6-32bit platform, It works ok. I copy the build result to Debian6-64bit platform and run, it shows:error while loading shared libraries:libboost_regex.so.1.42.0:can not open shared object file:No such file or directory Then i do whereis libboost_regex.so.1.42.0, it shows: libboost_regex.so.1.42: /usr/lib/libboost_regex.so.1.42.0 /usr/lib64/libboost_regex.so.1.42.0 Then i add /usr/lib/ in ld.so.conf, then i run my project, it shows:error while loading shared libraries: libboost_regex.so.1.42.0: wrong ELF class: ELFCLASS64 I'm sure that install libboost-regex on Debian6-64bit platform, the lib don't compatible 32bit. How can i install 32bit libboost lib on Debian6-64bit platform?

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Re: [Boost-users] Is boost::asio::ip::tcp::iostream thread safe?
by boost 11 May '12

11 May '12

Thank you all ----- Original Message -----From: Michael Chisholm <chisholm(a)mitre.org> To: boost-users(a)lists.boost.org On 5/10/2012 5:34 PM, Michael Chisholm wrote: > On 5/10/2012 10:38 AM, Igor R wrote: >>> hi all, >>> I use ip::tcp::iostream but I don't know if it is thread safe, and I >>> cannot find the answer in boost document. >>> I read from ip::tcp::iostream in the receiver thread, and send >>> request in another thread. >>> Now I protected the stream with a mutex. But the problem is that, if >>> I do not send request, the server will not response, >>> and the receiver will block on read with lock, and the sender cannot >>> hold the lock and cannot send the request, deadlock. >>> >>> Is there anyone know that? Please kindly give me an answer. >> >> >> As far as I can see, it's not thread-safe. >> _______________________________________________ >> Boost-users mailing list >> Boost-users(a)lists.boost.org >> http://lists.boost.org/mailman/listinfo.cgi/boost-users >> >> > > Definitely not. I had to create my own socket-based stream with > boost.iostreams to avoid crashes. > > Andy I should add that boost.iostreams isn't thread-safe either. But you can create different istream and ostream objects which wrap the same underlying raw socket descriptor, to get concurrent reads and writes to the socket. Andy _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Is boost::asio::ip::tcp::iostream thread safe?
by boost 10 May '12

10 May '12

hi all, I use ip::tcp::iostream but I don't know if it is thread safe, and I cannot find the answer in boost document. I read from ip::tcp::iostream in the receiver thread, and send request in another thread. Now I protected the stream with a mutex. But the problem is that, if I do not send request, the server will not response, and the receiver will block on read with lock, and the sender cannot hold the lock and cannot send the request, deadlock. Is there anyone know that? Please kindly give me an answer. Best Regards Zhanwei Wang

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[Boost users] [ublas] Type conversion warning with ublas::bounded_vector
by Matija Kecman 10 May '12

10 May '12

Hi Boost users! Is there a way for boost.ublas to warn of type conversions with ublas::bounded_vector's? I'm using this library for scientific computations and I came across this problem, I have quite a large code so I would be useful to know if this mistake occurs elsewhere. Here is a code example: int main() { double d = M_PI; unsigned u = d; cout << "d = " << d << endl; cout << "u = " << u << endl; bounded_vector<double,3> dVec = ublas::scalar_vector<double>(3,M_PI); bounded_vector<unsigned,3> uVec = dVec; // ATTENTION: type conversion! cout << "dVec = " << dVec << endl; cout << "uVec = " << uVec << endl; return 0; } When I compile this using g++ 4.6.1: g++ -g3 -Wall -Wextra -ansi -pedantic -Wconversion -std=c++0x test.cpp -o test I get the following warnings: test.cpp: In function ‘int main()’: test.cpp:11:22: warning: conversion to ‘unsigned int’ from ‘double’ may alter its value [-Wconversion] Program output: $ ./test d = 3.14159 u = 3 dVec = [3](3.14159,3.14159,3.14159) uVec = [3](3,3,3) The compiler produced a warning for the conversion of the scalars but there was no warning for the ublas conversion, is there a way of having the compiler write a warning in that case? -Wconversion or any of the other options don't do this. Best, Matija

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[Boost users] [Program_options] Is Boost.Program_options available as a header?
by Matija Kecman 10 May '12

10 May '12

Hi Boost users, I'm quite new to boost. I have written a program using the Boost Program Options library. In order to compile it I have to link with the boost program options library. I would like to run my program on a computer which only has access to boost headers. I was wondering if the program options library is available as a header only? If not, it would be interesting to know the reason for that :) Best, Matija

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