February 2013 - Boost-users - lists.preview.boost.org

Re: [Boost-users] [Graph] "Weighted Bacon number" (depth from node) with dijkstra visitor
by Tasos 04 Feb '13

04 Feb '13

Yes, Im just blind, it was so simple. Thanks a lot for your help. Best, Tasos

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[Graph] "Weighted Bacon number" (depth from node) with dijkstra visitor
by The Maschine 04 Feb '13

04 Feb '13

Hi all, In order to find the depth of a source_node from other nodes in my graph, without weights, I use this simple example of the bacon BFS visitor via the tree_edge(). I also count the number of nodes from that source. //////// class bfs_vis : public boost::default_bfs_visitor { public: bfs_vis(unGraph::vertex_descriptor source, boost::shared_ptr< VertexStorage> storage) : s(source), cont(storage) { } template <typename Edge, typename Graph> void tree_edge(Edge e, const Graph& g) const { typename boost::graph_traits<Graph>::vertex_descriptor u = source(e, g), v = target(e, g); cont->depth_from->at(v) = cont->depth_from->at(u) + 1.0; } template <typename Edge, typename Graph> void discover_vertex(Edge e, Graph& g) { cont->node_count = cont->node_count + 1; } private: boost::shared_ptr<VertexStorage> cont; unGraph::vertex_descriptor s; }; //////// What would be an equivalent visitor for Dijkstra? Node count is ok but how do I calculate a "weighted bacon number" with dijkstra (boost::property<boost::edge_weight_t, float>)?? Thanks, Tasos

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Re: [Boost-users] Boost-users Digest, Vol 3349, Issue 1
by Torsten＠Robitzki.de 04 Feb '13

04 Feb '13

Hi Igor, Am 04.02.2013 um 14:15 schrieb boost-users-request(a)lists.boost.org: > Send Boost-users mailing list submit >> >> s.close(); // first time to cancel outstanding handlers >> s.close(); // a second time, later in the d'tor >> But what does 'Bad file descriptor' mean in this context? Is the underlying socket is somehow broken/corrupted? If so, there must be >> a bug in my code. If not, is it save to simply ignore the error? > > > It means that tcp::socket is closed (and the underlying native > descriptor is something like -1). do you think there is something wrong with closing the socket a second time? The documentation doesn't states any precondition. kind regards Torsten

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[function / bind] How to register callbacks using boost::function/bind?
by Olivier Tournaire 04 Feb '13

04 Feb '13

Hi all, I am trying to use a callback mechanism for logging in my app. I thus have a class with : class coordinates_converter { public: coordinates_converter(int id); ~coordinates_converter(); void register_error_callback (const boost::function<void(std::string message)> &callback ) { _error_callback = callback; } private: boost::function<void(std::string message)> _error_callback; } Now, if I want to register a log error callback in another object instance, how should I do this? Cannot find the right syntax ... void another_class::do() { acute_coordinates_converter* converter = new coordinates_converter(2154); converter->register_error_callback( boost::bind(&another_class::log_error, converter, _1) ); } where log_error is a Qt SIGNAL: signals: void log_error(const std::string& error); Hope you could help. Rehads, Olivier

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[asio] How to handle 'Bad file descriptor'
by Torsten＠Robitzki.de 03 Feb '13

03 Feb '13

Hello, I have problems to understand, what might causing a 'Bad file descriptor' exception to be thrown in my application. The exception is most likely thrown by a call to tcp::socket::close. From the logs I have, I'm quit certain, that the last function calls on a socket are: s.shutdown(tcp::socket::shutdown_receive); s.shutdown(tcp::socket::shutdown_send); s.close(); // first time to cancel outstanding handlers s.close(); // a second time, later in the d'tor I'm not sure, whether it's the first or the second call to close(), that causes the exception. But what does 'Bad file descriptor' mean in this context? Is the underlying socket is somehow broken/corrupted? If so, there must be a bug in my code. If not, is it save to simply ignore the error? The program is not single threaded, but there is only one boost::io_service object which is run by a single dedicated thread. Kind reagards Torsten P.S: if someone interested in the code: https://github.com/TorstenRobitzki/Sioux/blob/master/source/server/connecti…; it's open source

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[program options] count problem
by Olivier Tournaire 03 Feb '13

03 Feb '13

Hi all, I am having troubles with program options. I try to test if at least some of the available options are passed on the command line, but fail for some reason using count("option_name"). Here is my code: int main(int argc, char** argv) { string hierarchy; vector<string> files, directories; double vertical_shift; bool show_progress, single_file, single_dir; int target_EPSG, nb_threads; po::options_description desc("Allowed options"); desc.add_options() ("help ,h" , "Produce help message") ("hierarchy ", po::value<string>(&hierarchy) , "process a hierarchy) ("file ", po::value<vector<string> >(&files) , "process the specified files") ("directory ", po::value<vector<string> >(&directories) , "process the specified directories"); po::variables_map vm; try { po::store(po::parse_command_line(argc, argv, desc), vm); if (vm.count("help")) { cout << desc << "\n"; return 1; } po::notify(vm); } catch (const po::error &e) { cerr << "Exception caught ! --> " << e.what() << endl; cout << desc << endl; return 1; } if (vm.count("hierarchy")) { path input_path(hierarchy); // DO STUFF } else if (vm.count("files")) { for(unsigned int i=0;i<files.size();++i) { path input_path(files[i]); // DO STUFF } } else if (vm.count("directories")) { for(unsigned int i=0;i<directories.size();++i) { path input_path(directories[i]); // DO STUFF } } else { cout << "You must choose an option between --hierarchy --files --directories!" << endl; cout << desc << endl; return 1; } I always fall in the "else". What am I doing wrong? For instance with this command line : ./acute_coordinates_transform --hierarchy ~/work/data/ À other question: is there à way to specify that 1 of the 3 options is required (and only 1)? Hope you cloud help. Regards, Olivier

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SIGSEGV in libboost_serialization.so.1.40.0 type_unregister
by Prasanna .S 03 Feb '13

03 Feb '13

Hey guys, I'm getting a seg fault, after the program successfully runs, and is trying to exit. Stack trace is below. Program received signal SIGSEGV, Segmentation fault. 0x00007ffff709fa2f in boost::serialization::detail::extended_type_info_typeid_0::is_less_than(boost::serialization::extended_type_info const&) const () from /usr/lib/libboost_serialization.so.1.40.0 (gdb) bt #0 0x00007ffff709fa2f in boost::serialization::detail::extended_type_info_typeid_0::is_less_than(boost::serialization::extended_type_info const&) const () from /usr/lib/libboost_serialization.so.1.40.0 #1 0x00007ffff709faed in boost::serialization::detail::extended_type_info_typeid_0::type_unregister() () from /usr/lib/libboost_serialization.so.1.40.0 #2 0x000000000047985b in boost::serialization::detail::singleton_wrapper<boost::serialization::extended_type_info_typeid<DeltaStore::Location> >::~singleton_wrapper() () #3 0x00007ffff6567262 in exit () from /lib/libc.so.6 #4 0x00007ffff654cc54 in __libc_start_main () from /lib/libc.so.6 #5 0x0000000000411f59 in _start () I do `apt-get install libboost-all-dev` on a ubuntu 10.04 box; Any help is much appreciated. Thanks, -Prasanna $ g++ -v Using built-in specs. Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.4.3-4ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 --program-suffix=-4.4 --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-plugin --enable-objc-gc --disable-werror --with-arch-32=i486 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 4.4.3 (Ubuntu 4.4.3-4ubuntu5)

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[qi] parser stocks inside an endless loop
by Boost_mailinglist＠gmx.de 03 Feb '13

03 Feb '13

Hello, the attached example will stock inside an endless loop if I use /*loop*/ Variable = *char_("a-zA-Z_0-9")>> ... but works if I use /*works*/ Variable = &char_("a-zA-Z")>> *char_("a-zA-Z_0-9")>> ... or /*works also*/ Variable = +char_("a-zA-Z_0-9")>> ... . Why does it happen? And how can I prevent this behaviour? Best regards

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how to use boost::shared_ptr?
by young 01 Feb '13

01 Feb '13

I have a class member (boost::shared_ptr): class XYZ { private: boost::shared_ptr<int> m_pBuff; // other member ... public: void func(int n) { m_pBuff.reset(new int[n]); // or m_pBuff = boost::shared_ptr<int>(new int[n]) ...; } // other functions ... } The func(n) will be called many times inside / outside the class. Can I use shared_ptr here like: m_pBuff.reset(new int[n]); or m_pBuff = boost::shared_ptr<int>(new int[n]); I tried both and get error said heap corruption. -- View this message in context: http://boost.2283326.n4.nabble.com/how-to-use-boost-shared-ptr-tp4642120.ht… Sent from the Boost - Users mailing list archive at Nabble.com.

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Re: [Boost-users] [Graph] visitor dijkstra_shortest_paths
by The Maschine 01 Feb '13

01 Feb '13

Thanks a lot, even though I read half of the BGL book I didnt get this difference. I cant say Im good with techniques like that. Best, Tasos > > ---------------------------------------------------------------------- > > Message: 1 > Date: Thu, 31 Jan 2013 11:12:29 -0500 (EST) > From: Jeremiah Willcock <jewillco(a)osl.iu.edu> > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] [Graph] visitor dijkstra_shortest_paths > Message-ID: <alpine.LRH.2.03.1301311111140.64740(a)cs.indiana.edu> > Content-Type: text/plain; charset="iso-8859-1"; Format="flowed" > > On Thu, 31 Jan 2013, The Maschine wrote: > > > > > Hi all, > > > > > > Can someone explain me why I get an error with the first one and not the > second? > > > > > > 1) > (error)?boost::dijkstra_shortest_paths(m_ugraph,*vertex_iterator_begin,? ? > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? > > ?boost::distance_map(boost::make_iterator_property_map(dist_map.begin(), > boost::get(boost::vertex_index, > > m_ugraph))), > > > > boost::visitor(dijkstra_vis( *vertex_iterator_begin, superStorage ) )); > > The syntax for named parameters in Boost.Graph requires periods, so all > named arguments show up as a single argument to C++. > > > 2) > (good)?boost::dijkstra_shortest_paths(m_ugraph,*vertex_iterator_begin,? ? ? > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? > > ?boost::distance_map(boost::make_iterator_property_map(dist_map.begin(), > boost::get(boost::vertex_index, > > m_ugraph))).visitor(dijkstra_vis( *vertex_iterator_begin, superStorage > ))?); > > > > > > > > Why I need to "." the visitor on the distance_map? > > That's how it was implemented (before Boost.Parameter or variadic > templates existed). > > > > > > > BFS is ok with it: > > > > (good) boost::breadth_first_search(m_ugraph, *vertex_iterator_begin , > boost::visitor(bfs_vis( > > *vertex_iterator_begin, superStorage ) )); > > You only have one named argument there; if you had more, you would need to > use a period between those as well. > > -- Jeremiah Willcock > >

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