January 2008 - Boost-users - lists.boost.org

Newbie question
by Eric Fowler 11 Jan '08

11 Jan '08

Hate to keep peppering the list with these, but I am stuck: In the Kevin Bacon sample, there appears this fragment: // Convenience function template <typename DistanceMap> bacon_number_recorder<DistanceMap> record_bacon_number(DistanceMap d) { return bacon_number_recorder<DistanceMap>(d); } Which is used thus: std::vector<int> bacon_number(num_vertices(g)); breadth_first_search(g, src, visitor(record_bacon_number(&bacon_number[0]))); I am puzzled about the convenience function ... why use it at all? But when I take it out: vector<int> numbers(num_vertices(g)); numbers[s] = 0; breadth_first_search(g, s, visitor(my_distance_recorder<vector<int> >(numbers))); All entries for vector<int> numbers are zero. I changed the declaration for the recorder's ctor to look like this: my_distance_recorder(Map& _m):m(_m){}; Making it get a reference to that vector, because I assumed I was recording into a local copy that was being thrown away. No dice, still zeroes. My "graph" is a straight line of v---v---v---v---v---etc. for simplicity, so I should be seeing a bfs count of 0, 1, 2, 3, etc. The visitor function is being called and is writing incremented values into the vector - but when it comes back, all are zero. What's going on? The convenience function must be related to this problem but I don't see the connection. Eric Also noticed that: breadth_first_search(g, s, visitor(my_distance_recorder<vector<int> >(&numbers[0]))); for breadth_first_search(g, s, visitor(my_distance_recorder<vector<int> >(numbers))); gets a compile time error.

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[Serialization] XML serialization (newbie question)
by Hasse Carlsson 11 Jan '08

11 Jan '08

I have a newbie question regarding Boost XML serialization: In the example of an XML archive ( http://www.boost.org/libs/serialization/example/demo_save.xml) there are lots of attributes (class_id, tracking_level, class_id_reference etc) included in the XML output. I would like to produce an XML archive _without_ these attributes - how do I achieve that? Can such an XML archive be restored, or are the attributes needed for "de-serialization" to work properly? Thanks, hcsson(a)gmail.com

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Fwd: Serialization problems, shared_ptr etc...
by Hannes Baldursson 10 Jan '08

10 Jan '08

Hi everybody.I'm having problems understanding the Boost::Serialization library. I've managed to get it to save my object... but once I try to load them in to the code doesn't compile. It fails on the line where the ifstream writes to the object. Basically what I'm trying to do is to save a hierarchy of objects that build up a filesystem namespace for a virtual filesystem I'm trying to code. It's something like this: Filesystem_NS --> fsFile -->--> fsFileChunk -->--> fsFileChunk --> fsFile -->--> fsFileChunk -->--> fsFileChunk The code isn't commented very well but it's nothing more than saving and loading the data structures at the moment. There is no code/methods note: There are more errors but they're so many that the forum doesn't allow me to post all of them because of a character limit It looks there's a problem that I'm boost::shared_ptr or something... I don't know I've been probably looking at this for too long. The code compiles if I remove the line where it loads the fsImage file back in to an object. Note that it does save properly. That is, I believe all the data shows up in the saved archive although I can't be sure unless I'm able to restore the state. Could someone here give me a hand? *hdfs.cpp* Code: #ifdef HAVE_CONFIG_H #include <config.h> #endif #include <iostream> #include <fstream> #include <cstdlib> #include <utility> #include "FileSystem.h" #include "fstypes.h" #include "fsFile.h " #include "fsFileChunk.h" #include <boost/shared_ptr.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/shared_ptr.hpp> #include <boost/serialization/vector.hpp> #include <boost/serialization/map.hpp> using namespace std; int main(int argc, char *argv[]) { // string s1 = Path::normalizePath("http://asdfasd/fasdfa//asdf//"); string fsPath = "./fsImage"; FileSystem_NS * const fs = new FileSystem_NS(fsPath); fileId_t fid = ++(*fs).nextFileId; fsFile_Ptr ff(new fsFile(fid)); (*fs).files.insert(pair<string, fsFile_Ptr>("biomynd",ff)); chunkVersion_t cv = 1; size_t cs = 67108864; fsFileChunk_Ptr fc(new fsFileChunk(++(*fs).nextChunkId, (*ff).fID, cv, cs)); ff->addChunk(fc); ofstream ofs("./fsImage"); { boost::archive::text_oarchive oa(ofs); // write class instance to archive oa << (const FileSystem_NS)(*fs); // archive and stream closed when destructors are called } ofs.close(); FileSystem_NS const *newFilesystem = new FileSystem_NS("lol"); ifstream ifs("./fsImage"); { // open the archive boost::archive::text_iarchive ia(ifs); // restore the schedule from the archive ia >> (*newFilesystem); } ifs.close(); cout << fs->fsImage_Path << endl; return EXIT_SUCCESS; } *FileSystem.h* Code: /************************************************************************ FileSystem.h - Copyright Hannes Baldursson **************************************************************************/ #ifndef FILESYSTEM_H #define FILESYSTEM_H #include "fstypes.h" #include "fsFile.h" #include "fsFileChunk.h" #include <string> #include <map> #include <vector> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/vector.hpp> #include <boost/serialization/map.hpp> #include <boost/serializati #ifdef HAVE_CONFIG_H #include <config.h> #endif #include <iostream> #include <fstream> #include <cstdlib> #include <utility> #include "FileSystem.h" #include "fstypes.h" #include "fsFile.h" #include "fsFileChunk.h" #include <boost/shared_ptr.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/shared_ptr.hpp> #include <boost/serialization/vector.hpp> #include <boost/serialization/map.hpp> using namespace std; int main(int argc, char *argvon/tracking.hpp> #include <boost/shared_ptr.hpp> using namespace std; // Filesystem namespace class FileSystem_NS { public: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) const { ar & nextFileId; ar & nextChunkId; ar & files; } fileId_t nextFileId; chunkId_t nextChunkId; const string fsImage_Path; FileSystem_NS(string fsImage = "./fsImage"); map<string, fsFile_Ptr> files; // Maps filenames to fileIds }; BOOST_CLASS_TRACKING(FileSystem_NS, boost::serialization::track_always) #endif // FILESYSTEM_H *fsFile.h* Code: #ifndef FSFILE_H #define FSFILE_H #include <string> #include <map> #include "fstypes.h" #include "fsFileChunk.h" #include <boost/shared_ptr.hpp> #include <boost/serialization/vector.hpp> using namespace std; class fsFile { public: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) const { ar & fname; ar & fID; ar & chunks; } string fname; fileId_t fID; vector<fsFileChunk_Ptr> chunks; // Create a fsFile fsFile(fileId_t fileID); void addChunk(fsFileChunk_Ptr ptr); }; typedef boost::shared_ptr<fsFile> fsFile_Ptr; BOOST_CLASS_TRACKING(fsFile, boost::serialization::track_always) #endif *fsFileChunk.h* Code: #ifndef FSFILE_CHUNK_H #define FSFILE_CHUNK_H #include <vector> #include <string> #include "fstypes.h" #include <boost/shared_ptr.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> using namespace std; class fsFileChunk { public: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) const { ar & cID; ar & fID; ar & cVersion; ar & cSize; } chunkId_t cID; fileId_t fID; // This chunk belongs to file "fileID" chunkVersion_t cVersion; // Current version size_t cSize; std::vector<string> hosts; // vector of hostIP:port for the datanodes that host this chunk. fsFileChunk(chunkId_t chunkID, fileId_t fileID, chunkVersion_t chunkVersion, size_t chunkSize); }; typedef boost::shared_ptr<fsFileChunk> fsFileChunk_Ptr; BOOST_CLASS_TRACKING(fsFileChunk, boost::serialization::track_always) #endif // FSFILE_CHUNK_H *fstypes.h* Code: #ifndef COMMON_FSTYPES_H #define COMMON_FSTYPES_H #include <stdint.h> typedef unsigned long long fileId_t; typedef unsigned long long chunkId_t; typedef unsigned int chunkVersion_t; #endif These are all the header files plus the "main program". Code: /usr/lib/gcc/x86_64-pc-linux-gnu/4.1.2/include/g++-v4/istream:231: note: std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_streambuf<_CharT, _Traits>*) [with _CharT = char, _Traits = std::char_traits<char>] <near match> /home/hannson/Projects/HDFS/src/boost/serialization/access.hpp: In static member function 'static void boost::serialization::access::serialize(Archive&, T&, unsigned int) [with Archive = boost::archive::text_iarchive, T = const std::map<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_ptr<fsFile>, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_ptr<fsFile> > > >]': /home/hannson/Projects/HDFS/src/boost/serialization/serialization.hpp:81: instantiated from 'void boost::serialization::serialize(Archive&, T&, unsigned int) [with Archive = boost::archive::text_iarchive, T = const std::map<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_ptr<fsFile>, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_ptr<fsFile> > > >]' /home/hannson/Projects/HDFS/src/boost/serialization/serialization.hpp:140: instantiated from 'void boost::serialization::serialize_adl(Archive&, T&, unsigned int) [with Archive = boost::archive::text_iarchive, T = const std::map<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_ptr<fsFile>, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_ptr<fsFile> > > >]' /home/hannson/Projects/HDFS/src/boost/archive/detail/iserializer.hpp:158: instantiated from 'void boost::archive::detail::iserializer<Archive, T>::load_object_data(boost::archive::detail::basic_iarchive&, void*, unsigned int) const [with Archive = boost::archive::text_iarchive, T = const std::map<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_ptr<fsFile>, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_ptr<fsFile> > > >]' /home/hannson/Projects/HDFS/src/hdfs.cpp:70: instantiated from here /home/hannson/Projects/HDFS/src/boost/serialization/access.hpp:109: error: 'const class std::map<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::shared_ptr<fsFile>, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<ch These are not all the error messages I get.. One important thing. I'm clearly missing something because even when I comment out the fsFile part from the serialization (that is I'm only saving nextFileId and nextChunkId in FileSystem_NS) it still doesn't compile when I'm including the loading code so it seems I'm having two problems. One problem is restoring the object in general, and the other is restoring the objects when using a shared_ptr. Btw, sorry about the html if you like it plain :)

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Problems with msvc 8.0 and build example - please help
by mo mony 10 Jan '08

10 Jan '08

While running cl for msvc 8.0, following the tutorial directions for the example.cpp I get an error " can't find file utility - which is the include file in example. I notice that the path returned in the error has the slashes reversed after the BOOST_ROOT dir. The file definitely exits so I thought it must be a pathing type error. Anyone see this before ? Sorry, I am new to this program/list. I am trying to right some wrappers for C++ to be used by Python. Thanks, Ed ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ

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Non-blocking i/o using ASIO socket
by Chauhan, Vikas 10 Jan '08

10 Jan '08

Hello all, Can you please advise where we need to use "non_blocking_io" flag in ASIO sockets. IIUC, we can do the same using all of the async_xxxx functions provided in the various socket classes. Does it mean that if we do not wish to use ioservice::post() mechanism, we have the option to use "non_blocking_io" flag and implement async functionality? Thanks, Vikas

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Problem compiling some simple code ..
by Eric Fowler 10 Jan '08

10 Jan '08

I have been fiddling with this library off and on for some time ... now am getting this error: /home/eric/boostplay/g0/src/g0.cpp:55: error: no matching function for call to 'add_vertex(Graph (&)())' /home/eric/boostplay/g0/src/g0.cpp:56: error: no matching function for call to 'add_edge(Vertex&, Vertex&, Graph (&)())' on this code: <boost-users(a)lists.boost.org> #ifdef HAVE_CONFIG_H #include <config.h> #endif #include <iostream> #include <cstdlib> #include <boost/config.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/tuple/tuple.hpp> using namespace std; using namespace boost; typedef adjacency_list<vecS, vecS, undirectedS> Graph; typedef graph_traits<Graph>::vertex_descriptor Vertex; typedef graph_traits<Graph>::edge_descriptor Edge; int main(int argc, char *argv[]) { Graph g(); Vertex v = 0; for(int iv = 0; iv < 10; ++iv) for(int iu = 0; iu < 5; ++iu) { Vertex u; Edge e; bool inserted; u = v; tie(v, inserted) = add_vertex(g); tie(e, inserted) = add_edge(u, v, g); if(inserted) cout << "Inserted edge " << e << " from vertex " << u << " to vertex " << v << endl; else cout << "Failed to insert edge " << e << " from vertex " << u << " to vertex " << v << endl; } return EXIT_SUCCESS; } There was a thread on this a while back which suggested casting the call: tie(e, inserted) = add_edge(u, v, g); to tie(e, inserted) = add_edge(std::size_t(u), std::size_t(v), g); but that did not work. Notice my graph has no properties .. usually I don't make 'em that way, but that should be fine, right? Thanks very much, Eric

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A* implemenation using BGL
by Christopher Gay 09 Jan '08

09 Jan '08

I'm having a problem implementing A*. I used Mr Beevers cities example as a spring board for my own version. I am using bundled properties and I am getting an error that I am unsure of how to correct. The error revolves around the CostMap template parameter for the astar_search. It typedefs the value_type to 'C' and the error tells me that I cannot convert int to 'C' in the std::numeric_limits<C>::max call in astar_dispatch2. I am not passing an object/container for the CostMap parameter. Attached are the files I am working with. Thanks for your help! Chris Gay

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can a edge have more than 2 nodes?
by Meththa 09 Jan '08

09 Jan '08

Hi everyone, I am trying to draw a graph which contains nets with more than 2 nodes. At the moment in the program I am using add_edge() to add the edges to the graph. I give the 2 nodes and also a custom parameter of the net name that this edge belongs to. This solution seems to be a long way of doing things specially when I need to access all the nodes of a particular net. For this I end up running two FOR loops checking each edge to see the net name it belongs to and then accessing the nodes belonging to that edge. Does anyone know of how I can have more than 2 nodes attached to an edge (or net)? Thanks in advance Meth ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs

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Bind with Tuple gcc error
by Moyukh 09 Jan '08

09 Jan '08

I was using boost::bind with boost::tuple as shown in the code snippet below. This piece of code compiles and executes fine in Visual Studio 2005 but while compiling with gcc-4.1 It throws error "unresolved overloaded function type" (This code actually does nothing except reproduce the error) I guess its because gcc was unable to figure out which get() to call as there are two version const and non const. Any suggestion how to make it work with gcc as well as VS2005. Code ---------------- #include <boost/tuple/tuple.hpp> #include <boost/bind.hpp> int main(int argc, char * argv[]) { typedef boost::tuple<int, bool, int > myTuple; myTuple mt; boost::bind(&myTuple::get<0>, _1)(mt); return 0; } gcc error.. -------------------- Test.cpp: In function 'int main(int, char**)': Test.cpp:13: error: call of overloaded 'bind(<unresolved overloaded function type>, boost::arg<1> (&)())' is ambiguous ../../../../../Boost/boost/bind/bind_mf_cc.hpp:20: note: candidates are: boost::_bi::bind_t<R, boost::_mfi::mf0<R, T>, typename boost::_bi::list_av_1<A1>::type> boost::bind(R (T::*)(), A1) [with R = int&, T = boost::tuples::cons<int, boost::tuples::cons<bool, boost::tuples::cons<int, boost::tuples::null_type> > >, A1 = boost::arg<1> (*)()] ../../../../../Boost/boost/bind/bind_mf_cc.hpp:30: note: boost::_bi::bind_t<R, boost::_mfi::cmf0<R, T>, typename boost::_bi::list_av_1<A1>::type> boost::bind(R (T::*)()const, A1) [with R = const int&, T = boost::tuples::cons<int, boost::tuples::cons<bool, boost::tuples::cons<int, boost::tuples::null_type> > >, A1 = boost::arg<1> (*)()] Thanks Moyukh

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[iostreams] how to say a filter is closable
by frederic.bron＠alcan.com 09 Jan '08

09 Jan '08

I want to write a filter but this filter needs to do some things when the stream is ending. Is it enough to do the following? I want the close function to be called at the end of the stream. Do I need to category_flag to inherit from (closable_tag)? class my_filter : public io::dual_use_filter { public: template<typename Source> int get(Source&) ; template<typename Sink> bool put(Sink&, int) ; template<typename Device> void close(Device&, std::ios_base::openmode) ; } ; Fred Avis : Ce message et toute pièce jointe sont la propriété d'Alcan et sont destinés seulement aux personnes ou à l'entité à qui le message est adressé. Si vous avez reçu ce message par erreur, veuillez le détruire et en aviser l'expéditeur par courriel. Si vous n'êtes pas le destinataire du message, vous n'êtes pas autorisé à utiliser, à copier ou à divulguer le contenu du message ou ses pièces jointes en tout ou en partie. Notice: This message and any attachments are the property of Alcan and are intended solely for the named recipients or entity to whom this message is addressed. If you have received this message in error please inform the sender via e-mail and destroy the message. If you are not the intended recipient you are not allowed to use, copy or disclose the contents or attachments in whole or in part.

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