July 2006 - Boost-users - lists.boost.org

Serialization problem on 64-bit Windows release
by Sigurd Saue 31 Oct '06

31 Oct '06

We've started to use boost serialization and I've run into problems with serialization of derived classes. The "funny" thing is that this happens only on 64-bit Windows release compiled with MS Visual 2005. The same code works fine on Linux 32/64 bit debug/release, on Windows 32-bit debug/release and on Windows 64-bit debug. But not Windows 64-bit release. We use boost version 1.33.1. Here's the code that causes problems (Parameter is the base class, ParamCollection is a vector of Parameters): template<class Archive> static void serialize(Archive & ar, ParamCollection & col, const unsigned int /*version*/) { ar.register_type(static_cast<FloatParameter*>(NULL)); ar.register_type(static_cast<IntParameter*>(NULL)); ar.register_type(static_cast<ChoiceParameter*>(NULL)); ar.register_type(static_cast<StringParameter*>(NULL)); ar.register_type(static_cast<BlobParameter*>(NULL)); ar & boost::serialization::base_object<std::vector<Parameter*> >(col); } When serializing the ParamCollection (serializing, not deserializing) an archive exception is thrown: unregistered class. I've tried to use both abstract and non-abstract base class without any success. I did some research in the boost code and found that the exception was thrown in polymorphic::save (oserializer.hpp) by the last condition (NULL == bpos_ptr). Any clues? Is there a workaround? Thanks, Sigurd

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Converting epoch(long) to ptime in Boost.Date_Time
by gdprosch＠micron.com 23 Aug '06

23 Aug '06

I would like to convert epoch(long) time values to boost ptime and vice versa. On the surface this seems relatively easy but some of the functions needed are missing and there is an issue ensuring that the local time is properly applied. Has someone come up with an easy way to do this? I can convert to ptime like this... long epoch_in = 1140411002; // 2006-Feb-19 21:50:02 std::time_t stdtime ( epoch_in ); ptime = from_time_t( stdtime ); To convert from ptime back to epoch(long) there is no conversion provided the other way. I found some code the author supplied a few years ago here: http://lists.boost.org/MailArchives/boost-users/msg07254.php Unfortunately, the result does not correctly apply local time. The following code... std::time_t to_time_t(ptime t) { ptime start(gregorian::date(1970,1,1),time_duration(0,0,0)); return (t-start).total_seconds(); } ... produces a date with the value: 2006-Feb-20 04:50:02 and not 2006-Feb-19 21:50:02 (I am in US MST). I've played around with applying the local offset but I end up with a lot of lines of code that leave me wondering if there is a better way. It would be nice if it were simple like this (assuming local time adjustment is correctly applied)... long epoch_in = 1140411002; // 2006-Feb-19 21:50:02 ptime pt = from_epoch( epoch_in ); long epoch_out = to_epoch( pt ); Many thanks, > Greg Prosch > Micron Technology, Inc.

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segfault and no segfault with 2 different boost versions.
by Thierry Dumont 22 Aug '06

22 Aug '06

I develop a C++ code which uses boost::threads * This code performs perfectly well with the boost library wich comes with Debian sarge (libboost-thread1.32.0 for thread library). But I want a more complete implementation of boost (I want to use property tree library). So I have installed and compiled boost_1_33_1. * Using this library, all the programs which use the thread library segfault (at thread-create). Where is the problem ? With the Debian sarge library, I compile with the options: -DBOOST_HAS_THREADS -D_REENTRANT -O2 -funroll-all-loops -fomit-frame-pointer Do I need to change something? Did I missed something when I installed boost_1_33_1? In both cases, g++ version is 3.3.5. -- Thierry Dumont. Institut Camille Jordan -- Mathematiques-- Univ. Lyon I,43 Bd du 11 Novembre 1918, 69622 - Villeurbanne Cedex - France. Thierry.Dumont(a)maply.univ-lyon1.fr web: http://maply.univ-lyon1.fr/~tdumont

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Building boost for 64-bit on AIX
by Patrik Jonsson 17 Aug '06

17 Aug '06

Hi, I'm trying to build boost (1.32.0) on an IBM SP2 under AIX5, using the 64-bit ABI. This is troublesome. I do: bjam "-sTOOLS=gcc" "-sGXX=g++ -maix64 -pthread" --prefix=$HOME --libdir=$HOME/lib64-gcc --includedir=$HOME/include-gcc install But it doesn't work. I get loads of errors like: gcc-Link-action bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/libboost_date_time-gcc-d-1_32.so ld: 0711-738 ERROR: Input file bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/greg_month.o: XCOFF32 object files are not allowed in 64-bit mode. collect2: ld returned 8 exit status set -e LIBPATH=bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true:$LIBPATH export LIBPATH "g++" -maix64 -pthread -g -fPIC -shared -o "bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/libboost_date_time-gcc-d-1_32.so" "bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/greg_month.o" "bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/greg_weekday.o" "bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/date_generators.o" ...failed gcc-Link-action bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/libboost_date_time-gcc-d-1_32.so... ...skipped <@boost!lib64-gcc>libboost_date_time-gcc-d-1_32.so for lack of <@boost!libs!date_time!build/libboost_date_time.so/gcc/debug/shared-linkable-true>libboost_date_time-gcc-d-1_32.so... It seems it's using -maix64 ok when trying to build the library, but not when compiling... Can anyone tell me what the proper way of building boost under these conditions are? Thanks, /Patrik Jonsson

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[array] VC++ 7.1 bug and a proposed fix
by Johan Råde 08 Aug '06

08 Aug '06

The following code does not compile with VC++ 7.1 and Boost 1.33.1. I believe the code should compile, and that this is a VC++ 7.1 bug. ----------------------------------------------------- #include <boost/array.hpp> using boost::array; struct X { array<int,4> f() { return array<int,4>(); } }; template<class X, class T> void g(X& x, T (X::*h)()) {} void f() { X x; g(x, &X::f); } ------------------------------------------------------ When I compile the code I get the bizarre error message error C2664: 'g' : cannot convert parameter 2 from 'boost::array<T,N> (__thiscall X::* )(void)' to 'boost::array<T,N> (__thiscall X::* )(void)' with [T=int,N=4] and [T=int, N=4] Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast If I modify the array class by adding a non-templatized assignment operator, as follows, then the code does compile. --------------------------------------------------------- namespace boost { template<class T, std::size_t N> class array { ... array<T,N>& operator=(const array<T,N>& rhs) { std::copy(rhs.begin(), rhs.end(), begin()); return *this; } ... }; } ---------------------------------------------------------- So I propose that this assignment operator is added, as a VC++ 7.1 bug workaround, to the array class. I have contacted Nicolai Josuttis concerning this, and he told me he is not maintaining the array library anymore. --Johan Råde

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shmem on multi-user machine
by Steven Wooding 07 Aug '06

07 Aug '06

Hi Ion, I've noticed that the "file" /dev/shmem/sem.boost_shmem_shm_global_mutex keeps hanging around after my program finishes. This file has write permission only for the user that created it. When different user comes along a runs another program that uses shmem, it seg faults on sem_wait(), probably due to the file permissions. Should this global mutex be cleaned up after use? Or could the permissions be changed somehow to let other use it (though probably not a good idea if user A and user B run a shmem based program at the same time). Thanks for your advice. Cheers, Steve.

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boost-python Newbie tutorial needed.
by chun ping wang 06 Aug '06

06 Aug '06

Hmm k i have a simple question, how would I build boost.python given this following information. I am using dev-cpp and its install in "c:\dev-cpp" folder. IN it contains the mingw32 sub directory My project folder is "c:\cs classes\cs386\c++". In it contains FiniteAutomta.cpp which maps to python module... my boost folder is "C:\boost_1_33_1" in it contains the bjam.exe file. PYTHON_ROOT = "C:\python24" Thanks for the help. I look at the tutorial but is confused on how I can build my project.

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tsp 2-approximation using triangle inequality
by Matyas W Egyhazy 04 Aug '06

04 Aug '06

Hello, I recently implemented an approximation for the traveling salesperson using the boost graph library. The interface as well as the implementation are not polished and they require improvement, mostly due to the work being part of a school homework assignment. If anyone is interested, I would like outside comments before spending (or wasting, if no one is interested) effort to fix it up. I have attached the .h,a driver .cpp, and a sample input file. The driver program will produce output files that are viewable in a neato dot renderer. I have tested this only on VC++ 2005 (8.0) although I cannot think of any specific reason why it would not compile on other compilers. The approximation algorithm runs in polynomial time and solves the TSP problem with the worst possible solution producing a path twice as long as the optimal solution. More information can be found regarding the algorithm/heuristic on page 1028 in "Introduction to Algorithms" by Cormen, Leiserson, Rivest, and Stein. A slightly different description can be found on Wikipedia: http://en.wikipedia.org/wiki/Traveling_salesperson_problem#Triangle_inequal… My implementation matches the Introduction to Algorithms description as I use a preorder walk of the MST without bothering to create an Euler tour. I believe the Euler tour part of the algorithm is only used to prove the limit on the length of the produced solution. Regards, Matt //tsp_2_approximation //Takes a sequence of simple_points and performs 2-approximation triangle inequality to //generate a solution for the traveling salesperson problem. //Outputs the graphs in dot format to passed ostream objects //Also returns the MST generated as part of the approximation and a predecessor map //for a tour #include <algorithm> #include <vector> #include <map> #include <string> #include <iostream> #include <complex> #include <boost/graph/graph_as_tree.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/prim_minimum_spanning_tree.hpp> #include <boost/graph/simple_point.hpp> #include <boost/graph/graphviz.hpp> #include <boost/graph/iteration_macros.hpp> #include <boost/graph/graph_traits.hpp> template<typename Pt> std::istream& operator >> (std::istream& is, const boost::simple_point<Pt>& p) { return is >> boost::lexical_cast<std::string>(p.x) >> std::string(", ") >> boost::lexical_cast<std::string>(p.y); } template<typename Pt> std::ostream& operator << (std::ostream& os, const boost::simple_point<Pt>& p) { return os << boost::lexical_cast<std::string>(p.x) << std::string(",") << boost::lexical_cast<std::string>(p.y) << "!"; } //g is returned as the MST //preds is the predecessor map for the TSP approximation tour //the PositionMap is a coordinate map of the vertices represented as simple_points //the ostreams are optional, if they are provided the dot graphs are printed to them template<typename Graph, typename PositionMap, typename PredecessorMap> void tsp_2_approximation(Graph& g, const PositionMap& pos, PredecessorMap preds, std::ostream& pts_out = std::ostream(), std::ostream& mst_out = std::ostream(), std::ostream& tour_out = std::ostream()) { using namespace boost; using namespace std; typedef graph_traits<Graph>::vertex_iterator VertexItr; typedef graph_traits<Graph> GraphTraits; typedef property_map<Graph, vertex_index_t>::type IndexMap; typedef graph_traits<Graph>::vertex_descriptor Vertex; typedef iterator_property_map<vector<Vertex>::iterator, property_map<Graph, vertex_index_t>::type> ParentMap; typedef graph_as_tree<Graph, ParentMap> Tree; typedef tree_traits<Tree>::node_descriptor Node; typedef graph_traits <Graph>::edge_descriptor Edge; typedef vector<simple_point<double> > PositionVec; typedef iterator_property_map<PositionVec::iterator, property_map<Graph, vertex_index_t>::type> PositionMap; int cnt(0); property_map<Graph, vertex_name_t>::type name_map(get(vertex_name, g)); //setup name map for the vertices IndexMap index(get(vertex_index, g)); for (pair<VertexItr, VertexItr> vp(vertices(g)); vp.first != vp.second; ++vp.first) { cnt++; name_map[*(vp.first)] = lexical_cast<string>(index[*(vp.first)]); } //print point layout to dot format if (pts_out) { dynamic_properties dp; dp.property("pos", pos); dp.property("id", get(vertex_name, g)); write_graphviz(pts_out, g, dp, string("id")); } property_map<Graph, edge_weight_t>::type weight_map(get(edge_weight, g)); graph_traits<Graph>::edge_iterator ei, ei_end; for (int q(0); q < cnt; ++q) { for (int i(q); i < cnt; ++i) { if (q != i) { //Calculate distance double weight(sqrt(pow(static_cast<double>(pos[q].x - pos[i].x), 2.0) + pow(static_cast<double>(pos[i].y - pos[q].y), 2.0))); graph_traits<Graph>::edge_descriptor e; bool inserted; tie(e, inserted) = add_edge(q, i, g); weight_map[e] = weight; } } } index = get(vertex_index, g); //extract the mst using prim's minimum spanning tree algorithm vector<Vertex> p(num_vertices(g)); prim_minimum_spanning_tree(g, &p[0]); Graph mst(cnt); vector<Vertex> parent(num_vertices(mst)); Tree t(mst, 0, make_iterator_property_map(parent.begin(), get(vertex_index, mst))); property_map<Graph, edge_weight_t>::type mst_weight_map(get(edge_weight, mst)); //build mst graph using the predecessor map from prim's mst algorithm for (tie(ei, ei_end) = edges(g); ei != ei_end; ++ei) { Edge e(*ei); Vertex u(source(e, g)); Vertex v(target(e, g)); if (p[v] == u || p[u] == v) { add_edge(u, v, mst); } } name_map = get(vertex_name, mst); for (tie(ei, ei_end) = edges(mst); ei != ei_end; ++ei) { Edge e(*ei); Vertex u(source(e, g)); Vertex v(target(e, g)); double weight(sqrt(pow(static_cast<double>(pos[u].x - pos[v].x), 2.0) + pow(static_cast<double>(pos[u].y - pos[v].y), 2.0))); mst_weight_map[e] = weight; preds[v] = u; name_map[u] = lexical_cast<string>(u); name_map[v] = lexical_cast<string>(v); } //print mst in dot format if (mst_out) { dynamic_properties dp; dp.property("pos", pos); dp.property("label", get(edge_weight, mst)); dp.property("id", get(vertex_name, mst)); write_graphviz(mst_out, mst, dp, string("id")); } //create tour using a preorder traversal of the mst property_map<Graph, edge_weight_t>::type tour_weight_map(get(edge_weight, mst)); PreorderTraverser<Node, Tree> vis; traverse_tree_ref(0, t, vis); const vector<Node>& v(vis.getPath()); Graph tour(cnt); //print out tour in dot format for (vector<Node>::const_iterator itr(v.begin()); itr != v.end() - 1; ++itr) { Node s(*itr); Node d(*(itr + 1)); add_edge(s, d, tour); } add_edge(*(v.end() - 1), *(v.begin()), tour); name_map = get(vertex_name, tour); for (tie(ei, ei_end) = edges(tour); ei != ei_end; ++ei) { Edge e(*ei); Vertex u(source(e, g)); Vertex v(target(e, g)); double weight(sqrt(pow(static_cast<double>(pos[u].x - pos[v].x), 2.0) + pow(static_cast<double>(pos[u].y - pos[v].y), 2.0))); tour_weight_map[e] = weight; name_map[u] = lexical_cast<string>(u); name_map[v] = lexical_cast<string>(v); } if (tour_out) { dynamic_properties dp; dp.property("pos", pos); dp.property("label", get(edge_weight, tour)); dp.property("id", get(vertex_name, tour)); write_graphviz(tour_out, tour, dp, string("id")); } g = mst; } //Recursive function that traverses a tree with a custom visttor template <class Tree, class TreeVisitor> void traverse_tree_ref(typename boost::tree_traits<Tree>::node_descriptor v, Tree& t, TreeVisitor& visitor) { visitor.preorder(v, t); typename boost::tree_traits<Tree>::children_iterator i, end; tie(i, end) = children(v, t); if (i != end) { traverse_tree_ref(*i++, t, visitor); visitor.inorder(v, t); while (i != end) { traverse_tree_ref(*i++, t, visitor); } } else { visitor.inorder(v, t); } visitor.postorder(v, t); } //Keeps track of a preorder traversal of a tree template<typename Node, typename Tree> class PreorderTraverser { private: std::vector<Node> path_; public: void preorder(Node n, Tree& t) { path_.push_back(n); } void inorder(Node n, Tree& t) {} void postorder(Node, Tree& t) {} const std::vector<Node>& getPath() { return path_; } }; //Main test harness for the tsp_2_approximation solution generator #include <iostream> #include <utility> #include <vector> #include <fstream> #include <boost/lexical_cast.hpp> #include "tsp_2_approximation.h" int main(int,char*[]) { using namespace boost; using namespace std; typedef adjacency_list<vecS, vecS, directedS, property <vertex_name_t, string>, property <edge_weight_t, double > > Graph; typedef vector<simple_point<double> > PositionVec; typedef iterator_property_map<PositionVec::iterator, property_map<Graph, vertex_index_t>::type> PositionMap; ifstream fin("graph.txt"); if (!fin) { cerr << "To run this program properly please place a file called graph.txt" << endl << "into the current working directory." << endl << "Each line of this file should be a coordinate specifying the" << endl << "location of a vertex" << endl << "For example: " << endl << "1,2" << endl << "20,4" << endl << "15,7" << endl << endl << "The output of the program will be three DOT formatted files in the" << endl << "current working directory: " << endl << "pts.dot - Only displays the points as described in graph.txt" << endl << "mst.dot - Displays an MST for the points in graph.txt" << endl << "tour.dot - Displays the TSP 2-approximation triangle inequality tour " << endl << "for the points in graph.txt" << endl << endl << "These files should be viewed with a 'neato'" << "DOT graph viewer" << endl << "as it can handle forced coordinates" << endl; return -1; } ofstream ptsOut("pts.dot"); ofstream mstOut("mst.dot"); ofstream tourOut("tour.dot"); string line; PositionVec position_vec; int n(0); while (getline(fin, line)) { simple_point<double> vertex; size_t idx(line.find(",")); string xStr(line.substr(0, idx)); string yStr(line.substr(idx + 1, line.size() - idx)); vertex.x = lexical_cast<double>(xStr); vertex.y = lexical_cast<double>(yStr); position_vec.push_back(vertex); n++; } fin.close(); Graph g(n); PositionMap pos(position_vec.begin(), get(vertex_index, g)); vector<graph_traits<Graph>::vertex_descriptor> preds(n); tsp_2_approximation(g, pos, &preds.front(), ptsOut, mstOut, tourOut); return 0; } 1,2 2,4 10,20 45,20 15,1 17,20 20,25 30,20

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[Graph] float/double weights and brandes_betweenness_centrality
by Ioannis Filippis 03 Aug '06

03 Aug '06

Hi, I wonder whether float/double weights may cause a bug in brandes_betweenness_centrality. In the brandes_dijkstra_visitor, in the case where edge is not relaxed, there is an equality check if (d_w == combine(d_v, w_e)) in order to find if there is equally-short path from v to w. If d_w, d_v, w_e are float/doubles, isn't there gonna be a problem with the "=="? Thanks Ioannis

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filtered graph with bundled properties
by moritz Hilger 03 Aug '06

03 Aug '06

hi, i hava a problem using bundled properties with filtered graph. i've modified the example from the filtered-graph page ( http://www.boost.org/libs/graph/doc/filtered_graph.html) to use edge properties and woul like to create a filter using these bundled properties, but am experiencing problems with the types of the property_map and/or filter. since i'm quite new to c++ and boost i would aprectiate any suggestin, thanks in advance i'm using gcc-3.3.5 and boost-1.34 moritz modified code: struct myEdge { int id; int weight; }; template <typename EdgeWeightMap> struct positive_edge_weight { positive_edge_weight() { } positive_edge_weight(EdgeWeightMap weight) : m_weight(weight) { } template <typename Edge> bool operator()(const Edge& e) const { return 0 < boost::get(m_weight, e); } EdgeWeightMap m_weight; }; int main() { using namespace boost; typedef adjacency_list<vecS, vecS, directedS, //no_property, property<edge_weight_t, int> > Graph; no_property, myEdge > Graph; typedef property_map<Graph, int myEdge::*>::type EdgeWeightMap; typedef graph_traits<Graph>::edge_iterator edge_iter_t; typedef filtered_graph<Graph,positive_edge_weight<EdgeWeightMap> > f_graph_t; typedef graph_traits<Graph>::edge_descriptor Edge; enum { A, B, C, D, E, N }; const char* name = "ABCDE"; Graph g(N); Edge e; bool ins; tie(e,ins)=add_edge(A, B, g); /.../ positive_edge_weight<EdgeWeightMap> filter(get(&myEdge::weight, g)); f_graph_t fg(g, filter); std::cout << "filtered edge set: "; print_edges(fg, name); std::cout << "filtered out-edges:" << std::endl; print_graph(fg, name); return 0; } g++ output: error: no matching function for call to ` boost::bundle_property_map<main()::Graph, boost::detail::edge_desc_impl<boost::directed_tag, size_t>, myEdge, int>:: bundle_property_map()' /homes/combi/Software/Boost/boost/graph/properties.hpp:330: error: candidates are: boost::bundle_property_map<main()::Graph, boost::detail::edge_desc_impl<boost::directed_tag, size_t>, myEdge, int>::bundle_property_map(const boost::bundle_property_map<main()::Graph, boost::detail::edge_desc_impl<boost::directed_tag, size_t>, myEdge, int>&) /homes/combi/Software/Boost/boost/graph/properties.hpp:336: error: boost::bundle_property_map<Graph, Descriptor, Bundle, T>::bundle_property_map(Graph*, T Bundle::*) [with Graph = main()::Graph, Descriptor = boost::detail::edge_desc_impl<boost::directed_tag, size_t>, Bundle = myEdge, T = int] -- /* ICQ 291996214 */ /* MSN moritz.hilger(a)gmail.com */ /* moe1234(a)jabber.ccc.de */ /* del.icio.us/new/moritz.hilger */

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