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Boost::Timer problem
by Simon Pickles 12 Dec '07

12 Dec '07

Hello, Using gcc on ubuntu, can anyone tell my why this simple code: ///////////////////////////////////////////////// #include <iostream> using namespace std; #include "boost/timer.hpp" #include <time.h> int main() { clock_t t = clock(); boost::timer bt; cout << t << " : " << bt.elapsed() << endl; sleep(10); t = clock(); cout << t << " : " << bt.elapsed() << endl; sleep(10); t = clock(); cout << t << " : " << bt.elapsed() << endl; return 0; } //////////////////////////////////////////////////////////////// produces output like this: 0 : 0 0 : 0 0 : 0 Its not cout, since pausing the program shows the values to be 0 in the watch window. Many thanks Simon -- Linux Counter: User# 424693

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boost::serialization - prevent object creation when loading a pointer
by Darryl Lawson 12 Dec '07

12 Dec '07

Peter Dimov wrote: > You can add > > virtual void load( boost::archive::text_iarchive& ar, unsigned v ) > = 0; > virtual void save( boost::archive::text_oarchive& ar, unsigned v ) > = 0; > > to base and call them in A::serialize, but this obviously only works > for a > specific archive type. I specifically need to be able to support different archives, so this won't work - but I think something similar to what you have suggested will. Robert Ramey wrote: > How about the following: > > template<class Archive> > void save(Archive& ar, const unsigned int version) const { > ar << _m; > cout << "serialise A, _m = " << (unsigned long)_m << endl;} > > void save(Archive& ar, const unsigned int version) const { > base * t; > ar >> t; // deserialize to a temporary > // modify _m according to t > cout << "serialise A, _m = " << (unsigned long)_m << endl; > delete t; > > } Yeh something like this would do the trick. So actually, what I am thinking of is a kind of a mix of Robert's and Peter's suggestions (see code below). It is not the prettiest, but I think I should only have to do this for one class hierarchy in particular, so it isn't too bad. Thanks for your help. The serialization library is going to make my life a lot easier! Darryl Lawson #include <iostream> #include <fstream> #include <cassert> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/export.hpp> using namespace std; struct base { virtual ~base() {} template<class Archive> void serialize(Archive& ar, const unsigned int version) {} virtual void load(const base* rhs) {} }; struct derived : public base { derived() : base(), _value(0) {} template<class Archive> void serialize(Archive& ar, const unsigned int version) { boost::serialization::void_cast_register<derived, base>(); ar & _value; } virtual void load(const base* rhs) { const derived* t = dynamic_cast<const derived*>(rhs); assert(t); if (!t) return; _value = t->_value; } int _value; }; BOOST_CLASS_EXPORT(derived); struct A { A() { _m = new derived; cout << "construct A, _m = " << (unsigned long)_m << endl; } template<class Archive> void save(Archive & ar, const unsigned int version) const { ar << _m; cout << "save A, _m = " << (unsigned long)_m << endl; } template<class Archive> void load(Archive & ar, const unsigned int version) { base* t; ar >> t; _m->load(t); delete t; cout << "load A, _m = " << (unsigned long)_m << endl; } BOOST_SERIALIZATION_SPLIT_MEMBER(); private: base* _m; }; void save(const A& a, const char* filename) { std::ofstream ofs(filename); boost::archive::text_oarchive oa(ofs); oa << a; } void load(A& a, const char* filename) { std::ifstream ifs(filename); boost::archive::text_iarchive ia(ifs); ia >> a; } int main(int argc, char* argv[]) { A a; save(a, "archive.txt"); A new_a; load(new_a, "archive.txt"); return 0; }

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boost::serialization - prevent object creation when loading a pointer
by Darryl Lawson 12 Dec '07

12 Dec '07

I realise that what I am doing is no doubt an unconventional usage of boost::serialization, but I wonder if any one has done a similar thing before. I wish to serialize a derived class through a baseclass pointer, but on deserilize I do not want the object to be created (I do not want memory allocated) - as the object will have all ready been created. An example, hopefully showing what I mean, is given at the end. The program will output something like, construct A, _m = 155640808 serialise A, _m = 155640808 construct A, _m = 155649400 serialise A, _m = 155649808 But essentially I want the program to output something lke, construct A, _m = 155640808 serialise A, _m = 155640808 construct A, _m = 155649400 serialise A, _m = 155649400 i.e. the second lot of construct A/serialise A will have the same address for _m. The reason why I need this behaviour, is that only a sub-set of the derived class will be seriliazed, with the other parts of the class intialised differently depending on the session, and the initialisation of the class is always done _before_ deserialisation. Is there anyway to get this behaviour from the boost::serialization library? Many thanks, Darryl Example ------- #include <fstream> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/export.hpp> using namespace std; struct base { virtual ~base() {} template<class Archive> void serialize(Archive& ar, const unsigned int version) {} }; struct derived : public base { derived() : base(), _value(0) {} template<class Archive> void serialize(Archive& ar, const unsigned int version) { boost::serialization::void_cast_register<derived, base>(); ar & _value; } int _value; }; BOOST_CLASS_EXPORT(derived); struct A { A() { _m = new derived; cout << "construct A, _m = " << (unsigned long)_m << endl; } template<class Archive> void serialize(Archive& ar, const unsigned int version) { // On deserialize this will create a new object, but I do not want it to, // rather I would like it to deserialize into the all ready created // object. ar & _m; cout << "serialise A, _m = " << (unsigned long)_m << endl; } base* _m; }; void save(const A& a, const char* filename) { std::ofstream ofs(filename); boost::archive::text_oarchive oa(ofs); oa << a; } void load(A& a, const char* filename) { std::ifstream ifs(filename); boost::archive::text_iarchive ia(ifs); ia >> a; } int main(int argc, char* argv[]) { A a; save(a, "archive.txt"); A new_a; load(new_a, "archive.txt"); return 0; }

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statechart unit testing
by Sean Kelly 12 Dec '07

12 Dec '07

Hi All, I have statechart implementation that I have spread over multiple translation units - I would like to unit test the control logic by inserting mock transition actions. The library is explicitly designed not to be dynamic - Can anyone suggest a way I could accomplish this - Its also likely that I could reuse the statechart control logic with different implementations of transition actions so if it is possible to inject this dependency I can reuse the code. Thanks Sean

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[ptr_container] How do I partition a ptr_vector
by Michael Marcin 11 Dec '07

11 Dec '07

How do I partition a ptr_vector? Most of the other standard algorithms seems to be members but I cannot find partition. Thanks, Michael Marcin

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[logging] Re: Getting started problem (on behalf of Benjamin de Dardel)
by John Torjo 10 Dec '07

10 Dec '07

Hi Benjamin, From what you've explained in your mail, it seems that you're trying to use Boost.Logging from a DLL and an EXE as well. I need to know more details about your scenario. My suggestion: - defining the logs (BOOST_DEFINE_LOG) should happen in the DLL - declaring the logs (BOOST_DECLARE_LOG) should happen in both EXE and DLL - DO NOT define the logs in the EXEcutable as well Note that at this time if you do logging before initializing the logs, nothing will happen - I will fix this very soon. Note: there's some problem with your email address and I can't reply to you directly. Please fix it. Best, John -- http://John.Torjo.com -- C++ expert ... call me only if you want things done right

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zero_vector, is it broken?
by Neal Becker 10 Dec '07

10 Dec '07

Either I completely misunderstand something, or zero_vector is seriously broken: #include <boost/numeric/ublas/vector.hpp> #include <iostream> #include <iterator> #include <algorithm> using namespace std; namespace ublas = boost::numeric::ublas; int main() { ublas::zero_vector<double> zeros (10); copy (zeros.begin(), zeros.end(), ostream_iterator<double> (cout, " ")); } I expect this to print 10 '0'. Instead, it prints nothing.

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BGL Max flow min cut
by Line B. Reinhardt 10 Dec '07

10 Dec '07

Dear All I would like some help with graph structure for the edmund_karp max flow min cut function. I have a general graph in which I have many properties + edge and vertex. I sould like to run edmund karp on this graph however I have not been able to make the structure right for edmund karp and therefore I have made a second graph a flow graph. However I do not want to copy edges over every time I change something in the original graph. I was wundering if I could make it the same graph or just make the flow graph a filteret version of the original graph. The graphs are defined as follows:: original:: typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::bidirectionalS, VertexProperties, EdgeProperties, GraphProperties> Graph; typedef boost::graph_traits<Graph> DirectedTraits; typedef DirectedTraits::vertex_descriptor DirectedVertex; typedef DirectedTraits::edge_descriptor DirectedEdge; typedef DirectedTraits::vertex_iterator VertexIterator; typedef DirectedTraits::edge_iterator DirectedEdgeIterator; typedef DirectedTraits::out_edge_iterator DirectedOutEdgeIterator; typedef DirectedTraits::in_edge_iterator DirectedInEdgeIterator; typedef boost::property_map<Graph, boost::edge_name_t>::type EdgeNameMap; flow graph:: typedef boost::adjacency_list_traits<boost::vecS, boost::vecS, boost::directedS> FlowTraits; typedef FlowTraits::edge_descriptor edge_descriptor; typedef FlowTraits::vertex_descriptor vertex_descriptor; typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, boost::no_property, boost::property<boost::edge_capacity_t, double, boost::property<boost::edge_residual_capacity_t, double, boost::property<shipping_graph::vertex_start_indicator_t, double, boost::property<boost::edge_reverse_t, FlowTraits::edge_descriptor> > > > > FlowGraph; typedef boost::graph_traits<FlowGraph> DirectedFlowTraits; typedef DirectedFlowTraits::out_edge_iterator FlowOutEdgeIterator; typedef boost::property_map<FlowGraph, boost::edge_capacity_t>::type MaxEdgeWeightMap; Thanks for your help Line

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I can not run dijkestra example
by Mahmood NT 10 Dec '07

10 Dec '07

Hello, As http://www.boost.org/libs/graph/doc/quick_tour.html said (section "Adding Some Color to your Graph"), the ouput of "examples/dijkstra-example.cpp" is: The output is: distances from start vertex: distance(0) = 0 distance(1) = 6 distance(2) = 1 distance(3) = 4 distance(4) = 5 but when I run the file, the ouput is not this!! why? Mahmood NT ____________________________________________________________________________________ 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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how to use dijkestra code
by Mahmood NT 10 Dec '07

10 Dec '07

Hello, I am new in mailing list.... I run the code for dijkstra-example but seem that the section for dijkstra function does not run. I see in "dijkstra-example-listS.cpp": #if defined(BOOST_MSVC) && BOOST_MSVC <= 1300 How can I define it. I use visual .NET 2003. Thanks, Mahmood NT ____________________________________________________________________________________ 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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