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[Graph] Issue with remove_edge function and subgraphs
by Marcus Fontaine 10 May '10

10 May '10

According to the online documentation, http://www.boost.org/doc/libs/1_38_0/libs/graph/doc/subgraph.html The remove_edge function when used on a subgraph should, "Remove the edge (u,v) from the subgraph and from all of the ancestors of g in the subgraph tree." In the example I have here, it just seems to remove the edge between vertices 0 and 2 from the ancestor and not the subgraph. Any advice or explanation would be greatly appreciated. #include <iostream> #include <vector> #include <boost/config.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/subgraph.hpp> using namespace std; using namespace boost; typedef subgraph< adjacency_list<vecS, vecS, undirectedS, property<vertex_index_t, int>, property<edge_index_t, int> > > Graph; int main() { Graph G; add_edge(0, 1, G); add_edge(0, 2, G); add_edge(1, 2, G); add_edge(2, 3, G); add_edge(0, 3, G); Graph subG = G.create_subgraph(); add_vertex(0, subG); add_vertex(1, subG); add_vertex(2, subG); add_vertex(3, subG); remove_edge(subG.global_to_local(2), subG.global_to_local(0) ,subG); graph_traits<Graph>::adjacency_iterator ai; graph_traits<Graph>::adjacency_iterator ai_end; cout << "Adjacent vertices of 0 in G: "; //Should be 1 3, and correctly is so. for(tie(ai, ai_end) = adjacent_vertices(0, G); ai != ai_end; ++ai) { cout << *ai << " "; } cout << endl; cout << "Adjacent vertices of 0 in subG: "; //Should be 1 3, but gives 1 2 3. for(tie(ai, ai_end) = adjacent_vertices(subG.global_to_local(0), subG); ai != ai_end; ++ai) { cout << subG.local_to_global(*ai) << " "; } cout << endl; return 0; }

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Serialization of a complex data structure
by Marco Meoni - Sbaush 10 May '10

10 May '10

Hi all. I've to serialize a structure that has as attributes two structures. An example is: struct Example{ Container* results_container; MyMap this_is_a_map; Example(){} ... ... }; where Container* is a pointer to another struct, defined by me, and MyMap is a c++ map. I've tried to serialize it using the shared_ptr example of boost serialization: struct Example{ friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int /* file_version */){ } Container* results_container; MyMap this_is_a_map; Example(){} ... ... }; and in the main i call: boost::shared_ptr<Example> myExample(new Example); ... ... // serialize it { std::ofstream ofs(filename.c_str()); boost::archive::text_oarchive oa(ofs); oa << myExample; } boost::shared_ptr<Example> myNewExample(new Example); { // open the archive std::ifstream ifs(filename.c_str()); boost::archive::text_iarchive ia(ifs); // restore the schedule from the archive ia >> myNewExample; } Now myNewExample is a well format instance of Example, but the attributes are empty. Can anyone help me? I would not have to change all files with nested structures, as are many, not just two as in the example Thanks all. Marco. -- Marco Meoni - Sbaush www.marcomeoni.net

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boost::thread condition variables
by Eric J. Holtman 09 May '10

09 May '10

(using windows XP, VS2008) Is there a limit to the number that can be constructed/destructed in a single process over time? I have a loop which was doing while (1) { condition_variable cv; mutex mx; // do some things with cv and mx } that while loop would run maybe 200 or 300 times. Occasionally, I'd get a crash in notify_all (), where it seemed like a handle wasn't valid. When I move the declaration of the variables outside the while loop, this doesn't happen. Now, it's entirely possible that I have some other bizarre race condition. In fact, if my previous years of experience have taught me anything, I will discover that error in the very next session after I hit "send" on this email. However..... is there some limit to constructing/destructing and using up Windows handles that I should know about?

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[1.43.0] PDF build of docs now available.
by John Maddock 09 May '10

09 May '10

The PDF build of the documentation for 1.43 (for those libraries that support this) is now available from the sourceforge download page: http://sourceforge.net/projects/boost/files/ The direct links are: http://sourceforge.net/projects/boost/files/boost-docs/1.43.0/boost_pdf_1_4… http://sourceforge.net/projects/boost/files/boost-docs/1.43.0/boost_pdf_1_4… http://sourceforge.net/projects/boost/files/boost-docs/1.43.0/boost_pdf_1.4… http://sourceforge.net/projects/boost/files/boost-docs/1.43.0/boost_pdf_1.4… Enjoy! John.

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[test] To Advertise the availble tests in XML format: -xml
by Jeff Flinn 09 May '10

09 May '10

When I [mis]type my desired test, test prints to the console: Usage: Run All tests: No Args Run Specific Test or Suite: <suite name> [<test name>] Available tests: To Advertise the availble tests in XML format: -xml So what is the argument to Advertise all available tests? Thanks, Jeff

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Serialization and std::move
by Brian Wood 09 May '10

09 May '10

B"H I'm doing some research. I grep'ed through the 1.43 version of the libs/serialization directories for uses of std::move and didn't find any. I also looked at the "To Do" section of the documentation and didn't find any mention of move semantics. Does Boost Serialization take advantage of std::move to improve the performance of it's load operations? Something like the following: template <typename B> void Receive(B* buf, vector<deque<string> >& abt1) { uint32_t headCount[2]; buf->Give(headCount[0]); abt1.reserve(abt1.size() + headCount[0]); while (headCount[0] > 0) { --headCount[0]; deque<lil_string> rep4; buf->Give(headCount[1]); while (headCount[1] > 0) { --headCount[1]; string rep5; stringReceive(buf. rep5); rep4.push_back(std::move(rep5)); } abt1.push_back(std::move(rep4)); } } Thanks in advance. -- Brian Wood

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Problem with Property Tree and xml_read
by Rouven Walter 08 May '10

08 May '10

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[Random] Passing an arbitrary uniform random number generator to a function
by Joseph Wakeling 08 May '10

08 May '10

Hello, Suppose that I have a function that takes a uniform random number generator as an argument, e.g. double foo(mt19937 &urng) { double x = uniform_real<double> (0.0, 10.0) (urng); double y = uniform_real<double> (5.0, 7.0) (urng); return (x*y); } Is there a way to make the choice of random number generator arbitrary (i.e. not limited to mt19937) without making the function a template? Alternatively, is there a better way of passing around the basic uniform random number generator? The reason for the no-template rule is that I would like to pass a URNG to a virtual function in a class, and I would really not like to have to make the class itself a template dependent on the type of URNG. Can someone recommend a solution? Thanks and best wishes, -- Joe

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[boost][filesystem] Rename throws exception if target file exists
by Sanjit Jhala 08 May '10

08 May '10

I need to achieve an atomic move to replace an existing file. Is there anyway to do this using boost::filesystem? I thought rename would do this but it throws the following exception: " boost::filesystem::rename: File exists:" when the target file exists. -Sanjit

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Trouble with templating of adjacency_list
by Eric Fowler 08 May '10

08 May '10

Perhaps this should go to a g++ group but I have a feeling the answer is Out There: Why is g++ having trouble with this? Error is ../main.cpp:19: error: template declaration of ‘boost::adjacency_list<boost::vecS, boost::vecS, boost::bidirectionalS, POS<T>, boost::no_property, boost::no_property, boost::listS> DG’ template<typename T = int> struct POS { T x, y; }; template<typename T> adjacency_list<vecS, vecS, bidirectionalS, POS<T> > DG;

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