August 2007 - Boost-users - lists.preview.boost.org

Linking to DLLs on Windows with GCC
by John Pye 29 Aug '07

29 Aug '07

Hi all, I am having trouble linking against Boost DLLs. Even though I think I am using the correct compiler commands, I seem to end up with statically linked binaries (everything works fine, but Dependency Walker shows that I have no DLL dependency on Boost). Specifically, I am trying to link against Boost:Serialization. Because I'm using MinGW, my Boost libraries had to be compiled by me, so I used "bjam --toolset=gcc --layout=system". I then ran "bjam install" with the same options, which resulted in (over 1GB of) files in c:\Boost. Next I build my own program. It compiles against the Boost files using GCC parameters "-IC:\Boost\include" and then links against Boost::Serialisation using "-LC:\Boost\lib" -lboost_serialization-mt So, what can I do to set GCC to use dynamic linking to the DLL in this case, instead of the static linking that it appears to be using at the moment? (I am a little unclear about the purpose of the .a files currently present in the c:\Boost\lib directory. Do they refer in some way to the DLLs or are they self-contained static libraries?) Cheers JP

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[ptr_container]Swap/reorder elements in ptr_vector
by Bill Buklis 28 Aug '07

28 Aug '07

What is the best or recommended way to swap or reorder elements in a ptr_vector? Naturally, I simply want to swap pointers and not copy any elements. Using swap with the "base" iterator works (see below), but it feels like I'm using an undocumented feature or something. Is there a preferred method? Or is this the best approach? typedef boost::ptr_vector<int> VEC; VEC v; v.push_back( new int(1) ); v.push_back( new int(2) ); VEC::iterator a = v.begin(); VEC::iterator b = v.begin() + 1; // Swap the two underlying pointers using the base iterator std::swap( *a.base(), *b.base() ); -- Bill --

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Adding content to a vertex in a graph
by Stephen Torri 28 Aug '07

28 Aug '07

I made this property graph according to the documentation: class Component { public: typedef boost::shared_ptr<Component> ptr_t; }; class My_Graph { typedef boost::property< boost::vertex_name_t, Component::ptr_t > VertexProperty_t; typedef boost::adjacency_list<boost::vecS, // OutEdgeList boost::vecS, // VertexList boost::directedS, // Directed VertexProperty_t> // VertexProperties Graph_t; Graph_t m_graph; }; I cannot see from the MutablePropertyGraph page how I am suppose to add the VertexProperty_t to the vertex when its created. The documentation for the MutablePropertyGraph shows a use of "add_vertex" giving a vertex_propety_type with the graph. template <class G> struct MutablePropertyGraphConcept { typedef typename boost::graph_traits<G>::edge_descriptor edge_descriptor; void constraints() { function_requires< MutableGraphConcept<G> >(); v = add_vertex(vp, g); p = add_edge(u, v, ep, g); } G g; std::pair<edge_descriptor, bool> p; typename boost::graph_traits<G>::vertex_descriptor u, v; typename boost::graph_traits<G>::vertex_property_type vp; typename boost::graph_traits<G>::edge_property_type ep; }; My confusion lies in the fact that the add_vertex function requires a vertex_property_type the first parameter. So I am unsure how to create a vertex_property_type from a Component::ptr. Is a vertex_property_type equivalent to a Component::ptr? boost::graph_traits<Graph_t>::vertex_property_type vertex_propert_obj = Component::ptr ( new Component() ); boost::graph_traits<Graph_t>::vertex_descriptor new_vertex = add_vertex ( vertex_property_obj, m_graph ); Stephen

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[BGL] Bundled Properties and setS Edgelist container
by Sam Peterson 28 Aug '07

28 Aug '07

I know that if I use a setS for the edgelist container for an adjacency_list class, each edge of my graph will only be added once as I build it. This functionality is very desirable for me, but I've found I can't seem to use it with the equally desirable Bundled Property Maps. Specifically, this line of code doesn't seem to work: (*g)[i].paper_id = atoi(row[0]); g is a pointer to my graph. The exact compiler error with g++ 4.1.1 is: error: invalid conversion from 'size_t' to 'void*' Is there anyway I can use these two features together? If not, I'm going to be very disappointed. If that's the case I'd advise making a large note of it in the bundled properties documentation as I wouldn't have bothered with bundled properties if I knew they carried this limitation. -- Sam Peterson peabody(a)freeshell.org peabodyenator(a)gmail.com

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Short mailing list outage at 9:00PM EDT
by Doug Gregor 28 Aug '07

28 Aug '07

There will be a brief outage of the Boost mailing lists from 9:00PM-9:30PM EDT today. No mail will be lost. Subversion and the Trac will still be available during this time. - Doug

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[BGL] read_graphviz and dynamic properties
by Sam Peterson 28 Aug '07

28 Aug '07

I have been trying (unsuccessfully for the past hour), to read a graphviz file into an adjacency_list type. The program stops with a SIGABRT because I haven't mapped "node_id" to anything within the dynamic properties argument. However, I really have no desire to map node_id to anything; this is a very large graph and I'd like to avoid the memory consumption. If I try to map node id to the vertex_index_t map I receive a compiler error stating that's a const property map. If I want to map node_id to vertex_name_t map, I have to add that property to my adjacency_list type which will bloat the memory consumption. I just want to build the graph without worry about the properties. Is there anyway this can be done easily? The documentation on read_graphviz and write_graphviz are sorely lacking on this subject in my opinion. -- Sam Peterson peabody(a)freeshell.org peabodyenator(a)gmail.com

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boost undefined reference md5.
by chun ping wang 28 Aug '07

28 Aug '07

while trying to link to lib boost md5 i get these errors I build using make with -l"boost_md5-mgw41-1_34_1. booost md5 was build using gcc 4.1.2 mingw. C:/Boost/include/boost-1_34_1/boost/md5.hpp:33: undefined reference to `boost::md5::context::context()' C:/Boost/include/boost-1_34_1/boost/md5.hpp:33: undefined reference to `boost::md5::context::context()' C:/Boost/include/boost-1_34_1/boost/md5.hpp:57: undefined reference to `boost::md5::process(void const*, unsigned int, bool)' C:/Boost/include/boost-1_34_1/boost/md5.hpp:46: undefined reference to `boost::md5::clear()' C:/Boost/include/boost-1_34_1/boost/md5.hpp:46: undefined reference to `boost::md5::clear()'

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[Boost.Test] User Exception handling
by Ewgenij Sokolovski 28 Aug '07

28 Aug '07

Hello. On the webpage I read: In case if your test cases may throw custom exceptions (see here for list of exceptions translated by default), you could register translator specific for that exception. http://www.boost.org/libs/test/doc/components/utf/index.html So, if I understand it right, if I throw some custom exception in my test program and do not catch it, then it is catched by the boost test framework and reported in the proper way - if the exception can be translated by default. Now I look at the exceptions, which can be translated by default and see: In majority of the cases the monitored function doesn't need to throw the boost::execution_exception to report an error in the Execution Monitor. If you want a custom error message to be included into the execution_exception's error message, use one of the following C++ types as an exception: * C string. * std:string. * any exception class in std::exception hierarchy. http://www.boost.org/libs/test/doc/components/execution_monitor/index.html#… So, I can use a C string for my exception. I have written a small example test case and included throwing of an uncaught exception in it: try{ throw "blub"; } catch(char* ex){ throw; } As I started the testing process I didn't get a "blub"-Exception message, but Boost.Test internal framework error: unknown reason So, what's wrong? Why is "blub" not reported as "blub"? Can anybody explain that? Regards Ewgenij

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Serialization in an array
by Hansi Hansi 27 Aug '07

27 Aug '07

Hello, is it possible to serialize a class in a byte-array(e.g. array stream)? best regards Hansjörg _______________________________________________________________________ Jetzt neu! Schützen Sie Ihren PC mit McAfee und WEB.DE. 3 Monate kostenlos testen. http://www.pc-sicherheit.web.de/startseite/?mc=022220

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boost::thread Destructor being called multiple times
by kaliwanagan 27 Aug '07

27 Aug '07

I was just curious as to why the class destructor are (apparently) being called multiple times. I have tried searching the archives to no avail (which prompted me to register and post to the mailinglist). #include <boost/thread/thread.hpp> struct TestingClass { TestingClass() { std::cout << "constructor called" << std::endl; } ~TestingClass() { std::cout << "destructor called" << std::endl; } void operator()() { std::cout << "operator() called" << std::endl; } } testclass; void testBoostThread() { boost::thread thrd (testclass); thrd.join(); } int main () { testBoostThread(); return 0; } The output: constructor called destructor called destructor called destructor called destructor called operator() called destructor called I would appreciate if someone can enlighten me on this. Will having the destructor called multiple times be a cause of concern? Will it cause some undefined symptoms? Is there a way to completely avoid this situation?

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