January 2009 - Boost-users - lists.preview.boost.org

example of factory where derived class constructors have different signatures
by Victor Whiskey Yankee 09 Jan '09

09 Jan '09

Hi, How factory can be used when derived classes need constructing with different args? Could someone show an sample? Thank you, Vic

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[Boost.Graph] - problem with A* and bundled properties
by David Conner 08 Jan '09

08 Jan '09

I'm trying to use Bundled properties with astar. But I get the following error, below. 1>C:\Program Files\Microsoft Visual Studio 9.0\VC\include\limits(109) : error C2440: '<function-style-cast>' : cannot convert from 'int' to 'C' 1> No constructor could take the source type, or constructor overload resolution was ambiguous 1> C:\Program Files\Microsoft Visual Studio 9.0\VC\include\limits(107) : while compiling class template member function 'C std::numeric_limits<_Ty>::max(void) throw()' 1> with 1> [ 1> _Ty=C 1> ] 1> C:\Boost\include\boost-1_36\boost/graph/astar_search.hpp(342) : see reference to class template instantiation 'std::numeric_limits<_Ty>' being compiled 1> with 1> [ 1> _Ty=C 1> ] I noticed that this is the same problem as a post from January 2008 (Date: 2008-01-09 17:56:40), but there was no reply posted. The source code is attached; I get the same error with Boost 1.36 or 1.37 Here are my structures: class EdgePropertyMap { public: cost weight; }; typedef boost::property_map<mygraph_t, cost EdgePropertyMap::*>::type WeightMap; WeightMap weightmap = boost::get(&EdgePropertyMap::weight, g); boost::astar_search (g, start, distance_heuristic<mygraph_t, cost, location*>(locations, goal), boost::visitor(astar_goal_visitor<vertex>(goal)). // Only the first of named parameters needs boost:: predecessor_map(&p[0]).distance_map(&d[0]) );//. Any help? Thanks, David ----- Earlier post -------------------------------------------------------------------------- Christopher Gay (cgay_at_[hidden]) Date: 2008-01-09 17:56:40 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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Error during mipsel cross compile of asio example
by Gordon Smith 08 Jan '09

08 Jan '09

Hello, I'm cross compiling an asio http server example from x86 linux to mipsel linux using boost-1.37.0 and gcc 4.1.2. I've compiled libraries successfully using bjam but the http server code produces the following errors: # export ARCH=mipsel # export CC=mipsel-ssd-linux-gnu-gcc # export CXX=mipsel-ssd-linux-gnu-g++ # export LD=mipsel-ssd-linux-gnu-ld # make mipsel-ssd-linux-gnu-gcc -L/usr/cross/mipsel/mipsel-ssd-linux-gnu/lib -L../boost-1.37.0/lib-mipsel connection.o connection_manager.o mime_types.o posix_main.o reply.o request_handler.o request_parser.o server.o -o httpd -lpthread -lstdc++ -lboost_thread-gcc-mt-1_37 -lboost_system-gcc-mt-1_37 connection.o: In function `boost::detail::atomic_conditional_increment(int*)': connection.cpp:(.text._ZN5boost6detail28atomic_conditional_incrementEPi[boost::detail::atomic_conditional_increment(int*)]+0x78): undefined reference to `__sync_val_compare_and_swap_4' connection.o: In function `boost::detail::atomic_decrement(int*)': connection.cpp:(.text._ZN5boost6detail16atomic_decrementEPi[boost::detail::atomic_decrement(int*)]+0x2c): undefined reference to `__sync_fetch_and_add_4' connection.o: In function `boost::detail::atomic_increment(int*)': connection.cpp:(.text._ZN5boost6detail16atomic_incrementEPi[boost::detail::atomic_increment(int*)]+0x2c): undefined reference to `__sync_fetch_and_add_4' ../boost-1.37.0/lib-mipsel/libboost_thread-gcc-mt-1_37.a(thread.o): In function `boost::thread::get_thread_info() const': thread.cpp:(.text+0x478): undefined reference to `__sync_fetch_and_add_4' ../boost-1.37.0/lib-mipsel/libboost_thread-gcc-mt-1_37.a(thread.o): In function `boost::detail::thread_data_base::~thread_data_base()': thread.cpp:(.text+0x7ac): undefined reference to `__sync_fetch_and_add_4' thread.cpp:(.text+0x7e0): undefined reference to `__sync_fetch_and_add_4' ... snip ... I've seen "Disable sync use for arm and hppa" at https://svn.boost.org/trac/boost/changeset/44440 I've also glanced at detail/sp_counted_base.hpp and detail/atomic_count_sync.hpp. Is this a simple matter of avoiding this code as in the changeset, or should it be written? I don't know much about the MIPS architecture. Thank you, Gordon

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serilalization of union
by niranjan bangera 08 Jan '09

08 Jan '09

Hi all, I am using the boost version 1.36.0 , linux platform. In my project i have to srialize a Union . i tried in the same way that classes and structures been serialized. But it gives a compilation error. How can i do that.. Please help me doing this. union myunion { uint32_t a; float t; }; i tried using like this. union myunion { uint32_t a; float t; template <class Archive> void serialize(Archive & ar, const unsigned int file_version) { ar & a; ar & t; } i get an error when iwant to serialize the object of the union saying myunion is not a class or struct type. Pls help me to do this. thanks in Advance.

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[ublas] why is there no constructor that fills the matrix with a default value
by Thorsten Ottosen 08 Jan '09

08 Jan '09

Hi, I was a bit surprised that there is no way to fill a triangular_matrix with a default value. Say, I would have expected this to work: triangular_matrix<double> m(42,42,42); Is there any reason why this constructor is not provided? Thanks -Thorsten

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[tuples] Lifting hardcoced limitations by using BOOST_PP
by Joel Falcou 08 Jan '09

08 Jan '09

I've been extensively using boost::tuple for a while and stumbled upon various tuple size limitation bound to the fact that the tuple implementation has hardcoded the maximum size of the tuple<> class and related function/meta-functions like tie for example or make_tuple. Is there anything in tuple design that prevent using Boost::Preprocessor to make it more customizable ? Is there an interest to such an update or is tuples more or less on the way to deprecation considering boost::fusion ?

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XML serialization of non-std::string types
by Thomas Sondergaard 08 Jan '09

08 Jan '09

I'm using boost::serialization with QString, and I'm having the same problem as this poster: http://lists.boost.org/boost-users/2006/10/22940.php boost::serialization doesn't deal ideally with non-std::strings, and there are enough of them in use, that it is important (QString, CString, wxString, etc). Would it be possible to add a mechanism that would make it easy to extend boost::serialization to handle new string types as conveniently as std::string/std::wstring? I'm currently using the following helper-function to do the job, but ideally I'd want the same syntax for serializing QStrings as other strings. template<class Archive> inline void serializeQString(Archive &ar, const char *name, QString &s) { if (Archive::is_saving::value) { std::string tmp(s.toUtf8().constData()); ar & boost::serialization::make_nvp(name, tmp); } else if (Archive::is_loading::value) { std::string tmp; ar & boost::serialization::make_nvp(name, tmp); s = QString::fromUtf8(tmp.c_str()); } } Regards, Thomas Sondergaard

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Re: [Boost-users] [Units] Molecular units base_units trouble: please help
by Christopher Bruns 07 Jan '09

07 Jan '09

Matthias Schabel wrote: > In general, it's easiest to avoid explicitly creating unit systems by > using the ::unit_type approach. For most cases, the unit system ought > to be considered an implementation detail since the library supports > heterogeneous units transparently. That is, for any given unit, the > appropriate system is just the set of units needed to fully describe > the unit itself... Thank you Matthias for the code example. It was exactly what I needed to get back into implementation flow. Yet I still feel the urge to create an md_units_system. For instance, once I create a system including base_units picoseconds, daltons, and nanometers, I can automatically create an energy unit in that system which magically has units of kilojoules per mole, without having to remember how mass, time, length, and energy are related. I am now pondering the creation of a clever set of base units such that Avogadro's constant appears in only one conversion factor to SI units. Either mass or amount would need to be a derived unit. But perhaps this topic is drifting outside the scope of the boost users list... Steven Watanabe wrote: > This was definitely a bug in the library. Fixed in the trunk. Thank you Steven Watanabe so much for your rapid analysis and fix of this bug. I have updated to the latest trunk and can verify that the compile errors no longer occur. I now have all I need to proceed to more sophisticated use of boost.units in molecular computation. Thanks again for the thoughtful and diligent help Matthias and Steven. --Chris Bruns

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[BGL] Trouble linking read_graphviz
by Michael Olea 07 Jan '09

07 Jan '09

Hi. I have been working through the tutorial portion of "The Boost Graph Library: User Guide and Reference Manual", and have been unable to get example code that includes calls to read_graphviz to link. For example, code including this line: read_graphviz("figs/ospf-graph.dot", g_dot); when compiled like this: g++ -I/usr/local/include//boost-1_37 ospf-example.cpp \ -o ospf /usr/local/lib/libboost_graph-xgcc40-mt-1_37.a generates the message: /usr/libexec/gcc/i686-apple-darwin8/4.0.1/ld: Undefined symbols: boost::read_graphviz(std::basic_string<char, std::char_traits<char>, \ std::allocator<char> > const&, boost::subgraph<boost::adjacency_list ... <very long signature ending in...> ... boost::no_property> > > >, boost::listS> >&) collect2: ld returned 1 exit status However, the test code graphviz.cpp, which has the lines: std::ifstream in(filename.c_str()); BOOST_REQUIRE(in); Graph g; dynamic_properties dp; dp.property("id", get(vertex_name, g)); dp.property("weight", get(edge_weight, g)); BOOST_CHECK(read_graphviz(in, g, dp, "id")); compiles, links, and runs just fine. I also tried (desperation) building an earlier version of boost -- 1.34.1 -- with the same results. Any ideas what I'm missing and how I might fix it, or what I need to read to find out, would be appreciated. -- Michael

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is there a way to exclude wchar support in boost 1.36.0?
by Shidong Chen 07 Jan '09

07 Jan '09

Hello everyone, I'm having issues in compiling boost 1.36.0 on a linux platform. I need to turn off wchar support. Is there anyway to exclude those files/libraries? Thanks a lot, Shidong

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