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lexical cast: changesign is not a member of boost::math
by Philipp Münzel 18 Dec '11

18 Dec '11

Hi folks, I'm trying to compile the http server example of boost::asio: http://www.boost.org/doc/libs/1_48_0/doc/html/boost_asio/example/http/serve… I'm using gcc 4.6 on ubuntu Linux 11.10. When compiling the reply.cpp, I get the following error: In file included from reply.cpp:13:0: /usr/local/include/boost/lexical_cast.hpp: In function ‘bool boost::detail::parse_inf_nan_impl(const CharT*, const CharT*, T&, const CharT*, const CharT*, const CharT*, const CharT*, CharT, CharT)’: /usr/local/include/boost/lexical_cast.hpp:676:31: error: ‘changesign’ is not a member of ‘boost::math’ /usr/local/include/boost/lexical_cast.hpp:693:31: error: ‘changesign’ is not a member of ‘boost::math’ /usr/local/include/boost/lexical_cast.hpp: In function ‘bool boost::detail::lcast_ret_float(T&, const CharT*, const CharT*)’: /usr/local/include/boost/lexical_cast.hpp:1025:50: error: ‘changesign’ is not a member of ‘boost::math’ I remember having compiled this example some time ago with boost 1.46 or so. Is there some regression in 1.48 that prevents this from compiling? Regards, Philipp

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lexical_cast throws when used with empty vector (1.48.0)
by Braden Northington McDaniel 18 Dec '11

18 Dec '11

Boost 1.48.0's lexical_cast throws bad_lexical_cast when used with an empty vector. This is observable in the following program: #include <boost/lexical_cast.hpp> #include <cassert> #include <iostream> #include <iterator> #include <string> #include <vector> std::ostream & operator<<(std::ostream & out, const std::vector<long> & v) { std::ostream_iterator<long> it(out); std::copy(v.begin(), v.end(), it); assert(out); return out; } int main() { std::vector<long> v; //v.push_back(1); std::cout << boost::lexical_cast<std::string>(v); } If the commented line is uncommented (making the vector nonempty), the program runs without an exception. Is this the intended behavior? -- Braden McDaniel e-mail/Jabber IM: braden(a)endoframe.com http://endoframe.com

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[Range] Generating a singular range.
by Robert Jones 17 Dec '11

17 Dec '11

Hi All Is there an easy and obvious way to construct a single element range from a value_type of that range? Thx - Rob.

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[boost-users][container] associative placement insertion
by Cromwell Enage 17 Dec '11

17 Dec '11

Hi, all! I'm wondering how placement insertion works for pair-associative Boost.Container types. For example, given: //[ex_code struct D { D(char,char) {} // Insert Boost.Move awareness here... }; boost::container::map<int,D> my_map; //] Will my_map.emplace(0, 't', 'p') call D('t', 'p') and move the object into the map? Will Boost.Unordered work the same way? TIA! Cromwell D. Enage

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[call_traits] Having trouble with call traits combined with type deduction
by Rhys Ulerich 17 Dec '11

17 Dec '11

'Afternoon, I have a quick question on call traits and template argument deduction. I want to use call_traits' value_type and param_type to deduce a signature like double desired_result(double const& x); given an argument of type double. Is there any way to get type deduction working on a snippet like lousy_attempt (below) to produce my desired_result? #include <boost/call_traits.hpp> template<typename Scalar> typename boost::call_traits<Scalar>::value_type lousy_attempt(typename boost::call_traits<Scalar>::param_type x) { return x; } int main() { double y = 5; // Works... lousy_attempt<double>(y); // "No matching function call to lousy_attempt(double&)" lousy_attempt(y); return 0; } Thanks in advance, Rhys

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[MPI] compilation with c++0x and gcc-4.6
by tcb 17 Dec '11

17 Dec '11

hi, I have a problem compiling simple boost mpi programs with gcc4.6 on osx. The broadcast_test.cpp from libs/mpi/test compiles just fine with the -std=gnu++98, but when I use -std=gnu++0x I get a compilation error which seems to implicate boost::serialization. The code compiles just fine with gcc-4.4 and gcc-4.7 with the -std=gnu++0x flags. There is no c++0x specific code in the test file itself. Any ideas what the problem is with gcc-4.6 and -std=gnu++0x? $ OMPI_CXX=g++-mp-4.6 openmpic++ -std=c++0x -m64 -o broadcast_test broadcast_test.cpp -lboost_mpi-mt -lboost_serialization-mt In file included from /opt/local/include/boost/mpi/collectives.hpp:21:0, from /opt/local/include/boost/mpi/collectives_fwd.hpp:19, from /opt/local/include/boost/mpi/collectives/broadcast.hpp:11, from broadcast_test.cpp:8: /opt/local/include/boost/mpi/communicator.hpp:1633:58: error: specialization of 'boost::mpi::status boost::mpi::communicator::recv(int, int, T&) const [with T = boost::mpi::packed_iarchive]' after instantiation /opt/local/include/boost/mpi/communicator.hpp:1668:65: error: specialization of 'boost::mpi::request boost::mpi::communicator::isend(int, int, const T&) const [with T = boost::mpi::packed_oarchive]' after instantiation In file included from /opt/local/include/gcc46/c++/vector:64:0, from /opt/local/include/gcc46/c++/bits/random.h:34, from /opt/local/include/gcc46/c++/random:50, from /opt/local/include/gcc46/c++/bits/stl_algo.h:67, from /opt/local/include/gcc46/c++/algorithm:63, from /opt/local/include/boost/optional/optional.hpp:19, from /opt/local/include/boost/optional.hpp:15, from /opt/local/include/boost/mpi/communicator.hpp:18, from /opt/local/include/boost/mpi/collectives.hpp:21, from /opt/local/include/boost/mpi/collectives_fwd.hpp:19, from /opt/local/include/boost/mpi/collectives/broadcast.hpp:11, from broadcast_test.cpp:8: /opt/local/include/gcc46/c++/bits/stl_uninitialized.h: In function 'void std::__uninitialized_default_n_a(_ForwardIterator, _Size, _Allocator&) [with _ForwardIterator = char*, _Size = long unsigned int, _Allocator = boost::mpi::allocator<char>]': /opt/local/include/gcc46/c++/bits/vector.tcc:474:8: instantiated from 'void std::vector<_Tp, _Alloc>::_M_default_append(std::vector<_Tp, _Alloc>::size_type) [with _Tp = char, _Alloc = boost::mpi::allocator<char>, std::vector<_Tp, _Alloc>::size_type = long unsigned int]' /opt/local/include/gcc46/c++/bits/stl_vector.h:592:4: instantiated from 'void std::vector<_Tp, _Alloc>::resize(std::vector<_Tp, _Alloc>::size_type) [with _Tp = char, _Alloc = boost::mpi::allocator<char>, std::vector<_Tp, _Alloc>::size_type = long unsigned int]' /opt/local/include/boost/mpi/detail/packed_oprimitive.hpp:96:46: instantiated from here /opt/local/include/gcc46/c++/bits/stl_uninitialized.h:576:6: error: no matching function for call to 'boost::mpi::allocator<char>::construct(char*)' /opt/local/include/gcc46/c++/bits/stl_uninitialized.h:576:6: note: candidate is: /opt/local/include/boost/mpi/allocator.hpp:168:8: note: void boost::mpi::allocator<T>::construct(boost::mpi::allocator<T>::pointer, const T&) [with T = char, boost::mpi::allocator<T>::pointer = char*] /opt/local/include/boost/mpi/allocator.hpp:168:8: note: candidate expects 2 arguments, 1 provided In file included from /opt/local/include/boost/serialization/extended_type_info_typeid.hpp:37:0, from /opt/local/include/boost/archive/detail/oserializer.hpp:38, from /opt/local/include/boost/mpi/detail/mpi_datatype_oarchive.hpp:14, from /opt/local/include/boost/mpi/detail/mpi_datatype_cache.hpp:13, from /opt/local/include/boost/mpi/datatype.hpp:27, from /opt/local/include/boost/mpi/communicator.hpp:20, from /opt/local/include/boost/mpi/collectives.hpp:21, from /opt/local/include/boost/mpi/collectives_fwd.hpp:19, from /opt/local/include/boost/mpi/collectives/broadcast.hpp:11, from broadcast_test.cpp:8: /opt/local/include/boost/serialization/access.hpp: In static member function 'static void boost::serialization::access::serialize(Archive&, T&, unsigned int) [with Archive = boost::mpi::packed_oarchive, T = boost::mpi::packed_oarchive]': /opt/local/include/boost/serialization/serialization.hpp:69:5: instantiated from 'void boost::serialization::serialize(Archive&, T&, unsigned int) [with Archive = boost::mpi::packed_oarchive, T = boost::mpi::packed_oarchive]' /opt/local/include/boost/serialization/serialization.hpp:128:9: instantiated from 'void boost::serialization::serialize_adl(Archive&, T&, unsigned int) [with Archive = boost::mpi::packed_oarchive, T = boost::mpi::packed_oarchive]' /opt/local/include/boost/archive/detail/oserializer.hpp:148:5: instantiated from 'void boost::archive::detail::oserializer<Archive, T>::save_object_data(boost::archive::detail::basic_oarchive&, const void*) const [with Archive = boost::mpi::packed_oarchive, T = boost::mpi::packed_oarchive]' broadcast_test.cpp:153:1: instantiated from here /opt/local/include/boost/serialization/access.hpp:118:9: error: 'class boost::mpi::packed_oarchive' has no member named 'serialize' /opt/local/include/boost/serialization/access.hpp: In static member function 'static void boost::serialization::access::serialize(Archive&, T&, unsigned int) [with Archive = boost::mpi::packed_iarchive, T = boost::mpi::packed_iarchive]': /opt/local/include/boost/serialization/serialization.hpp:69:5: instantiated from 'void boost::serialization::serialize(Archive&, T&, unsigned int) [with Archive = boost::mpi::packed_iarchive, T = boost::mpi::packed_iarchive]' /opt/local/include/boost/serialization/serialization.hpp:128:9: instantiated from 'void boost::serialization::serialize_adl(Archive&, T&, unsigned int) [with Archive = boost::mpi::packed_iarchive, T = boost::mpi::packed_iarchive]' /opt/local/include/boost/archive/detail/iserializer.hpp:188:5: instantiated from 'void boost::archive::detail::iserializer<Archive, T>::load_object_data(boost::archive::detail::basic_iarchive&, void*, unsigned int) const [with Archive = boost::mpi::packed_iarchive, T = boost::mpi::packed_iarchive]' broadcast_test.cpp:153:1: instantiated from here /opt/local/include/boost/serialization/access.hpp:118:9: error: 'class boost::mpi::packed_iarchive' has no member named 'serialize'

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Re: [Boost-users] [BGL] Issue using connected_components
by Nicolas Saunier 16 Dec '11

16 Dec '11

Hi everyone, I finally found a solution by myself to get connected_components from a graph of type adjacency_list<listS, listS, undirectedS> with bundled properties for the vertices and edges. So I will post it here so that others can find it, to get feedback and make sure I am doing it right: #include <boost/graph/adjacency_list.hpp> #include <boost/graph/connected_components.hpp> using namespace boost; using namespace std; struct FeatureConnection { float minDistance; float maxDistance; }; struct VertexInformation { int featureId; int index; }; typedef adjacency_list<listS, listS, undirectedS, VertexInformation, FeatureConnection> UndirectedGraph; int main() { UndirectedGraph g; UndirectedGraph::vertex_descriptor u, v, w, x, y; UndirectedGraph::edge_descriptor e, f; u = add_vertex(g); v = add_vertex(g); w = add_vertex(g); x = add_vertex(g); y = add_vertex(g); bool unused; tie(e, unused) = add_edge(u, v, g); tie(f, unused) = add_edge(x, y, g); cout << num_vertices(g) << " " << num_edges(g) << endl; graph_traits<UndirectedGraph>::vertex_iterator vi, vend; graph_traits<UndirectedGraph>::vertices_size_type cnt = 0; for(tie(vi,vend) = vertices(g); vi != vend; ++vi) g[*vi].index = cnt++; property_map<UndirectedGraph, int VertexInformation::*>::type components = get(&VertexInformation::index, g); int num = connected_components(g, components, vertex_index_map(get(&VertexInformation::index, g))); cout << num << endl; for(tie(vi,vend) = vertices(g); vi != vend; ++vi) cout << *vi << " " << components[*vi] << " " << g[*vi].index << endl; return 0; } Thanks, Nicolas -- Nicolas Saunier, ing. jr, Ph.D. Professeur Adjoint / Assistant Professor Département des génies civil, géologique et des mines (CGM) École Polytechnique de Montréal http://nicolas.saunier.confins.net

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Boost on Mac w/ C++2011
by John M. Dlugosz 16 Dec '11

16 Dec '11

A co-worker reports that on a Mac, turning on the C++2011 dialect (to enable 'auto', lvalue references, etc.) makes the Boost headers choke. The release notes for the latest Boost show an older version of the compiler (Clang) as what is supported. Is there a simple way, like with a #define or a published patch to the config files, to make it work? —John

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Condition Variable and optimization
by John M. Dlugosz 16 Dec '11

16 Dec '11

The example in the documentation for Condition Variables illustrates the implication that these are Mesa-style (non-blocking signals) with this example: boost::condition_variable cond; boost::mutex mut; bool data_ready; void process_data(); void wait_for_data_to_process() { boost::unique_lock<boost::mutex> lock(mut); while(!data_ready) { cond.wait(lock); } process_data(); } This needs to declare data_ready as mutable, so the compiler doesn't reduce the while loop to a no-op and assume the value doesn't change, or just hold it in a register so it doesn't see the change made by another thread. More generally, how do you write it in this case? while ( !collection.empty() ) cond.wait(lock); where the condition is a function of an existing class? The compiler might inline that function and give the same issue. I think a form of wait that takes a predicate ought to be introduced, that prevents this particular issue and ensures correct use. —John

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Parsing statements from ascii files in arbitrary order into hierarchies of structs using boost spirit
by Stefan Zellmann 16 Dec '11

16 Dec '11

Hello! I'd like to parse one-line statements from an ascii file using boost spirit into structs. Statements may be quite different and may occur in arbitrary order. I'm wondering how I can achieve something like the following: /qi::rule<T, Statement(), Skipper> r_statement; qi::rule<T, DerivedStatement0(), Skipper> r_derivedStatement0; qi::rule<T, DerivedStatement1(), Skipper> r_derivedStatement1;/ With: /struct Statement { // empty }; struct DerivedStatement0 : public Statement { // members }; struct DerivedStatement1 : public Statement { // members };/ First thing I'm not sure about is how to adapt (using /BOOST_FUSION_ADAPT_STRUCT/) this hierarchy, since /Statement/ has no members. I've seen some snippets on the internet where inherited members (data members are good for me, no member functions) were adapted using /BOOST_FUSION_ADAPT_STRUCT/, so I'm right to believe that inheritance in my case shell pose no problem? Well, I'm actually not sure if the idea I came up with is the right way to accomplish this in the first place, so I'm grateful for any suggestions on how to do this more appropriately. Thanks in advance! Cheers, Stefan -- Stefan Zellmann Dipl.-Wirt.-Inf. Universität zu Köln RRZK Phone: +49 221 478 86578 Mail: zellmans(a)uni-koeln.de

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