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Using boost to eliminate an ugly facade function
by Chris Stankevitz 29 Aug '12

29 Aug '12

Hello, Can boost help me eliminate the ugly facade function I use below? I have a boost::signals2::signal that passes an object ("CPerson"). I want to connect to this signal not to receive the object ("CPerson") but to receive the result of one of its methods ("CPerson::GetAge()"). Can boost help me with this? If so I'm eager to read and learn about it, I just need to know what it is called. Thank you! Chris //=== #include <boost/signals2/signal.hpp> //---------- // A CPerson offers GetAge() //---------- struct CPerson { int GetAge() const { return 0; } }; //---------- // A CCompany has a boss and a signal // to tell when boss is hired //---------- struct CCompany { CPerson GetBoss() const { return mBoss; } boost::signals2::signal<void(const CPerson&)> BossHired; CPerson mBoss; }; //---------- // A CProcessor processes int ages. // It does not know aobut CPerson //---------- struct CProcessor { void f(int Age) {} }; //---------- // ProcessorFacade is used to strip // an age of a CPerson before // passing the age to CProcessor //---------- void ProcessorFacade(CProcessor& Processor, const CPerson& Person) { Processor.f(Person.GetAge()); } //---------- // main puts it all together //---------- int main() { CCompany Company; CProcessor Processor; // Compiler error: the signal sends an instance of CPerson, // not the result of CPerson::GetAge(). Too bad because // CProcessor does not have know about CPerson // // Company.BossHired.connect( // boost::bind(&CProcessor::f, &Processor, _1)); // So we use an ugly facade instead Company.BossHired.connect( boost::bind(ProcessorFacade, boost::ref(Processor), _1)); return 0; }

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[Graph] compilation error under Windows but not under Linux
by Gaël de Chalendar 29 Aug '12

29 Aug '12

Hello, I have a compilation error under Windows (Visual C++ 2008) with a code that works well under Linux (gcc 4.6.1 and before). The compilation error is: =========== /FsaAccess16.tcc(833) : error C2784: 'std::pair<graph_traits<G>::in_edge_iterator,graph_traits<G>::in_edge_iterator> boost::in_edges(graph_traits<G>::vertex_descriptor,const boost::subgraph<Graph> &)'ÿ: impossible de d‚duire l'argument modŠle pour 'const boost::subgraph<Graph> &' … partir de 'FrCeaLic2m::Common::FsaAccess::selected_graph_types16::spareGraphType' C:\PROGRA~1\boost\BOOST_~1\boost/graph/subgraph.hpp(432)ÿ: voir la d‚claration de 'boost::in_edges' Z: \Projets\MoteurMultimedia\mm_common\src\common/FsaAccess/FsaAccess16.tcc(778)ÿ: lors de la compilation de la fonction membre '<Inconnu>' de la classe <Inconnu> z: \projets\moteurmultimedia\mm_common\src\common\fsaaccess\FsaAccessReader16.h(118)ÿ: voir la r‚f‚rence … l'instanciation de la classe modŠle 'FrCeaLic2m::Common::FsaAccess::FsaAccess16<graphType>' en cours de compilation with [ graphType=FrCeaLic2m::Common::FsaAccess::selected_graph_types16::spareGraphType ] z: \projets\moteurmultimedia\mm_common\src\common\fsaaccess\FsaAccessSpare16.h(35)ÿ: voir la r‚f‚rence … l'instanciation de la classe modŠle 'FrCeaLic2m::Common::FsaAccess::FsaAccessReader16<graphType>' en cours de compilation with [ graphType=FrCeaLic2m::Common::FsaAccess::selected_graph_types16::spareGraphType ] =========== The line that does not compile is boost::tie(iei,ie_end) = boost::in_edges(commonTarget,m_graph); The function being compiled is declared like that: template <typename graphType > std::pair< const typename boost::graph_traits<graphType>::vertex_descriptor, bool > FsaAccess16<graphType>::findEquivalentInRegister( dicoVertexType tempState ){ ... And here graphType, the type of m_graph is spareGraphType defined by: struct selected_graph_types16 { ... typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, dicoVertexCountProperty> spareGraphType; ... This is a cmake based project that I compile using qtcreator. I'm a Linux developer and I'm a little bit lost with VC outputs and tools under Windows... Regards, Gaêl -- Gael de Chalendar CEA LIST Centre de Fontenay-aux-Roses Laboratoire Vision et Ingénierie des Contenus (Vision and Content Engineering Laboratory) Bat. 38-2 ; 18, rue du Panorama ; BP 6 92265 Fontenay aux Roses Cedex ; France Tél.:01.46.54.80.18 ; Fax.:01.46.54.75.80 Email : Gael.D.O.T.de-Chalendar.A(a)T.cea.D.O.T.fr

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[Locale] inconsistent results for utf-8 collation
by Patrick Ohly 29 Aug '12

29 Aug '12

Hello! When comparing the following UTF-8 string pairs using Boost.Locale (any backend) at the "identical" level (accents are relevant) and a UTF-8 locale (I tried de_DE.utf-8) on Debian Testing (boost 1.49), I get a result that does not make sense to me. "Muller" is considered less than "Müller" (as expected), but "Muller 2" is considered more than "Müller 1", despite the different result for the names alone. Do I have bug in my code, in the underlying libraries or in my expectations? #include <locale.h> #include <boost/locale.hpp> #include <boost/assign/std/vector.hpp> #include <boost/foreach.hpp> #include <boost/assign/list_of.hpp> #include <boost/algorithm/string/join.hpp> #include <iostream> int main(int argc, char **argv) { setlocale(LC_ALL, ""); std::cout << "backends: " << boost::join(boost::locale::localization_backend_manager::global().get_all_backends(), ", ") << std::endl; boost::locale::localization_backend_manager::global().select(argc > 2 ? argv[2] : "icu"); std::locale loc = boost::locale::generator()(argc > 1 ? argv[1] : "de_DE.UTF-8"); typedef boost::tuple<std::string, std::string> string_pair_t; std::vector<string_pair_t> pairs = boost::assign::tuple_list_of("Muller", "Müller") ("Muller 2", "Müller 1") ("Muller B", "Müller A"); BOOST_FOREACH (const string_pair_t &pair, pairs) { const std::string &a = boost::get<0>(pair), &b = boost::get<1>(pair); int cmp = std::use_facet<boost::locale::collator<char> >(loc). compare(boost::locale::collator_base::identical, a, b); std::cout << a << " and " << b << " are " << (cmp == 0 ? "identical" : "different") << " (" << (cmp < 0 ? '<' : cmp > 0 ? '>' : '=') << ")" << std::endl; } return 0; } The output on my system: $ /tmp/mueller de_DE.utf-8 icu backends: icu, posix, std Muller and Müller are different (<) Muller 2 and Müller 1 are different (>) Muller B and Müller A are different (>) Bye, Patrick

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using boost with net-snmp
by Ashish Lal 29 Aug '12

29 Aug '12

Hi, I am trying to integrate net-snmp using AgentX into a C++ app which uses boost libraries extensively. Has anyone integrated net-snmp with boost's ASIO based event loop? Appreciate any help and pointers.

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query about multi_linestring in boost::geometry
by rakesh patil 29 Aug '12

29 Aug '12

Hello, I am planning to make use of multi_linestring in my application. Before that I have some queries, for which I'm running short of answers. Here are few questions 1. Is it possible to redistribute the number of points in a particular linestring of a multi_linestring variable? 2. Is it possible to split one linestring into two linestrings and store them in the same multi_linestring variable? 3. In regards to point 2, is it possible to merge two different linestrings within a multi_linestring variable and make a single linestring instead of two? If possible, can any one provide any reference to some links, or some examples? Thanks

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Using boost::Asio for connected UDP socket
by Gheorghe Marinca 28 Aug '12

28 Aug '12

Hi, I want to implement an UDP server and have problems on defining on how the server handles coming concurrent udp "connections" from multiple clients. What I basically want to implement is an DNS proxy. Is there something equivalent to an tcp::acceptor for udp ? Looking over asio docs I see: template< typename Protocol <http://www.boost.org/doc/libs/1_35_0/doc/html/boost_asio/reference/Protocol…>, typename SocketAcceptorService <http://www.boost.org/doc/libs/1_35_0/doc/html/boost_asio/reference/SocketAc…> = socket_acceptor_service<Protocol>>class basic_socket_acceptor : public basic_io_object< SocketAcceptorService >, public socket_base For tcp we have following typedef: typedef basic_socket_acceptor< tcp > acceptor; Can I use basic_socket_acceptor with socket_acceptor_service<UDP> so that I can create additional udp sockets for every udp client that wants to send data to my server ? I've observed that if I use async_receive_from on the same socket I receive data from multiple clients making impossible exchanging data (read/write) with multiple clients at the same time. Any hints are appreciated. -Ghita

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Re: [Boost-users] boost.Iostream OpenSSL Filter
by Neil Nelson 28 Aug '12

28 Aug '12

exocoder, Upon just reading the docs at http://www.boost.org/doc/libs/1_50_0/libs/iostreams/doc/index.html and particularly 2.2.8. Multi-Character Filters It looks like you could take the code from the following page http://stackoverflow.com/questions/1007337/encrypting-and-decrypting-a-smal… with the critical line being AES_cfb128_encrypt(indata, outdata, bytes_read, &key, ivec, &num, AES_ENCRYPT); that reads and writes to memory buffers. Two other aspects are: (1) software using encryption is export restricted and you can research that if needed for your application, (2) key management is likely the more complicated part, and (3) use of initialization vectors (added random bytes at the beginning of the input data). Neil Nelson > I am currently looking at using OpenSSL to write information to an > encrypted file on-the-fly so to speak. I have been researching my > options for doing this, and have come across the Boost.Iostream library, > which promises to be a very elegant solution (The documentation even > suggests that filters can be written to provide encryption/decryption > using OpenSSL). > It would seem that my best approach would be to use the BIO_f* interface > to encrypt a memory buffer, which could be written by overloading > write(). However the OpenSSL documentation is particularly sparse when > it comes to file/memory encryption and I would appreciate any advice on > how to do this. > Thank you in advance for any help proffered.

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[Filesystem] path::generic_u16string() seems not to exist?
by Craig Dickson 28 Aug '12

28 Aug '12

Hello all, The online reference for Boost 1.50 show methods called u16string() and generic_u16string() to obtain the native and generic forms of the path as std::u16strings. However, if I try to compile code that uses them, the compiler can't find them, and the text "u16string" does not occur in boost/filesystem.hpp. (The same remarks apply to u32string and generic_u32string.) My workaround for now is to provide my own implementation of string<u16string>() and generic_string<u16string>(). This gets the job done, but the discrepancy between the docs and the code still bugs me. Will these methods be provided in a future release? If not, shouldn't they be removed from the docs? Thanks, Craig

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[1.51] valgrind problem in boost::math::erfc_inv
by Jan Boehme 28 Aug '12

28 Aug '12

Hello, after switching to 1.51, I observe that none of the created apps or tests can be profiled using valgrind. When using 1.50 there's no problem in it. The issue that valgrind complains is the following: ==26716== Memcheck, a memory error detector ==26716== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al. ==26716== Using Valgrind-3.6.1 and LibVEX; rerun with -h for copyright info ==26716== Command: optiSLang/optiSLang_4_0/kernel/tests/bin/serialize.test/782744749150d7ee13cdc314b59c8e95/serialize ==26716== terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<std::overflow_error> >' what(): Error in function boost::math::erfc_inv<e>(e, e): Overflow Error The system is a Fedora 16 powered by kernel 3.4.9-1.fc16.x86_64 Thanks for giving an advice, Jan.

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Using boost::Asio for connected UDP socket
by Eugene Mamin 28 Aug '12

28 Aug '12

>>I want to implement an UDP server and have problems on defining on how the server handles coming concurrent udp "connections" from multiple clients. What I basically want to implement is an DNS proxy. You should see following implementation of transport layer from maidsafe-dht project: https://github.com/maidsafe/MaidSafe-Transport/tree/master/src/maidsafe/tra… Also, this code reviewed by boost.asio author Christopher M. Kohlhoff.

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