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Re: [Boost-users] Query on Boost.Log
by Leo Carreon 13 Jul '13

13 Jul '13

From: Leo Carreon Sent: Friday, July 12, 2013 8:42 AM To: Boost Users Mailing List Subject: Query on Boost.Log Hi everyone, I’m trying to learn how to use Boost.Log from Boost 1.54.0 on Fedora 18. When I attempt to call boost::log::init_from_stream() even with BOOST_LOG_DYN_LINK defined, I get the error message”undefined reference to `void boost::log::v2_mt_posix::init_from_stream<char>(std::basic_istream<char, std::char_traits<char> >&)'” for the line where I called the function. Note that I have included the header file “boost/log/utility/setup/from_stream.hpp” and added –lboost_log to my link command line. Am I missing something. I have noticed that boost::log::init_from_stream() is a template. Is an instance of this template added into the shared library? Kind regards, Leo Hi again everyone, FYI. I built Boost 1.54.0 using the following bjam options – link=shared runtime-link=shared I have also checked the build logs from the above and discovered that not all of the .cpp files in libs/log/src have been included during the build. Kind regards, Leo

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[exception] exception_ptr missing virtual base parameters
by Michael Caisse 13 Jul '13

13 Jul '13

The basic problem I'm experiencing is that getting an exception_ptr results inherited parameters getting lost when virtual inheritance is used. The code below demonstrates a simple example. "bar" is lost in the print. Changing derived_except to be: struct derived_except : base_except { int i; }; will cause the inherited values to be copied into the exception_ptr; however, this has all the standard problems associated that come with not using virtual inheritance. This looks like a bug to me. The C++11 equivalent behaves has expected and inherited values are maintained in the exception_ptr. Any thoughts? michael -------------- boost::exception_ptr version -------------- #include <boost/exception/all.hpp> #include <string> #include <iostream> struct base_except { std::string s; }; struct derived_except : virtual base_except { int i; }; int main() { derived_except e; e.i = 8; e.s = "bar"; boost::exception_ptr ptr = boost::copy_exception(e); try { boost::rethrow_exception(ptr); } catch(derived_except & e) { std::cout << "derived_except: " << e.s << " " << e.i << std::endl; } catch(...) {} return 0; } -------------- c++11 version --------------------- #include <exception> #include <string> #include <iostream> struct base_except { std::string s; }; struct derived_except : virtual base_except { int i; }; int main() { derived_except e; e.i = 8; e.s = "bar"; std::exception_ptr ptr = std::make_exception_ptr(e); try { std::rethrow_exception(ptr); } catch(derived_except & e) { std::cout << "derived_except: " << e.s << " " << e.i << std::endl; } catch(...) {} return 0; } -- Michael Caisse ciere consulting ciere.com

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Re: [Boost-users] [graph] in-depth parsing and modifications of the graph
by Orianne Siret 12 Jul '13

12 Jul '13

I mean traverse when i said parse. So the problem is i can't traverse in depth-first order my graph and modify node (or edge) properties. I wrote a basic case which doesn't work. ----------------------------------------- // Begin main.cpp #include <boost/graph/adjacency_list.hpp> #include <boost/graph/depth_first_search.hpp> #include <vector> // Node properties struct MyNode { int node_id; MyNode() : node_id() {} MyNode(int id) : node_id(id) {} }; //Edge Properties struct MyEdge { int edge_id; MyEdge() : edge_id() {} MyEdge(int id) : edge_id(id) {} }; // Graph definition typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::directedS, MyNode, MyEdge > MyGraph; typedef boost::graph_traits<MyGraph>::vertex_descriptor MyGraphVD; //My idiot visitor class my_dfs_visitor : public boost::default_dfs_visitor { public: template < typename Vertex, typename Graph > void discover_vertex(Vertex u, Graph & g) { // here i cant assign 0 to m node_id. however g is not cont.. I didn't find a code with a depth-first traversal and assign ment. g[u].node_id = 0; } }; int main() { MyGraph g; MyGraphVD vd0 = boost::add_vertex(MyNode(0), g); MyGraphVD vd1 = boost::add_vertex(MyNode(1), g); boost::add_edge(vd0, vd1, MyEdge(), g); boost::add_edge(vd1, vd0, MyEdge(), g); my_dfs_visitor visitor; boost::depth_first_search(g, boost::visitor(visitor)); return 0; } // end ------------------------------------------ This code doesn't work. I have the following error : ../main.cpp:35:3: erreur: assignment of member 'MyNode::node_id' in read-only object. (I do: "g++ -O3 -Wall -c -o main.o main.cpp " for compilation, i run on linux ubuntu 12.04 with gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3) I didn't find any example on the web.. Thanks for spending time on my problem. It is very nice of you. Best regards. Orianne Siret

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BOOST_STATIC_ASSERT with boost::array.static_size
by Anton Daneyko 12 Jul '13

12 Jul '13

Dear boost users, could someone tell me why this short program does not compile? #include <boost/array.hpp> #include <boost/static_assert.hpp> int main(int argc, const char *argv[]) { boost::array<int, 3> a1 = {{1, 1, 1}}; BOOST_STATIC_ASSERT(a1.static_size == 3); return 0; } With g++ (4.3.4) I get the following error: tmp.cpp: In function ‘int main(int, const char**)’: tmp.cpp:7: error: ‘a1’ cannot appear in a constant-expression tmp.cpp:7: error: `.' cannot appear in a constant-expression tmp.cpp:7: error: template argument 1 is invalid With icc (12.1.6) I get the following error: tmp.cpp(7): error: this operator is not allowed in a template argument expression BOOST_STATIC_ASSERT(a1.static_size == 3); ^ tmp.cpp(7): error: incomplete type is not allowed BOOST_STATIC_ASSERT(a1.static_size == 3); ^ compilation aborted for tmp.cpp (code 2) However I can compile using IBM xlC compiler. I thought that static_size is a compile time constant and can be used in this context...

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Query on Boost.Log
by Leo Carreon 11 Jul '13

11 Jul '13

Hi everyone, I’m trying to learn how to use Boost.Log from Boost 1.54.0 on Fedora 18. When I attempt to call boost::log::init_from_stream() even with BOOST_LOG_DYN_LINK defined, I get the error message”undefined reference to `void boost::log::v2_mt_posix::init_from_stream<char>(std::basic_istream<char, std::char_traits<char> >&)'” for the line where I called the function. Note that I have included the header file “boost/log/utility/setup/from_stream.hpp” and added –lboost_log to my link command line. Am I missing something. I have noticed that boost::log::init_from_stream() is a template. Is an instance of this template added into the shared library? Kind regards, Leo

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Procedure entry point _ZNSt16invalid_argumentD2Ev could not be located in the dynamic link library libstdc++-6.dll
by Joe Hays 11 Jul '13

11 Jul '13

Hello all, I have a newbie question for you. I'm trying Boost for the very first time. I'm also not terribly experienced with C++. I'm using, Eclipse Kepler (latest) Mingw 3.20 (latest) Boost_1_54_0 on a 64-bit Windows 7 machine. I followed this tutorial to configure Boost to be used with Mingw and Eclipse: http://theseekersquill.wordpress.com/2010/08/24/howto-boost-mingw/ Sections 1-6 performed as expected. The 7th and final step is when a "hello world" like application finally compiles and links Boost into a .exe. I cut-n-paste the following code from Boost's Getting Started tutorial ( http://www.boost.org/doc/libs/1_54_0/more/getting_started/windows.html) <snip> #include <boost/regex.hpp> #include <iostream> #include <string> int main() { std::string line; boost::regex pat( "^Subject: (Re: |Aw: )*(.*)" ); while (std::cin) { std::getline(std::cin, line); boost::smatch matches; if (boost::regex_match(line, matches, pat)) std::cout << matches[2] << std::endl; } } </snip> The output of the build is, <snip> 12:20:46 **** Rebuild of configuration Debug for project BoostRegexExample1 **** Info: Internal Builder is used for build g++ "-Ic:\\boost_1_54_0" -O0 -g3 -Wall -c -fmessage-length=0 -o BoostRegexExample1.o "..\\BoostRegexExample1.cpp" g++ "-LC:\\boost_1_54_0\\stage\\lib" -o BoostRegexExample1.exe BoostRegexExample1.o -lboost_regex-mgw46-mt-1_54 12:20:52 Build Finished (took 5s.992ms) </snip> If I try to run that application within Eclipse the terminal simply states the application terminated. If I go to a terminal and run the .exe (using a text file as in input as directed in the Getting Started document) I get, *"Procedure entry point _ZNSt16invalid_argumentD2Ev could not be located in the dynamic link library libstdc++-6.dll"* Any ideas why this is happening? And, what I can do to get past this? Thanks, Joe

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boost::uuid
by John Emmas 11 Jul '13

11 Jul '13

Hello there, I'm developing an app (originally written for Linux) which uses some UUID functionality that originally came from a set of e2fs utilities for Linux. I'm porting the app to Windows so naturally, the e2fs stuff doesn't build. I need to find a UUID implemntation that's more cross-platform - and of course, the obvious one to try is boost::uuid. I first installed boost when it was at version 1.40 (1-2 years ago?) Anyway, my installed version doesn't include UUID so I decided to update to a more recent version. The most recent Windows installer I could find was for version 1.51, from BoostPro:- http://www.boostpro.com/download/ Unfortunately, it probably isn't the absolute latest because BoostPro is apparently now discontinued - but it should be recent enough to include the UUID modules. From what I can gather, boost::uuid has been around since at least version 1.42. However, I hit a couple of problems:- 1) Firstly, I seem to get errors, no matter which mirror I use. I'll try again later, in case the errors go away. 2) Despite the errors, something does seem to get downloaded. However, rather than installing all the source files / DLLs etc, I just get a subdirectory called "lib" which contains a bunch of zip files (over 100). My original (1.40) installation seemed to unpack everything for me. 3) AFAICT even ver 1.51 doesn't include any UUID functionality. There was nothing for UUID that was selectable in the installer - and none of the modules look like UUID. I seem to have boost::regex, boost::filesystem, boost:date_time and a whole load of other stuff - but no boost::uuid :-( I then came across this web page which seems to suggest that all I need to do is add one header file to my existing installation (boost/uuid.hpp). Am I over-thinking this?? Is that all there is to it?? Thanks. John

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[graph] in-depth parsing and modifications of the graph
by Orianne Siret 11 Jul '13

11 Jul '13

Hello, I would like to know if it is possible to parse a boost graph in depth while being able to modify the properties of the verices you parse ? I saw there is a in-depth parser but it seems to not allow the modifications of properties ? Thanks in advance for your help ! Orianne Siret

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[asio] Incorrect reporting of bytes transferred in write handler in 1.54
by Darren 11 Jul '13

11 Jul '13

Is anybody else seeing problems with the bytes_transferred reported to the write_handler after a successful async_write? I am seeing a value of zero despite the fact that the peer receives the bytes and no error is reported to the write_handler. My example code when built against 1.54 exhibits the problem whereas building against 1.53 works correctly. I am running on Windows 7 with MSVC 2010. A couple of notes: * I only see the problem when the number of threads is > 1, even though the handlers are invoked on a strand. * Defining BOOST_ASIO_DISABLE_IOCP makes everything work properly. When running my code a failure shows itself like this: Client: Writing value 85 Server: Received 4 bytes, value 85 Client: bytesWritten = 0 In other words, the client used async_write to send 4 bytes with long value 85 the server. The server received these bytes. The client write_handler was called with no error but a bytes_transferred value of 0. Is there something I don't understand or is this a problem introduced in 1.54? #include <boost/asio.hpp> #include <boost/thread.hpp> #include <boost/thread/mutex.hpp> #include <iostream> using namespace boost::asio; const std::size_t NumThreads = 2; const unsigned short Port = 12345; // Prevent interleaved output boost::mutex logMutex; struct Server { Server(io_service& svc) : m_socket(svc), m_acceptor(svc, ip::tcp::endpoint(ip::tcp::v4(), Port)), m_buffer(0) { } void Run() { m_acceptor.accept(m_socket); // Simple blocking reads while(std::size_t bytesRead = read(m_socket, buffer(&m_buffer, sizeof(m_buffer)))) { boost::mutex::scoped_lock lock(logMutex); std::cout << "Server: Received " << bytesRead << " bytes, value " << m_buffer << std::endl; } } ip::tcp::socket m_socket; ip::tcp::acceptor m_acceptor; unsigned long m_buffer; }; struct Client { Client(io_service& svc) : m_strand(svc), m_socket(svc), m_buffer(0) { m_socket.connect( ip::tcp::endpoint(ip::address_v4::from_string("127.0.0.1"), Port)); ScheduleWrite(); } void WriteHandler(const boost::system::error_code& err, std::size_t bytesWritten) { assert(!err); if(bytesWritten != sizeof(m_buffer)) { boost::mutex::scoped_lock lock(logMutex); std::cout << "Client: bytesWritten = " << bytesWritten << std::endl; return; } ScheduleWrite(); } void ScheduleWrite() { { boost::mutex::scoped_lock lock(logMutex); std::cout << "Client: Writing value " << ++m_buffer << std::endl; } async_write(m_socket, buffer(&m_buffer, sizeof(m_buffer)), m_strand.wrap( std::bind(&Client::WriteHandler, this, std::placeholders::_1, std::placeholders::_2))); } io_service::strand m_strand; ip::tcp::socket m_socket; unsigned long m_buffer; }; int main(int argc, char* argv[]) { boost::asio::io_service svc; Server server(svc); Client client(svc); boost::thread_group threads; for(int n = 0; n < NumThreads; ++n) threads.create_thread(std::bind(&io_service::run, &svc)); server.Run(); return 0; }

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Using boost with cray c++
by avib369 . 11 Jul '13

11 Jul '13

Does any one have any experience of using boost with cray C++ compiler ? Are any known problematic areas/issues ? Ok I know its not in the official list of supported compilers, but neither is the HPUX acc, which seems to work fine for most libs. Any help appreciated . Ta, Avi

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