July 2013 - Boost-users - lists.preview.boost.org

[Boost.Geometry] - Union generates polygon with punctures
by Olivier Heriveaux 14 Jul '13

14 Jul '13

Hello ! I'm trying to use Boost.Geometry library to implement Minkowsky algorithm (i.e. polygon convolution). I try to implement it in the same way Boost.Polygon does, but during the algorithm execution, a boost::geometry::overlay_invalid_input_exception is raised. It seems that one of the input polygons to the union_ function is invalid. To understand my mistake, I outputed the operand polygons to SVG files and I discovered punctures in one of them. I believe Boost.Geometry thinks my polygon is self-intersecting (may be due to precision error with floats ?) - but this polygon itself is the result of a previous union operation. For info, I attached the SVG file (use inkscape to see it completely since segments are out of the box due to negative coordinates). I don't know if solutions to this problem exists or if the library is faulty (the bad polygon is the result of an union operation). One workaround would be to detect punctures and remove them, but it's kind of ugly imho... Some more details: - point coordinates type is float, - I use custom class instead of point_xy model, - polygon winding is counter-clockwise. Thank you in advance for any help, Olivier

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[multi_index][ann] Boost.MultiIndex 1.55 preview: major update with C++11 capabilities
by Joaquín Mª López Muñoz 14 Jul '13

14 Jul '13

Dear Boost.MultiIndex user: I've completed a major update of Boost.MultiIndex retrievable from the SVN repository, trunk branch, or at: https://www.dropbox.com/s/xipv129az88vgd1/multi_index_130713.zip This update includes many C++11 capabilities (most emulated by various means in pre-C++11 compilers,) among them the following: * multi_index_container is now efficiently movable employee_set extract_employees(const std::string& db); employee_set cont=extract_employees("employees.dat"); // no data copying * Initializer lists supported (if the compiler provides them) employee_set es8{{0,"Rose",40,4512},{1,"Mary",38,3345},{2,"Jo",25,7102}}; * Emplace functions es.emplace(0,"Joe",31,1123); es.get<3>().emplace_back(3,"Judy",39,6201); * Non-copyable elements allowed typeded multi_index_container< std::unique_ptr<employee>, indexed_by<...> > employee_ptr_set; How does this update affect you? 1. Of course, you can now begin using the new capabilities, even in non-C++11 compilers with some limitations (explained at the documentation). 2. Your code can get some transparent performance gain without you doing anything es.insert(employee(4,"Jill",52,3379)); // temporary's moved rather than copied 3. The internal code has been refactored to implement the new features, and this refactoring touches on preexisting functionality, hopefully without producing regressions --this has been thoroughly tested, but: It is now #3 that worries me the most: if you use Boost.MultiIndex and have some time to test this preview with your code, please do so and report the results. The more this update is tested before the official release, the less problems it will cause (ideally none.) As the update is major, every bit of testing helps. Hope you enjoy the new features. Best regards, Joaquín M López Muñoz Telefónica Digital ________________________________ Este mensaje se dirige exclusivamente a su destinatario. Puede consultar nuestra política de envío y recepción de correo electrónico en el enlace situado más abajo. This message is intended exclusively for its addressee. We only send and receive email on the basis of the terms set out at: http://www.tid.es/ES/PAGINAS/disclaimer.aspx

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Boost.Log SimpleEventLog question
by Pieter 13 Jul '13

13 Jul '13

LS, I am currently configuring my logging configuration using a property tree. When I include a SimpleEventLog sink, how can I apply an event type mapping to that sink? In the stated example this is done before the sink is added to the core: typedef sinks::synchronous_sink< sinks::simple_event_log_backend > sink_t; boost::shared_ptr< sink_t > sink(new sink_t()); sinks::event_log::custom_event_type_mapping< severity_level > mapping("Severity"); // . define mapping here . sink->locked_backend()->set_event_type_mapper(mapping); // Add the sink to the core logging::core::get()->add_sink(sink); but adding the sink happens behind the scenes when using the configuration utilities. BTW, in the section "Simplified library initialization tools" of the documentation Table 1.15 seems to miss a 'Format' parameter that I assume is still needed? Many thanks, Pieter

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[Boost.Log] More queries
by Leo Carreon 13 Jul '13

13 Jul '13

Hi everyone, As I have mentioned in a previous post, I have been trying to learn how to use Boost.Log. I have been experimenting with logging to a file with filtering and specifying the log formatting in three different ways, namely: 1. Specifying the log formatting using a lambda type expression. 2. Specifying the log formatting using a plain text string with placeholders for the attributes that I have defined. 3. Specifying the log formatting in a settings file. (However, the formatting string is exactly the same as in 2 above.) I have attached a copy of my source code and settings file. Note that I comment out parts of the source code file depending on which option I use above. The problem I’m encountering is when I use options 2 & 3 above, the severity level string does not appear in the log. But if I use option 1, the severity level string appears as expected. It is my understanding that severity level is a pre-defined attribute when using a severity_logger. Am I missing something when using options 2 & 3? If I decide to use my own severity level enumeration, what do I need to do? Kind regards, Leo

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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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