November 2016 - Boost-users - lists.preview.boost.org

[interprocess] Determine size of managed_shared_memory
by Kai Benndorf 12 Oct '19

12 Oct '19

Hi all, I want to create a managed_shared_memory in exactly the size I needed. Therefore I do something like this: size = sizeof( common_managed_shared_memory ); size += sizeof( MyClassInSharedMem ); managed_shared_memory segment(create_only, "name", size ); MyClassInSharedMem allocates itself some memory by segment->allocate(). I added this also to the size, but get a boost::interprocess::bad_alloc exception on allocating this additional memory. Are there some magic bytes I forgot to add? Many thanks in advance Kai

3 2

Weird compilation error when using boost::geometry
by 邓尧 16 Nov '17

16 Nov '17

Hi, I have implemented my own "point" as specified by the point concept http://www.boost.org/doc/libs/1_59_0/libs/geometry/doc/html/geometry/refere… When I use it along with boost::geometry::model::polygon/multi_polygon, GCC refuses to compile, tested on GCC 4.9/5.2. What's even more weird is that CLANG 3.6 would happy accept my code. BTW, the Point implementation is part of a large project, it difficult to replace it with boost::geometry::model::point. Here is my code: Point.hpp > #ifndef RAPTOR_POINT_HPP_INCLUDED_ > > #define RAPTOR_POINT_HPP_INCLUDED_ > > >> #include <boost/mpl/int.hpp> > > #include <boost/geometry/core/access.hpp> > > #include <boost/geometry/core/cs.hpp> > > #include <boost/geometry/core/coordinate_type.hpp> > > #include <boost/geometry/core/coordinate_system.hpp> > > #include <boost/geometry/core/coordinate_dimension.hpp> > > #include <boost/geometry/geometries/polygon.hpp> > > #include <boost/geometry/multi/geometries/multi_polygon.hpp> > > >> namespace raptor { > > >> template<typename T, int tDimension = 2> > > class Point { > > public: > > Point() = default; > > >> Point(T a, T b) { > > data[0] = a; > > data[1] = b; > > } > > >> Point(T a, T b, T c) { > > data[0] = a; > > data[1] = b; > > data[2] = c; > > } > > >> T& operator [] (long index) { > > return data[index]; > > } > > >> const T& operator [] (long index) const { > > return data[index]; > > } > > >> private: > > T data[tDimension]; > > }; > > >> using CubicPoint = Point<long, 3>; > > using PlanarPoint = Point<long>; > > using SphericalPoint = Point<double>; > > >> template<typename T> > > using Polygon = boost::geometry::model::polygon<T>; > > >> template<typename T> > > using PolySet = boost::geometry::model::multi_polygon<Polygon<T>>; > > >> } // namespace raptor > > >> namespace boost { namespace geometry { namespace traits { > > >> template<typename Type, std::size_t tDimension> > > struct tag<::raptor::Point<Type, tDimension>> { > > typedef point_tag type; > > }; > > >> template<typename Type, std::size_t tDimension> > > struct coordinate_type<::raptor::Point<Type, tDimension>> { > > typedef Type type; > > }; > > >> template<typename Type, std::size_t tDimension> > > struct coordinate_system<::raptor::Point<Type, tDimension>> { > > typedef boost::geometry::cs::cartesian type; > > }; > > >> template<typename Type, std::size_t tDimension> > > struct dimension<::raptor::Point<Type, tDimension>> > > : public boost::mpl::int_<tDimension> { > > // EMPTY > > }; > > >> template<typename Type, std::size_t tDimension, std::size_t tIndex> > > struct access<::raptor::Point<Type, tDimension>, tIndex> { > > static Type get(const ::raptor::Point<Type, tDimension>& p) { > > return p[tIndex]; > > } > > >> static void set(::raptor::Point<Type, tDimension>& p, > > const Type& value) { > > p[tIndex] = value; > > } > > }; > > >> }}} // namespace boost::geometry::traits > > >> #endif // RAPTOR_POINT_HPP_INCLUDED_ > > A real simple main.cpp: > #include "Point.hpp" > > >> int main() { > > raptor::Polygon<raptor::SphericalPoint> pl; > > raptor::PolySet<raptor::SphericalPoint> set; > > return sizeof(pl) + sizeof(set); > > } > > > GCC compilation error: g++ main.cpp -std=c++14 > In file included from /usr/include/boost/geometry/core/access.hpp:20:0, from Point.hpp:5, from main.cpp:1: /usr/include/boost/geometry/core/point_type.hpp: In instantiation of > 'struct boost::geometry::traits::point_type<raptor::Point<double> >': /usr/include/boost/geometry/core/point_type.hpp:66:17: required from > 'struct boost::geometry::core_dispatch::point_type<void, > raptor::Point<double> >' /usr/include/boost/geometry/core/coordinate_type.hpp:58:62: required from > 'struct boost::geometry::core_dispatch::coordinate_type<void, > raptor::Point<double> >' /usr/include/boost/geometry/core/coordinate_type.hpp:92:25: required from > 'struct boost::geometry::coordinate_type<raptor::Point<double> >' /usr/include/boost/geometry/geometries/concepts/point_concept.hpp:90:54: > required from 'class boost::geometry::concept::Point<raptor::Point<double> > >' /usr/include/boost/concept/detail/has_constraints.hpp:32:62: required by > substitution of 'template<class Model> boost::concepts::detail::yes > boost::concepts::detail::has_constraints_(Model*, > boost::concepts::detail::wrap_constraints<Model, (& Model:: constraints)>*) > [with Model = boost::geometry::concept::Point<raptor::Point<double> >]' /usr/include/boost/concept/detail/has_constraints.hpp:42:5: required from > 'const bool > boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >::value' /usr/include/boost/concept/detail/has_constraints.hpp:45:31: required > from 'struct > boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >' /usr/include/boost/mpl/if.hpp:67:11: required from 'struct > boost::mpl::if_<boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >, > boost::concepts::constraint<boost::geometry::concept::Point<raptor::Point<double> > > >, boost::concepts::requirement<boost::concepts::failed************ > boost::geometry::concept::Point<raptor::Point<double> >::************> >' /usr/include/boost/concept/detail/general.hpp:50:8: required from 'struct > boost::concepts::requirement_<void > (*)(boost::geometry::concept::Point<raptor::Point<double> >)>' /usr/include/boost/geometry/geometries/ring.hpp:60:5: required from > 'class boost::geometry::model::polygon<raptor::Point<double>, true, true, > std::vector, std::vector, std::allocator, std::allocator>' main.cpp:4:42: required from here /usr/include/boost/geometry/core/point_type.hpp:45:5: error: no matching > function for call to 'assertion_failed(mpl_::failed************ > (boost::geometry::traits::point_type<raptor::Point<double> > >::NOT_IMPLEMENTED_FOR_THIS_POINT_TYPE::************)(mpl_::assert_::types<raptor::Point<double>, > mpl_::na, mpl_::na, mpl_::na>))' BOOST_MPL_ASSERT_MSG ^ /usr/include/boost/mpl/assert.hpp:82:5: note: candidate: template<bool C> > int mpl_::assertion_failed(typename mpl_::assert<C>::type) int assertion_failed( typename assert<C>::type ); ^ /usr/include/boost/mpl/assert.hpp:82:5: note: template argument > deduction/substitution failed: /usr/include/boost/geometry/core/point_type.hpp:45:5: note: cannot > convert > 'boost::geometry::traits::point_type<Geometry>::NOT_IMPLEMENTED_FOR_THIS_POINT_TYPE48::assert_arg<raptor::Point<double> > >()' (type 'mpl_::failed************ > (boost::geometry::traits::point_type<raptor::Point<double> > >::NOT_IMPLEMENTED_FOR_THIS_POINT_TYPE::************)(mpl_::assert_::types<raptor::Point<double>, > mpl_::na, mpl_::na, mpl_::na>)') to type 'mpl_::assert<false>::type {aka > mpl_::assert<false>}' BOOST_MPL_ASSERT_MSG ^ In file included from > /usr/include/boost/geometry/core/coordinate_type.hpp:21:0, from /usr/include/boost/geometry/core/access.hpp:24, from Point.hpp:5, from main.cpp:1: /usr/include/boost/geometry/core/point_type.hpp: In instantiation of > 'struct boost::geometry::core_dispatch::point_type<void, > raptor::Point<double> >': /usr/include/boost/geometry/core/coordinate_type.hpp:58:62: required from > 'struct boost::geometry::core_dispatch::coordinate_type<void, > raptor::Point<double> >' /usr/include/boost/geometry/core/coordinate_type.hpp:92:25: required from > 'struct boost::geometry::coordinate_type<raptor::Point<double> >' /usr/include/boost/geometry/geometries/concepts/point_concept.hpp:90:54: > required from 'class boost::geometry::concept::Point<raptor::Point<double> > >' /usr/include/boost/concept/detail/has_constraints.hpp:32:62: required by > substitution of 'template<class Model> boost::concepts::detail::yes > boost::concepts::detail::has_constraints_(Model*, > boost::concepts::detail::wrap_constraints<Model, (& Model:: constraints)>*) > [with Model = boost::geometry::concept::Point<raptor::Point<double> >]' /usr/include/boost/concept/detail/has_constraints.hpp:42:5: required from > 'const bool > boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >::value' /usr/include/boost/concept/detail/has_constraints.hpp:45:31: required > from 'struct > boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >' /usr/include/boost/mpl/if.hpp:67:11: required from 'struct > boost::mpl::if_<boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >, > boost::concepts::constraint<boost::geometry::concept::Point<raptor::Point<double> > > >, boost::concepts::requirement<boost::concepts::failed************ > boost::geometry::concept::Point<raptor::Point<double> >::************> >' /usr/include/boost/concept/detail/general.hpp:50:8: required from 'struct > boost::concepts::requirement_<void > (*)(boost::geometry::concept::Point<raptor::Point<double> >)>' /usr/include/boost/geometry/geometries/ring.hpp:60:5: required from > 'class boost::geometry::model::polygon<raptor::Point<double>, true, true, > std::vector, std::vector, std::allocator, std::allocator>' main.cpp:4:42: required from here /usr/include/boost/geometry/core/point_type.hpp:66:17: error: no type named > 'type' in 'struct boost::geometry::traits::point_type<raptor::Point<double> > >' >::type type; ^ In file included from > /usr/include/boost/geometry/geometries/polygon.hpp:26:0, from Point.hpp:10, from main.cpp:1: /usr/include/boost/geometry/geometries/concepts/point_concept.hpp: In > instantiation of 'class > boost::geometry::concept::Point<raptor::Point<double> >': /usr/include/boost/concept/detail/has_constraints.hpp:32:62: required by > substitution of 'template<class Model> boost::concepts::detail::yes > boost::concepts::detail::has_constraints_(Model*, > boost::concepts::detail::wrap_constraints<Model, (& Model:: constraints)>*) > [with Model = boost::geometry::concept::Point<raptor::Point<double> >]' /usr/include/boost/concept/detail/has_constraints.hpp:42:5: required from > 'const bool > boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >::value' /usr/include/boost/concept/detail/has_constraints.hpp:45:31: required > from 'struct > boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >' /usr/include/boost/mpl/if.hpp:67:11: required from 'struct > boost::mpl::if_<boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >, > boost::concepts::constraint<boost::geometry::concept::Point<raptor::Point<double> > > >, boost::concepts::requirement<boost::concepts::failed************ > boost::geometry::concept::Point<raptor::Point<double> >::************> >' /usr/include/boost/concept/detail/general.hpp:50:8: required from 'struct > boost::concepts::requirement_<void > (*)(boost::geometry::concept::Point<raptor::Point<double> >)>' /usr/include/boost/geometry/geometries/ring.hpp:60:5: required from > 'class boost::geometry::model::polygon<raptor::Point<double>, true, true, > std::vector, std::vector, std::allocator, std::allocator>' main.cpp:4:42: required from here /usr/include/boost/geometry/geometries/concepts/point_concept.hpp:93:10: > error: 'value' is not a member of > 'boost::geometry::dimension<raptor::Point<double> >' enum { ccount = dimension<Geometry>::value }; ^ Where is the problem ? or it's a GCC bug ? Thanks

3 4

[Range, Phoenix] What am I missing...
by Robert Jones 25 Apr '17

25 Apr '17

Hi Folks Can anyone explain the output of this program... #include <iostream> #include <boost/range/algorithm/copy.hpp> #include <boost/range/counting_range.hpp> #include <boost/range/adaptor/reversed.hpp> #include <boost/range/adaptor/transformed.hpp> #include <boost/phoenix/bind/bind_function.hpp> #include <boost/phoenix/core/argument.hpp> int f( int i ) { return i * 2; } int main( ) { using boost::adaptors::reversed; using boost::adaptors::transformed; using boost::counting_range; using boost::copy; using boost::phoenix::arg_names::_1; copy( counting_range( 1, 5 ) | reversed | transformed( f ), std::ostream_iterator<int>( std::cout, " " ) ); std::cout << std::endl; copy( counting_range( 1, 5 ) | reversed | transformed( bind( f, _1 ) ), std::ostream_iterator<int>( std::cout, " " ) ); std::cout << std::endl; } Which is... 8 6 4 2 1768406272 1768406272 1768406272 1768406272 I'm using Gcc 4.6.2 & Boost 1.53 Thx All.

3 4

[serialize] using virtual inheritance causes compiler error
by Douwe Gelling 02 Mar '17

02 Mar '17

Hi all, When trying to serialize a class with a virtual base class, I'm getting compilation errors. It seems to be part of a bug in type_traits, but I'm wondering if anyone knows a workaround for making it work anyhow. ultimately, the error boils down to "error: virtual function 'A::foo' has more than one final overrider in 'boost_type_traits_internal_struct_X'", using the code listing below.. It's simplified as much as possible, but obviously I need virtual inheritance due to using diamond inheritance. #include <boost/archive/text_oarchive.hpp> #include <boost/serialization/base_object.hpp> #include <boost/serialization/export.hpp> #include <boost/serialization/serialization.hpp> struct A { virtual ~A(){}; virtual void foo() = 0; template <class Archive> void serialize(Archive& ar, const unsigned int version) { } }; struct B : public virtual A { virtual void foo() { } template <class Archive> void serialize(Archive& ar, const unsigned int version) { ar& boost::serialization::base_object<A>(*this); } }; struct C : public B { template <class Archive> void serialize(Archive& ar, const unsigned int version) { ar& boost::serialization::base_object<B>(*this); } }; BOOST_CLASS_EXPORT(C); int main() { C c; return 0; }

4 7

[Log] Random "double free or corruption" in dtor of attribute_value_set
by robin.lorke＠jenoptik.com 01 Dec '16

01 Dec '16

Hi Gentlemen, I have an application that is using Boost.Log. The application is long-term running (days, weeks, maybe months). Currently I am experiencing random crashes in my application that seem related to Boost.Log. I dont't say that is is a bug in Boost.Log, but probably I am doing something wrong. I am using version 1.55.0 but I also tried upgrading to version 1.61.0 but it is still happening there. I am currently able to reproduce the crash by forcing logs at a pace of 3 records per second. Then it takes up to 3 days for the crash to happen. The application is multi-threaded and therefore several threads may be logging at the same time. For that reason I chose "severity_logger_mt". It seems related to the destruction of objects of type attribute_value_set. This is a gdb stacktrace of the crash (gcc O0 build): (gdb) bt #0 0xb6bdbed8 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:66 #1 0xb6bdf960 in __GI_abort () at abort.c:90 #2 0xb6c139fc in __libc_message (do_abort=2, fmt=0xb6cc8c44 "*** glibc detected *** %s: %s: 0x%s ***\n") at ../sysdeps/unix/sysv/linux/libc_fatal.c:200 #3 0xb6c1e17c in malloc_printerr (action=3, str=0xb6cc8d80 "double free or corruption (!prev)", ptr=<optimized out>) at malloc.c:4949 #4 0xb6b3fcb8 in boost::log::v2_mt_posix::attribute_value_set::~attribute_value_set() () from /usr/lib/libboost_log.so.1.55.0 #5 0xb6b42688 in boost::log::v2_mt_posix::record_view::public_data::destroy (boost::log::v2_mt_posix::record_view::public_data const*) () from /usr/lib/libboost_log.so.1.55.0 #6 0xb6b44c7c in boost::log::v2_mt_posix::core::push_record_move (boost::log::v2_mt_posix::record&) () from /usr/lib/libboost_log.so.1.55.0 #7 0xb6e66814 in Logger::addLog(Logger::LEVEL, char const*, char const*, int) () from /usr/lib/libtslog.so.1 #8 0x0005ba50 in addLogRusp (iMessageId=2, sMessage=<optimized out>, sProcess=0x8dee8 "Application", eLevel=Logger::LEVEL_INFO) at ../src/RLS-V/Platform/System.inl.h:303 #9 RLS::Application::fnThreadRuspOut (thread=...) at ../src/RLS-V/Application.cpp:1447 #10 0xb6e7aa4c in Thread::startFunction(void*) () from /usr/lib/libtscommon.so.1 #11 0xb6edae38 in start_thread (arg=0xb3eff460) at pthread_create.c:313 #12 0xb6c7c318 in ?? () from /lib/libc.so.6 Backtrace stopped: previous frame inner to this frame (corrupt stack?) This is the global logger initialization (using some custom attributes): BOOST_LOG_GLOBAL_LOGGER_INIT(appLogger, boost::log::sources::severity_logger_mt< robot::log::Severity >) { core::get()->add_global_attribute("TimeStamp", attributes::local_clock()); core::get()->add_global_attribute("ProcessID", AttrProcessId()); core::get()->add_global_attribute("LineCounter", attributes::counter< unsigned int >()); core::get()->add_global_attribute("Process", attributes::current_process_name()); core::get()->add_global_attribute("Scopes", attributes::named_scope ()); core::get()->add_global_attribute("LineID", attributes::counter< unsigned int >(1)); core::get()->add_global_attribute("SimpleTimeStamp", AttrSimpleTime ()); Logger::init(); sources::severity_logger_mt< Severity > lg; return lg; } These are are my macros for logging: //these are needed to convert a macro into a string #define STRINGIFY(x) #x #define TOSTRING(x) STRINGIFY(x) /* NOTE: * __FUNCTION__ is not a macro. It's a char pointer. So we use an empty std::string as basis to concatenate the char* to it */ #define R_LOG_ID(x,y) BOOST_LOG_SEV (robot::log::appLogger::get(), y) << boost::log::add_value("LogID", x) << boost::log::add_value("FLF", ROBOT_FLF) #define R_LOG(x) R_LOG_ID(0, x) #define ROBOT_FLF std::string() + TOSTRING(__FILE__) + ":" + TOSTRING (__LINE__) + " (" + __FUNCTION__ + ")" While "R_LOG_ID" is the only one that is used currently. There are currently three sinks active: syslog, console and a custom sink sending log records via an IPC mechanism (http://www.cs.cmu.edu/~./IPC/). I am currently testing if it will still happen if I deactivate one or more of those sinks. I imagine it will be hard to tell the exact problem from the information above but maybe you guys could point me in the right direction where to dig deeper. I will happily provide any missing information and/or code snippets that could help. Possibly there are well-known common mistakes that can lead to that memory corruption in attribute_value_set? Maybe something like lazy evaluation of log expressions or multi-threading issues? Many thanks in advance for any help! Robin Lorke

2 1

std::future::wait_for() not working in Boost UDP socket async receive operation
by jc.francois＠gmail.com 30 Nov '16

30 Nov '16

The good people over at stackoverflow were not able to help me with this issue that I expected to be trivial. I am writing a UDP server app with Boost that should listen on a socket for 5 seconds and if no datagram has been received within these 5 seconds, move on to do other things. After some research I decided to try the solution based on std::future. The problem is that the call to wait_for() always times out as if no data was received. But if I set a breakpoint on the line that executes after the timeout and that I inspect variables I see that the buffer contains the received datagram and the remote_endpoint object contains the address of the client. In other words the socket receive works as expected but the std::future::wait_for() does not react. why? Here is my test server code: { try { boost::asio::io_service io_service; boost::asio::io_service::work work(io_service); std::thread thread([&io_service]() { io_service.run(); }); udp::socket socket(io_service, udp::endpoint(udp::v4(), 10000)); char recv_buf[8]; for (;;) { ZeroMemory(recv_buf, 8); udp::endpoint remote_endpoint; std::future<std::size_t> recv_length; recv_length = socket.async_receive_from( boost::asio::buffer(recv_buf), remote_endpoint, 0, boost::asio::use_future); if (recv_length.wait_for( std::chrono::seconds(5)) == std::future_status::timeout) { printf("time out. Nothing received.\n"); } else { printf("received something: %s\n", recv_buf); } } io_service.stop(); thread.join(); } catch (std::exception& e) { printf("Error: %s\n", e.what()); } return 0; }

4 5

Question on data structure usage
by Ram 29 Nov '16

29 Nov '16

Hi, I have a map as follows, boost::unordered_map<string, string> sample_map; I would like to look up the keys using wildcards/regex from the user and get the values corresponding to it(get multiple matches). It looked like there is no straightforward way to do it. So, I was thinking as an when I populate the map, I create a seperate data structure to store the keys, so that I can get the values(list) that match my user inputted regex/wildcard search. The I use this list to get the values from the map. What data structure can I use for this purpose? Is my approach correct? Or can I do this directly using the map? Please help me solve this problem. Thanks, -R

4 10

Re: [Boost-users] Do we have plan to support VS 2017?
by senthil vel 29 Nov '16

29 Nov '16

Hi All, I am using VS 2017 for my software development.The last official release of boost ( boost_1_62_0 ) supports VS 2015. When will we get VS 2017 supported boost library? Is there any workaround, till we get the support? Regards, Senthil

2 1

[Boost.DateTime] How to bypass checks in boost::gregorian::date constructor
by dariomt＠gmail.com 28 Nov '16

28 Nov '16

>From the docs I see: "date(greg_year, greg_month, greg_day) Construct from parts of date. Throws bad_year, bad_day_of_month, or bad_day_month (derivatives of std::out_of_range) if the year, month or day are out of range." In my use case, I know for sure that the year, month and date are all in the valid range of values, so all the validity checks done by the library become redundant. Is it possible to somehow bypass those checks?

1 0

Re: [Boost-users] Building Boost 1.62 With Visual Studio 2017 RC
by Trueman, Chris 24 Nov '16

24 Nov '16

1 0

Building Boost 1.62 With Visual Studio 2017 RC
by Trueman, Chris 24 Nov '16

24 Nov '16

2 1

Assertion failure in r_c_shortest_paths.hpp
by Amit Prakash Ambasta 23 Nov '16

23 Nov '16

Hi, I have a sample r_c_shortest_paths use case demonstrated below. However on executing this code, assertion error occurs at /usr/include/boost/graph/r_c_shortest_paths.hpp:473: Assertion `p_cur_label->b_is_valid' failed. I've referred to the prior issue reported at https://svn.boost.org/trac/boost/ticket/11723 However, against his example specified, I can not reproduce the error.

1 0

[release] Boost 1.63.0 Beta 1
by Marshall Clow 21 Nov '16

21 Nov '16

The first beta packages for 1.63.0 beta 1 are now available: <https://sourceforge.net/projects/boost/files/boost/1.63.0.beta.1/> The SHA256 checksums are as follows: 3dbc1bca10941710755c13a00b1ae56d2d37fe90bbadcf9746203194f9d33e3a boost_1_63_0.7z c8b986fd57e436fd88dbc70e51d3e21efa2be3bdf835fa499b2cf6c0a8cc2985 boost_1_63_0.tar.bz2 745d99e4be9c0f324ec7ba15b7d228fd780067f2e8aeae2f16660a4cf6e6a051 boost_1_63_0.tar.gz e66bd6e2f637148c314398b92bc1f3cbdc777ee282f9de7885697afad3d9c202 boost_1_63_0.zip As always, the release managers would appreciate it if you download the archive of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. Thanks! -- The release managers

3 4

beginner boost::statechart questions
by Bedeho Mender 20 Nov '16

20 Nov '16

Hi, I have a few questions about the statechart library. 1) I would like to pass around a representation of the current configuration of a machine, to allow inspection of local variables and active states. The easiest approach would be to just pass around a copy of the machine, but this is not possible since the state_machine class is noncopyable. An alternative could have been to pass around a constant ref/ptr to the machine, but this is also not workable because the inspection will happen in another thread, and synchronisation is not feasible. Any suggestions? One alternative is to create a new snapshot representation, but it will be a headache to keep in synch with the primary machine. 2) A related question is whether there is a good way to start a machine in a given configuration? Using a sequence of events works in principle, but its a very impractical way to do so. For example if one wishes to restore a configuration from a prior session, then the client code has to log the full event history, and it may have a very hard time determining how many events need to be logged to reconstruct the given configuration. Logging and storing *all* events from the prior session will in many cases be wasteful, or even infeasible. 3) Suppose a machine makes a certain callback to client code in a set of different reactions. It would be nice if the client could inspect the currently active state, from which the given reaction is originating. However, my understanding is that the machine is unstable when processing a reaction, hence this is not possible. Is there a way around this? Best Bedeho Mender ᐧ

1 0

[geometry] Cannot compile boost::geometry::intersection
by Stanley Friesen 17 Nov '16

17 Nov '16

I am using boost library version 1.54 with gcc --std=c++11. I am trying a simple use of geometry::intersection as follows: #include <boost/geometry.hpp> #include <boost/geometry/geometries/point_xy.hpp> #include <boost/geometry/geometries/polygon.hpp> #include <boost/geometry/geometries/adapted/boost_polygon.hpp> using namespace boost::geometry; ...... typedef model::d2::point_xy<double> point_xy; model::polygon<point_xy> clipBounds; // add points to clipBounds model::polygon<point_xy> area; // add points to area model::polygon<point_xy> result; if(boost::geometry::intersection(area, clipBounds, result)) { std::cout << std::endl << "Boost intersection, size = " << num_points(result) << std::endl; } If I comment out the call to intersection, everything compiles. With it I get: In file included from /usr/include/boost/serialization/level.hpp:28:0, from /usr/include/boost/serialization/nvp.hpp:31, from ...: /usr/include/boost/mpl/eval_if.hpp: In instantiation of ‘struct boost::mpl::eval_if_c<false, boost::range_const_iterator<boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double, boost::geometry::cs::cartesian> > >, boost::range_mutable_iterator<boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double, boost::geometry::cs::cartesian> > > >’: /usr/include/boost/range/iterator.hpp:63:63: required from ‘struct boost::range_iterator<boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double, boost::geometry::cs::cartesian> > >’ /usr/include/boost/range/value_type.hpp:30:12: required from ‘struct boost::range_value<boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double, boost::geometry::cs::cartesian> > >’ /usr/include/boost/geometry/algorithms/intersection.hpp:97:64: required from ‘static bool boost::geometry::dispatch::intersection<Geometry1, Geometry2, Tag1, Tag2, Reverse>::apply(const Geometry1&, const Geometry2&, GeometryOut&, const Strategy&) [with GeometryOut = boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double, boost::geometry::cs::cartesian> >; Strategy = boost::geometry::strategy_intersection<boost::geometry::cartesian_tag, boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double, boost::geometry::cs::cartesian> >, boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double, boost::geometry::cs::cartesian> >, boost::geometry::model::d2::point_xy<double, boost::geometry::cs::cartesian>, void>; Geometry1 = boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double, boost::geometry::cs::cartesian> >; Geometry2 = boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double, boost::geometry::cs::cartesian> >; Tag1 = boost::geometry::polygon_tag; Tag2 = boost::geometry::polygon_tag; bool Reverse = false]’ /usr/include/boost/geometry/algorithms/intersection.hpp:201:67: required from ‘bool boost::geometry::intersection(const Geometry1&, const Geometry2&, GeometryOut&) [with Geometry1 = boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double, boost::geometry::cs::cartesian> >; Geometry2 = boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double, boost::geometry::cs::cartesian> >; GeometryOut = boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double, boost::geometry::cs::cartesian> >]’ /home/stanley/workspace/worldmodel/metric/map/GISCache.cpp:2492:62: required from here /usr/include/boost/mpl/eval_if.hpp:60:31: error: no type named ‘type’ in ‘boost::mpl::eval_if_c<false, boost::range_const_iterator<boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double, boost::geometry::cs::cartesian> > >, boost::range_mutable_iterator<boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double, boost::geometry::cs::cartesian> > > >::f_ {aka struct boost::range_mutable_iterator<boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double, boost::geometry::cs::cartesian> > >}’ typedef typename f_::type type; Since my code is virtually identical to the sample code in the documentation, I am very puzzled by this. What have I missed? How do I get this to compile? (I do find it odd that this error refers to boost/serialization rather than boost/geometry, but I suppose that has to do with the order of inclusion). -- View this message in context: http://boost.2283326.n4.nabble.com/geometry-Cannot-compile-boost-geometry-i… Sent from the Boost - Users mailing list archive at Nabble.com.

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[statechart] Pass event data to state constructor using triggering_event
by ramonpadilla1＠yahoo.co.uk 16 Nov '16

16 Nov '16

I would like to be able to communicate the data from an event to a state that gets constructed as a result of a transition. From this post in 2009 and this one in 2010 the use of triggering_event() is suggested. However, I can't find an example anywhere that demonstrates how to use it. Can anyone help? Links in the message | Google Groups | | | | Boost - Users - [statechart] Passing pa... | |

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[statechart] Passing parameters from event to State Local Storage
by Christophe Bourez 16 Nov '16

16 Nov '16

I need to maintain a parameter into the state local storage. This parameter is initially contained in the event that causes the transition to the target state. I give hereafter a small illustrative example. typename sc = boost::statechart; class EvTest : public sc::event<EvTest> { public: EvTest(std::size_t val) : value(val) {} std::size_t getValue() const { return this->value; } private: std::size_t value; }; class MyStateMachine; class StSource; class StTarget; class StSource : public sc::simple_state<StSource, MyStateMachine> { public: typedef sc::custom_reaction<EvTest> reactions; sc::result react(const EvTest &event) { // How to pass event.getValue() to the target state ? transit<StTarget>(); } }; class StTarget : public sc::simple_state<StTarget, MyStateMachine> { public: StTarget(std::size_t val) : val(value) {} private: std::size_t value; }; Thanks, Christophe

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Help needed for boost polygon get trapezoid
by Lei Yin 15 Nov '16

15 Nov '16

Hello all, I recently moved to use boost.polygon for doing non-manhattan shape boolean operation, and I'm using get_trapezoids() function to convert output polygons to trapezoids. There're two problems I'm facing and couldn't overcome: 1. Somehow boost.polygon not always give me the largest polygon as possible. In the result, frequently I saw there are two trapezoids are neighboring each other, and they can be perfectly combined into one big trapezoid, but for some reason, boost.polygon give me separated two instead of one. 2. It maybe due to floating point snapping issue (I'm operating on integer base), for some special cases, I got very slim trapezoid like 1 db unit in width. Preferably, this trapezoid Any suggestion to solve above issues would be much appreciated! Thanks in advance. Lei

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How to get response of the questions I posted?
by Bruce 15 Nov '16

15 Nov '16

Hi, I am not familiar with emails list. First time use or I don't known where to post boost.log questions. I found I can't receive the response of my thread by email. I have to check the boost.user archive and I can't response in the archive list. I do subscribed to this list or I can't post. Anybody can help me? Many thanks.

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Questions about extending boost::log sink backend based on app_luncher example
by Bruce 15 Nov '16

15 Nov '16

Hi,I am extending the boost::log backend sink to show log record into GUI ListBox control, which is gui_logger. I modify based on the app_luncher example which extends backend sink of :basic_formatted_sink_backend. Below are the questions that I have for now: 1) when modifying the consume function, I don't know how to get the message body. void consume(logging::record_view const& rec, string_type const& command_line); I using TRACE of visualstudio 2015 to first log the message out into vs2015 console. But I don't know how the get the message from record_view? 2) When I TRACE(command_line.c_str()) of consume function, I logged every record out into vs2015 console. I need to set a filter to only output some of the log. How to set filters with gui_logger? I notice there is sink->set_filter function, but I don't know how to set in my situation.In my scenario, I setup a src::severity_channel_logger (db_logger) with keywords::channel = "dblog", which output to db.log file. I want to use gui_logger to show the latest 200 records on the ListBox. gui_logger should use the same filter with db_logger. gui_logger log the latest 200 records into gui ListBox. db_logger log all the records into text file. So I need to set the same filter with db_logger. 3) I read settings from the ini file for db_logger. I want also to read setting from ini file for gui_logger. How to do it?

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How to wrap boost::log class to user?
by Bruce 14 Nov '16

14 Nov '16

Hi, I am coding a project and I use boost::log. I need to supply the log function to user, but I don't want the user use boost::log directly. I want to wrap the boost::log into my class. But I still want to keep the << cascade feature. Basically, I need to implement a MyLogger class, which support: MyLogger(info) << bla bla bla; MyLogger(trace) << bla bla bla; and in the operator << function, I can use: BOOST_LOG_SEV macro. I don't know how to implement the operator << in MyLogger class. Can anybody helps me, Thanks.

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How to use boost::log to setup multiple logger?
by 刘宝良 14 Nov '16

14 Nov '16

Hi, I want to use boost::log to setup 3 logger for different purpose. Not one logger to have multiple output file. And I also want one logger to have one file output and a GUI output to be viewed by the end user. How to do it? -Bruce

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boost::filesystem::path::iterator and libstdc++ std::search
by Oleksandr Senkovych 11 Nov '16

11 Nov '16

Hi guys. Several days ago I've faced a strange issue with boost::filesystem::path::iterator - it segfaults when used in some STL algorithms. Here's a sample code that crashes: http://melpon.org/wandbox/permlink/58aIbfJWeGgMKMdF I looked at the issue a little bit and discovered that the reason for that is this part of iterator code: const path& dereference() const { return m_element; } So when using std::search libstdc++ has to convert binary predicate to unary for later use in std::find_if: __first1 = std::__find_if(__first1, __last1, __gnu_cxx::__ops::__iter_comp_iter(__predicate, __first2)); It does this by capturing dereferenced value of second iterator (__first2 in a piece of code above) but since iterator is passed by-value, this wrapper holds dangling reference to local member of iterator.m_element. Now according to C++ standard part 24.2.1 [iterator.requirements.general]: 10. Destruction of an iterator may invalidate pointers and references previously obtained from that iterator. So this looks like a violation of a standard by libstdc++ library. Unfortunately I couldn't get my account registered at https://gcc.gnu.org/bugzilla/ and was not able to file a bug, so can I ask you to help me with it?

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boost::filesystem::native
by Christopher J. Pisz 10 Nov '16

10 Nov '16

I did a Google search to see how to check if a given path is valid, preferably using boost. It brought me here: http://stackoverflow.com/questions/10426671/how-to-check-if-path-is-valid-i… Great! I say to myself. I then Google up the boost doc here: http://www.boost.org/doc/libs/1_62_0/libs/filesystem/doc/portability_guide.… I then write myself a test: #include <iostream> #include <sstream> #include <boost/filesystem.hpp> int main() { const std::string test1 = "D:\\Programing Projects\\Git Workspace\\Common\\x64\\Debug"; const std::string test2 = "D:\Programing Projects\\Git Workspace\\Common\\x64\\Debug\\"; const std::string test3 = "D:/Programing Projects/Git Workspace/Common/x64/Debug"; const std::string test4 = "D:/Programing Projects/Git Workspace/Common/x64/Debug/"; if (!boost::filesystem::native(test1)) { std::cout << "Boost says the following path is not valid for the native operating system: " << test1 << std::endl; } if (!boost::filesystem::native(test2)) { std::cout << "Boost says the following path is not valid for the native operating system: " << test2 << std::endl; } if (!boost::filesystem::native(test3)) { std::cout << "Boost says the following path is not valid for the native operating system: " << test3 << std::endl; } if (!boost::filesystem::native(test4)) { std::cout << "Boost says the following path is not valid for the native operating system: " << test4 << std::endl; } return 0; } The Test's Output: Boost says the following path is not valid for the native operating system: D:\Programing Projects\Git Workspace\Common\x64\Debug Boost says the following path is not valid for the native operating system: D:Programing Projects\Git Workspace\Common\x64\Debug\ Boost says the following path is not valid for the native operating system: D:/Programing Projects/Git Workspace/Common/x64/Debug Boost says the following path is not valid for the native operating system: D:/Programing Projects/Git Workspace/Common/x64/Debug/ What is wrong with that path that it says it is not valid for my native Windows 10 operating system?

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Boost.ASIO stuck on some requests?
by Matthieu Brucher 10 Nov '16

10 Nov '16

Hi, I have an app that serves different clients and it is based on Boost.ASIO. My current issue is that if the first client is fast enough (a continuous fast loop with Python module requests), then the other clients may time out with no good reason when trying to connect. Is there a way of figuring out who is actually waiting on who? Maybe the clients are starved because of an issue on their box, or there is an issue in ASIO that serves always the first connection? Or is it Windows? I tried multithreading the server, but that didn't help, and a run with VTune Amplifier shows me that the app is mainly waiting. But if I add a 100ms sleep between requests, then everything is fine. But this is not an acceptable solution, as the clients in real life will want to launch requests all the time. Regards, Matthieu Brucher -- Information System Engineer, Ph.D. Blog: http://blog.audio-tk.com/ LinkedIn: http://www.linkedin.com/in/matthieubrucher

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