June 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

[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

[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

5 6

iostreams: ceased devolopment?
by Christian Meesters 01 Sep '16

01 Sep '16

Hi, I noticed that there are numerous issues in the bug list, regarding boost iostreams. However, the current doc states Copyright 2004-2007 and Tickets do not receive responses. (I even read: "(I tried e-mailing Jonathan Turkanis directly, but the e-mail address on the website seems to be not used anymore)" in ticket 7574. So, my question is: I anyone maintaining this library? If not: I doubt that there is a good alternative, because iostreams just is convenient to use and a selling point to for boost. It would be a pitty. Best regards, Christian

7 15

State of context and coroutine
by Michael Steinberg 06 Jul '16

06 Jul '16

Hello, I find myself working on a project which makes use of boost::context functionality which got moved to the detail namespace somewhen before booost 1.61 . Now this project is mimicing something along the lines of boost::coroutine on top of context. I could try to adapt to the new intended usage of context or change the setup to use coroutine. Hence my question is whether the public coroutine interface, specifically the asymmetric parts, is stable yet? Im seeing 1's and 2's there side by side, so I could imagine there's still deciding on a good interface going on. Kind Regards, Michael

4 12

filesystem path{}.string() interface brittle when developing cross platform
by Werner Erasmus 05 Jul '16

05 Jul '16

Firstly, I would like to than the author/s of filesystem for their great work and their time. I've recently written some code on Linux where I had to adapt a filesystem::path object to string. I noticed that the return value was of type [const std::string&], and used the same return value in my getter that exposed the underlying string. Moving over to windows, I had strange crashes (undefined behaviour) as result of the type under windows being converted to [std::string]. The reason for the "undefined behaviour" took me a while to figure out. While understanding why the author returned by value (Windows API underlying type not a std::string...), I think that for a specific type, the contract concerning return value "semantics" should no be broken. There is a significant difference between returning by const reference as opposed to returning by value. If the contract cannot be held, the decision should be made to (in the interest of consistency/clarity) to return the same type for all OS's/platforms if the code is to be considered platform independent. This might mean to compromise by returning by value, or to, in the case of Windows (where the underlying string has a different type), cache the string, or at the very least document a *BOLD* note that caution must be taken. I can comprehend that if conversion is required, return by value is the only option. I expect type consistency per type, as this to me is part of the contract of a function. I don't consider this a bug, but would appreciate some response. Kind Regards

3 2

Re: [Boost-users] Multiprecison: converting a complex class to a number<> backend (John Maddock)
by Daniel Brake 30 Jun '16

30 Jun '16

Hi Boost, particularly John Maddock and Christopher Kormanyos *first my response to John:* > From: John Maddock <jz.maddock(a)googlemail.com> > Date: Wed, 29 Jun 2016 19:28:19 +0100 Subject: Re: [Boost-users] Multiprecison: converting a complex class to a > number<> backend I suggest you take a look at rational_adaptor which does more or less > exactly this but for rational types - if you basically just gut the > function implementations from that file, search and replace the class > names, and then fill in the blanks you should be 95% there. > this is exactly the kind of advice i was looking for, thanks very much!!! i think i can get started almost right away. > This is actually something that's been on our TODO list for far too long, > ideally this should be part of the library - fancy helping out - or at > least being a testing guinea pig? > absolutely, i would love to help with this. the major challenge I see for getting everything fully functional in my active codebase using the new backend is Eigen. I continue to push the boundaries of Eigen with respect to expression templated numeric types, ha. i absolutely love that library! by the time I am done with my code, it will be expressions and templates the whole way down. i am guessing that personal emails or the dev list are the best place to continue discussion of helping work on this part of the library? > I quickly mocked up an example (attached) of how I think this should look > if we were to add it to the library, basically: > thanks for the mock-up! > As noted in the attached example, we really need another number category > for complex types, and while mixed arithmetic with (real) scalars will just > work, if you wanted an imaginary type as well, that would involve a whole > lot more work, as class number does not currently support return a type > different from either argument type in the binary operators (for real + > imaginary for example). > mixed real-complex is enough for me for now, adding imag-real specializations won't affect much of my codebase, so not currently a high priority for me. sometime over the rainbow, it might become important, but not right now. > And finally... there is this: > https://code.google.com/archive/p/cpp-imaginary-numbers/ which takes a > different view of things (but loses multiprecision's expression templates). > I really need the expression templates, but this is a good resource. thanks for the link. > PS, one final note: ideally this would be handled by std::complex, but > sadly that class can not be instantiated on any type other than > float/double/long double with invoking undefined behaviour. > agreed. the STL's most disappointing template to me: the std::complex. i was disheartened to feed in higher precision types, and get only double precision out of atan. then i found out about the invocation of UB resulting from what i had done... thanks for the response, John. you are always most helpful, and I really appreciate your time. ---------- *second, my response to Christopher and John* On 29/06/2016 22:17, Christopher Kormanyos wrote: > >> >> In my opinion, trying to adapt a complex number class to the backend >> requirements of number might not be the best way to go. >> >> I would recommend writing an extended complex template class >> that is intended to be instantiated for both user-defined types as well as >> float, double and long double. >> > should be a relatively easy conversion, to add template parameters to my class, and replace the hard-code of real_ and imag_ type. this is definitely a desirable modification, though not a pressing need in my context. It would be nice to be able to use any type. John, I think we should talk about the final needs of a complex_backend for inclusion in the multiprecision library. Thanks for the response Christopher. Thanks for reading and responding! Daniel

2 1

Re: [Boost-users] boost::serialize 1.61 ticket #12141 not quite fixed for VS2015? (Robert Ramey)
by Colin Humphries 30 Jun '16

30 Jun '16

Hello Robert, Thank you for your quick reply. Today I down-loaded and rebuilt boost 1.61.0, for both .zip and .7z versions from boost.org but I still see that final expanded line. Regards Colin Humphries On 6/26/16 3:33 PM, Colin Humphries wrote: > After converting to boost 1.61 and Visual Studio 15 we now see a > problem closely related to one reported in ticket #12141. Our XML > archives now end with the following 2 lines: > > </boost_serialization> > </boost_serialization> > > Could someone suggest a quick fix please? I think the problem must be > in archive/impl/xml_woarchive_impl.ipp but I cannot grasp how > the archive destructor emits the last line. When this was reported we took emergency action to make sure it was addressed before the final release. Are you sure you have the actual 1.61 final release? Robert Ramey >

1 0

boost unit test framework exports std::basic_ostringstream
by Sascha Kremers 30 Jun '16

30 Jun '16

The boost unit test framework exports std::basic_ostringstream to the dll. This causes linker errors on visual studio 2012 (LNK 2005), if the tested code contains std::basic_ostringstream. You can confirm the symbol std::basic_ostringstream is in boost_unit_test_framework-vc110-mt-1_61.dll by using dependency walker. I have the same problem with my self-built dlls as well as the ones downloaded from https://sourceforge.net/projects/boost/files/boost-binaries/. Is this a problem with boost or did I configure the build wrong? Thank you. I posted the issue on Stack Overflow a week ago [1]. Please excuse, if this still counts as cross posting. Regards Sascha [1] http://stackoverflow.com/questions/37922117/stdbasic-ostringstream-exported…

2 2

Re: [Boost-users] Multiprecison: converting a complex class to a number<> backend
by John Maddock 30 Jun '16

30 Jun '16

On 29/06/2016 22:17, Christopher Kormanyos wrote: > > In my opinion, trying to adapt a complex number class to the backend > requirements of number might not be the best way to go. > > I would recommend writing an extended complex template class > that is intended to be instantiated for both user-defined types as well as > float, double and long double. > > The real and imag parts are template parameter types. They could be > of type mpfr_float because the template parameter type is > determined at compile-time when the class is instantiated. > > In the winter, I wrote an extended complex class and tested it extensively > with multiprecision and fixed point. There was also another candidate > implementation of extended complex a few years ago from another > developer, but it never got to review. > > I have not yet made my extended complex code available. > > I am not subscribed to the user's list. If the post gets to the > developer's > list, there is a good chance I will see it. I'm curious as to what you see as the stumbling block to providing a complex number backend to class number<> ? The main advantages are that the expression-template code and all operator overloads are "just there" already, what do you see as the drawbacks? Best, John.

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Multiprecison: converting a complex class to a number<> backend
by Daniel Brake 29 Jun '16

29 Jun '16

Hi Boost, I have implemented my own complex class wrapping around Boost.Multiprecision number<>, particularly mpfr_float. Now, I'd like to take the class I've written, and extend/convert it into a backend suitable for use in number<>. While I've read the documentation describing the requirements for a backend <http://www.boost.org/doc/libs/1_61_0/libs/multiprecision/doc/html/boost_mul…>, and think I understand what I need to do, I have found 0 examples in the wild. My current setup has a pair of files mpfr_complex.hpp, mpfr_complex.cpp describing something like (just what you'd expect, really) --------- class complex{ mpfr_float real_, imag_; public: // the *= family of operators, getters, setters, // some factory functions, etc }; //the free operators defined down here, along with pow, exp, etc. -------------- I think what I'd like to write is a new complex_backend.hpp file which implements the required functions for the complex wrapper around mpfr_float. In this file, I believe I implement the family of functions such as eval_multiply(b, a) in terms of the operators for my complex class. Is this right? In a related vein, with et_on for mpfr_float, I've started adding templated overloads for the complex operators and math function accepting expressions of reals, and I think this is going to get out of hand, so using number<> would conceivably save me a ton of time writing my own functions. It will also save me a ton of errors for hand-writing the expression templates for complexes, which appear to be ready to go from Boost.Multiprecision once I get a backend implemented. Again, my goal is expression templates for complexes with real and imaginary fields consisting of mpfr_floats, leveraging the number<> template, with et_on, and my own backend. Do you have any advice? Any references to any other custom backends? Daniel Brake University of Notre Dame Applied and Computational Mathematics and Statistics

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Boost interprocess mutex with shared memory
by Ashok Palaniswamy 28 Jun '16

28 Jun '16

Hi all, I want to implement boost interprocess mutex with shared memory. This mutex will protect the SMBUS access between multiple processes. In the entire source code, this mutex will be used across different the files. Please let me know if you have any sample programs available. Thanks, P.Ashok L&T Technology Services Ltd www.LntTechservices.com<http://www.lnttechservices.com/> This Email may contain confidential or privileged information for the intended recipient (s). If you are not the intended recipient, please do not use or disseminate the information, notify the sender and delete it from your system.

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boost::serialize 1.61 ticket #12141 not quite fixed for Visual Studio 15?
by Colin Humphries 27 Jun '16

27 Jun '16

After converting to boost 1.61 and Visual Studio 15 we now see a problem closely related to one reported in ticket #12141. Our XML archives now end with the following 2 lines: </boost_serialization> </boost_serialization> Could someone suggest a quick fix please? I think the problem must be in archive/impl/xml_woarchive_impl.ipp but I can't seem to grasp how the archive destructor emits the last line. Regards, Colin Humphries

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Backend of multi_index container
by Anaswara Nair 27 Jun '16

27 Jun '16

Hi, I was going through the documentation of boost::multi_index container. I would like to know what is in its back end. Something like B-Tree,B+tree,etc.? Actually I want to create a database(in the sense it contains millions of records), but need not be reusable at a later period of time. i.e, I am looking only for run-time persistent data. Once data is inserted to this, it will not be modified. And there will be a unique id for each record. I would also like to know whether multi_index is the best suited one for the implementation of my so called database.. Thankyou

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Re: [Boost-users] Backend of multi_index container
by anaswara 26 Jun '16

26 Jun '16

I have 7 fields in each record,two strings and five 64 bit integers. Of these,one of the integers is unique. I need to store all such records into the DB. In multi-index, I have a structure and this structure is being indexed by that integer value. If I have to similarly create a structure and store it as the value in LMDB, then what is its difference from multimap? I can do the same in multimap also. Then how does LMDB become a database. Sent from Samsung Mobile -------- Original message -------- From: degski <degski(a)gmail.com> Date: 24/06/2016 7:43 PM (GMT+05:30) To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] Backend of multi_index container On 24 June 2016 at 15:51, Anaswara Nair <anaswara.nn(a)gmail.com> wrote: I have gone through LMDB. However AFAIK LMDB stores the data as a key-value pair. Yes, it's a key-value store. Though duplicate keys are allowed, I couldn't find any relation between these entries. I couldn't understand its use as a database as well. It's like std::(multi)map, maybe the wikipedia entry helps. Can you provide some help so that I can go deeper into this. In your original question, you refer to having one unique ID and some related data per record. Maybe you could expand a bit on what you would like to achieve. degski

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[Boost.PropertyTree] Application hangs (Boost 1.61)
by Andrew C 25 Jun '16

25 Jun '16

Hi! It seems to be a bug that this application hangs inside "erase" method: #include <boost/property_tree/ptree.hpp> int main() { boost::property_tree::ptree pt; pt.erase(pt.begin()); // enters infinite loop... } Compiled with Cygwin/GCC-5.4.0. Is it really a bug or my misuse? Thanks!

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CPack, CMake and Boost's shared libraries
by r＠primef.actor 25 Jun '16

25 Jun '16

What is the canonical cross-platform way to package boost shared libraries with CPack (and/or CMake)? On Windows, DLLs can be copied to the executable's folder and it will "just work". On OS X, one can use install_name_tool to set up a so-called rpath pointing to a relative location where the libraries reside, relative to the executable. On Ubuntu, one can similarly use ldd for setting up the correct pointers to where the libraries will reside relative to the executable. The question is then: is there some documentation on how to ship boost libraries along with your executable, in a cross-platform and canonical way, with CPack? Here's a question on stack overflow [1] that addresses the same problem, however the proposed solution of using set(CMAKE_EXE_LINKER_FLAGS "-Wl,-rpath='$ORIGIN'") in CMake does not seem cross-platform to me (MSVC won't recognize the command). Regards, Raoul [1]: http://stackoverflow.com/questions/26142948/packaging-c-program-using-boost…

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[Interprocess] Sharing FFMPEG Datatypes
by Loren Garavaglia 25 Jun '16

25 Jun '16

Hi All, I'm trying to figure out if it's possible using Boost to share FFMPEG data between 2 processes. What I'm trying to do is have one process read from a video stream and place the received packets in a buffer. The other process then reads from the buffer, decodes the packet, and does some analysis on the image. Unfortunately, due to some constraints I cannot take a multi-threaded approach to this problem. My data that I would like to share is as follows: struct FFMPEGData { AVFormatContext *pFormatCtx; AVCodecContext *pCodecCtx; AVCodec *pCodec; AVFrame *pFrame, dst; AVPacket *packet; AVPacket* pack = new AVPacket[packetNum]; struct SwsContext *convert_ctx; }; With "pack" being my buffer with a set size. I tried following the boost example here <http://www.boost.org/doc/libs/1_57_0/doc/html/interprocess/allocators_conta…> but it seems to be for a simpler form of complex data. All of the FFMPEG datatypes are structs themselves, so I wasn't sure what to do. My question is, is it even possible to share these kinds of datatypes between processes using Boost Interprocess and if so do I need to create allocators and containers for all of the data fields within these FFMPEG datatypes? Thanks, Loren

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Boost + Android NDK r11 + Clang
by Robert Dailey 23 Jun '16

23 Jun '16

How can I cross-compile static boost libraries for Clang in Android NDK r11 (arm) along with LLVM C++ (static)? Thanks in advance for detailed instructions

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[iostreams] use of gzip_compressor with strings
by Boncek, John 23 Jun '16

23 Jun '16

I need to do some in-memory manipulation of strings, including compression to gzip format. I am new to the use of Boost and to the use of gzip. I found the following snippet on the Internet, compressing a std::string and producing a new std::string as output. This implies that gzip_compressor never produces a null byte in its output but the gzip_compressor documentation doesn't say that and my search of the underlying library zlib documentation doesn't say anything like that either. So is this a correct use? std::string compress(const std::string& data) { namespace bio = boost::iostreams; std::stringstream compressed; std::stringstream origin(data); bio::filtering_streambuf<bio::input> out; out.push(bio::gzip_compressor(bio::gzip_params(bio::gzip::best_compression))); out.push(origin); bio::copy(out, compressed); return compressed.str(); } Thanks, John Boncek

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[Context] Console output problem under Cygwin
by Andrew C 23 Jun '16

23 Jun '16

Hi! Boost.Context examples (libs\context\example\v2) behave strangely under Cygwin/GCC-5.4.0. The problem is that all of the example applications output nothing to console. For example, jump_void.exe just ends at first "std::cout" command in execution context without any crash. This is the command line arguments I use to build both Boost.Context library and examples: b2.exe variant=debug link=static cxxflags="-std=c++14 -Wall -pedantic -D_GNU_SOURCE" Does anyone else ever met such a problem? Could it be a compiler bug or Boost.Context defect? Note: Under MinGW/GCC-4.9.3 all works OK. Thanks!

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[polygon] get_trapezoids not reporting holes?
by David Thompson 22 Jun '16

22 Jun '16

Hi all, I am having trouble with boost::polygon: when get_trapezoids is called on a polygon_set_data containing a polygon_with_holes_data, it returns trapezoids covering the outer loop but that cover the hole (i.e., the hole is being ignored). A small example is below to demonstrate. I've tried with boost 1.60, 1.55, and 1.50. Am I doing something wrong? Thanks, David #include "boost/polygon/polygon.hpp" #include <vector> namespace poly = boost::polygon; typedef long long Coord; typedef poly::point_data<Coord> Point; Coord outerPts[] = { -37205784000000LL, -22528321200000LL, -20252740200000LL, -40391736000000LL, 19228717200000LL, -39708900000000LL, 37774737000000LL, 32882157000000LL, -37205784000000LL, -22528321200000LL, }; Coord innerPts[] = { -8808676800000LL, -4351000500000LL, 29799924000000LL, 21288613500000LL, 8185023000000LL, -10611816600000LL, -8808676800000LL, -4351000500000LL, }; template<typename T> void liftPt(double x[2], const T& pt, double sf) { x[0] = sf * pt.x(); x[1] = sf * pt.y(); } template<typename T> void print_polyarray(const std::string& msg, T& parr, double scale, double iscale) { std::cout << msg << " has " << parr.size() << " polygons\n"; std::vector<poly::polygon_data<Coord> >::const_iterator pit; int pp = 0; for (pit = parr.begin(); pit != parr.end(); ++pit, ++pp) { poly::polygon_data<Coord>::iterator_type pcit; std::cout << " Polygon " << pp << " has " << pit->size() << " points\n"; double p0[2]; for (pcit = poly::begin_points(*pit); pcit != poly::end_points(*pit); ++pcit) { liftPt(p0, *pcit, iscale); std::cout << " " << p0[0] << " " << p0[1] << "\n"; } std::cout << "--\n"; } } int main() { const double scale = 2.31e13; const double iscale = 1./2.31e13; poly::polygon_with_holes_data<Coord> pface; std::vector<poly::polygon_data<Coord> > holes; poly::polygon_data<Coord> loop; std::vector<Point> polypts1; for (unsigned ii = 0; ii < sizeof(outerPts)/sizeof(outerPts[0])/2; ++ii) { polypts1.push_back(Point(outerPts[2*ii], outerPts[2*ii + 1])); } pface.set(polypts1.begin(), polypts1.end()); std::vector<Point> polypts2; for (unsigned ii = 0; ii < sizeof(innerPts)/sizeof(innerPts[0])/2; ++ii) { polypts2.push_back(Point(innerPts[2*ii], innerPts[2*ii + 1])); } loop.set(polypts2.rbegin(), polypts2.rend()); holes.push_back(loop); pface.set_holes(holes.begin(), holes.end()); Point holecenter( 9725423400000LL, 2108598800000LL); Point nonholepnt(37774730000000LL, 32882150000000LL); // ^^ Compare to 37774737000000LL, 32882157000000LL, which is a vertex in outerPts. std::cout << "Polygon has " << pface.size() << " vertices and " << pface.size_holes() << " holes\n"; std::cout << "Winding is " << (poly::winding(pface) == poly::CLOCKWISE ? "cw" : "ccw") << "\n"; std::cout << "Contains hole center? " << (poly::contains(pface, holecenter) ? "Y" : "N") << "\n"; std::cout << "Contains point it should? " << (poly::contains(pface, nonholepnt) ? "Y" : "N") << "\n"; // The above demonstrates that pface appears to be a valid polygon with a hole. // However, now when we ask for trapezoids, no hole is provided: // Add pface to polys so we can get trapezoids: poly::polygon_set_data<Coord> polys; std::vector<poly::polygon_data<Coord> > parr; polys.insert(pface); polys.get(parr); // This prints that parr (and thus polys) contains 0 polygons, which seems wrong: print_polyarray("Original polygon set", parr, scale, iscale); polys.get_trapezoids(parr); // This prints 2 polygons that form only the outer boundary, which seems wrong: print_polyarray("Tessellation ", parr, scale, iscale); return 0; }

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[boost] Checking interest in stacktrace library
by Antony Polukhin 22 Jun '16

22 Jun '16

Hi, I've got some prototype for getting stack traces: https://github.com/apolukhin/stacktrace It's design is based on the idea that class for stacktrace must be fully noexcept, without dynamic allocations in constructors and as simple as possible. Is there interest in it? What functionality would you like to have in it? -- Best regards, Antony Polukhin

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