July 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

Windows installation issues
by Alexander Carôt 01 Aug '16

01 Aug '16

Hi all, after having switched from OSX and Linux to Windows 10 I have issues compiling boost (1.61)with the MinGW compiler. The very first step fails: bootstrap.bat mingw results in not finding a right path, denying access and aborting the installation. So far I only found this article: https://andres.jaimes.net/698/use-c-with-mingw-and-netbeans-in-windows/ but it does not contain further info how (and where) to add additional info (I added c:\MinGW\bin to my PATH but it didn’t help). Any help appreciated, thanks in advance Alex --

6 8

Python TypeError with application compiled with CXX11_ABI=0
by Jackson Wiegman 29 Jul '16

29 Jul '16

Hi, I have an application I am trying to compile on Ubuntu 16.04. This is using GCC 5.4.0 and libboost 1.58.0 (stock libraries). The application has a linking to a library that was built with GCC 4.*, so I have to compile with D_GLIBCXX_USE_CXX11_ABI=0 to get backwards comparability (otherwise I have undefined abi:cxx11 links). However when I do this, I get a TypeError in Python: TypeError: No registered converter was able to produce a C++ rvalue of type > std::string from this Python object of type str It looks like boost is having a problem working without the ABI. Does anyone have a work-around or a patch for this? Jackson

2 2

[Python] gcc error compiling boost
by Àlex Jarauta 29 Jul '16

29 Jul '16

Dear all, my name is Alex and I am a postdoc at the University of Alberta, Edmonton, Canada. I am working with an in-house opensource code that uses boost to wrap C++ code with Python. In the latest version of our code, one has to download boost manually and compile it. I have tried wot two different versions (1.59 and 1.60) and I can compile them with python 2.7. However, if I try to compile it using either Python 3.3 or 3.5, I always get the same error: "./boost/python/detail/wrap_python.hpp:50:23: fatal error: pyconfig.h: No such file or directory # include <pyconfig.h>" I have been looking for this error for a while, but I have not been able to find a proper solution. I wonder if you could help me on this matter. Thank you very much for your attention. Best regards, Àlex

2 1

Graph: Trying to filter on custom properties
by Amit Prakash Ambasta 29 Jul '16

29 Jul '16

How should I be writing the get_filtered_graph in a generic way? #include <map> #include <string> #include <vector> #include <iostream> #include <boost/graph/adjacency_list.hpp> #include <boost/property_map/property_map.hpp> #include <boost/graph/filtered_graph.hpp> #include <boost/graph/graph_utility.hpp> template <typename F> struct EdgeProperty { F features; EdgeProperty() = default; EdgeProperty(const F& f) : features(f) {} }; template <typename EM, typename F> struct filtered_edge { F filters; EM emap; filtered_edge() = default; filtered_edge(EM emap_, F filters_) : emap(emap_), filters(filters_) {} template <typename E> bool operator()(const E& e) { auto e_prop = get(emap, e); auto e_feat = e_prop.features; for (auto it: e_feat) { if (get(e_feat, it.first) != it.second) { return false; } } return true; } }; template<typename G, typename F> G get_filtered_graph(G& g, F& filters) { typedef filtered_edge<boost::property_map<G, EdgeProperty<F> >, F> filter_fn; filter_fn filter{get(&EdgeProperty<F>::features, g), filters}; boost::filtered_graph<G, filter_fn> fg(g, filter); return fg; } typedef std::map<std::string, int> dict; typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::directedS, boost::no_property, EdgeProperty<dict> > Graph; Graph create_empty_graph() noexcept { return {}; } int main() { const char* name = "ABCDE"; auto g = create_empty_graph(); auto v0 = boost::add_vertex(g); auto v1 = boost::add_vertex(g); auto v2 = boost::add_vertex(g); dict d01; d01["a"] = 1; dict d12; d12["b"] = 1; dict fil; fil["a"] = 1; auto ep01 = EdgeProperty<dict>{ dict{} }; boost::add_edge(v0, v1, d01, g); boost::add_edge(v1, v2, d12, g); std::cout << "Before filter" << std::endl; boost::print_graph(g, name); auto fg = get_filtered_graph(g, fil); std::cout << "After filter" << std::endl; boost::print_graph(fg, name); Graph ga; }

2 2

[boost.geometry] concept namespace conflicts with new concept keyword (gcc 6.1)
by kique G 28 Jul '16

28 Jul '16

Hello, I am using boost.geometry with gcc 6.1 and I am finding conflicts between the new concept keyword (-fconcepts) and the concept namespace: /usr/include/boost/geometry/geometries/concepts/point_concept.hpp:33:50: error: expected identifier before 'concept' Am I missing something? If not, are there any plans for renaming this namespace? Do you know of any other incompatibilities between the boost libraries and the concepts TS? Thanks and best regards, Enrique Garcia

2 2

SVGMath no longer available
by Je suis la poubelle 27 Jul '16

27 Jul '16

Hi, I don't have any question to ask (yet :) ) but have a comment. In the folder "libs\math\doc\html\math_toolkit", there's the file sf_implementation.html. Inside this file, there's a section called "Creating and Managing the Equations". Inside it, you talked about a program called SVGMath (with a hyperlink). However, the hyperlink points to a website which no longer exists. Have a nice day

2 1

[boost.geometry] Why point coordinates are stored to SVG as integers?
by Mikhail Matrosov 27 Jul '16

27 Jul '16

Hello, I'm using boost::geometry::svg_mapper to save my shapes with floating point coordinates into an .svg file. It works great, but they are stored as integers. I can see this line in svg_mapper.hpp: namespace detail { namespace svg { typedef model::point<int, 2, cs::cartesian> svg_point_type; }} Thus svg_point is clearly defined to have integer coordinates. However, it is not convenient - SVG handles floating point coordinated perfectly well. Why not using original type of the serialized collection and let streams handle representation? ----- Best regards, Mikhail Matrosov

2 1

Re: [Boost-users] lockfree : getting a move only type into spsc_queue
by Bjorn Reese 24 Jul '16

24 Jul '16

On 07/23/2016 11:36 PM, Thomas Novotny wrote: > In the end Imade a custom version of spsc_queue. Getting this working > (as a hack) was fairly easy, so I wanted to share it in the hope that a > better solution might make it into a future version of the library. FYI, there is a pull request about adding move support to spsc_queue, but the consequences have not been fully examined yet: https://github.com/boostorg/lockfree/pull/24 In the meanwhile, you can make a cleaner solution with a unique_ptr specialization of spsc_queue. See attachment. > bool push( T & t, T * buffer, size_t max_size ) T&& t

2 1

lockfree : getting a move only type into spsc_queue
by Thomas Novotny 23 Jul '16

23 Jul '16

I had a unique_ptr from a pool with a custom deleter that I needed to get int a lockfree queue. This did not work out of the box with either boost::lockfree::queue or boost::lockfree::spsc_queue. There were three main issues: * default construction * copying * copy construction To solve the issue with default constructability I had to wrap the unique_ptr in a class. In the end Imade a custom version of spsc_queue. Getting this working (as a hack) was fairly easy, so I wanted to share it in the hope that a better solution might make it into a future version of the library. In essence, I only had to add some std::move calls and adjust the api for push. two lines here: bool push(T const & t, T * buffer, size_t max_size) { const size_t write_index = write_index_.load(memory_order_relaxed); // only written from push thread const size_t next = next_index(write_index, max_size); if (next == read_index_.load(memory_order_acquire)) return false; /* ringbuffer is full */ new (buffer + write_index) T(t); // copy-construct write_index_.store(next, memory_order_release); return true; } to bool push( T & t, T * buffer, size_t max_size ) { const size_t write_index = write_index_.load( memory_order_relaxed ); // only written from push thread const size_t next = next_index( write_index, max_size ); if( next == read_index_.load( memory_order_acquire ) ) return false; /* ringbuffer is full */ new (buffer + write_index) T(); // default-construct *(buffer + write_index) = std::move( t ); // move write_index_.store( next, memory_order_release ); return true; } a line here: bool push(T const & t) { return base_type::push(t); } to bool push(T & t) { return base_type::push(t); } and a few lines here template< class OutputIterator > OutputIterator copy_and_delete( T * first, T * last, OutputIterator out ) { if (boost::has_trivial_destructor<T>::value) { return std::copy(first, last, out); // will use memcpy if possible } else { for (; first != last; ++first, ++out) { *out = *first; first->~T(); } return out; } } to template< class OutputIterator > OutputIterator copy_and_delete( T * first, T * last, OutputIterator out ) { for (; first != last; ++first, ++out) { *out = std::move(*first); first->~T(); } return out; } In copy_payload there is only one change struct copy_convertible { template <typename T, typename U> static void copy(T & t, U & u) { u = t; } }; became template <typename T, typename U> static void copy(T & t, U & u) { u = std::move(t); } and that was it. The result is not pretty but works (only single element push and pop used).

1 0

Boost Social Event at CppCon 2016
by Jon Kalb 23 Jul '16

23 Jul '16

Boost Users, Because a lot of Boosters are going to be attending CppCon, we¹d like to arrange a social event for Boosters/C++Now attendees. http://cppcon.org/ If you are planning to attend CppCon or even If you are just going to be in or around Bellevue, Washington between September 17th and 23rd and you¹d like to join us for dinner, please let us know so we can get a count. Please send mail to: social(a)boost.org Once we settle on a date, etc, we¹ll let everyone who responded know when and where, so please let us know, even if you are a ³maybe.² If you are attending, please make your hotel reservations soon. We are likely to sell out of our room block. http://cppcon.org/lodging/ I hope to see you at CppCon. Jon

1 0

Problem using Boost 1.61.0 with VTK Marching Cubes
by PAUL SMITH 15 Jul '16

15 Jul '16

To whom it may concern, I asked this question to boost-bugs, but I was told not to expect a response from that email address and instead ask here. I seem to be having a problem using Boost 1.61.0 in conjunction with VTK 7.0.0. My purpose for using Boost is to obtain the filenames of all PNG files in any given folder using the following code: #define BOOST_FILESYSTEM_VERSION 3 #define BOOST_FILESYSTEM_NO_DEPRECATED #include "boost/filesystem.hpp" namespace fs = ::boost::filesystem; // return the filenames of all files that have the specified extension // in the specified directory and all subdirectories void get_all(const fs::path& root, const string& ext, vector<fs::path>&ret) { if(!fs::exists(root) || !fs::is_directory(root)) return; fs::recursive_directory_iterator it(root); fs::recursive_directory_iterator endit; while(it != endit) { if(fs::is_regular_file(*it) && it->path().extension() == ext) ret.push_back(it->path().filename()); ++it; } } This code is used as part of the CXX file, which is built with an appropriate CMakeLists file using CMake 3.5.1 to produce a corresponding .xcodeproj file. CXX and CMakeLists files are attached. However, the main problem that I'm facing is that attempting to build the project using an ALL_BUILD scheme in Xcode 7.0.1 leads to a series of errors pointing to the #include statements of the header files in the Boost folder (which is located in the same folder as the CXX and CMakeLists files). For instance, it starts off saying that "'boost/filesystem/config.hpp' file not found" in response to the following line of boost/filesystem.hpp: # include <boost/filesystem/config.hpp> Such errors could be resolved if I were to modify the syntax of the #include statements to follow a different format: # include "./filesystem/config.hpp" i.e., replacing the <> with "" and using relative paths to find the other required header files. However, going in to modify every single header file is a sort of tedium that I find it difficult to handle, and therefore I was hoping for a simpler solution to this problem. By the way, I am on a Mac, and my operating system is El Capitan version 10.11.5. Thank you in advance.

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回复：Re: the performance of boost::lock_free is slow in centos 6 and 7
by gao1738＠sina.com 12 Jul '16

12 Jul '16

Thanks for the response! What I want to know are: 1. when I should use the boost::lock_free? 2. What is the main usage of boost::lock_free? Not for better performance? 3. what is the best practice for boost::lock_free? 4. why the better the machine is, the worse the performance for boost::lock_free? In my test 3, by using 32core machine, I test threads from 1 to 32. In all of the test cases, the boost::lock_free is much slower than mutex, why? Best regards, dennis ----- 原始邮件 ----- 发件人：james <dirtydroog(a)gmail.com> 收件人：boost-users(a)lists.boost.org 主题：Re: [Boost-users] the performance of boost::lock_free is slow in centos 6 and 7 日期：2016年07月08日 21点21分 I suspect the main issue with your test is the effects of false sharing being magnified when the number of cores is >= the number of threads. I'd also suggest using the mm_pause intrinsic when busy spinning if your CPU supports it. (It's a real shame there's no official spinlock class in C++) Also, use something like a countdown latch to make sure your threads all start the actual work at the same time. On Fri, Jul 8, 2016 at 1:50 PM, Michael <mwpowellhtx(a)gmail.com> wrote: On July 8, 2016 1:39:13 AM EDT, gao1738(a)sina.com wrote: > Hi all, > >I try the boost::lockfree::queue and find some performance issue： > >I use the following test programs: > >lock_free_test.cc > >#include <boost/thread/thread.hpp> >#include <boost/lockfree/queue.hpp> >#include <iostream> >#include<cstdio> > >#include <boost/atomic.hpp> > >boost::atomic_int producer_count(0); >boost::atomic_int consumer_count(0); > >boost::lockfree::queue<int> queue(128); > >const int iterations = 1000000; >const int producer_thread_count = 4; >const int consumer_thread_count = 4; > >void producer(void) >{ > for (int i = 0; i != iterations; ++i) { > int value = ++producer_count; > while (!queue.push(value)) > ; > } >} > >boost::atomic<bool> done (false); >void consumer(void) >{ > int value; > while (!done) { > while (queue.pop(value)) > ++consumer_count; > } > > while (queue.pop(value)) > ++consumer_count; >} > >int main(int argc, char* argv[]) >{ > using namespace std; > cout << "boost::lockfree::queue is "; > if (!queue.is_lock_free()) > cout << "not "; > cout << "lockfree" << endl; > > boost::thread_group producer_threads, consumer_threads;//线程组 > > for (int i = 0; i != producer_thread_count; ++i) > producer_threads.create_thread(producer); > > for (int i = 0; i != consumer_thread_count; ++i) > consumer_threads.create_thread(consumer); > > producer_threads.join_all(); > done = true; > > consumer_threads.join_all(); > > cout << "produced " << producer_count << " objects." << endl; > cout << "consumed " << consumer_count << " objects." << endl; >} > > >locktest.cc > >#include <boost/thread/thread.hpp> >#include <boost/lockfree/queue.hpp> >#include <iostream> >#include<cstdio> >#include <queue> > >#include <boost/atomic.hpp> >using namespace std; > >boost::mutex producer_count_mu; >boost::mutex consumer_count_mu; >int producer_count = 0; >int consumer_count = 0; > >std::queue<int> message_queue; > >boost::mutex queue_mutex; > >const int iterations = 1000000; >const int producer_thread_count = 4; >const int consumer_thread_count = 4; > >void producer(void) >{ > for (int i = 0; i != iterations; ++i) { > queue_mutex.lock(); > int value = ++producer_count; > message_queue.push(value); > queue_mutex.unlock(); > } >} I haven't used lockfree per se but my understanding is that it solves what its name says. My guess is that most of the time is spent contending for the mutex. Incidentally, why not use one of the proper lock classes? You are already using boost, so this is also there. That'll save you having to lock and unlock, at least. I haven't explored lockfree that much, I could be wrong, but I thought the whole point of running lockfree was to avoid expensive locks, but not absolving you of being aware of exhausted conditions when your queue was empty. Also, doing a test like this what are you really asserting? Lock free; not expense free. There are no free lunches. Less so ever before. Anyhow, HTH Regards, Michael Powell >bool done (false); >void consumer(void) >{ > int value; > while (!done) { > queue_mutex.lock(); > while (!message_queue.empty()) { > message_queue.pop(); > ++consumer_count; > } > queue_mutex.unlock(); > } > > queue_mutex.lock(); > while (!message_queue.empty()) { > message_queue.pop(); > ++consumer_count; > } > queue_mutex.unlock(); >} >int main(int argc, char* argv[]) >{ > using namespace std; > cout << "boost::lockfree::queue is "; >// if (!queue.is_lock_free()) > cout << "not "; > cout << "lockfree" << endl; > > boost::thread_group producer_threads, consumer_threads;//线程组 > > for (int i = 0; i != producer_thread_count; ++i) > producer_threads.create_thread(producer); > > for (int i = 0; i != consumer_thread_count; ++i) > consumer_threads.create_thread(consumer); > > producer_threads.join_all(); > done = true; > > consumer_threads.join_all(); > > cout << "produced " << producer_count << " objects." << endl; > cout << "consumed " << consumer_count << " objects." << endl; >} > > >The compile command is: >g++ -I/usr/local/inlcude -L/usr/local/lib lock_free_test.cc >-lboost_thread -lboost_system -o lock_free_test >g++ -I/usr/local/inlcude -L/usr/local/lib lock_test.cc -lboost_thread >-lboost_system -o lock_test > >1. I first test in on my work computer, which use ubuntu 14.04 with >2core(i5), with >boost version: 1.54 >gcc version: 4.8.4 >g++ version: 4.8.4 > >The test result is that: > >time ./lock_test > >boost::lockfree::queue is not lockfree > >produced 4000000 objects. > >consumed 4000000 objects. > > > >real 0m3.844s > >user 0m1.800s > >sys 0m12.308s > time ./lock_free_test > >boost::lockfree::queue is lockfree > >produced 4000000 objects. > >consumed 4000000 objects. > > > >real 0m1.745s > >user 0m6.886s > >sys 0m0.000s > > >We can see that the lock free solution has better performance, about >50%. > >2. then I test it in a PC server with centos 6.4 , and 8 core (CPU >Intel(R) Xeon(R) CPU E5-2650 0 @ 2.00GHz ) > >boost version: 1.54 >gcc version: 4.4.7 >g++ version:4.4.7 > >The test result is that: > >time ./lock_test >boost::lockfree::queue is not lockfree >produced 4000000 objects. >consumed 4000000 objects. > >real 0m3.900s >user 0m2.593s >sys 0m27.282s > > time ./lock_free_test >boost::lockfree::queue is lockfree >produced 4000000 objects. >consumed 4000000 objects. > >real 0m5.470s >user 0m43.105s >sys 0m0.000s > > >Non lock free solution is better than lock free solution. > >3. I test it in a better PC server with centos 7.1 and 32 core CPU >(Intel(R) Xeon(R) CPU E7-4820 v2 @ 2.00GHz) >boost version: 1.53 >gcc version: 4.8.3 >g++ version: 4.8.3 > >time ./lock_test >boost::lockfree::queue is not lockfree >produced 4000000 objects. >consumed 4000000 objects. > >real 0m3.023s >user 0m1.929s >sys 0m20.706s > >time ./lock_free_test >boost::lockfree::queue is lockfree >produced 4000000 objects. >consumed 4000000 objects. > >real 0m9.804s >user 1m14.900s >sys 0m0.100s > >The lock free solution will be 3 times lower than the non-lock free >solution! > > >My question is that: >1. why lock free solution will get better performance in ubuntu but >much slower in centos 6 and 7? > Is it the issue of kernal or the gcc version or the boost version? >The more cpu in the machine the worse performance for lock free >solution? > >2. In which case, we should use the boost lock free solution to get >better performance? > > > >Best Regards! > >dennis > > > > >------------------------------------------------------------------------ > >_______________________________________________ >Boost-users mailing list >Boost-users(a)lists.boost.org >http://lists.boost.org/mailman/listinfo.cgi/boost-users -- Sent from my Android device with K-9 Mail. Please excuse my brevity. _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

3 2

[boost.test] Don't report skipped test as failure
by Florian Lindner 11 Jul '16

11 Jul '16

Hello, I use boost.test precondition in an MPI application to disable test at ranks != 0 if they do not use MPI: boost::test_tools::assertion_result isMaster(boost::unit_test::test_unit_id) { return precice::utils::Parallel::getProcessRank() == 0; } BOOST_AUTO_TEST_SUITE(NearestNeighborMapping) BOOST_AUTO_TEST_CASE(ConsistentNonIncremental, * boost::unit_test::precondition(isMaster)) {...} That works perfect, I just don't like that sipped test are reported as errors. Example with all tests deactivated: % ./testprecice Global setup Running 2 test cases... Global teardown *** Errors were detected in the test module "Master Test Suite"; see standard output for details Here you think it's an error, but it's just skipped tests: % ./testprecice -r detailed Global setup Running 2 test cases... Global teardown Test module "Master Test Suite" has failed with: 2 test cases out of 2 skipped Test suite "NearestNeighborMapping" has failed with: 2 test cases out of 2 skipped Test case "NearestNeighborMapping/ConsistentNonIncremental" was skipped Test case "NearestNeighborMapping/ConservativeNonIncremental" was skipped Could this behavior be changed somehow and skipped test not be reported as failures? Thanks, Florian

2 2

substantial lag time difference from boost::thread 1.57 and 1.60
by David Medine 09 Jul '16

09 Jul '16

Hello, I am an engineer in a neurosciences lab. We have some data acquisition software that uses boost::thread and some other boost libraries as well. Part of my job is to measure the lag time for our devices' data acquisition. I have been testing the acquisition software when linking against boost v.1.57.0 and v.160.0. Basically I generate a test signal and read it in with an NIDAQ and our EEG system. The signal is a series of 3ms long pulses. When the input to the NIDAQ goes high, I generate a timestamped marker. Meanwhile the EEG system is getting the same pulse train input and I record that digital data on its own thread and timestamp that as well. Then I compare the timestamps at which the EEG signal has a rising edge with the timestamps of the markers. The difference between these time values is the lag of the EEG system. The app I use to get the EEG signal uses boost::thread. The lag time is consistently ~2.7 ms when linking against boost v.1.57.0 and is a whopping 11.6 ms when I link against v.1.60.0. Since the data acquisition happens in a tight loop on its own thread, I am guessing that there is some kind of increased latency of boost threads in newer versions of the library. Does anybody know what might be causing this? I am on Windows 7, 64-bit and am using the pre-compiled boost libraries (i.e. I am not compiling them myself). Cheers, David

2 2

Acquiring and rebuilding C++ libraries on Windows
by Eric Mittelette 08 Jul '16

08 Jul '16

Hello I'm Program Manager at Microsoft, working on VC++ Libraries team (VC runtime, STL...) We are working on the spec of a tool to acquire 3rd party libraries on Windows. We are targeting mainly OSS libraries, our tool will help dev to rebuild locally from the source code on Windows. Today we have a proto, based on a port tree approach. (having a repo with the build script and the associated patch file) I wanted to have a discussion with the Boost community about this project, and how dev could acquire Boost this way. Feel free to contact me to initiate this discussion, we'll be happy to share our idea and prototype with you and collect feedback and suggestions. Best, Eric Mittelette Senior Program Manager - Visual C++ (VCLib) Microsoft Corp.

6 10

the performance of boost::lock_free is slow in centos 6 and 7
by gao1738＠sina.com 08 Jul '16

08 Jul '16

Hi all, I try the boost::lockfree::queue and find some performance issue： I use the following test programs: lock_free_test.cc #include <boost/thread/thread.hpp> #include <boost/lockfree/queue.hpp> #include <iostream> #include<cstdio> #include <boost/atomic.hpp> boost::atomic_int producer_count(0); boost::atomic_int consumer_count(0); boost::lockfree::queue<int> queue(128); const int iterations = 1000000; const int producer_thread_count = 4; const int consumer_thread_count = 4; void producer(void) { for (int i = 0; i != iterations; ++i) { int value = ++producer_count; while (!queue.push(value)) ; } } boost::atomic<bool> done (false); void consumer(void) { int value; while (!done) { while (queue.pop(value)) ++consumer_count; } while (queue.pop(value)) ++consumer_count; } int main(int argc, char* argv[]) { using namespace std; cout << "boost::lockfree::queue is "; if (!queue.is_lock_free()) cout << "not "; cout << "lockfree" << endl; boost::thread_group producer_threads, consumer_threads;//线程组 for (int i = 0; i != producer_thread_count; ++i) producer_threads.create_thread(producer); for (int i = 0; i != consumer_thread_count; ++i) consumer_threads.create_thread(consumer); producer_threads.join_all(); done = true; consumer_threads.join_all(); cout << "produced " << producer_count << " objects." << endl; cout << "consumed " << consumer_count << " objects." << endl; } locktest.cc #include <boost/thread/thread.hpp> #include <boost/lockfree/queue.hpp> #include <iostream> #include<cstdio> #include <queue> #include <boost/atomic.hpp> using namespace std; boost::mutex producer_count_mu; boost::mutex consumer_count_mu; int producer_count = 0; int consumer_count = 0; std::queue<int> message_queue; boost::mutex queue_mutex; const int iterations = 1000000; const int producer_thread_count = 4; const int consumer_thread_count = 4; void producer(void) { for (int i = 0; i != iterations; ++i) { queue_mutex.lock(); int value = ++producer_count; message_queue.push(value); queue_mutex.unlock(); } } bool done (false); void consumer(void) { int value; while (!done) { queue_mutex.lock(); while (!message_queue.empty()) { message_queue.pop(); ++consumer_count; } queue_mutex.unlock(); } queue_mutex.lock(); while (!message_queue.empty()) { message_queue.pop(); ++consumer_count; } queue_mutex.unlock(); } int main(int argc, char* argv[]) { using namespace std; cout << "boost::lockfree::queue is "; // if (!queue.is_lock_free()) cout << "not "; cout << "lockfree" << endl; boost::thread_group producer_threads, consumer_threads;//线程组 for (int i = 0; i != producer_thread_count; ++i) producer_threads.create_thread(producer); for (int i = 0; i != consumer_thread_count; ++i) consumer_threads.create_thread(consumer); producer_threads.join_all(); done = true; consumer_threads.join_all(); cout << "produced " << producer_count << " objects." << endl; cout << "consumed " << consumer_count << " objects." << endl; } The compile command is: g++ -I/usr/local/inlcude -L/usr/local/lib lock_free_test.cc -lboost_thread -lboost_system -o lock_free_test g++ -I/usr/local/inlcude -L/usr/local/lib lock_test.cc -lboost_thread -lboost_system -o lock_test 1. I first test in on my work computer, which use ubuntu 14.04 with 2core(i5), with boost version: 1.54 gcc version: 4.8.4 g++ version: 4.8.4 The test result is that: time ./lock_test boost::lockfree::queue is not lockfree produced 4000000 objects. consumed 4000000 objects. real 0m3.844s user 0m1.800s sys 0m12.308s time ./lock_free_test boost::lockfree::queue is lockfree produced 4000000 objects. consumed 4000000 objects. real 0m1.745s user 0m6.886s sys 0m0.000s We can see that the lock free solution has better performance, about 50%. 2. then I test it in a PC server with centos 6.4 , and 8 core (CPU Intel(R) Xeon(R) CPU E5-2650 0 @ 2.00GHz ) boost version: 1.54 gcc version: 4.4.7 g++ version:4.4.7 The test result is that: time ./lock_test boost::lockfree::queue is not lockfree produced 4000000 objects. consumed 4000000 objects. real 0m3.900s user 0m2.593s sys 0m27.282s time ./lock_free_test boost::lockfree::queue is lockfree produced 4000000 objects. consumed 4000000 objects. real 0m5.470s user 0m43.105s sys 0m0.000s Non lock free solution is better than lock free solution. 3. I test it in a better PC server with centos 7.1 and 32 core CPU (Intel(R) Xeon(R) CPU E7-4820 v2 @ 2.00GHz) boost version: 1.53 gcc version: 4.8.3 g++ version: 4.8.3 time ./lock_test boost::lockfree::queue is not lockfree produced 4000000 objects. consumed 4000000 objects. real 0m3.023s user 0m1.929s sys 0m20.706s time ./lock_free_test boost::lockfree::queue is lockfree produced 4000000 objects. consumed 4000000 objects. real 0m9.804s user 1m14.900s sys 0m0.100s The lock free solution will be 3 times lower than the non-lock free solution! My question is that: 1. why lock free solution will get better performance in ubuntu but much slower in centos 6 and 7? Is it the issue of kernal or the gcc version or the boost version? The more cpu in the machine the worse performance for lock free solution? 2. In which case, we should use the boost lock free solution to get better performance? Best Regards! dennis

3 2

BOOST_PP_SEQ_ENUM troubles
by Cherotek Music 08 Jul '16

08 Jul '16

Hi, I'm trying to make a macro chain that expands something like this *A, B, C* into something like this *{"A", create<AFile>}, {"B", create<BFile>}, {"C", create<CFile>}* This is what I have come up with *#define FORMATS A, B, C // Add new formats here* *#define SEQ_FORMATS BOOST_PP_VARIADIC_TO_SEQ(FORMATS)* *#define ARG_PAIR(s, data, x) {#x, create<x##File>}* *#define SEQ_ARG_PAIRS BOOST_PP_SEQ_TRANSFORM(ARG_PAIR, ~, SEQ_FORMATS)* *#define ARG_PAIRS BOOST_PP_SEQ_ENUM(SEQ_ARG_PAIRS)* The SEQ_ARG_PAIRS macro does expand into *({"A", create<AFile>}) ({"B", create<BFile>}) ({"C", create<CFile>})* but ARG_PAIRS fails with the following error: test.cpp:20:1: error: macro "BOOST_PP_SEQ_SIZE_0" passed 2 arguments, but takes just 1 ARG_PAIRS ^ BOOST_PP_SEQ_ENUM_0 ({"B", create<BFile>}) ({"C", create<CFile>}) ({"A", create<AFile>}) ({"B", create<BFile>}) ({"C", create<CFile>}) Any ideas? thanks a lot

3 7

boost::any with const value types
by Robert Dailey 07 Jul '16

07 Jul '16

I'm finding that if I store a `char*` versus `char const*` in a boost::any object, that this impacts the behavior of boost::any_cast. I do not find this documented anywhere. For example, if I store a const qualified character pointer in a boost::any object, then I do `boost::any_cast<char*>(......)`, it will throw. Changing the type to `char const*` fixes it. Is this by design? I find this makes things more difficult to deal with since I don't always know if the type I'm getting is const or not. Also my implementation does not change depending on constness.

4 3

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

Re: [Boost-users] Acquiring and rebuilding C++ libraries on Windows
by LeMay.Steve 06 Jul '16

06 Jul '16

Probably a great topic for CPPCON. Sent from my iPad From: Ernest Zaslavsky Sent: 7/5/16, 8:44 PM To: , Boost Subject: Re: [Boost-users] Acquiring and rebuilding C++ libraries on Windows Hi, And what happened to the native NuGet packages idea? It is quite convenient way to get, use and update third parties. From: Boost-users [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Eric Mittelette Sent: Wednesday, July 06, 2016 2:49 AM To: boost-users(a)lists.boost.org Subject: [Boost-users] Acquiring and rebuilding C++ libraries on Windows Hello I’m Program Manager at Microsoft, working on VC++ Libraries team (VC runtime, STL…) We are working on the spec of a tool to acquire 3rd party libraries on Windows. We are targeting mainly OSS libraries, our tool will help dev to rebuild locally from the source code on Windows. Today we have a proto, based on a port tree approach. (having a repo with the build script and the associated patch file) I wanted to have a discussion with the Boost community about this project, and how dev could acquire Boost this way. Feel free to contact me to initiate this discussion, we’ll be happy to share our idea and prototype with you and collect feedback and suggestions. Best, Eric Mittelette Senior Program Manager – Visual C++ (VCLib) Microsoft Corp. CONFIDENTIALITY NOTICE: This message is the property of International Game Technology PLC and/or its subsidiaries and may contain proprietary, confidential or trade secret information. This message is intended solely for the use of the addressee. If you are not the intended recipient and have received this message in error, please delete this message from your system. Any unauthorized reading, distribution, copying, or other use of this message or its attachments is strictly prohibited.

1 0

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

[coroutine2] - exceptions from constructor fail
by Tamas.Ruszkai＠leica-geosystems.com 01 Jul '16

01 Jul '16

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