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[release] Boost 1.77.0 beta 1 released
by Marshall Clow 14 Jul '21

14 Jul '21

Boost release 1.77.0 beta 1 is now available at: <https://boostorg.jfrog.io/artifactory/main/beta/1.77.0.beta1/source/> The SHA256 checksums are as follows: 1aba2bf9416d71026c9e6bbd10a2b7cfb31b0950baa7ad0861dfb74984d96bd9 boost_1_77_0_b1.zip 55126d149664541ffc9fd1f41b2ec67146d69bdab92e41da4bb8610b755ca9ec boost_1_77_0_b1.7z 1aabe7704e91f4f8d97b81d03ddc21c3396f4b72fc4041f01bfcfc128bac0d73 boost_1_77_0_b1.tar.gz 3d5801790c96d2bc9ed23372c4f9fd963bc2f39fe540e35d7b4fe586ba77dfa7 boost_1_77_0_b1.tar.bz2 For details of what's in the release, see <https://www.boost.org/users/history/version_1_77_0.html>. Please download the beta, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team

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geometry: knn search of point to many linestrings?
by Jens Thiele 14 Jul '21

14 Jul '21

Hi, I have lots of linestrings and want to find the k nearest linestrings to some point. Looking at the example /libs/geometry/doc/index/src/examples/rtree/polygons_shared_ptr.cpp I first thought this should be close to the solution and I just could replace the polygons with linestrings. But now I think the nearest query in that example only finds the nearest polygon bounding boxes and not the nearest polygons. Am I correct? If yes, how would one extend that example to find the nearest polygons? Greetings Jens

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[Serialization] Xml serialization extremely slow after upgrade to boost 1.74
by Elizabeta Petreska 14 Jul '21

14 Jul '21

Hi I upgraded my project to use boost 1.74 instead of boost 1.49. After the upgrade serialization time for my project archive is extremely slow. With boost 1.49 my project archive was serialized about 1 to 2 minutes. With boost 1.74 it takes more than 50 minutes (I stopped the process so I do not know the exact time it takes) to do the serialization. I am experiencing this only when doing xml serialization. Binary serialization is good, maybe just one second difference between 1.49 and 1.74. What could be the problem with xml serialization ? Repeatedly stopping and playing the debugger gets me into this function in the call stack: save_start i.e in save(*) where it saves the name of the attribute in the xml archive. and then in save_iterator. basic_xml_oarchive<Archive>::save_start(const char *name) { if(NULL == name) return; // be sure name has no invalid characters std::for_each(name, name + std::strlen(name), detail::XML_name<const char>()); end_preamble(); if(depth > 0){ this->This()->put('\n'); indent(); } ++depth; this->This()->put('<'); this->This()->save(name); (*) pending_preamble = true; indent_next = false; } And then save(name) calls this function template<class InputIterator> void save_iterator(std::wostream &os, InputIterator begin, InputIterator end){ typedef iterators::wchar_from_mb< iterators::xml_escape<InputIterator> > xmbtows; std::copy( xmbtows(begin), xmbtows(end), boost::archive::iterators::ostream_iterator<wchar_t>(os) ); }

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[Boost.Python] Making Python classes and functions available to C++
by Sean Farrow 13 Jul '21

13 Jul '21

Hi all, What is the easiest way of making Python classes and functions available to external C++ applications. The Boost.Python documentation seems to show making C++ classes available to Python, but I can't find anything that shows going the other way. Any help appreciated. Kind regards Sean.

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assembler error while using boost_geometry on HPUX IA64
by Ananta Swain 13 Jul '21

13 Jul '21

Hi Boost Experts, I am using boost geometry headers in our code. While compiling the code on HPUX IA64 with +std=c++11 and +stl=gnu flags, we get a cryptic assembler error. Appreciate any help to understand/debug this error. The testcase: *bash-4.3$ cat geom1.cpp* #include <boost/geometry.hpp> #include <boost/geometry/geometries/linestring.hpp> #include <boost/geometry/geometries/point_xy.hpp> #include <boost/geometry/geometries/multi_linestring.hpp> typedef boost::geometry::model::point<double, 2, boost::geometry::cs::geographic<boost::geometry::degree> > point_t; typedef boost::geometry::model::linestring<point_t > linestring_t; typedef boost::geometry::model::multi_linestring<linestring_t > multilinestring_t; using namespace std; template<typename T, typename S> bool Inside(string one, string two) { T objOne; S objTwo; bool inside = false; boost::geometry::read_wkt(one, objOne); boost::geometry::read_wkt(two, objTwo); inside = boost::geometry::within(objOne, objTwo); return inside; } bool Inside(string wktOne, string wktTwo) { bool inside; inside = Inside<multilinestring_t, linestring_t>(wktOne, wktTwo); return inside; } Compilation command: *bash-4.3$ aCC -c +DD64 +std=c++11 +stl=gnu -I <boost_headers path> geom1.cpp* *ASM_BACKEND fatal error: symbol* `_ZN5boost8geometry6detail7overlay27get_turn_info_linear_linearINS1_6relate5turns13assign_policyILb1EEEE22append_opposite_spikesILNS3_INS6_ILb1EEEE14append_versionE1ENS2_9turn_infoINS0_5model5pointIdLm2ENS0_2cs10geographicINS0_6degreeEEEEENS0_13segment_ratioIdEENS2_21turn_operation_linearINSB_IdLm2ENSD_ISE_EEEENSF_IdEEEENS_5arrayINSG_INSB_IdLm2ENSD_ISE_EEEENSF_IdEEEELm2EEEEENS2_17intersection_infoINS1_9get_turns29unique_sub_range_from_sectionILb0ENS0_7sectionINSA_3boxINSB_IdLm2ENSD_ISE_EEEEEELm2EEENSB_IdLm2ENSD_ISE_EEEENS0_22ever_circling_iteratorIN9__gnu_cxx17__normal_iteratorIPKNSB_IdLm2ENSD_ISE_EEEESt6vectorINSB_IdLm2ENSD_ISE_EEEESaINSB_IdLm2ENSD_ISE_EEEEEEEEEENS0_8strategy12intersection18spherical_segmentsIvEENS1_17no_rescale_policyEEENSK_ILb0ENSL_INSM_INSB_IdLm2ENSD_ISE_EEEEEELm2EEENSB_IdLm2ENSD_ISE_EEEENSN_INSP_ISR_SS_INSB_IdLm2ENSD_ISE_EEEESaINSB_IdLm2ENSD_ISE_EEEEEEEEEENSV_IvEESW_EENSB_IdLm2ENSD_ISE_EEEENSV_IvEESW_EESt20back_insert_iteratorISS_INS9_INSB_IdLm2ENSD_ISE_EEEENSF_IdEENSG_INSB_IdLm2ENSD_ISE_EEEENSF_IdEEEENSH_INSG_INSB_IdLm2ENSD_ISE_EEEENSF_IdEEEELm2EEEEESaINS9_INSB_IdLm2ENSD_ISE_EEEENSF_IdEENSG_INSB_IdLm2ENSD_ISE_EEEENSF_IdEEEENSH_INSG_INSB_IdLm2ENSD_ISE_EEEENSF_IdEEEELm2EEEEEEEEEEbRT0_RKT1_T2_' already defined Thanks, Ananta

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interprocess, how to grow managed_mapped_file when it used to store map<>
by i.nixman＠autistici.org 12 Jul '21

12 Jul '21

hi guys! I want to use boost::interprocess to store some resources (strings) into `bi::map<bi::string, bi::string>` that uses `bi::managed_mapped_file` so I can put the resources in the map once, take the file, and distribute it with the program. the problem is that I cannot calculate the required size in advance, so I want to use `bi::managed_mapped_file::grow ()` before inserting another element into the map. but it doesn't work as i expected, at some point i get exception: what(): boost::interprocess::bad_alloc I know the length of the key string and the length of the value string, how can I find out the size by which I must `grow()` before inserting another element into the map? now my code looks like this: #include <boost/interprocess/managed_mapped_file.hpp> #include <boost/interprocess/allocators/allocator.hpp> #include <boost/interprocess/containers/map.hpp> #include <boost/interprocess/containers/string.hpp> #include <iostream> int main () { namespace bi = boost::interprocess; using segment_manager_t = bi::managed_mapped_file::segment_manager; using void_allocator = bi::allocator<void, segment_manager_t>; using char_allocator = bi::allocator<char, segment_manager_t>; using char_string = bi::basic_string<char, std::char_traits<char>, char_allocator>; using map_value_type = std::pair<const char_string, char_string>; using map_value_type_allocator = bi::allocator<map_value_type, segment_manager_t>; using map_type = bi::map<char_string, char_string, std::less<char_string>, map_value_type_allocator>; static const char *mapfname = "map.dat"; bi::managed_mapped_file mmfile(bi::open_or_create, mapfname, 1024); { void_allocator alloc_inst(mmfile.get_segment_manager()); map_type *mymap = mmfile.find_or_construct<map_type>("MyMap")(alloc_inst); assert(mymap); for ( int i = 0; i < 100; ++i ) { std::string s = std::to_string(i); char_string key(s.c_str(), alloc_inst); char_string value(s.c_str(), alloc_inst); // bi::managed_mapped_file::grow(mapfname, ???); <<<<<<<<<<<<<<<<<<<<<< mymap->emplace(std::move(key), std::move(value)); } } bi::managed_mapped_file::shrink_to_fit(mapfname); return 0; } (or: https://wandbox.org/permlink/jtTOzlMh16ZS8jG6) any ideas? best!

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[release] Boost 1.77.0 Beta 1 Release Candidate 1 is available
by Marshall Clow 10 Jul '21

10 Jul '21

The first release candidates for the 1.77.0 beta release are now available at: https://boostorg.jfrog.io/artifactory/main/beta/1.77.0.beta1/source/ 1aba2bf9416d71026c9e6bbd10a2b7cfb31b0950baa7ad0861dfb74984d96bd9 boost_1_77_0_b1_rc1.zip 55126d149664541ffc9fd1f41b2ec67146d69bdab92e41da4bb8610b755ca9ec boost_1_77_0_b1_rc1.7z 1aabe7704e91f4f8d97b81d03ddc21c3396f4b72fc4041f01bfcfc128bac0d73 boost_1_77_0_b1_rc1.tar.gz 3d5801790c96d2bc9ed23372c4f9fd963bc2f39fe540e35d7b4fe586ba77dfa7 boost_1_77_0_b1_rc1.tar.bz2 The web site has NOT YET been updated. As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. -- The Release managers

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Boost on apple silicon
by simsicon 06 Jul '21

06 Jul '21

Hi, I was following the tutorial ( https://www.boost.org/doc/libs/1_76_0/doc/html/boost_asio/tutorial/tuttimer…) on macbook with m1 chip, and try to run the simple code and I meet the following error: Undefined symbols for architecture arm64: "boost::chrono::steady_clock::now()", referenced from: boost::asio::detail::chrono_time_traits<boost::chrono::steady_clock, boost::asio::wait_traits<boost::chrono::steady_clock> >::now() in mock-93ab24.o ld: symbol(s) not found for architecture arm64 clang: error: linker command failed with exit code 1 (use -v to see invocation) I am kind of new to C++ and boost, but I think this issue may be related to apple silicon compatibility? -- Thanks&Best Regards Zhang Zheng

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boost iterator range and filter iterator exception using MSVC
by Olaf Peter 02 Jul '21

02 Jul '21

Hi, using MSVC 2019 in debug mode I get an exception "cannot compare incompatible string_view iterators for equality". Using release mode and Clang/G++ all went fine as expected. - Boost: 1.76 - Visual Studio 2019 16.10.3 in C++17 mode How can it changed to be "portable" for all compiler? What's the reason behind? Using range.data() + size or data.front() + size for e.g. end iterator didn't compile. Thanks in advance! Olaf #include <boost/iterator/filter_iterator.hpp> #include <boost/range/iterator_range.hpp> #include <boost/range/iterator_range_core.hpp> #include <boost/range/iterator_range_io.hpp> #include <string_view> #include <iostream> template <typename RangeType> static auto filter_range(RangeType const& range) { struct separator_predicate { bool operator()(char x) { return '_' != x; } }; // FixMe: MSVC 2019 with '_CONTAINER_DEBUG_LEVEL > 0' triggers // assertion: // "cannot compare incompatible string_view iterators for equality" return boost::make_iterator_range( boost::make_filter_iterator( separator_predicate{}, range.begin(), range.end()), boost::make_filter_iterator( separator_predicate{}, range.end())); } using iterator_type = std::basic_string_view<char>::const_iterator; using string_span = boost::iterator_range<iterator_type>; int main() { // input std::string_view const sv = "Hello_World"; // algorithm get boost::iterator_range, aka string_span auto const range = string_span(sv); // here we are auto const range_f = filter_range(range); std::cout << range_f << '\n'; }

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[nowide] Convert wstring to u8string (C++20)
by Jim Orcheson 01 Jul '21

01 Jul '21

In C++17 and earlier, nowide::narrow can be used to convert from UTF-16 encoded strings (std::wstring) to UTF-8 encoded strings, stored in std::string. C++20 introduced std::u8string for UTF-8 encoded strings and it is incompatible with std::string. Is there some way I can get from std::wstring to std::u8string? It is not at all obvious from the nowide documentation.

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