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Re: [Boost-users] [boost] Interest in a Unicode library for Boost?
by Zach Laine 30 Oct '19

30 Oct '19

On Wed, Oct 30, 2019 at 9:47 AM Peter Koch Larsen < peter.koch.larsen(a)gmail.com> wrote: > I saw that talk (on video) and was quite impressed but never got to > try your library out. > Would be happy to use a library like this! Can you tell me how it > relates to the proposed std? > There is no relationship yet. Boost.Text is an experiment meant to gather feedback, which will in turn drive the standardization effort. I believe all large libraries should have Boost-equivalent visibility in the C++ community before being standardized. That being said, some of my fellow SG-16 members (that's the committee's Unicode Study Group) have started proposing some actual APIs for standardization. The first of these is the most low-level: transcoding (see http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1629r0.html ). JeanHeyd's approach is more ambitious than mine -- I really only care about Unicode. His proposal covers conversions among all possible encodings, including an API that lets users add implementations for the encodings they care about that are not covered by the standard. There are no other in-flight Unicode API proposals that I'm aware of. Zach

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Boost.Numeric.Interval: Please specify rounding control mechanism Inbox x UVI x
by Bastien Commelongue 29 Oct '19

29 Oct '19

Hello, I am building an app for IOS (ARM) and I had this issue while compiling: *Boost.Numeric.Interval: Please specify rounding control mechanism.* C99 version should be used in this case but __USE_ISOC99 is not defined. Modifying the condition with this code (using __cplusplus) fixed the issue: *boost/numeric/interval/hw_rounding.hpp(36)* *#if defined(BOOST_NUMERIC_INTERVAL_NO_HARDWARE) && (defined(__USE_ISOC99) || defined(__MSL__) || (defined __cplusplus && __cplusplus >= 201103L))# include <boost/numeric/interval/detail/c99_rounding_control.hpp>#endif* Let me know if I missed something or if you plan to integrate this modification in a next version. Cheers, Bastien Commelongue -- [image: UVI] <http://www.uvi.net/> Bastien Commelongue | Software Development A. 159 rue Amelot - 75011 Paris - France T. 0033671833955 • M. b.commelongue(a)uvi.net <email(a)uvi.net> [image: Facebook] <http://www.facebook.com/UVI.Official> [image: Twitter] <http://twitter.com/UVIofficial> [image: Youtube] <http://www.youtube.com/user/UVIofficial> [image: SoundCloud] <http://soundcloud.com/uvi-official> [image: Instagram] <http://instagram.com/weareuvi/>

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[BGL] minimum cut separating two given vertices on undirected graph
by Ziye Tang 18 Oct '19

18 Oct '19

Hi all, This is my first time posting, and I've read the posting guideline. I might still make some mistakes in the posting style. In particular, I am not sure how to insert code snippet into email. Please let me know when I do make such mistakes. I need to find a min-cut separating a given pair of vertices on an undirected graph. Conceptually this is how I would solve it: first I bidirect the graph, treat one vertex as the source and the other as the sink. Then run any max flow algorithm from source to sink. When the algorithm finishes, in the residual graph, identify connected component which contains a given vertex. This gives the min-cut. In order to implement it, I use push_relabel_max_flow. According to the doc I need to augment each edge with a reverse edge. Since I bi-directed the graph already, this would give rise to a multi-graph where each edge, say (i,j) has two copies, with the first copy treated as the `true' edge and the second copy as the reverse edge of arc (j,i). Then I set capacity and residual capacity map accordingly. But now I am getting a segmentation error when calling push_relabel_max_flow. Could you help me understand what is going on? I've attached my code snippet below. Here g is my graph, n is the number of vertices, xval is a 2 by 2 positive matrix where each corresponding entry is the capacity of the edge. for (int i=0; i<n; i++) for (int j=i+1; j<n; j++) { graph_traits<Graph>::out_edge_iterator e_start, e_end, e_start2, e_end2;; boost::tie(e_start, e_end) = boost::edge_range(i,j,g); // check if an edge exists if (e_start == e_end) continue; boost::tie(e_start2, e_end2) = boost::edge_range(j,i,g); // set reverse edge, set its capacity to be zero g[*e_start].rev = *(--e_end2); g[*e_start2].rev = *(--e_end); g[*e_start].capacity = xval[i][j]; g[*e_start].res_capacity = xval[i][j]; g[*e_start2].capacity = xval[i][j]; g[*e_start2].res_capacity = xval[i][j]; // now end points to the second parallel edge g[*e_end].capacity = 0; g[*e_end].res_capacity = 0; g[*e_end2].capacity = 0; g[*e_end2].res_capacity = 0; //g[e].rev = boost::edge(j,i,g).first; std::cout << "(" << i << ", " << j << "): " << g[*e_start].capacity << ", " << g[*e_start2].capacity << endl; } Thanks in advance!

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Re: [Boost-users] Help needed with boost::process::child and mysql cli
by Label 17 Oct '19

17 Oct '19

Hello, > Date: Tue, 15 Oct 2019 07:28:54 +0000 > From: name name <jerry-dev(a)outlook.com> > To: "boost-users(a)lists.boost.org" <boost-users(a)lists.boost.org> > Subject: [Boost-users] Help needed with boost::process::child and > mysql cli > Message-ID: > <MN2PR01MB5710C3F35D092D2FDF0B376DF0930(a)MN2PR01MB5710.prod.exchangelabs.com> > > > Content-Type: text/plain; charset="windows-1252" > > Hi, > > Im use boost::process::child to create a mysql cli child process to > import sql file. > Normally im use this command: > /usr/bin/mysql mysql -h127.0.0.1 -utestuser --password='!@#QWE123qwe' > -P3306 --default-character-set=utf8mb4 --max-allowed-packet=1GB < > /root/create_db.sql > It?s worked well in bash. > > But when use boost::process::child, std_err report ERROR 1045 (28000): > Access denied for user 'testuser'@'localhost' (using password: YES). > Is there any bugs in my code? [...] I have no experience with boost::process, only one idea: Maybe the apostrophs around the password are normally eaten by the Linux shell, and you have to leave them out when building your arguments? // connection info args.push_back("-h127.0.0.1"); args.push_back("-utestuser"); args.push_back("--password=!@#QWE123qwe"); // <= args.push_back("-P3306"); Freundliche Grüße * Best regards * Met vriendelijke groeten * Meilleures salutations Holger Gerth _________________________________________________________________________________ EB-Soft Gesellschaft fuer elektronische Beschriftungs-Software mbH Neckargartacher Str. 114, 74080 Heilbronn, Germany Tel: +49 (0)7131 / 9466-0 Email: info(a)ebsoft.de Fax: +49 (0)7131 / 1099-0 Homepage: www.ebsoft.de Amtsgericht-Registergericht-Stuttgart HRB 102882 Geschaeftsfuehrer: Michael Ehring, Helmut Sigler _________________________________________________________________________________

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Help needed with boost::process::child and mysql cli
by name name 15 Oct '19

15 Oct '19

Hi, Im use boost::process::child to create a mysql cli child process to import sql file. Normally im use this command: /usr/bin/mysql mysql -h127.0.0.1 -utestuser --password='!@#QWE123qwe' -P3306 --default-character-set=utf8mb4 --max-allowed-packet=1GB < /root/create_db.sql It’s worked well in bash. But when use boost::process::child, std_err report ERROR 1045 (28000): Access denied for user 'testuser'@'localhost' (using password: YES). Is there any bugs in my code? Os: ubuntu 18.04 LTS Boost: 1.71.0 MySql:5.7.27 Create_db.sql: DROP DATABASE IF EXISTS test_db; CREATE DATABASE test_db; Thanks [code] #include <iostream> #include <boost/algorithm/string/join.hpp> #include <boost/iostreams/copy.hpp> #include <boost/asio/io_context.hpp> #include <boost/process.hpp> using namespace boost::process; using namespace boost::iostreams; using namespace boost::asio; std::string SearchExecutableInPath(std::string const& filename) { try { return search_path(filename).generic_string(); } catch (...) { return ""; } } int RunProcess( std::string const& executable, std::vector<std::string> const& args, std::string input_file_path ) { io_context ioCtx; auto work = make_work_guard(ioCtx); std::thread ioThread([&ioCtx] { ioCtx.run(); }); std::future<std::string> dataOut, dataErr; child c; if (!input_file_path.empty()) { c = child( boost::filesystem::absolute(executable), boost::process::args(args), std_out > dataOut, std_err > dataErr, std_in < boost::filesystem::absolute(input_file_path), ioCtx ); } else { c = child( boost::filesystem::absolute(executable), boost::process::args(args), std_out > dataOut, std_err > dataErr, std_in.close(), ioCtx ); } c.wait(); int result = c.exit_code(); std::string output = dataOut.get(); std::string error = dataErr.get(); if (!output.empty()) { std::cout << output << std::endl; } if (!error.empty()) { std::cout << error << std::endl; } work.reset(); ioThread.join(); return result; } int main() { // /usr/bin/mysql mysql -h127.0.0.1 -utestuser --password='!@#QWE123qwe' -P3306 --default-character-set=utf8mb4 --max-allowed-packet=1GB < /root/create_db.sql std::vector<std::string> args; args.reserve(8); // mysql cli args.push_back("mysql"); // connection info args.push_back("-h127.0.0.1"); args.push_back("-utestuser"); args.push_back("--password='!@#QWE123qwe'"); args.push_back("-P3306"); // encoding args.push_back("--default-character-set=utf8mb4"); // maybe large sql file args.push_back("--max-allowed-packet=1GB"); int const ret = RunProcess( SearchExecutableInPath("mysql"), args, "/root/create_db.sql"); std::cout << "ret code: " << ret << std::endl; return 0; } [/code]

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bg::cs::geographic and nearest query
by vexakul 14 Oct '19

14 Oct '19

Hi all! I need to store geographic points in rtree and be able to answer nearest query. Can someone provide an example similar to this <https://www.boost.org/doc/libs/1_65_1/libs/geometry/doc/html/geometry/spati…> but with point type bg::model::point<float, 2, bg::cs::geographic<bg::degree>>? Is that supported? For me it fails to compile. -- Kind regards, Sergey. -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Users-f2553780.html

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[gil][docs] Image Processing docs structure based on "Principles of Digital Image Processing" book
by Mateusz Loskot 13 Oct '19

13 Oct '19

Hi, (Copying to boost and boost-users lists) If you are passionate about C++ and image processing and interested in writing documentation about it, here is a good first issue for you if you'd like to start contributing to Boost.GIL. During the course of GSoC 2019 we have received first batch of IP features, there is not great deal of content yet, so shouldn't be overwhelming to get started. It's rather a clean slate under your control. Don't be shy! :-) Regards, Mateusz Loskot ---------- Forwarded message --------- From: Mateusz Loskot <mateusz(a)loskot.net> Date: Sun, 13 Oct 2019 at 20:08 Subject: [GH #396] Image Processing docs structure based on "Principles of Digital Image Processing" book To: <boost-gil(a)lists.boost.org> Hi, Following our successful GSoC 2019, I have started discussion on proposal of improved and future-proof structure of the "Image Processing" chapters of GIL documentation. Here are details: https://github.com/boostorg/gil/issues/396 Please, have a look and share your feedback. If there is anyone experienced in writing docs, a technical write, who is looking for ways to contribute to Boost and Boost.GIL, this is a very good first issue to pick :-) Best regards, -- Mateusz Loskot, http://mateusz.loskot.net -- Mateusz Loskot, http://mateusz.loskot.net

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Attributes of sequence and list operator in boost.spirit qi?
by kila 12 Oct '19

12 Oct '19

I also open the same question on stackoverflow. For better formatting of code, please refer to https://stackoverflow.com/questions/58353782/attributes-of-sequence-and-lis… <https://stackoverflow.com/questions/58353782/attributes-of-sequence-and-lis…> I want to parse something like "{xxxx} {xxxx}" which is separated by eol into a *vector<vector<wchar_t>> *: ({xxxx},{xxxx}) so that "{" and "}" stays with internal characters together. Note there are only two elements on the outer vector. My code is: #define BOOST_SPIRIT_UNICODE #include <iostream> #include<boost/spirit/include/qi.hpp> #include<string> #include<vector> using namespace std; namespace sw=boost::spirit::standard_wide; namespace qi= boost::spirit::qi; using boost::spirit::standard_wide::char_; int main() { wstring s = L"{\"id\":23,\"text\":\"sf\nsf\"}\n{\"id\":23,\"text\":\"sfsf\"}"; qi::rule<wstring::iterator, vector<vector<wchar_t>>(), sw::blank_type> ru; ru = (qi::char_(L"{") >> *(char_-char_(L"}")) >> char_(L"}")) % qi::eol; vector<vector<wchar_t>> result; qi::phrase_parse(s.begin(), s.end(), ru, sw::blank, result); for (auto& v : result) { //cout << "Size of string: " << v.size() << endl; for (auto& s : v) { wcout << s; }; cout << endl; }; std::cout << "Size of result"<<result.size()<<endl ; } However ouput is: { "id":23,"text":"sf sf" } { "id":23,"text":"sfsf" } Size of result6 It looks like that "{" becomes a single element of type vector<wchar_t> for the outer vector. Then consider the rule: *ru = (qi::char_(L"{") >> *(char_-char_(L"}")) >> char_(L"}")) % qi::eol;* According to the documentation, *(char_-char_(L"}")) should be vector . And because *a: A, b: vector --> (a >> b): vector *, then I think that *(qi::char_(L"{") >> *(char_-char_(L"}")) >> char_(L"}"))* should be *vector<wchar_t>*. This is contracdicted to the result. Where I'm wrong? -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Users-f2553780.html

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[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

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[outcome] Major changes for Boost 1.72 release
by Niall Douglas 10 Oct '19

10 Oct '19

Just as a heads up to those who care, and any pretesting of these changes in advance of the Boost release is welcome. There are two breaking changes: 1. The git submodule mechanism used by standalone Outcome of specifying dependent libraries has been replaced with a cmake superbuild of dependencies mechanism instead. Upon cmake configure, an internal copy of quickcpplib will be git cloned, built and installed into the build directory from where an internal `find_package()` uses it. This breaks the use of the unconfigured Outcome repo as an implementation of Outcome, one must now do one of: 1. Add Outcome as subdirectory to cmake build 2. Use cmake superbuild (i.e. `ExternalProject_Add()`) to build and install Outcome into a local installation. 3. Use one of the single header editions. 2. For standalone Outcome, the current compiler is now checked for whether it will compile code containing C++ Concepts, and if it does, all cmake consumers of Outcome will enable C++ Concepts. Set the cmake variable `CXX_CONCEPTS_FLAGS` to an empty string to prevent auto detection and enabling of C++ Concepts support occurring. There are two new features: - Standalone outcome is now `make install`-able, and cmake `find_package()` can find it. Note that you must separately install and `find_package()` Outcome's dependency, quickcpplib, else `find_package()` of Outcome will fail. - Support for C++ Coroutines has been added. This comes in two parts, firstly there is now an `OUTCOME_CO_TRY()` operation suitable for performing the `TRY` operation from within a C++ Coroutine. Secondly, in the header `outcome/coroutine_support.hpp` there are implementations of `eager<OutcomeType>` and `lazy<OutcomeType>` which let you more naturally and efficiently use `basic_result` or `basic_outcome` from within C++ Coroutines -- specifically, if the result or outcome will construct from an exception pointer, exceptions thrown in the coroutine return an errored or excepted result with the thrown exception instead of throwing the exception through the coroutine machinery (which in current compilers, has a high likelihood of blowing up the program). Both `eager<T>` and `lazy<T>` can accept any `T` as well. Both have been tested and found working on VS2019 and clang 9. More detail can be found at: https://boostorg.github.io/outcome/changelog.html Niall

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Regarding the End of life of Boost version 1.56
by kamallochan Jena 05 Oct '19

05 Oct '19

Hi, In one of our project we are using Boost 1.56 version. And want to upgrade Boost C++ to a version that is not in an end of life state. My queries are: 1> When is the End Of Life of Boost 1.56 version ? 2> What is the latest stable Boost version we can use instead of Boost version 1.56 ? Can someone help on answering those questions. Thank you in advance! Thanks & Regards, Kljena

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boost::geometry: intersection of a point with a linestring
by Giorgino R 04 Oct '19

04 Oct '19

Hi there, Is there any boost functionality to "split" a linestring with an intersecting point? I was expecting that boost::geometry::intersection could return a multi-linestring (of size two) or a vector of linestrings (size two). For example, please see a very simple case below which doesn't compile: point_2d pt(0.5, 0); > linestring_2d ls({ point_2d(0, 0), point_2d(1, 0), point_2d(3, 0), > point_2d(5, 0) }); > std::vector<linestring_2d> inter; > bg::intersection(pt, ls, inter); Is there any way to get inter vector with two linestrings (linestring_2d({point_2d(0, 0), point_2d(0.5, 0) }) and linestring_2d({point_2d(0.5, 0), point_2d(1, 0), point_2d(3, 0), point_2d(5, 0) }) ) or any multi geometry container that will hold the spatial information of two lines connected in this point? Or should I create these two lines myself by working out which points of the linestring are left and right of the intersecting point? Many thanks in advance.

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Assigning to a boost::asio::ssl::context while asynchronous operations are using it
by Martijn Otto 30 Sep '19

30 Sep '19

I cannot find any definitive documentation on whether it's safe to move-assign to an ssl-context while it is used for asynchronous operations, assuming of course the application is single-threaded. In my tests I could not trigger any failures, but that may be pure luck (or not lucky at all depending on point of view).

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catmull_rom returning a single point
by hgrwilson 30 Sep '19

30 Sep '19

Hi all, I am trying to interpolate some data with a *catmull_rom* spline available in boost math (interpolation). However, the resulting spline collapses to a single point for all /s/, corresponding to the first control point, /points_intr[0]/. Below, the c++ code segment of the interpolation is depicted: std::vector<std::array<double, 2>> points_intr(16); points_intr[0] = { 1.263270, 0.774614 }; points_intr[1] = { 1.876, 2.480 }; points_intr[2] = { 1.651110, 4.550 }; points_intr[3] = { 1.426340, 5.688 }; points_intr[4] = { 1.429, 7.054 }; points_intr[5] = { 2.073220, 8.377020 }; points_intr[6] = { 3.910, 9.140 }; points_intr[7] = { 6.430, 9.537 }; points_intr[8] = { 8.950, 9.859 }; points_intr[9] = { 11.470, 10.317 }; points_intr[10] = { 12.730, 10.6456 }; points_intr[11] = { 13.990, 11.0741 }; points_intr[12] = { 15.335, 11.6928 }; points_intr[13] = { 16.680, 12.5661 }; points_intr[14] = { 18.3538, 14.830 }; points_intr[15] = { 18.700, 16.056 }; boost::math::catmull_rom<std::array<double, 2>> interpolator_cr(std::move(points_intr)); auto max_s = interpolator_cr.max_parameter(); std::array<double, 2> inter_points; for (int i = 0; i < 100; i++) { inter_points = interpolator_cr(max_s * (i / num_points)); geometry_msgs::Point p; p.x = inter_points[0]; p.y = inter_points[1]; p.z = z; //p.z = inter_points[2]; marker.points.push_back(p); DEBUG_INFO("spline %d: (x, y) %f, %f, current_s: %f", i, p.x, p.y, max_s * (i / 100.0)); } I'm using boost 1.71.0 -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Users-f2553780.html

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[Log] using std::shared_ptr and other std primatives rather than the boost counterparts
by Sean Farrow 30 Sep '19

30 Sep '19

Hi, Is is possible ot use std::shared_ptr and other std primatives with boost.log rather than the boost counterparts. I'm converting a codebase from boost namespaces and would like to add logging. Thanks, Sean.

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Re: [Boost-users] <boost/timer/timer.hpp> deprecated ?
by Kenneth Porter 23 Sep '19

23 Sep '19

--On Friday, September 13, 2019 3:35 PM +0100 "avib369 . via Boost-users" <boost-users(a)lists.boost.org> wrote: > How do I get rid of this message ? You could do what it says to do?

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Community blog or tutorial posting for C++
by Matt Zand 22 Sep '19

22 Sep '19

Hi, Does anyone know if there is a way for members to post blogs or tutorials on C++ in the Boost community or website? -- Cheers, Matt Zand Cell: 202-420-9192 Work: 240-200-6131 High School Technology Services <https://myhsts.org/> DC Web Makers <https://dcwebmakers.com/> Coding Bootcamps <https://coding-bootcamps.com/>

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<boost/timer/timer.hpp> deprecated ?
by avib369 . 13 Sep '19

13 Sep '19

How do I get rid of this message ? /tmp/ma0/boost/gcc-7.3/boost_1_71_0/boost/timer.hpp:21:70: note: #pragma message: This header is deprecated. Use the facilities in <boost/timer/timer.hpp> instead. BOOST_HEADER_DEPRECATED( "the facilities in <boost/timer/timer.hpp>" ) Ta, Avi

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boost.asio: win_iocp_serial_port_service::open changes broke FTDI support
by Michael Steinberg 12 Sep '19

12 Sep '19

Hello, the changes to win_iocp_serial_port_service::open in commit c113adc19004770d945672009b3d26f9498099cd broke at least FTDI 4232H but probably all FTDI support for me. SetCommState(handle, &dcb) in new line 99 fails with error code 57. Reverting the commit seems to recover correct behaviour. Kind Regards Michael

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Building Boost with C++17 standard
by Osman Zakir 12 Sep '19

12 Sep '19

Okay, so how do I build Boost under the C++17 standard? There's something I need to do in the configuration file, right?

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Compile error using property_tree
by Rui Pedro 11 Sep '19

11 Sep '19

Hello guys, I wanted to use boost to parse an INI file. in my code i used this includes: #include "boost/property_tree/ptree.hpp" #include "boost/property_tree/ini_parser.hpp" when I compile my code "g++ test.cpp -o Test" with only this two includes I get an error from one of the included files: In file included from test.cpp:15:0: boost/property_tree/ptree.hpp:15:45: fatal error: boost/property_tree/ptree_fwd.hpp: File or directory not found #include <boost/property_tree/ptree_fwd.hpp> ^ compilation terminated. This is an error in the ptree.hpp imported file. Maybe this has a quick fix but I'm kinda new to C++. I've checked and both files exist (boost/property_tree/ptree and boost/property_tree/ptree_fwd.hpp). Thanks, Rui

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[asio] using fork in coroutine composed operations
by Stephan Menzel 11 Sep '19

11 Sep '19

Hello all, my experiments with custom composed operations in asio have led me to another question regarding the use of such methods. What do I do in order to have multiple handlers in flight, e.g. for a timer? My example is here: https://github.com/MrMoose/moose_tools/blob/master/TimedConnect.hpp I'm trying to realize an old dream in asio. A function that will take a socket and asynchronously do a resolve and connect to the result while having a timeout around the operation. Here in the test cases (lower part) is how I imagine usage: https://github.com/MrMoose/moose_tools/blob/master/test/TestAsioHelpers.cpp… This works (the unit test does...) but I think it's no good and illustrate the problem. In the coroutine impl I can safely jump in and out and resume the code represented by the coroutine object as was explained to me yesterday. But what can I do with the timer? I cannot std::move(self) into it because it gets moved again moments later and I cannot yield on the timer wait operation. I want the timer handler and the async ops handlers both be in flight and have called whichever completes first. I tried coroutine fork thinking it might be the right tool but that seems to clash with the move-self-ahead pattern which is used here. If I don't yield and set the timer to a fixed lambda (as in the example above) it seems to work but I guess that's not how it's supposed to be, right? Any hints as to how I can make this better? Cheers, Stephan

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Program Options MacOS Error
by Michael Chiu 10 Sep '19

10 Sep '19

Hi All, I was trying to use boost program options to capture a std::string like the examples in the documentation. However I keep getting the error: libc++abi.dylib: terminating with uncaught exception of type boost::wrapexcept<boost::bad_any_cast> when i try to retrieve the value from the valuemap, i.e. vm["source"].as<std::string>(); The code that I have (which right now is essentially the tutorial example) runs fine on linux but has the above error on macos. Am i doing something wrong or is this a genuine platform specific bug? Sincerely, --Michael

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Re: [Boost-users] xlcpp: use of undeclared identifier 'decltype' used in boost/thread/lockable_traits.hpp
by Roy Musselman 10 Sep '19

10 Sep '19

Greetings, While attempting to build boost 1.70.0 for IBM Power9 using the IBM XL compilers using the SPACK tool, the following errors occur repeatedly for every header file that eventually includes boost/thread/lockable_traits.hpp In file included from ./boost/thread/lock_types.hpp:14: ./boost/thread/lockable_traits.hpp:157:11: error: use of undeclared identifier 'decltype' decltype(void(boost::declval<T&>().lock())) ^ ./boost/thread/lockable_traits.hpp:165:11: error: use of undeclared identifier 'decltype' decltype(void(boost::declval<T&>().unlock())) ^ ./boost/thread/lockable_traits.hpp:173:11: error: use of undeclared identifier 'decltype' decltype(bool(boost::declval<T&>().try_lock())) ^ These errors could be resolved if the -std=c++11 compiler option is used. Attempting to use SPACK options cxxflags=-std=c++11 or cxxstd=11 failed as if they were ignored. I was able to work-around this pervasive error by adding the following line to the file tools/build/src/tools/xlcpp.jam flags xlcpp.compile.c++ OPTIONS <cxxstd>11 : -std=c++11 ; Can you update the xlcpp.jam file to support the cxxstd=11 option, similar to what is implemented in pgi.jam? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Roy Musselman IBM HPC Application Analyst at Lawrence Livermore National Lab email: roymuss(a)us.ibm.com

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[asio] writing composed operations example
by Stephan Menzel 03 Sep '19

03 Sep '19

Hi everyone, as a long time asio user I often had needs to wrap up repeating patterns of async calls for re-use. Normally I went for some kind of specialized object that wraps smaller pieces but I recently came across a series of examples which try to explain how own composed operations may be created. https://www.boost.org/doc/libs/1_71_0/doc/html/boost_asio/examples/cpp11_ex… Now, looking at the examples they are of course way over my head but since own composed operations would be very much exactly what I need I thought I'd give it a shot. But as I now look at this example here: https://www.boost.org/doc/libs/1_71_0/doc/html/boost_asio/example/cpp11/ope… I notice something that I hope somebody can explain. In the coroutine implementation it says: delay_timer_->expires_after(std::chrono::seconds(1)); yield delay_timer_->async_wait(std::move(self)); if (error) break; yield boost::asio::async_write(socket_, boost::asio::buffer(*encoded_message_), std::move(self)); I'm puzzled about the double std::move() of self. In the comments above it says that self is a reference to an intermediate completion handler. How can this be moved twice? Can anyone give me hint about what this means? I would also appreciate any hints in general about own composed operations. Perhaps there are other approaches that are a bit less intimidating? Cheers, Stephan

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[MSM] Substatemachine with constructor arguments
by jcbastosportela＠gmail.com 30 Aug '19

30 Aug '19

Hi all, My question regards boost's Meta State Machine (MSM) usage. In my current design of a state machine it would be desirable to pass arguments to the substate machine; this would be done at time of creation of "main state machine". I found something on the documentation close to what I am looking for, however not exactly. State machine constructor with arguments <https://www.boost.org/doc/libs/1_71_0/libs/msm/doc/HTML/ch03s05.html#d0e2502> . This works very well for states, but doesn't work for the substate machine. Fails in compilation with the following log: In the example <https://www.boost.org/doc/libs/1_71_0/libs/msm/doc/HTML/examples/Constructo…> found in the documentation I would changed the *Playing* substate machine to look like: and in creation of the *player* to do something like: See the file attached. msm_substm.cpp <http://boost.2283326.n4.nabble.com/file/t371477/msm_substm.cpp> Is there a way of achieving this? Many thanks in advance. Regards, Joao Portela -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Users-f2553780.html

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Re: [Boost-users] Template specialization for Boost.Polygon
by Bjorn Reese 28 Aug '19

28 Aug '19

On 8/26/19 5:39 PM, Phil Endecott via Boost-users wrote: > Can anyone suggest how I can write my specialisations so that they > are unambiguous? By adding another level of indirection. Create your own trait template. Let both the generalization and your specialization redirect to polygon_traits. Something like this (warning untested code ahead) template <typename T, typename Enable = void> struct my_polygon_traits : public polygon_traits<T, Enable> { }; template <std::size_t N> struct my_polygon_traits<std::array<Point, N>> : public polygon_traits<std::array<Point, N>> { };

4 5

Template specialization for Boost.Polygon
by Phil Endecott 26 Aug '19

26 Aug '19

Dear Experts, This is a question about Boost.Polygon but please keep reading even if you've never used that library as it's really just about how to resolve ambiguous template specialisations. Boost.Polygon has a mechanism by which you can tell it about your own types by specialising templates. I want to tell it that std::array<Point,N> is a polygon, which I try to do like this: template <size_t N> struct geometry_concept< std::array<Point,N> > { using type = polygon_concept; }; template <size_t N> struct polygon_traits< std::array<Point,N> > { ....... }; This doesn't work because of ambiguity between that specialisation of polygon_traits and a default specialization that is in the library itself; the library code looks something like this: template <typename T, typename enable = gtl_yes> struct polygon_traits {}; template <typename T> struct polygon_traits<T, ...some SFINAE stuff.... > { ......... }; If I try to just specialize one size of array it works: template <> struct polygon_traits< std::array<g2i::Point,3> > { ....... }; The error is: test_template_specialization.cc:64:19: error: ambiguous partial specializations of 'polygon_traits<std::__1::array<Point, 3>, boost::polygon::gtl_yes>' boost::polygon::polygon_traits<std::array<Point,3>>::iterator_type i = nullptr; ^ /usr/local/include/boost/polygon/polygon_traits.hpp:100:10: note: partial specialization matches [with T = std::__1::array<Point, 3>] struct polygon_traits<T, ^ test_template_specialization.cc:32:8: note: partial specialization matches [with N = 3] struct polygon_traits< std::array<Point,N> > ^ I have the same issue when I attempt to use a Point class that takes the coordinate type as a template parameter. Can anyone suggest how I can write my specialisations so that they are unambiguous? A complete test program follows. I'm testing with Boost 1.69.0, but I don't think anything has changed in Polygon since then. Thanks, Phil. #include <boost/polygon/polygon.hpp> #include <array> struct Point { int x; int y; }; namespace boost { namespace polygon { template <> struct geometry_concept<Point> { using type = point_concept; }; template <> struct point_traits<Point> { using coordinate_type = int; static inline coordinate_type get(const Point& point, orientation_2d orient) { return (orient==HORIZONTAL) ? point.x : point.y; } }; template <size_t N> struct geometry_concept< std::array<Point,N> > { using type = polygon_concept; }; template <size_t N> struct polygon_traits< std::array<Point,N> > { using coordinate_type = int; using iterator_type = typename std::array<Point,N>::const_iterator; using point_type = Point; static inline iterator_type begin_points(const std::array<Point,N>& p) { return p.begin(); } static inline iterator_type end_points(const std::array<Point,N>& p) { return p.end(); } static inline std::size_t size(const std::array<Point,N>&) { return N; } static inline winding_direction winding(const std::array<Point,N>&) { return unknown_winding; // Hmm. } }; }; }; // namespace boost, polygon int main() { boost::polygon::polygon_traits<std::array<Point,3>>::iterator_type i = nullptr; return 0; }

1 0

Help building one module with cross-compiler
by Adrian C 25 Aug '19

25 Aug '19

Hi, I am trying to build boost module "log" on a raspberry PI as a dependency to another project. The RPI runs out of virtual memory during the build process, although I do limit building to just log (I think it builds some dependencies though). So I decided to cross compile it on a x86 machine with plenty of resources. I followed the instructions and built using: BUILD_CXXFLAGS="-std=gnu++11 -pthread" BUILD_CXX=arm-linux-gnueabihf-gcc ./bootstrap.sh --with-libraries=log --with-toolset=cross-cxx The build fails with the bootstrap.log showing the content below. Your advice is appreciated. thank you ubuntu@ryu:~/arm-toolkit/boost_1_71_0$ cat bootstrap.log######### Using 'cross-cxx' toolset.######arm-linux-gnueabihf-gcc --versionarm-linux-gnueabihf-gcc (crosstool-NG linaro-1.13.1+bzr2650 - Linaro GCC 2014.03) 4.8.3 20140303 (prerelease)Copyright (C) 2013 Free Software Foundation, Inc.This is free software; see the source for copying conditions. There is NOwarranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. ######arm-linux-gnueabihf-gcc -std=gnu++11 -pthread -DNDEBUG builtins.cpp class.cpp command.cpp compile.cpp constants.cpp cwd.cpp debug.cpp debugger.cpp execcmd.cpp filesys.cpp frames.cpp function.cpp glob.cpp hash.cpp hcache.cpp hdrmacro.cpp headers.cpp jam.cpp jambase.cpp jamgram.cpp lists.cpp make.cpp make1.cpp md5.cpp mem.cpp modules.cpp native.cpp object.cpp option.cpp output.cpp parse.cpp pathsys.cpp regexp.cpp rules.cpp scan.cpp search.cpp strings.cpp subst.cpp sysinfo.cpp timestamp.cpp variable.cpp w32_getreg.cpp modules/order.cpp modules/path.cpp modules/property-set.cpp modules/regex.cpp modules/sequence.cpp modules/set.cpp execunix.cpp fileunix.cpp pathunix.cpp -o b2/tmp/ccFB5qkl.o: In function `(anonymous namespace)::std_thread_hardware_concurrency()':sysinfo.cpp:(.text+0x118): undefined reference to `std::thread::hardware_concurrency()'collect2: error: ld returned 1 exit status

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License Issue with boost_intrusive
by Gerald Wiltse 23 Aug '19

23 Aug '19

During an annual third-party audit of our source code, boost intrusive was flagged as containing unlicensed code. Specifically, there are several pieces of code in this file which are explicitly attributed to external parties on external websites, which still exist and show no license. https://github.com/boostorg/intrusive/blob/develop/include/boost/intrusive/… https://github.com/boostorg/intrusive/blob/develop/include/boost/intrusive/… Original sources: http://stackoverflow.com/questions/11376288/fast-computing-of-log2-for-64-b… http://www.flipcode.com/archives/Fast_log_Function.shtml I don't claim to be a license expert. I've read a lot over the years, but this is the first time that I've actually been between an attorney and a codebase having to figure out practical implications of a scenario like this. I first want to make sure that Boost committee is aware of this situation. Second, I would like to know what the official conclusion would be from the Boost Committee about the license implications in cases like these. Maybe it has come up before and is well established. On the surface, the implications seems ambiguous to me when: DEVELOPER_A takes unlicensed code off the internet, prefixes it with a comment that says "Thanks to DEVELOPER_B ", then prefixes the whole file with a file-level copyright notice that says "COPYRIGHT DEVELOPER_A", and then says it's distributed under BSL-1.0 license, and then the boost team re-distributes the source code. Internally at my company, there was little discussion about it. There is no room for ambiguity, so the directive from management was to delete the file from our SCM system completely and ensure it never is included in our products. VERY fortunately, deleting it doesn't seem to have broken our builds. In future cases like this, that's really not what we want to be doing with your OSS libraries for obvious reasons. So, I'd like to know if there's any chance this situation changes in a future version of Boost (I.E., the code be removed/re-written with clean-room approach, etc). Regards, Jerry Gerald R. Wiltse jerrywiltse(a)gmail.com

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[release] Boost 1.71.0
by Michael Caisse 21 Aug '19

21 Aug '19

Release 1.71.0 of the Boost C++ Libraries is now available. These open-source libraries work well with the C++ Standard Library, and are usable across a broad spectrum of applications. The Boost license encourages both commercial and non-commercial use. This release contains 1 new library (Variant2) and numerous enhancements and bug fixes for existing libraries. For details, including download links, see <http://www.boost.org/users/news/version_1.71.0> You can also download directly from: <https://dl.bintray.com/boostorg/release/1.71.0/> To install this release on your system, see <http://www.boost.org/doc/libs/release/more/getting_started/index.html> Thanks to everyone who participated in this release. Thanks, -- The Boost Release Team Marshall Clow, Michael Caisse

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[Dll] e0077 with BOOST_DLL_ALIAS
by Sean Farrow 20 Aug '19

20 Aug '19

Hi, I'm getting the following error when using BOOST_DLL_ALIAS to export a function to create a plugin using visual studio 2019 and boost 1.71. This isn't new, just the first time I've noticed it. E0077 this declaration has no storage class or type specifier I've cross-checked this with the example (specifically tutorial 2) to ensure that it wasn't just me. For reference, the offending line in the my_plugin_aggregator.cpp file is: BOOST_DLL_ALIAS( my_namespace::my_plugin_aggregator::create, // <-- this function is exported with... create_plugin // <-- ...this alias name ) Other than suppressing this specific error, is there any other work around given I'm compiling with treat warnings as errors enabled? Any help appreciated as always. Thanks, Sean.

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[Dll] Inconsistent annotations reported under visual studio 2019
by Sean Farrow 20 Aug '19

20 Aug '19

Hi all, Whilst compiling a plugin in release mode with boost.dll 1.70 using Visual Studio 2019 and the latest Windows sdk, I'm getting several inconsistent annotation errors for functions like LoadLibraryA/W. Before I go to the trouble of creating a reproducible project and filing an issue, I wondered whether this is something that is know about and possibly fixed in 1.71 Any help appreciated. Kind regards Sean.

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Re: [Boost-users] [release] Boost 1.71.0 Release Candidate 2 available
by Michael Caisse 16 Aug '19

16 Aug '19

On 8/16/19 10:22, William Jagels wrote: > > > On Wed, Aug 14, 2019, 13:29 Michael Caisse via Boost-users > <boost-users(a)lists.boost.org <mailto:boost-users@lists.boost.org>> wrote: > > The release candidates for the 1.71.0 release are now available at: > <https://dl.bintray.com/boostorg/release/1.71.0/source/> > > The SHA256 checksums are as follows: > > 1b3949ffddf56129141032542523920034f2e69775fb9332a52ba37c548dbf35 > boost_1_71_0_rc2.7z > > d73a8da01e8bf8c7eda40b4c84915071a8c8a0df4a6734537ddde4a8580524ee > boost_1_71_0_rc2.tar.bz2 > > 96b34f7468f26a141f6020efb813f1a2f3dfb9797ecf76a7d7cbd843cc95f5bd > boost_1_71_0_rc2.tar.gz > > 85a94ac71c28e59cf97a96714e4c58a18550c227ac8b0388c260d6c717e47a69 > boost_1_71_0_rc2.zip > > 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 Boost Release Managers > > > > Built successfully with gcc 8.3.0. Was able to rebuild a large codebase > without any issues. > Thank you for giving it a spin and reporting back! -- Michael Caisse Ciere Consulting ciere.com

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[release] Boost 1.71.0 Release Candidate 2 available
by Michael Caisse 15 Aug '19

15 Aug '19

The release candidates for the 1.71.0 release are now available at: <https://dl.bintray.com/boostorg/release/1.71.0/source/> The SHA256 checksums are as follows: 1b3949ffddf56129141032542523920034f2e69775fb9332a52ba37c548dbf35 boost_1_71_0_rc2.7z d73a8da01e8bf8c7eda40b4c84915071a8c8a0df4a6734537ddde4a8580524ee boost_1_71_0_rc2.tar.bz2 96b34f7468f26a141f6020efb813f1a2f3dfb9797ecf76a7d7cbd843cc95f5bd boost_1_71_0_rc2.tar.gz 85a94ac71c28e59cf97a96714e4c58a18550c227ac8b0388c260d6c717e47a69 boost_1_71_0_rc2.zip 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 Boost Release Managers

2 1

Parallel Boost logging with multiple link units
by Simon Michalke 14 Aug '19

14 Aug '19

Hello all, I want to use boost logging with multiple link units. However all of the examples use only one source file (and only have some logging in the main function). In addition to that I need to have multithreading support as well. Do I have to initialize the sink for every module or only once for my program? Regards, Simon Michalke

1 0

Boost ASIO HTTP Server example design question
by TomJordan 12 Aug '19

12 Aug '19

Hi, I'm just starting to use ASIO. I have been reading the C++11 HTTP Server example at https://www.boost.org/doc/libs/1_70_0/doc/html/boost_asio/example/cpp11/htt… and want to make sure I understand use of shared_ptr in this example, because I didn't notice any explanation in the documentation. The connection class inherits from std::enable_shared_from_this<connection>, and is then passed in a shared_ptr (the captured 'self') to the handler function registered with the async_read_some in connection::do_read(). Is this approach, and the related design decsision that the server creates a shared_ptr to a new connection in its server::do_accept() function, taken simply in order to ensure that the connection object is kept alive for as long as any asynchronous read/write operation requires it? So is it implying that if the connection was NOT kept alive by a shared_ptr (i.e., was instead created by the server and stored by value in a std container) something bad could and likely would happen at some point, most likely due to the handler being called on an object that no longer exists? This might be when a boost::asio::error::operation_aborted is reported by the handler, when a current async operation is cancelled during the server/connection_manager shutdown process as a result of closing the socket, after the connection object value has been removed from the container, for example? Is this shared_ptr approach the idiomatic or even the only way to manage lifetimes in ASIO async calls? It just looks a bit ugly to me, bloats the code a bit and I was wondering if there is any other way to do it without the intrusion of shared_ptrs into the mix? Tom

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Interest in updated, standalone iterator_facade library?
by Zach Laine 11 Aug '19

11 Aug '19

I write a lot of iterators, and I'm getting sick of doing it by hand. I can't use Boost.Iterator's iterator_facade in library code, since it knows nothing about constexpr and noexcept. The design of Boost.Iterator's iterator_facade does not lend itself very well to being modified in a direction that is standardization-friendly (reasons why are outlined in the online docs). So, here is one take on this problem: GitHub: https://github.com/tzlaine/iterator_facade Online Docs: https://tzlaine.github.io/iterator_facade For those unfamiliar with the problem, iterators are very simple, at the highest level of abstraction. An iterator's implementation does not reflect this -- it is highly repetitive and easy to get subtly wrong. This library fixes that. The library is forward-looking, since I intend to write WG21 papers to standardize iterator_facade; there is good support for upcoming C++20 library features. In particular, the iterators created with iterator_facade model the C++20 iterator concepts, and therefore do not necessarily match the requirements of the C++17-and-earlier requirement tables. I have not found this to affect the usability of iterator-facade-based iterators with pre-C++20 code. Something to note: there was a recent-ish attempt to stanrdize iterator_facade, which is now abandoned, P0186 (http://wg21.link/P0186) This was very different from what I'm proposing for Boost. I talked to Eric Niebler about this, and he favors a return to the CRTP-based approach of my lib and the original Boost.Iterator iterator_facade library. Zach

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[rational] make rational constructors noexcept
by Frédéric 06 Aug '19

06 Aug '19

Hi, I think that some rational constructors can be marked noexcept. In particular: - default constructor: rational() - constructor from integer: rational(const T& n, typename enable_if_c<...>::type const* = 0) Concerning the constructor with numerator and denominator, if the denominator is always not null, it could be noexcept but I guess we cannot enforce not null unless we use some kind of gsl::not_null. Your thoughts? Thanks, F

3 3

Question regarding Boost Logging to Windows Event Logs
by Art Strutzenberg 06 Aug '19

06 Aug '19

I'm encountering an issue with the boost logging system, backend is using windows event log backend, and I'm honestly not sure what might be going on? The symptoms: * My code is building, events ARE getting logged and showing up in the event viewer * There is no additional data getting associated to the event (in this case a "processID", "threadID", and actual message text. * The events that do show up have the following text: "ProcessId: %1 ThreadId: %2 Message: %3, * Additionally I'm noticing that the severity of the message is showing up as "Error" Here is the code snippets that I <think> might be relevant: https://pastebin.com/ttzK4r0m The mc file I'm using is: https://pastebin.com/fNyL5Zua Thanks! --Art

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Boost.Build broken links in Getting started page
by David Demelier 01 Aug '19

01 Aug '19

Hello there, I was reading the page Getting started, but all references to Boost.Build point to 404. https://www.boost.org/doc/libs/1_70_0/more/getting_started/unix-variants.ht… Regards, -- David

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Fatal Error LNK1104: cannot open file
by Cg K 30 Jul '19

30 Jul '19

I posted this issue originally on the boost list, largely to inform that I have been able to compile boost_1_71_0_b1_rc1 using VS 2019. See that post here: <https://lists.boost.org/Archives/boost/2019/07/246678.php> I moved this post here because I think my subsequent problem has to do with setting up Visual Studio 2019. I have followed the Getting Started in Windows <https://www.boost.org/doc/libs/1_70_0/more/getting_started/windows.html> tutorial and was able to build the simple program, aka the header only project, in VS. It compiled and ran fine. I then built the project that links your program to the Boost Library described in the tutorial. I received the following message when I compiled as x64. 1>LINK : fatal error LNK1104: cannot open file 'libboost_regex-vc142-mt-gd-x64-1_71.lib' As you can see in my original email post referred to above, I built another simple program based upon a youtube video and on VS2017 and while it compiled in the youtube video, I received a the same linker error, LNK1104 message as well. Since the file referred toin the LNK1104 error has the prefix lib, it appears that VS is looking for a static library. I built boost as shared from the Develop command line using the command. .\bj2 link=shared . This method apparently worked in VS2017 but I can not replicate it in VS2019. What am I missing?

2 2

Result of out_ptr review.
by Zach Laine 29 Jul '19

29 Jul '19

I've compiled the results of the reviews of out_ptr during its recent review. Unfortunately, out_ptr is NOT ACCEPTED, though many of the reviewers indicated interest in seeing it come back in some future form. I counted these formal reviews: Andrey Semashev: reject Louis Dionne: accept David Sankel: reject Phil Endecott: reject Glen Fernandes: reject Gavin Lambert: reject Thanks to all of the above reviewers, and to all those who contributed to the ongoing discussions surrounding out_ptr, even if they did not have time for a full review. Points against out_ptr raised during the review: - Many reviewers indicated their puzzlement that this library was proposed at all, since they had never seen enough calls to C APIs in their own code to motivate the need for out_ptr. - Some reviewers who did find the motivating cases of the library compelling, still said that they would prefer to write wrappers instead of using something like out_ptr. - Multiple reviewers want the library to provide error-reporting help (it currently does not). In particular, for c_func(out_ptr(p)), there was a concern about whether p is assigned a value, when c_func() returns a failure-status. - There was concern from several reviewers about the fact that out_ptr's types' dtors may throw, though this is only limited to the use of out_ptr with shared_ptr and similar smart pointers. In particular, non-unique_ptr uses will never throw in out_ptr's types' dtors, unless the user provides a throwing deleter. - Multiple reviewers disagreed with the use of template specialization as a customization mechanism. - There was widespread concern about the use of potentially UB-invoking tricks to get max performance out of the implementation. - Many reviewers wanted a more typical Boost tutorial introduction in the documentation. Now please permit me a digression. The library attempts to take a call that looks like this (simplest call possible): // CASE 0 foo * new_foo; TODO if (!create_foo(&new_foo)) { // etc. ... } And turn it into something as close as possible to this: // CASE 1 std::unique_ptr<foo> new_foo; if (!create_foo(new_foo)) { // etc. ... } out_ptr does a great job of this lexically: // CASE 2 std::unique_ptr<foo> new_foo; if (!create_foo(out_ptr(new_foo))) { // etc. ... } If you have not written thousands of lines of code that look like case 0, stop for a second and consider what it would be like to drop those thousands of raw pointers into your code, and how much you would like to replace them all with unique_ptrs. Now consider what it would take you to write all the wrapping functions necessary to make those thousands of calls look like case 1. You may make tooling to generate the wrappers, and that's time consuming. Writing it by hand is even more so. out_ptr also has the nice property that using it as I have above with unique_ptr does not change the meaning of the code, except to ensure that new_foo is guaranteed to be treated in a RAII manner. Thus we get increased exception safety, memory leak mitigation, etc. -- y'know, all that RAII stuff. If out_ptr is implemented well, case 2 should produce nearly identical object code to case 0, except that case 2 handles calling new_foo's dtor at the right time. Note that because of this, you have the same relationship to the C API in all three cases. That is, you need to check for the success value returned from create_foo(), and you need to know what create_foo()'s contract is in the face of errors -- did it write to new_foo or not? out_ptr is how you get from raw pointers to RAII ones, not how you solve all programming problems related to calling functions. Hopefully that motivates the use case for out_ptr, even if you don't need it in your own code. Hopefully that also allays concerns that out_ptr is not doing enough -- doing more is outside the library's scope. Now, on to exceptions in out_ptr's types' dtors. I heard a lot of discussion about this during the review. To me, concerns about what happens when an out_ptr or an inout_ptr throws in its dtor misses the point entirely, because it is concerned with fixing corner cases we should not even care to support. Instead of worrying about the semantics of exceptions in those kinds of situations, we should instead be asking why we want to support user code like this: ... } catch { create_foo(in_out_ptr(my_shared_ptr_to_a_foo)); ... } In other words, we don't really care about the dtor exceptions, unless: - there is an active exception already, and - we are also calling a C API to create a new object (a possible, but certainly atypical thing to do when handling an exception), and - we're catching this new object in a shared_ptr-like smart pointer that might throw on construction. Who writes code like that? Few people, perhaps none. It's not impossible to see code like that, but until there are well-motivated cases for this, maybe leave it for a later version of the library. In other words, the question should have been "Why support anything other than nothrow-constructible RAII types like unque_ptr?" Note that I find this argument compelling for the WG21-facing version of this work too. To summarize: I think the first four bullet points listed at the beginning of this post are, or could easily be made to be, irrelevant. So, that leaves some issues still outstanding: - figure out how to provide customization points (I'm actually fine with the current approach...), - eliminate the UB-dangerous code, or make it opt-in, - rework the tutorial portion of the docs, and - many assorted doc cleanups. That does not seem like an unreasonable amount of stuff to resolve in post-review acceptance readiness. I bring all this up because I do in fact hope that JeanHeyd brings this back for a future review, and I hope that my arguments here will convince some of you that this library is a useful thing to have around. I waited until now to say any of these things in an attempt to remain impartial during the review; I've been bothered by seeing previous review managers clearly represent a pro-acceptance position from the start. Thanks to JeanHeyd for his submission. A no-vote from this group is a tough thing, and I hope that the feedback he has received takes some of the sting out. Zach

6 5

Need some help with Boost.Build
by Maarten Verhage 29 Jul '19

29 Jul '19

Dear Boost.Build expert, I do have Boost 1.69 and was able to build from the sources with Mingw-w64 gcc 8.1 on Windows 7. That was for boost itself, but now I need to build the tests for the Boost library Spirit (the parser). I cannot get this to work. My Boost.Build version is 2018.02-git. According to Boost.Build paragraph 3.3 Configuration, the option "b2 --debug-configuration" gives info how my boost.build is configured. In the folder <boost-build>\example\hello the output of "b2 --debug-configuration" looks fine. But when I run from the folder <boost-spirit-develop>\test "b2 --debug-configuration" the output contains: error: Could not find parent for project at '.'. So in the folder <boost-spirit-develop>\test I rename Jamfile to Jamroot.jam. Now with "b2 --debug-configuration" I get: output.txt (attachtment of this email) Also when I try to build the tests it I gets the same error messages strarting from: config.jam: No such file or directory How do I solve this? Best regards, Maarten Verhage

1 0

boost::test observing failures
by John Foster 27 Jul '19

27 Jul '19

I am using boost test within a home-grown GUI, and want to access test results (e.g. the failure message and location when a test fails) The unit_test::test_observer class provides the virtual method: void assertion_result(boost::unit_test::assertion_result) However, unit_test::assertion_result is just an enum indicating success or failure. From there, I cannot see how to access further information about the test result. The framework also provides the class test_tools::assertion_result, which encapsulates an error message, but this only appears to be used for evaluating pre-conditions. (I would have expected this type to be the argument to unit_test::test_observer::assertion_result). The log output classes appear to provide more information on test results. These are implemented as streams, which makes it non-trivial to extract test result data. Does anyone know how I can access the information on test results - success/failure, the test code, the location, etc? Thanks John John Foster [cid:image001.png@01D3CC10.659716E0]<http://en.wikipedia.org/wiki/Qantassaurus> Associate Director, Quant Analysis Regulatory Modelling Credit Risk Analytics and Portfolio National Australia Bank Level 15, 500 Bourke St, Melbourne VIC 3000 Tel: +61 (0)3 8641 5228 Email: john.x.foster(a)nab.com.au<mailto:John.X.Foster@nab.com.au> ________________________________ The information contained in this email communication may be confidential. If you have received this email in error, please notify the sender by return email, delete this email and destroy any copy. Any advice contained in this email has been prepared without taking into account your objectives, financial situation or needs. Before acting on any advice in this email, National Australia Bank Limited (NAB) recommends that you consider whether it is appropriate for your circumstances. If this email contains reference to any financial products, NAB recommends you consider the Product Disclosure Statement (PDS) or other disclosure document available from NAB, before making any decisions regarding any products. If this email contains any promotional content that you do not wish to receive, please reply to the original sender and write "Don't email promotional material" in the subject.

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[boost] [release] Boost 1.71.0 Beta 1 - déjà vu
by Michael Caisse 22 Jul '19

22 Jul '19

Note: The previous email announcement still had the rc1 tag in the filenames. This version of beta1 is identical in content to beta1 rc1. Boost release 1.71.0 beta 1 is now available at: <https://dl.bintray.com/boostorg/beta/1.71.0.beta1/source/> The SHA256 checksums are as follows: 451adc4f199c73e995e541f38c4dbd51faf4ce0db15537136ffd5213a1be5e55 boost_1_71_0_b1.7z a93d7066fc1514995aec0e726532a219447dd39b0ffa7cb97ca5736f16b0488b boost_1_71_0_b1.tar.bz2 34743b80466463e0c1b7fc71b677f326bdc242fe0b87a9c1599b6f7ea6e5c0cb boost_1_71_0_b1.tar.gz 5cd448bddc8394469391306e0ccada0a8f88c5c6cf8ec775ddf8e56adef8bbc2 boost_1_71_0_b1.zip For details of what's in the release, see <http://www.boost.org/users/history/version_1_71_0.html>. Note: Having some trouble getting the web page updated... check back with it soon. Please download the beta, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team

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trying to create a vector of histograms
by damien＠khubla.com 20 Jul '19

20 Jul '19

Hi all, As the subject says, I'm trying to create a vector of histograms. This needs to be a member variable of a class so I need to get the types right in the declaration. I keep getting type conversion errors when I pass the axis to the constructor, so I'm trying a non-vector example. Here's the base code: using UU = boost::histogram::unlimited_storage<std::allocator<double> >; using AA = std::tuple<boost::histogram::axis::variable<double> >; AA ax; boost::histogram::histogram<AA, UU> histo; histo = boost::histogram::histogram(ax); //this has a conversion problem The error on VS 2017 is: error C2440: '<function-style-cast>': cannot convert from 'boost::histogram::axis::variable<double,boost::use_default,boost::use_defau lt,std::allocator<_Ty>>' to 'boost::histogram::histogram<boost::histogram::axis::variable<double,boost:: use_default,boost::use_default,std::allocator<_Ty>>,boost::histogram::defaul t_storage>' with [ _Ty=double ] note: No constructor could take the source type, or constructor overload resolution was ambiguous I can see that the types are different, but no matter what I do with the template arguments of the axis type I still get that error. Can anyone help? Damien

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[release] Boost 1.71.0 Beta 1
by Michael Caisse 19 Jul '19

19 Jul '19

Boost release 1.71.0 beta 1 is now available at: <https://dl.bintray.com/boostorg/beta/1.71.0.beta1.rc1/source/> The SHA256 checksums are as follows: 451adc4f199c73e995e541f38c4dbd51faf4ce0db15537136ffd5213a1be5e55 boost_1_71_0_b1_rc1.7z a93d7066fc1514995aec0e726532a219447dd39b0ffa7cb97ca5736f16b0488b boost_1_71_0_b1_rc1.tar.bz2 34743b80466463e0c1b7fc71b677f326bdc242fe0b87a9c1599b6f7ea6e5c0cb boost_1_71_0_b1_rc1.tar.gz 5cd448bddc8394469391306e0ccada0a8f88c5c6cf8ec775ddf8e56adef8bbc2 boost_1_71_0_b1_rc1.zip For details of what's in the release, see <http://www.boost.org/users/history/version_1_71_0.html>. Note: Having some trouble getting the web page updated... check back with it soon. Please download the beta, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team

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boost::filtered_graph filtering on vertex color... if I only had a colormap
by Brian Davis 19 Jul '19

19 Jul '19

Lets say I have a graph g (of type graph_t) and a color map (boy I wish I had a colormap): typedef boost::property_map<graph_t, boost::vertex_color_t>::type color_map_t; or is it? auto indexmap = boost::get(boost::vertex_index, g); auto colors = boost::make_vector_property_map<boost::default_color_type>(indexmap); or maybe? auto indexmap = boost::get(boost::vertex_index, g); auto colors = boost::make_vector_property_map<boost::vertex_color_t>(indexmap); or possibly some goop found on the internet? boost::make_iterator_property_map(color_map.begin(), boost::get(boost::vertex_index, data_->g), color_map[0]) or other internet goop? typedef boost::property_map<GraphType, boost::vertex_color_t>::type color_map_t; color_map_t colorMap; boost::color_map(colorMap)) or other internet goop?? std::vector<int> colorMap(num_vertices(g), boost::white_color); so confused... (certainly not surprised why bgl is not a part of stl) Can someone help explain the various types and ways of specifying colormaps and the logic for each way and means? and a function (if I could get that far without VS syntax highlighter going bonkers and gobs of compiler errors.. you know the type): make_pretty(g, colormap ) which colors the graph colormap and a filter struct for boost::filtered_graph<Graph, EdgePredicate, VertexPredicate> (where I wonder why if I only want to filter vertices I have to set boost::keep_all for EdgePredicate... sigh... I know the answer... and also know how long it found me to find/figure out boost::keep_all - and if you are looking for boost::keep_all and found it here... your welcome ;-) ) and modifying (probably incorrectly) boost::filtered_graph example to: template <typename ColorMap> struct vertex_color_filter_eq { vertex_color_filter_eq() { } vertex_color_filter_eq(ColorMap colormap/*, boost::default_color_type c*/) : m_colormap(colormap)/*, m_c(c)*/ { } template <typename Vertex> bool operator()(const Vertex& v) const { return 0 < get(m_colormap, v); //return c < get(m_colormap, v); } ColorMap m_colormap; //boost::default_color_type m_c; }; auto indexmap = boost::get(boost::vertex_index, g); auto colors = boost::make_vector_property_map<boost::default_color_type>(indexmap); // some where here I would call make_pretty(g, colors) typedef property_map<graph_t, boost::vertex_color_t>::type ColorMap_t; vertex_color_filter<ColorMap_t> filter(colors); // boost::filtered_graph<graph_t, boost::keep_all, VertexPredicate> boost::filtered_graph<graph_t, boost::keep_all, vertex_color_filter> fg(g, filter); // Later say if I could get it compile and better if it compiled and worked I could move on and auto color = boost::red_color; typedef property_map<graph_t, boost::vertex_color_t>::type ColorMap_t; vertex_color_filter<ColorMap_t> filter(colors, color); boost::filtered_graph<graph_t, boost::keep_all, vertex_color_filter> fg(g, filter); Maybe if I color them yellow, I can then reach the wizard pull back the curtain and ask how to create a color map... If I only had a color map.

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How can I create an internal and modifiable color_map for boost DFS?
by Juergen 19 Jul '19

19 Jul '19

Hello, everybody, at the moment I am really lost. The problem is to create the color map that can be used in Depth_First_Search. A special feature that I have is that I want to change the Vertex color of DFS to modify the DFS. For example like this: If I make the color map global and pass it to the visitor, everything works: If the color map is not global but external, I can write the map, but it is not the same as the DFS color map and therefore I cannot manipulate the DFS algorithm: I then tried to create an internal map and work with the get() and put() functions, but I didn't succeed: I'd be so grateful if you'd give me a hint. -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Users-f2553780.html

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