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CMake's PCH support and boost.test linker error
by Olaf Peter 04 Mar '21

04 Mar '21

Hello Boost users I have here a strange problem which occurs only if I try to build with precompiled headers using CMake. I've configured the project for use with dynamically linking. The error is: /usr/bin/ld: /usr/lib/gcc/x86_64-redhat-linux/10/../../../../lib64/crt1.o: in function `_start': (.text+0x24): undefined reference to `main' Something obvious? Thanks in advance The project's reduce is: ---8<--- test_driver.cpp --- 8< ---- #defineBOOST_TEST_MODULE "My Test Suite" #include<boost/test/unit_test.hpp> --->8------>8------>8--- ---8<--- test_x.cpp --- 8< ---- #include<boost/test/unit_test.hpp> .... --->8------>8------>8--- ---8<--- src/CMakeLists.txt --- 8< ---- ... set_source_files_properties(src/test_xxx.cpp APPEND PROPERTIES COMPILE_DEFINITIONS "BOOST_TEST_DYN_LINK" ) .... --->8------>8------>8------>8------>8------>8--- ---8<--- pch.pp --- 8< ---- #pragma once #include<boost/test/unit_test.hpp> --->8------>8------>8---

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How should a "using zlib ..." jam statement look, for Boost to link to ZLib in the form of SO filename (libz.so) instead of by -lz?
by Bob 03 Mar '21

03 Mar '21

Hello Boost mailing list, I am building a code project in my user home directory on OpenBSD, and doing this involves both a local build of Boost and also a local build of ZLib. I do the whole build using GCC. This is a relatively ordinary build use case, however GCC on OpenBSD (at least in its current version) has a peculiarity to it, which is that it adds to LD the argument "-L/usr/lib" in the leading position, and this means that LD's search for libz.so will find and use the operating system's bundled ZLib binary which is /usr/lib/libz.so ALWAYS, and NEVER use my local libz.so . Can you help me understand if Boost can be customized to link to ZLib in the following way: I can force GCC/LD to use a particular libz.so file, by specifying it by filename, e.g. "gcc ... libz.so ...", "gcc ... /my/dir/libz.so ...", instead of by the conventional "-lz". Boost's build process is hardwired to "-lz" and I ask you to help me understand if there is a way to circumvent that. ZLIB_LIBRARY_PATH will not make "-lz" hit anything else than /usr/lib/libz.so , per the compiler's default -L/usr/lib in leading position, so it will not be of help to solve my problem. To my best awareness ZLIB_INCLUDE has nothing to do with linking, so it will not be of help to solve my problem. ZLIB_NAME would only be to customize the library name would it e.g. to "-lmycustomz", or what is it for? Please clarify so I could figure if it could be of help, though ideally i keep my local ZLib having its default name "libz.so". And this brings me to the path of solving the problem that I imagine could work, but that I don't understand fully from the Boost documentation: There is the possibility to customize ZLib build settings through the JAM configuration, that is user-config.jam . The syntax used is "using zlib ...". Can you please help me understand if this route works, if so how would that "using zlib ..." statement look, such that Boost's build process will NOT build ZLib itself, and then will NOT link to it via "-lz", but will instead link to it by "$MYCUSTOMBUILDDIR/libz.so"?

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Boost.Python + `RecursionError` during deallocation
by Andrew Jones 01 Mar '21

01 Mar '21

Hi, I just raised the following issue on the Python issue tracker: https://bugs.python.org/issue43351 But I'm sharing it here to widen the net ... Basically, when moving from Python 2.7.14 to Python 3.7.5, and when using Boost.Python (Boost version 1.6.9), I'm seeing a crash in finalisation due to: ``` Exception ignored in: <Boost.Python.life_support object at 0x2acf473c5d10> RecursionError: maximum recursion depth exceeded while calling a Python object Fatal Python error: Cannot recover from stack overflow. ``` Everything else with the Python that's running, and the Boost.Python interface, is consistent between 2.7.14 and 3.7.5 -- it is just the Python version that's changing. I should say, Python 3.7.5 does otherwise seem operable, it just falls over when running this certain code (which just walks a linked-list of ~1400 elements via Boost.Python). Has anyone seen anything like this before? Does this list feel this is more likely a Python-proper issue, or a Boost.Python issue? Cheers, Andrew

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[boost::units] Best practices for implementing custom units and quantities
by Alexandru Onea 01 Mar '21

01 Mar '21

Hello community, I am working on a project which works with units such as scale intervals (cents, moria, etc.) depending on the temperament system used (24-EDO, 72-EDO, etc.). My implementation defines a namespace for each tuning system. Within the namespaces I define base units, units and a system, as well as conversion factors between the systems. The base dimension is defined in only one of the namespaces (corresponding to the tuning system which I consider "standard" which is the 1200 cents per octave system). 1. Does such an approach qualify as a good approach in general (leaving aside the musical aspects)? 2. Is it a good practice to place all these namespaces in boost::units (extend boost::units)? Or should I keep them within my own namespaces? Learning the answer to #2 is more interesting to me, even in the absence of an answer to #1. Best regards, Alexandru Onea

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Question about Boost Integer
by Emilio Paolini 28 Feb '21

28 Feb '21

Hi everyone, i'm pretty new to Boost. I need to use as a default type for the CNL. The problem is that i would need an integer type that can assume only 2^4 values (so basically that stays on 4 bits). What i am asking is that if there is a way to define an integer like int128_t but instead of 128 i would need to have 4. Thank you very much for your answers. Emilio

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flyweights, nested flyweights and shared libraries
by Andreas Buykx 25 Feb '21

25 Feb '21

I want to use boost::flyweight to capture some structures containing const data. The documentation states that if flyweights are exported across shared library boundaries that the intermodule holder should be used. Since my flyweights are all created in the same shared library I would prefer to use the static holder but I keep getting crashes. I tried the intermodule holder but I'm having trouble compiling my sources with that. So my thinking was to wrap all flyweight types in accessor classes which are exposed instead, and the accessor classes create the flyweights within the same shared library to store the data. Would that be a valid approach? Also, is it possible to have nested flyweights (when they are wrapped by accessor classes)? And would that cause any additional problems in the above scenario? Below is an example of what I'm trying to achieve... Thanks for your advice! Andreas === Foo.h === struct FooDetails { FooDetails( std::string text_, std::vector<double> values ); std::string text; std::vector<double> values; }; class STUFF_EXPORT Foo { public: Foo( std::string text_, std::vector<double> values ); // rule-of-5 constructors declared, and default-implemented in cpp file const std::string& text() const; const std::vector<double>& values() const; private: boost::flyweight<FooDetails> m_data; }; === Foo.cpp === FooDetails( ( std::string text_, std::vector<double> values_ ) : text(text_), values( values_ ) { } Foo::Foo( std::string text_, std::vector<double> values_ ) m_data( FooDetails( text_, values_ ) ) { } std::string Foo::text() const { return m_data.get().text; } std::vector<double> Foo::values() const { return m_data.get().values; } === Bar.h === struct BarDetails { BarDetails( Foo foo_, std::vector<long> ids_ ); Foo foo; //< Foo holds a flyweight std::vector<long> ids; }; class STUFF_EXPORT Bar { public: Bar( std::string text_, std::vector<double> values_, std::vector<long> ids_ ); // rule-of-5 constructors declared, and default-implemented in cpp file const std::string& text() const; const std::vector<double>& values() const; const std::vector<long>& ids() const; private: boost::flyweight<BarDetails> m_bar; }; === Bar.cpp === BarDetails::BarDetails( Foo foo_, std::vector<long> ids_ ) : foo( foo_ ), ids( ids_ ) { } Bar::Bar( std::string text_, std::vector<double> values_, std::vector<long> ids_ ) : m_bar( Foo( text_, values), ids_ ) { } const std::string& Bar::text() const { return m_bar.get().m_foo.text(); } const std::vector<double>& Bar::values() const { return m_bar.get().foo.values(); } const std::vector<long>& Bar::ids() const { return m_bar.get().ids; }

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Re: [Boost-users] Boost-users Digest, Vol 5456, Issue 1
by philippe DALET 23 Feb '21

23 Feb '21

Hi, I have built some binaries for boost and python https://sourceforge.net/projects/pcpu/files/Boost/ boost 1.71 python3.7&numpy3.7 for ubuntu 20.04 64 bits boost 1.75 python3.789&numpy3.789 for visual studio 2019 mscv14.2 - win10 Ph.DALET Le mar. 23 févr. 2021 à 11:03, <boost-users-request(a)lists.boost.org> a écrit : > Send Boost-users mailing list submissions to > boost-users(a)lists.boost.org > > To subscribe or unsubscribe via the World Wide Web, visit > https://lists.boost.org/mailman/listinfo.cgi/boost-users > or, via email, send a message with subject or body 'help' to > boost-users-request(a)lists.boost.org > > You can reach the person managing the list at > boost-users-owner(a)lists.boost.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Boost-users digest..." > > > Today's Topics: > > 1. Re: Boost cannot find numpy37 on Dockerized Ubuntu 20.04 > (Roy de Bokx) > 2. Re: flyweights, nested flyweights and shared libraries > (Andreas Buykx) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 22 Feb 2021 15:49:11 +0100 > From: Roy de Bokx <rdebokx1990(a)gmail.com> > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] Boost cannot find numpy37 on Dockerized > Ubuntu 20.04 > Message-ID: > < > CAFLoxwXy8_an1jZh_PQMkjppbOWyixvR5Exw1DCeaUyV9xDfBA(a)mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > Op vr 19 feb. 2021 om 22:05 schreef Nathan Ernst via Boost-users < > boost-users(a)lists.boost.org>: > > > The missing symbols you quoted come from python itself. It looks like > > you're missing a "-lpython" linker flag. > > > Thanks! That definitely put me on the right track. Eventually I got it > working using the "-lpython3.6m" flag, since I found that the Python3.6 .so > file was situated at /usr/lib/x86_64-linux-gnu/libpython3.6m.so > Many thanks, this is much appreciated! I've pasted the full Dockerfile in > https://github.com/boostorg/boost/issues/462, in case anyone is > interested. > > > > > Regards, > > Nathan > > > > On Fri, Feb 19, 2021, 4:47 AM Roy de Bokx via Boost-users < > > boost-users(a)lists.boost.org> wrote: > > > >> > >> > >> Op wo 17 feb. 2021 om 20:30 schreef Anonymous Maarten < > >> anonymous.maarten(a)gmail.com>: > >> > >>> Thanks for your answer Maarten! > >>>> Please bare with me as I'm a little new to this. Is there some way I > >>>> can change the interpreter that is used for installing boost? Or do > you > >>>> think that adapting the --prefix flag may also work? > >>>> > >>> > >>> When using the pre-built boost packages of a linux distribution > >>> (ubuntu), you're generally stuck with the versions/options that its > >>> packagers have chosen. > >>> A distribution freezes versions to make a more robust experience. > >>> > >>> Adding a `--prefix` will not help because, first of all, it's not a > >>> valid gcc option, and second, ubuntu 18.04 does not provide a > >>> libboost-python-py37 shared/static library. > >>> Do you really need python 3.7? Doesn't 3.6 suffice? > >>> > >> > >> Thanks! This helped me understanding the issue a bit further. I think > 3.6 > >> should suffice indeed, so I tried using 3.6 by removing the 3.7 > >> installation from the Dockerfile and using the -lboost_numpy3 flag > instead. > >> It seems I ran into some linking issue after this. It was able to find > >> the right numpy3.so and libboost_python3-py36.so, but I'm getting a lot > of > >> errors like these: > >> > >> //usr/lib/x86_64-linux-gnu/libboost_numpy3.so: undefined reference to > >> `PyExc_ValueError' > >> > >> //usr/lib/x86_64-linux-gnu/libboost_python3-py36.so.1.65.1: undefined > >> reference to `PyLong_AsLong' > >> > >> //usr/lib/x86_64-linux-gnu/libboost_python3-py36.so.1.65.1: undefined > >> reference to `PyNumber_InPlaceFloorDivide' > >> > >> //usr/lib/x86_64-linux-gnu/libboost_python3-py36.so.1.65.1: undefined > >> reference to `PyBool_Type' > >> etc... > >> > >> I've pasted the full docker file and logs in > >> https://github.com/boostorg/boost/issues/462 > >> Thanks again for any help. > >> > >>> > >>> If you really want to use Boost.Python + python 3.7, you can do 2 > things: > >>> - stay on ubuntu bionic and build boost yourself (or use an alternative > >>> c/c++ package manager, e.g. [conan](https://conan.io/) has a [boost > >>> package](https://conan.io/center/boost)) > >>> - more to a more recent ubuntu release. e.g. ubuntu 20.10 has python > >>> 3.8: > >>> > https://packages.ubuntu.com/groovy/amd64/libboost-python1.71-dev/filelist > >>> > >> I've also given 20.10 a try, however I ran into the same linking issues > >> as mentioned above. > >> > >>> > >>> > >>> > >>> _______________________________________________ > >> Boost-users mailing list > >> Boost-users(a)lists.boost.org > >> https://lists.boost.org/mailman/listinfo.cgi/boost-users > >> > > _______________________________________________ > > Boost-users mailing list > > Boost-users(a)lists.boost.org > > https://lists.boost.org/mailman/listinfo.cgi/boost-users > > >

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Re: [Boost-users] Boost cannot find numpy37 on Dockerized Ubuntu 20.04
by Roy de Bokx 22 Feb '21

22 Feb '21

Op wo 17 feb. 2021 om 20:30 schreef Anonymous Maarten < anonymous.maarten(a)gmail.com>: > Thanks for your answer Maarten! >> Please bare with me as I'm a little new to this. Is there some way I can >> change the interpreter that is used for installing boost? Or do you think >> that adapting the --prefix flag may also work? >> > > When using the pre-built boost packages of a linux distribution (ubuntu), > you're generally stuck with the versions/options that its packagers have > chosen. > A distribution freezes versions to make a more robust experience. > > Adding a `--prefix` will not help because, first of all, it's not a valid > gcc option, and second, ubuntu 18.04 does not provide a > libboost-python-py37 shared/static library. > Do you really need python 3.7? Doesn't 3.6 suffice? > Thanks! This helped me understanding the issue a bit further. I think 3.6 should suffice indeed, so I tried using 3.6 by removing the 3.7 installation from the Dockerfile and using the -lboost_numpy3 flag instead. It seems I ran into some linking issue after this. It was able to find the right numpy3.so and libboost_python3-py36.so, but I'm getting a lot of errors like these: //usr/lib/x86_64-linux-gnu/libboost_numpy3.so: undefined reference to `PyExc_ValueError' //usr/lib/x86_64-linux-gnu/libboost_python3-py36.so.1.65.1: undefined reference to `PyLong_AsLong' //usr/lib/x86_64-linux-gnu/libboost_python3-py36.so.1.65.1: undefined reference to `PyNumber_InPlaceFloorDivide' //usr/lib/x86_64-linux-gnu/libboost_python3-py36.so.1.65.1: undefined reference to `PyBool_Type' etc... I've pasted the full docker file and logs in https://github.com/boostorg/boost/issues/462 Thanks again for any help. > > If you really want to use Boost.Python + python 3.7, you can do 2 things: > - stay on ubuntu bionic and build boost yourself (or use an alternative > c/c++ package manager, e.g. [conan](https://conan.io/) has a [boost > package](https://conan.io/center/boost)) > - more to a more recent ubuntu release. e.g. ubuntu 20.10 has python 3.8: > https://packages.ubuntu.com/groovy/amd64/libboost-python1.71-dev/filelist > I've also given 20.10 a try, however I ran into the same linking issues as mentioned above. > > > >

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Prooblem building software with fstream.hpp
by Mack Wallace 21 Feb '21

21 Feb '21

Hi all. I'm a noob and unfamiliar with boost. It has also been a long time since I have done any C++ programming. In any case, here are the details: I am trying to compile MecnRao/TCP-UDP-Proxy that uses the Boost Library. I am trying to compile this for Windows, ultimately Windows 10, but at the moment trying to compile on my Windows 7 VM. I am using Visual Studio Pro 2019. After trying the latest version of the Boost Library with some errors due to some deprecated members, I bounced around older versions until finding that Version 1.68.0 reduced my compile errors substantially, and of those 20 or so errors, are caused by some typedef problems in fstream.hpp. (I could be wrong, but the errors all seem to be related to fstream_fix.) Specifically, I get the following errors to begin with: 'fstream_fix<std::basic_ifstream<char,std::char_traits<char> > >' is not a variable template 'fstream_fix<std::basic_ofstream<char,std::char_traits<char> > >' is not a variable template This comes from the following lines in the fstream.hpp typedef basic_ifstream<char> ifstream; typedef basic_ofstream<char> ofstream; Where ifstream and ofstream are indicated as being redefined as #define ifstream fstream_fix<std::ifstream> #define ofstream fstream_fix<std::ofstream> Within the program with fstream_fix as template<class T> struct fstream_fix : public T { fstream_fix(){}; template<class T1> fstream_fix(T1 v1){ setlocale(LC_CTYPE, ""); T::open(v1); setlocale(LC_CTYPE, 0); } template<class T1,class T2> fstream_fix(T1 v1,T2 v2){ setlocale(LC_CTYPE, ""); T::open(v1,v2); setlocale(LC_CTYPE, 0); } template<class T1> void open(T1 v1){ setlocale(LC_CTYPE, ""); T::open(v1); setlocale(LC_CTYPE, 0); } template<class T1,class T2> void open(T1 v1,T2 v2){ setlocale(LC_CTYPE, ""); T::open(v1,v2); setlocale(LC_CTYPE, 0); } }; So I'm wondering if this is a newer/different compiler issue? Or the application itself? Or maybe just missing something like uses namespace std. I am hoping someone can help me nip this last problem so I can get this compiled. Thanks, Mack

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boost::asio::read() gets stuck when there's no internet
by Child OfGod 20 Feb '21

20 Feb '21

In TgBot library i use under MSVC++, in tgbot/net/BoostHttpOnlySslClient.cpp, a call to boost::asio::read() does not return when internet is disconnected for a few minutes. I would appreciate any help to get this resolved, i.e. for the read function to return if it fails after some timeout has passed the code block in the tgbot/net/BoostHttpOnlySslClient.cpp file: [code] string BoostHttpOnlySslClient::makeRequest(const Url& url, const vector<HttpReqArg>& args) const { tcp::resolver resolver(_ioService); tcp::resolver::query query(url.host, "443"); ssl::context context(ssl::context::tlsv12_client); context.set_default_verify_paths(); ssl::stream<tcp::socket> socket(_ioService, context); connect(socket.lowest_layer(), resolver.resolve(query)); #ifdef TGBOT_DISABLE_NAGLES_ALGORITHM socket.lowest_layer().set_option(tcp::no_delay(true)); #endif //TGBOT_DISABLE_NAGLES_ALGORITHM #ifdef TGBOT_CHANGE_SOCKET_BUFFER_SIZE #if _arm64 || _WIN64 || __amd64__ || __x86_64__ || __MINGW64__ || __aarch64__ || __powerpc64__ socket.lowest_layer().set_option(socket_base::send_buffer_size(65536)); socket.lowest_layer().set_option(socket_base::receive_buffer_size(65536)); #else //for 32-bit socket.lowest_layer().set_option(socket_base::send_buffer_size(32768)); socket.lowest_layer().set_option(socket_base::receive_buffer_size(32768)); #endif //Processor architecture #endif //TGBOT_CHANGE_SOCKET_BUFFER_SIZE socket.set_verify_mode(ssl::verify_none); socket.set_verify_callback(ssl::rfc2818_verification(url.host)); socket.handshake(ssl::stream<tcp::socket>::client); string requestText = _httpParser.generateRequest(url, args, false); write(socket, buffer(requestText.c_str(), requestText.length())); string response; #ifdef TGBOT_CHANGE_READ_BUFFER_SIZE #if _M_ARM64 || _WIN64 || __amd64__ || __x86_64__ || __MINGW64__ || __aarch64__ || __powerpc64__ char buff[65536]; #else //for 32-bit char buff[32768]; #endif //Processor architecture #else char buff[1024]; #endif //TGBOT_CHANGE_READ_BUFFER_SIZE boost::system::error_code error; while (!error) { std::size_t bytes = read(socket, buffer(buff), error); response += string(buff, bytes); } return _httpParser.extractBody(response); } [/code] Thankyou in advance😀🙏

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(no subject)
by Dk Jack 18 Feb '21

18 Feb '21

Hi, I am using boost 1.58 in my project. Ran into a crash in the boost filesystem library. I've included the relevant stack trace at the end of the email. My code is something like this: boost::filesystem::path fpath(mFilename.c_str()); if (!boost::filesystem::exists(fpath)) { // log a message and return. return; } auto curr_time = boost::filesystem::last_write_time(fpath); <== crash The crash is not consistent and happened randomly. I tested the above code in a small test program with just the above code. I made the input file unreadable etc, even then it was able to successfully read the last write timestamp of the file without any issues. Not sure why this particular call would throw an error. Since it's compiled with -O2, the error code is optimized out in the stack trace. Any ideas? Thanks for your help. Dk. (gdb) bt #0 0x00007f01651ba387 in raise () from /lib64/libc.so.6 #1 0x00007f01651bba78 in abort () from /lib64/libc.so.6 #2 0x00007f0160d087d5 in __gnu_cxx::__verbose_terminate_handler() () from /lib64/libstdc++.so.6 #3 0x00007f0160d06746 in ?? () from /lib64/libstdc++.so.6 #4 0x00007f0160d06773 in std::terminate() () from /lib64/libstdc++.so.6 #5 0x00007f0160d06993 in __cxa_throw () from /lib64/libstdc++.so.6 #6 0x00007f0161171f5f in boost::filesystem::detail::last_write_time(boost::filesystem::path const&, boost::system::error_code*) () from xxx.so #7 0x00007f0161089657 in last_write_time (p=...) at /usr/local/include/boost/filesystem/operations.hpp:594

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Boost cannot find numpy37 on Dockerized Ubuntu 20.04
by Roy de Bokx 17 Feb '21

17 Feb '21

Hi there, I've been trying to get GP-GOMEA running in a dockerized environment <https://github.com/marcovirgolin/GP-GOMEA/issues/2>, which is a project that is built using Boost. As part of the build process, the source code is compiled by the g++ compiler, using the flag -lboost_numpy37, which fails because (it seems) numpy cannot be found. I've reported this also as an issue also in the boost repository <https://github.com/boostorg/boost/issues/462>, but mclow advised me to send this to the boost-users mailinglist too. I've create the following Dockerfile as a minimal test case, which runs into the same problem. I'm a bit of a noob when it comes to Boost and numpy, but from what I found so far on the web, this should work (but it doesn't) FROM ubuntu:20.04 ENV DEBIAN_FRONTEND noninteractive RUN apt-get update && apt-get upgrade -y && apt-get clean RUN apt-get install -y curl python3.7 python3-dev python3-distutils python3-numpy # Install latest boost version RUN apt-get -y install wget g++ RUN wget https://dl.bintray.com/boostorg/release/1.75.0/source/boost_1_75_0.tar.bz2 && \ tar --bzip2 -xf boost_1_75_0.tar.bz2 && \ cd boost_1_75_0 && \ # this will generate ./b2 ./bootstrap.sh --prefix=/usr/local && \ ./b2 --with=all install && \ sh -c 'echo "/usr/local/lib" >> /etc/ld.so.conf.d/local.conf' && \ ldconfig # Check numpy installation RUN find / -name "numpy.hpp" RUN find / -name "libboost_numpy37.so" RUN find / -name "libboost_numpy3.so" RUN find / -name "libboost_numpy.so" RUN ld -lboost_numpy37 --verbose This eventually results in the following error: The command '/bin/sh -c ld -lboost_numpy37 --verbose' returned a non-zero code: 1, because it could not find any libboost_numpy37.so or libboost_numpy37.o file. The full logs are attached in the GH issue linked above. Did anyone encounter something similar, or does anyone have an idea what could cause this? Any help is much appreciated! -Roy

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How to change read/write method of source/sink device in C++ boost::iostreams?
by mostaan fereidooni 16 Feb '21

16 Feb '21

I'm trying to get familiar with boost::iostream, so in a example program I'm writing, I want to read a text from a file and write it to file. I would use my inherited class from file_source/file_sink as device to read/write. In the read method, my class needs to add each character with one and write method needs to subtract one from each character. First of all, I want to make sure that the reading part of the program works properly so you can see the code as follow: #include <boost/iostreams/stream.hpp>#include <fstream>#include "MyFileSource.h"#include <iostream>using namespace std;using namespace boost::iostreams;int main(){ MyFileSource<char> fileSource("source.txt"); stream<MyFileSource<char>> myStream(fileSource); std::cout << myStream.rdbuf(); fileSource.close(); } and my inherited source device code is as follow: template <typename charType>class MyFileSource : public boost::iostreams::file_source {public: MyFileSource(const std::string& path) : boost::iostreams::file_source(path) { file_path = path; if (!is_open()) open(path); seek(0, ios::end); sizeOfFile = seek(0, ios::cur); seek(0, ios::beg); buffer = new charType[sizeOfFile]; } std::streamsize read(charType*, std::streamsize) { std::streamsize readCount = boost::iostreams::file_source::read(buffer, sizeOfFile); if (readCount > 0) { std::string result(buffer, readCount); for (char& c : result) c++; finalResult = result; } return readCount; } private: string file_path; int sizeOfFile; charType* buffer; std::string finalResult; }; unfortunately, the result of *std::cout << myStream.rdbuf()* with above read method is nothing while if I delete the read method of MyFileSource class to use the read method of parent, the result will be correct. Any help will be appreciated.

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How to link boost library DLLs?
by Anand Arumugam 14 Feb '21

14 Feb '21

Hello all, How to properly link boost library DLLs? I have #define-d the following: #define BOOST_ALL_DYN_LINK #define BOOST_DYN_LINK #define BOOST_THREAD_USE_DLL #define BOOST_THREAD_PROVIDES_FUTURE_CONTINUATION #define BOOST_THREAD_VERSION 4 And I still get the following problem: --------------------------- testprogs.exe - System Error --------------------------- The code execution cannot proceed because boost_thread-vc142-mt-gd-x64-1_75.dll was not found. Reinstalling the program may fix this problem. --------------------------- OK --------------------------- I get the same error when I try to run the program using DLLs that I built and while running using the prebuilt binaries. Not sure what step I'm missing. The program runs fine if I build using static libs. The problem is only with DLLs. Any help is much appreciated. Thanks, Anand.

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Boost.Asio as "thread-pool": How to apply back-pressure?
by Dominique Devienne 10 Feb '21

10 Feb '21

Hi, I'm using Boost.ASIO, not for networking, but simply to parallelize work items, with a simple graph of "processing nodes" as detailed below. It's working fine, but uses too much memory. I'd like insights on limiting memory use via "throttling", or what I've also seen called "back-pressure". At a high level, I process two files (A and B) composed of several "entries" each, extracting a subset or a transformation of those entries, that I then write into an output file (C). (those 3 files reach into the many GBs, thus the need for parallelism, and limiting memory use). Extracting entries from A and B are independent operations, implemented single-threaded, producing independent work items (for subsetting or transforming each item), A#1...A#n, and B#1..B#m. That's the "fan-out" part, with each work-item (task) scheduled on any thread of the ASIO pool, since independent. Writing to C is also single-threaded, and needs to "fan-in" the work posted by the A#n and B#m functors, and I serialize that via posting to a C-specific strand (still on any thread, as long as serialized, doesn't matter). Lets call all those tasks writing to C the C#n+m tasks, which are posted to the strand via the A#s and B#s. My issue is that Boost.Asio seems to schedule an awful lots of A# and B# tasks, before getting to the C# tasks, which results in accumulating in memory too many C# tasks, and thus using too much memory. I don't see a way to force more C "downstream" tasks to be scheduled, before processing so much A and B tasks, and accumulating pending C tasks in the work queue, thus using too much memory again. Could someone please recommend a way to have a more balanced flow of tasks in the graph? Or alternative designs even, if what I do above is not ideal. Is Boost.Asio even suitable in this case? Thanks, --DD

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[boost-process] why does my child process not get EOF on stdin
by harald 01 Feb '21

01 Feb '21

Dear community, dear experts! I am trying to use boost::process to call weasyprint to convert HTML to a picture. To do that I wrote a test program (further down in the mail). This worked fine and did what i expected. But it stopped working as soon as I tried to convert two files at the same time by changing new renderer_t(io_context, "<head></head><body></body>"); in main to new renderer_t(io_context, "<head></head><body></body>"); new renderer_t(io_context, "<head></head><body></body>"); Now weasyprint hangs. I changed the call to weasyprint to weasyprint2, which is a short bash script for testing purposes: --------------------------------------------------------------------------------- #! /bin/bash cat > /dev/null echo "This should be a PNG picture" --------------------------------------------------------------------------------- It reads stdin until it gets EOF and then writes something to stdout before terminating. Same result. It seems that my program does not close stdin of the child, so it never gets EOF on stdin. But only when more than one child process is running at the same time. So obviously I am doing something wrong, but I have no idea what! Does anybody have a hint for me? I am on xubuntu 20.10 compiler is g++ (Ubuntu 10.2.0-13ubuntu1) 10.2.0, boost version 1.75.0 compiler command line (from my IDE): g++ -c main.cpp -g -O0 -Wall -Wextra -std=c++17 -o build-Debug/main.cpp.o -I. -I. --------------------------------------------------------------------------------- #include <boost/smart_ptr/intrusive_ptr.hpp> #include <boost/smart_ptr/intrusive_ref_counter.hpp> #include <boost/process.hpp> #include <boost/asio/write.hpp> #include <iostream> namespace bp = boost::process; bool is_eof( std::error_code error) { boost::system::error_code eof = boost::asio::error::eof; return error == eof; } struct renderer_t : public boost::intrusive_ref_counter<renderer_t> { using pointer = boost::intrusive_ptr<renderer_t>; boost::asio::io_context &io_context; const std::string html; bp::child child; bp::async_pipe in; bp::async_pipe out; bp::async_pipe err; std::array<unsigned char, 256> outbuf; std::array<char, 256> errbuf; std::vector<unsigned char> result; std::error_code result_error; std::string errmsg; ~renderer_t() { std::cout << "renderer_t::~renderer_t\n"; if (!errmsg.empty()) std::cerr << "renderer_t::~renderer_t: stderr: " << errmsg << "\n"; } renderer_t( boost::asio::io_context &io_context, const std::string &html) : io_context(io_context), html(html), in(io_context), out(io_context), err(io_context) { post( io_context, [self = pointer(this)]() { self->start(); }); } void start() { std::error_code ec; std::cout << "renderer_t::start\n"; bp::child c( "weasyprint2 -m screen -p -f png - /dev/stdout", bp::std_in < in, bp::std_out > out, bp::std_err > err, bp::on_exit=[self = pointer(this)]( int exit, std::error_code error) { self->on_exit(error, exit); }, bp::start_dir="/data/build/", io_context, ec); if (ec) { std::cerr << "renderer_t::start: creating child failed: " << ec.message() << "\n"; if (!result_error) result_error = ec; return; } child = std::move(c); boost::asio::async_write( in, boost::asio::buffer(html), [self = pointer(this)]( std::error_code error, std::size_t bytes) { self->on_write(error, bytes); }); out.async_read_some( boost::asio::buffer(outbuf), [self = pointer(this)]( std::error_code error, std::size_t bytes) { self->on_read_out(error, bytes); }); err.async_read_some( boost::asio::buffer(errbuf), [self = pointer(this)]( std::error_code error, std::size_t bytes) { self->on_read_err(error, bytes); }); } void on_write( std::error_code error, std::size_t bytes) { std::cout << "renderer_t::on_write\n"; if (error) { std::cerr << "renderer_t::on_write: failed: " << error.message() << "\n"; if (!result_error) result_error = error; return; } if (bytes != html.size()) { std::cerr << "renderer_t::on_write: short write\n"; } boost::system::error_code ec; in.close(ec); if (ec) { std::cerr << "renderer_t::on_write: close failed: " << error.message() << "\n"; } } void on_read_out( std::error_code error, std::size_t bytes) { std::cout << "renderer_t::on_read_out\n"; if (is_eof(error)) { std::cout << "renderer_t::on_read_out: EOF\n"; return; } else if (error) { std::cerr << "renderer_t::on_read_out: failed: " << error.message() << "\n"; if (!result_error) result_error = error; return; } else { result.insert( end(result), begin(outbuf), begin(outbuf) + bytes); out.async_read_some( boost::asio::buffer(outbuf), [self = pointer(this)]( std::error_code error, std::size_t bytes) { self->on_read_out(error, bytes); }); } } void on_read_err( std::error_code error, std::size_t bytes) { std::cout << "renderer_t::on_read_err\n"; if (is_eof(error)) { std::cout << "renderer_t::on_read_err: EOF\n"; return; } else if (error) { std::cerr << "renderer_t::on_read_err: failed: " << error.message() << "\n"; if (!result_error) result_error = error; return; } else { std::string e(begin(errbuf), begin(errbuf) + bytes); std::cerr << "renderer_t::on_read_err: from stderr: " << e << "\n"; errmsg.insert( end(errmsg), begin(errbuf), begin(errbuf) + bytes); err.async_read_some( boost::asio::buffer(errbuf), [self = pointer(this)]( std::error_code error, std::size_t bytes) { self->on_read_err(error, bytes); }); } } void on_exit( std::error_code error, int exit) { std::cout << "renderer_t::on_exit\n"; if (error) { std::cerr << "renderer_t::on_exit: error: " << error.message() << "\n"; if (!result_error) result_error = error; return; } if (exit) { std::cerr << "renderer_t::on_exit: weasyprint returned " << exit << "\n"; if (!result_error) result_error = make_error_code(std::errc::no_such_process); } } }; int main() { boost::asio::io_context io_context; bp::async_pipe in(io_context); new renderer_t(io_context, "<head></head><body></body>"); io_context.run(); return 0; } --------------------------------------------------------------------------------- Regards Harald

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TOMS748 question
by Shriramana Sharma 29 Jan '21

29 Jan '21

Namaste. This is wrt the TOMS748 math root finding implementation: Given that `if(fa == 0)` is handled at: https://github.com/boostorg/math/blob/develop/include/boost/math/tools/toms… … and the function returns in case of the above condition, it is not clear to me what the need is for the `if (fa != 0)` at: https://github.com/boostorg/math/blob/develop/include/boost/math/tools/toms… Note that I do not find the condition being applied at the SciPy implementation of this algorithm at: https://github.com/scipy/scipy/blob/v1.6.0/scipy/optimize/zeros.py#L1220 Now I also note similar checks at: https://github.com/boostorg/math/blob/develop/include/boost/math/tools/toms… https://github.com/boostorg/math/blob/develop/include/boost/math/tools/toms… … but regarding those lines, while I can understand the need for checking there after more bracketing work is done, it is not clear to me why `(fa == 0)` is alone checked for, and not `(fb == 0)` as well. I would have thought the algorithm is not biased towards a or b. Indeed, in the last steps from: https://github.com/boostorg/math/blob/develop/include/boost/math/tools/toms…, … both the conditions are checked for, which is what I would expect even in the intervening steps. Now the lines seem to have originated in the very first commit implementing this algorithm: https://github.com/boostorg/math/commit/79a8199f9c26ba353fb52ec4543f75ffc2a… … but I do not see a way to contact the author jzmaddock other than posting to this list, so I hope someone/they see here and reply. Thanks! -- Shriramana Sharma ஶ்ரீரமணஶர்மா श्रीरमणशर्मा 𑀰𑁆𑀭𑀻𑀭𑀫𑀡𑀰𑀭𑁆𑀫𑀸

2 7

Correct way to handle error in boost::filesystem::recursive_directory_iterator::increment()?
by Dominique Pellé 23 Jan '21

23 Jan '21

Hi I see code like this in an application to iterate over files in a directory with boost::filesystem (v1.70) without using exceptions: boost::filesystem::path dir("somedir"); boost::system::error_code error; boost::filesystem::directory_iterator node(dir, error), end; if (error) { return ...; } for (; node != end; node.increment(error)) { const boost::filesystem::path& path = node->path(); // ... } It appears to work... or mostly work since a crash was reported and the stack points to this area of the code. It's a rare crash that I could not reproduce myself. I suspect that there is a bug in the above code and it should instead be: boost::filesystem::path dir("somedir"); boost::system::error_code error; boost::filesystem::directory_iterator node(dir, error), end; for (; !error && node != end; node.increment(error)) { const boost::filesystem::path& path = node->path(); // ... } In other words, I suspect that we need to check that node.increment(error) in the for loop did not give an error before checking the condition "node != end", or else we may enter the loop in case of error and then it may access node->path() with an invalid node iterator. I could not find in the doc at ... https://www.boost.org/doc/libs/1_75_0/libs/filesystem/doc/reference.html ... what exactly happens when node.increment(error) gives an error. Perhaps the doc deserves clarification or an example illustrating how to reliably iterate over files without using exceptions would be welcome. Thanks Dominique

1 1

Serialization and static Libraries
by Wolfgang Meyerle 20 Jan '21

20 Jan '21

Hi, probably has been asked already thousand of times but I'm stuck currently with some code: Assuming I have the following files (The Base class Action is serialized in the same way): File: Ping.h #include"Action.h" classPing:publicAction{ public: voidoperator()(); Ping(); Ping*clone()const; ~Ping(); template<typenameArchive> voidserialize(Archive&ar,constunsignedint); }; BOOST_CLASS_EXPORT_KEY2(Ping,"Ping"); File: Ping.cpp #include"Ping.h" #include<iostream> #include<boost/serialization/base_object.hpp> #include<boost/serialization/export.hpp> #include<boost/serialization/tracking.hpp> #include"Action.h" #include"system.h" #include"pong.h" #include"serializerdeserializer.h" #include"system.h" #include"connection.h" #include"communication.h" voidPing::operator()(){ } Ping::Ping() { } Ping*Ping::clone()const{ Ping*ping=newPing(*this); returnping; } template<typenameArchive> voidPing::serialize(Archive&ar,constunsignedint){ ar&BOOST_SERIALIZATION_BASE_OBJECT_NVP(Action); } Ping::~Ping(){} BOOST_CLASS_EXPORT_IMPLEMENT(Ping); BOOST_CLASS_TRACKING(Ping,boost::serialization::track_never); If I now compile the project into a library. And link this library to a different project. If I try to serialize the class now it doesn't work. I get the following error: unregistered class - derived class not registered or exported According to the boost documentation I need to use BOOST_CLASS_EXPORT_KEY in the header file and BOOST_CLASS_EXPORT_IMPLEMENT in the corresponding cpp file. What did I miss? Regards, Wolfgang

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[Boost-MPI][Boost-ODEINT] Running odeint within MPI-context without using mpi_state
by Roland Richter 19 Jan '21

19 Jan '21

Hei, I am currently using the odeint-solver for calculating the right hand side of a non-linear equation. For speeding up the calculation of the right hand side, I decided to test the MPI-implementation. Now, after I would prefer to keep the code backwards compatible, I did not want to replace state_type with mpi_state, and instead split up the initial vector by hand before calling odeint without telling odeint that I am operating within an MPI context. I take care of all communications which involve the vectors, and therefore I assumed that this approach should work (especially after it worked correctly in small test programs). Nevertheless, I encountered the issue that after a certain amount of steps the step size between the different threads starts to differ by a small amount, even though I am in the same iteration. As example: step number rank step size n 1 0.00025 n 0 0.00025 //Ok n + 1 1 0.00051152 n + 1 0 0.000511523 //Not ok I checked my program with valgrind for possible memory leaks/corruption which could overwrite something, but nothing relevant came up. The problem is repeatable. Therefore, is the general idea correct at all, or am I doing something wrong here by neglecting a possible communication between the different threads within odeint? Thanks! Regards, Roland

2 2

Conversion numeric::array in numpy::ndarray
by philippe DALET 17 Jan '21

17 Jan '21

Hello, It's my first mail on this maillist. I started to upgrade a package for python 3.7, 3.8, 3.9 (linux and windows): vpython-wx. One file gives me some problems num_util.hpp My context: ubuntu 20.04: boost 1.71 python3.7 windows 10: boost 1.75 python3.7, 3.8, 3.9 I want to create a double_array class: Original version --------------------- namespace cvisual { namespace python { using boost::python::numeric::array; class double_array : public array { public: explicit double_array( const boost::python::handle<>& h ) : array(h) {} }; array makeNum(npy_intp n, NPY_TYPES t =NPY_DOUBLE); New version ----------------- namespace cvisual { namespace python { using boost::python::numpy::ndarray; class double_array : public ndarray { public: explicit double_array( const boost::python::handle<>& h ) : ndarray(h) {} }; ndarray makeNum(npy_intp n, NPY_TYPES t =NPY_DOUBLE); error message with VC2019 community error conversion 'const boost::python::handle<PyObject>' in 'boost::python::detail::borrowed_reference' error message with gcc 9.3 no matching function for call to ‘boost::python::numpy::ndarray::ndarray(const boost::python::handle<>&)’ Thanks a lot for your help. Philippe DALET Laboratoire de Physique Lyp Champollion, Figeac FRANCE

1 0

Re: [Boost-users] boost::regex: regex meta data or AST for regex?
by Frank Bergemann 16 Jan '21

16 Jan '21

On 16.12.20 18:05, Frank Bergemann via Boost-users wrote: > in concrete: > Is it possible to not only get the #no of groups (sub-expressions) via > basic_regex::mark_count(), but also their position (begin() / end() > iterators) in the given regex string (c'tor argument)? > > more general: > Can an AST be created for a the given regex string (c'tor argument)? > E.g with boost::spirit? I am busy with #2 parsers: 1) RegexParser: Intended to be a full regular expression parser https://github.com/F-Bergemann/RegexParser 2) RegexSplitter: to just break up regular expression into substrings for top level regex-group & non-regex-group substrings: https://github.com/F-Bergemann/RegexSplitter It's just a start and so much wrong within, i know. But i have one concrete question for the RegexSplitter: How can i avoid in RegexSplitter.cpp to use #157 ( tok_element >> *tok_element ) [ qi::_val = phx::new_<ASTNode> (qi::_1, qi::_2, ASTNode::COLLECTION_c) ]; I want to pass a SINGLE std::vector<ATSNode *> only to the receiving #51 // COLLECTION_c #52 ASTNode::ASTNode( #53 ASTNode const * first, #54 std::vector<ASTNode *> & others, #55 Type const type) without the SEPARATE parameter 'first'. I.e. i need to "merge" qi::_1 and qi::_2.

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Re: [Boost-users] boost ptr_map memory access violation
by roland kapl 08 Jan '21

08 Jan '21

Dear All! After finding some inspiration on https://stackoverflow.com/questions/4088387/how-to-store-pointers-in-map , I've succeeded storing the property tree pointers in a std::map... std::string TreeizeRelD::writeTree(const std::vector<std::vector<std::string>> &control, const std::vector<std::vector<std::vector<std::string>>> &data, pt::ptree & ptTree) { // now the map is local... typedef std::map<std::string, pt::ptree*> treeMap; std::map<std::string, treeMap> parentTableTrees; .... std::string subRootNode = parentNode + (subnodeOfParent != "" ? "." + subnodeOfParent : ""); std::string tableLookup = subRootNode + "." + rootElemRec; // simply add records if no foreign key name exists (usually the top (root) table) if (foreignKeyName == "") { for (std::pair<std::string, pt::ptree> && keyPair : tables[tableLookup]) { parentTableTrees[subRootNode].insert(std::make_pair(keyPair.first, &ptTree.add_child(subRootNode, keyPair.second))); ... // iterate through all parent key record collections referred to by subtables parentNode (rootnode + optional subnode) for (std::pair<std::string, pt::ptree*> && parentKeysPair : parentTableTrees.find(lookupNode)->second) { // iterate through all records (ptrees) in key collection for (pt::ptree::iterator parentRecPair = parentKeysPair.second->begin(); parentRecPair != parentKeysPair.second->end(); ++parentRecPair) { // important here: assign a reference to parentRecPtree (pointer!), otherwise a copy is created! pt::ptree &parentRecPtree = parentRecPair->second; ... parentTableTrees[subRootNode].insert(std::make_pair(rowsFK, &parentRecPair->second.get_child(subnodeFRec))); ... parentTableTrees[subRootNode].insert(std::make_pair(rowsFK, &parentRecPtree.put_child(subnodeOfParent, foreignRecordset))); The complete source of this: https://github.com/rkapl123/OreControl/blob/master/OreMgr/TreeizeRelD/treei… -regards, Roland ---------------------------------------------------------------------- Message: 1 Date: Wed, 6 Jan 2021 11:49:07 +0000 From: roland kapl <roland.kapl(a)hotmail.com<mailto:roland.kapl@hotmail.com>> To: "boost-users(a)lists.boost.org<mailto:boost-users@lists.boost.org>" <boost-users(a)lists.boost.org<mailto:boost-users@lists.boost.org>> Subject: [Boost-users] boost ptr_map memory access violation (stack/heap problem) Message-ID: <AM0PR03MB424285F7832EDC3C73C96860EDD00(a)AM0PR03MB4242.eurprd03.prod.outlook.com<mailto:AM0PR03MB424285F7832EDC3C73C96860EDD00@AM0PR03MB4242.eurprd03.prod.outlook.com>> Content-Type: text/plain; charset="us-ascii" Dear Boost-Experts! I'm trying to use a ptr_map along with boost property trees. I need to store pointers to specific parts of a built up property tree to access these parts later on for easy insertion there. However, when the ptr_map is cleared/destroyed, I get memory access violations/stack overflow messages for my test cases. The ptr_map (typedef treeMap) is globally defined within a std::map to a ptr_map to property trees as follows (I know this isn't good practice, but passing it as a reference didn't make a difference, so I left it that way): namespace pt = boost::property_tree; typedef boost::ptr_map<std::string, pt::ptree> treeMap; std::map<std::string, treeMap> parentTableTrees; The property tree is defined as follows in this function (this builds a property tree from tabular data in the passed table variable "data" using definitions form table variable "control"): std::string TreeizeRelD::writeTreeAndCreateXML(const std::vector<std::vector<std::string>>& control, const std::vector<std::vector<std::vector<std::string>>>& data, int *result) { std::string resultString; pt::ptree &propTree = pt::ptree(); std::string returnStr = TreeizeRelD::writeTree(control, data, propTree); *result = 0; if (returnStr != "") { *result = 1; return returnStr; } returnStr = TreeizeRelD::createXML(propTree, resultString); if (returnStr != "") { *result = 1; return returnStr; } // here the memory access violation occurs: parentTableTrees.clear(); return resultString; } In function writeTree the propTree (being passed by ref as ptTree) is populated in following three lines: std::string TreeizeRelD::writeTree(const std::vector<std::vector<std::string>> &control, const std::vector<std::vector<std::vector<std::string>>> &data, pt::ptree & ptTree) ... // FIRST LINE parentTableTrees[subRootNode].insert(keyPair.first, &ptTree.add_child(subRootNode, keyPair.second)); ... // iterate through all parent key record collections referred to by subtables parentNode (rootnode + optional subnode) for (treeMap::value_type && parentKeysPair : parentTableTrees.find(lookupNode)->second) { // iterate through all records (ptrees) in key collection for (pt::ptree::iterator parentRecPair = parentKeysPair.second->begin(); parentRecPair != parentKeysPair.second->end(); ++parentRecPair) { pt::ptree &parentRecPtree = parentRecPair->second; ... // SECOND LINE // parentRecPair is an iterator variable from the ptr_map: parentTableTrees[subRootNode].insert(rowsFK, &parentRecPair->second.get_child(subnodeFRec)); ... // THIRD LINE // parentRecPtree is the referenced property tree itself: parentTableTrees[subRootNode].insert(rowsFK, &parentRecPtree.put_child(subnodeOfParent, foreignRecordset)); I already have the suspicion that the memory access violation comes from ptr_map taking ownership of the pointers (references) passed to it in the above three lines and that these are all created on the stack and not the heap, where ptr_map expects them to be. When the ptr_map is finally destroyed, it tries to access memory, that's impossible to access... But I didn't manage to successfully create heap objects that also do NOT copy the property tree objects, which is important as I only need references to the property trees. Any help is appreciated. -regards, Roland

1 0

boost ptr_map memory access violation (stack/heap problem)
by roland kapl 06 Jan '21

06 Jan '21

Dear Boost-Experts! I'm trying to use a ptr_map along with boost property trees. I need to store pointers to specific parts of a built up property tree to access these parts later on for easy insertion there. However, when the ptr_map is cleared/destroyed, I get memory access violations/stack overflow messages for my test cases. The ptr_map (typedef treeMap) is globally defined within a std::map to a ptr_map to property trees as follows (I know this isn't good practice, but passing it as a reference didn't make a difference, so I left it that way): namespace pt = boost::property_tree; typedef boost::ptr_map<std::string, pt::ptree> treeMap; std::map<std::string, treeMap> parentTableTrees; The property tree is defined as follows in this function (this builds a property tree from tabular data in the passed table variable "data" using definitions form table variable "control"): std::string TreeizeRelD::writeTreeAndCreateXML(const std::vector<std::vector<std::string>>& control, const std::vector<std::vector<std::vector<std::string>>>& data, int *result) { std::string resultString; pt::ptree &propTree = pt::ptree(); std::string returnStr = TreeizeRelD::writeTree(control, data, propTree); *result = 0; if (returnStr != "") { *result = 1; return returnStr; } returnStr = TreeizeRelD::createXML(propTree, resultString); if (returnStr != "") { *result = 1; return returnStr; } // here the memory access violation occurs: parentTableTrees.clear(); return resultString; } In function writeTree the propTree (being passed by ref as ptTree) is populated in following three lines: std::string TreeizeRelD::writeTree(const std::vector<std::vector<std::string>> &control, const std::vector<std::vector<std::vector<std::string>>> &data, pt::ptree & ptTree) ... // FIRST LINE parentTableTrees[subRootNode].insert(keyPair.first, &ptTree.add_child(subRootNode, keyPair.second)); ... // iterate through all parent key record collections referred to by subtables parentNode (rootnode + optional subnode) for (treeMap::value_type && parentKeysPair : parentTableTrees.find(lookupNode)->second) { // iterate through all records (ptrees) in key collection for (pt::ptree::iterator parentRecPair = parentKeysPair.second->begin(); parentRecPair != parentKeysPair.second->end(); ++parentRecPair) { pt::ptree &parentRecPtree = parentRecPair->second; ... // SECOND LINE // parentRecPair is an iterator variable from the ptr_map: parentTableTrees[subRootNode].insert(rowsFK, &parentRecPair->second.get_child(subnodeFRec)); ... // THIRD LINE // parentRecPtree is the referenced property tree itself: parentTableTrees[subRootNode].insert(rowsFK, &parentRecPtree.put_child(subnodeOfParent, foreignRecordset)); I already have the suspicion that the memory access violation comes from ptr_map taking ownership of the pointers (references) passed to it in the above three lines and that these are all created on the stack and not the heap, where ptr_map expects them to be. When the ptr_map is finally destroyed, it tries to access memory, that's impossible to access... But I didn't manage to successfully create heap objects that also do NOT copy the property tree objects, which is important as I only need references to the property trees. Any help is appreciated. -regards, Roland

1 0

[statechart] Event dispatching for orthogonal states
by B A 03 Jan '21

03 Jan '21

Hello, I have following code : ///////////////////////////////////////////// #include <iostream> #include <boost/mpl/list.hpp> #include <boost/statechart/simple_state.hpp> #include <boost/statechart/state_machine.hpp> #include <boost/statechart/event.hpp> #include <boost/statechart/transition.hpp> #include <boost/statechart/custom_reaction.hpp> namespace sc = boost::statechart; struct Event1 : sc::event<Event1> {}; struct Event11 : sc::event<Event11> {}; struct Meta; struct Machine : sc::state_machine<Machine, Meta> {}; struct Meta2 : sc::simple_state<Meta2, Machine> { Meta2() { std::cout << "Meta2\n"; } }; struct Inner1; struct Inner2; struct Meta : sc::simple_state<Meta, Machine, boost::mpl::list<Inner1, Inner2>> { Meta() { std::cout << "Meta\n"; } typedef sc::transition<Event1, Meta2> reactions; }; struct Inner11 : sc::simple_state<Inner11, Meta::orthogonal<0>> { Inner11() { std::cout << "Inner11\n"; } typedef sc::custom_reaction<Event1> reactions; sc::result react(const Event1& ev) { std::cout << "Inner1 reaction\n"; return forward_event(); } }; struct Inner1 : sc::simple_state<Inner1, Meta::orthogonal<0>> { Inner1() { std::cout << "Inner1\n"; } typedef sc::transition<Event11, Inner11> reactions; }; struct Inner2 : sc::simple_state<Inner2, Meta::orthogonal<1>> { Inner2() { std::cout << "Inner2\n"; } }; int main() { Machine m; m.initiate(); m.process_event(Event11()); m.process_event(Event1()); return 0; } //////////////////// That gives me output: Meta Inner1 Inner2 Inner11 Meta2 The goal was to get Event1 processed first in Inner11 state and then forward it to outer state Meta for further processing but looks like event dispatching does not work as expected. I can make it work in that way only if I put Event1 handling into Inner1 state. I'm aware of limitation (https://www.boost.org/doc/libs/1_61_0/libs/statechart/doc/rationale.html#Li… #Event dispatch to orthogonal regions) but as far I understand that considers that case when both Inner1 and Inner11 have same event processing, please correct me if I'm wrong. Is current dispatching work correctly for my code? Regards, Andrew

1 0