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[Boost.Serialization] Exception during serialization through base pointer DLL & EXE
by Marc Viala 07 Mar '22

07 Mar '22

Hi, On our platform (VS2019, Windows x64, Boost 1.77) an exception occurs during the serialization of an instance through its base pointer. This error is systematic and I was able to reproduce w/ a minimal use test (cf. enclosed archive). This use case includes a solution w/ a DLL project and EXE project. The EXE project is a simple unit-test. On my platform when I execute the executable, I trigger an exception from Boost.Serialization ("unregistered void cast class cpe::derived_t<-class cpe::object_t"). I tried every recommandation that we can find on SO and Boost mailing lists without success. To be accurate, I prefer to mention that we are using Boost.Serialization Static Library flavor. Any help would be appreciated. -- Marc Viala

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Re: [Boost-users] Boost SSL handshake(http_server_sync_ssl) : still reachable memory keeps increasing
by Sandeep Bhardwaj 04 Mar '22

04 Mar '22

Hi, I tried the async program as suggested and I still see one of the stacks where the "still reachable" memory keeps increasing with duration. I have attached the relevant stack and the program. Sorry I had to resend this email multiple times due to size limitations. Hopefully this will go through. On Fri, 4 Feb 2022 at 12:28, Sandeep Bhardwaj <sandybharblore(a)gmail.com> wrote: > Thanks a lot. I will give it a try. > > On Thu, 3 Feb 2022 at 23:15, Vinnie Falco <vinnie.falco(a)gmail.com> wrote: > >> On Thu, Feb 3, 2022 at 9:41 AM Sandeep Bhardwaj via Boost-users >> <boost-users(a)lists.boost.org> wrote: >> > http_server_sync_ssl.cpp >> >> Oh, right. Synchronous APIs have no way to time out. So if the remote >> host does not close gracefully (i.e. just slams the connection shut) >> then you will be left with a connection object which either has no way >> to be destroyed, or has to wait what could be a very long time (up to >> 2 hours) for the operating system to time out the synchronous read. >> >> Please try the asynchronous example, http_server_async_ssl.cpp and >> determine if the problem persists. >> >> Thanks >> >

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Test post - please ignore
by Marshall Clow 02 Mar '22

02 Mar '22

I’ve got a report that posts to the lists are failing… Testing.

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Boost::coroutine2 and compiling for ASAN problems
by tjisana (泰志) 16 Feb '22

16 Feb '22

Team, I'm trying to get a simple coroutine2 program to work with address sanitizer and I'm running into a block. I'm building boost_1_78_0 as follows: ./b2 context-impl=ucontext and compiling with -DBOOST_USE_ASAN and -DBOOST_USE_CONTEXT. I've built and rebuilt the library thinking I've made an error somewhere and it boils down to jump_fcontext and make_fcontext. What am I doing wrong/missing? Cheers, TJ g++ -DBOOST_USE_ASAN -DBOOST_USE_UCONTEXT -I/home/tjisana/Downloads/boost_1_78_0 -O0 -g3 -fsanitize=address -pedantic -Wall -c -fmessage-length=0 -o src/Testbed II.o ../src/Testbed II.cpp g++ -L/home/tjisana/Downloads/boost_1_78_0/stage/lib -fsanitize=address -o Testbed II src/Testbed II.o -lboost_context -lboost_coroutine /usr/lib64/gcc/x86_64-suse-linux/11/../../../../x86_64-suse-linux/bin/ld: /home/tjisana/Downloads/boost_1_78_0/stage/lib/libboost_coroutine.so: undefined reference to `jump_fcontext' /usr/lib64/gcc/x86_64-suse-linux/11/../../../../x86_64-suse-linux/bin/ld: /home/tjisana/Downloads/boost_1_78_0/stage/lib/libboost_coroutine.so: undefined reference to `make_fcontext' collect2: error: ld returned 1 exit status #include <queue> #include <memory> #include "boost/coroutine2/coroutine.hpp" typedef boost::coroutines2::coroutine<int> coro_t; int main() { int l = 0; std::queue<int> y({1,2,3,4}); std::queue<std::unique_ptr<int>> w; coro_t::push_type sink([&](coro_t::pull_type& source) { for (const auto& i : source) { while (!w.empty()) { auto ptr = std::move(w.front()); w.pop(); if (*ptr == 1) { std::cout << "first: " << i << std::endl; auto item = 21; w.push(std::move(std::make_unique<int>(item))); } else if (*ptr == 21) { std::cout << "second: " << i+2*i << std::endl; auto item = 32; w.push(std::move(std::make_unique<int>(item))); } else if (*ptr == 32) { std::cout << "third: " << i*i << std::endl; } } } source(); }); while (!y.empty()) { if (!y.empty()) { l = y.front(); y.pop(); w.push(std::move(std::make_unique<int>(1))); sink(l); } } return 0; }

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std::launder and its usage in Boost
by Mikhail Kremniov 16 Feb '22

16 Feb '22

Hi, I wonder, what is the Boost community's opinion of std::launder? In particular, of its necessity when accessing an object that was created via placement-new in an aligned_storage. As I can see, it's used by Boost.Beast in its implementation of the variant type, but not in other parts of Boost. The reason I'm asking this is that I'm working on a C++14 code-base that uses Boost.Variant and Boost.Optional extensively (as well as other parts of Boost that use Variant and Optional internally). Now we're trying to switch to C++17 at least, and I worry whether it could potentially break things. To put things into context, C++ standard states in the [basic.life] section that if you had an object and then created a new one in the same location, you can use the pointer to the old object to refer to the new one only if (among other things) "the new object is of the same type as the original object (ignoring the top-level cv-qualifiers)". This means, as I understand it, that it's technically illegal to reinterpret_cast the pointer to aligned_storage to the pointer to the actual type of the object created via placement-new, because placement-new has already ended the lifetime of the aligned_storage object. So, implementations of Boost.Optional and Boost.Variant are illegal then (?). But it's been like that since C++03 and Boost worked fine all that time, so it looks like this UB existed only "on paper". But C++17 then added "Note: If these conditions are not met, a pointer to the new object can be obtained from a pointer that represents the address of its storage by calling std::launder". So now the language has the ability to deal with that UB, and a question arises, is it possible that compilers could start to use the UB to perform additional optimizations and make it a real UB? Also, I've seen a couple of times on stackoverflow.com people saying that it's actually fine to reinterpret_cast the storage in C++14, but in C++17 it's not (they didn't explain why though). So, can switching from -std=c++14 to -std=c++17 be a breaking change when using Boost? The fact that Boost.Variant and Boost.Optional don't use std::launder - is it an oversight or a conscious decision? Thanks!

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Does boost have something like small_function (with customizable buffer size)?
by Ivan Matek 16 Feb '22

16 Feb '22

I tried googling, but I found nothing. I presume that that means it does not exist, but it is possible it is maybe hidden under some name I could not think of. I am ok with using internal header of some library in case it is code that is covered by tests. regards, Ivan

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MSVC Hint File for Boost.Test macros?
by Dominique Devienne 16 Feb '22

16 Feb '22

Hi. I've just noticed for the first time MSVC (2019 in my case) "squiggles" in my Boost.Test-using unit-test sources, which pointed me to https://docs.microsoft.com/en-us/cpp/build/reference/hint-files?view=msvc-1… and I wonder if anyone has already defined a "Hint File" for Boost.Test, to improve the Navigation Bar experience in Boost.Test-using sources? A quick search didn't turn up anything. Thanks, --DD

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Very intermittent segmentation fault with boost::multiprecision
by tjisana (泰志) 11 Feb '22

11 Feb '22

Team, Trying to get to the root of a very intermittent seg fault in my program. Here's the snipped (not able to reproduce) as the section of code is part of a callback and I'm not sure how to reproduce it. Here's the tickPrice method and the trace from gdb is below that ... any thoughts? TJ void ib_trading_engine::tickPrice(TickerId tickerId, TickType field, double price, const TickAttrib& attribs) { this -> current_time(); ticksnapshot_complete_ = false; last_tick spy_call_trade; last_tick spy_put_trade; last_tick qqq_call_trade; last_tick qqq_put_trade; spy_call_trade.contract(spy_call_contract_); spy_call_trade.datetime(local_time_); spy_call_trade.symbol(spy_call_symbol_); spy_put_trade.contract(spy_put_contract_); spy_put_trade.datetime(local_time_); spy_put_trade.symbol(spy_put_symbol_); qqq_call_trade.contract(qqq_call_contract_); qqq_call_trade.datetime(local_time_); qqq_call_trade.symbol(qqq_call_symbol_); qqq_put_trade.contract(qqq_put_contract_); qqq_put_trade.datetime(local_time_); qqq_put_trade.symbol(qqq_put_symbol_); try { if (tickerId == 1001 && field == TickType::LAST) { spy_strike_ = (unsigned int)std::trunc(price); ticksnapshot_complete_ = true; last_spy_price_ = bmp::cpp_dec_float_50(price); } else if (tickerId == 1002) { switch (field) { case TickType::BID: last_call_bid_ = bmp::cpp_dec_float_50(price); break; case TickType::ASK: last_call_ask_ = bmp::cpp_dec_float_50(price); break; case TickType::LAST: spy_call_trade.last(bmp::cpp_dec_float_50(price)); trade_queue_.push(spy_call_trade); break; default: break; } } else if (tickerId == 1003) { switch (field) { case TickType::BID: last_put_bid_ = bmp::cpp_dec_float_50(price); break; case TickType::ASK: last_put_ask_= bmp::cpp_dec_float_50(price); break; case TickType::LAST: spy_put_trade.last(bmp::cpp_dec_float_50(price)); trade_queue_.push(spy_put_trade); break; default: break; } } else if (field == TickType::LAST && tickerId == 2001) { qqq_strike_ = (unsigned int)std::trunc(price); ticksnapshot_complete_ = true; last_qqq_price_ = bmp::cpp_dec_float_50(price); } else if (tickerId == 2002) { switch (field) { case TickType::BID: last_call_bid_ = bmp::cpp_dec_float_50(price); break; case TickType::ASK: last_call_ask_ = bmp::cpp_dec_float_50(price); break; case TickType::LAST: qqq_call_trade.last(bmp::cpp_dec_float_50(price)); trade_queue_.push(qqq_call_trade); break; default: break; } } else if (tickerId == 2003) { switch (field) { case TickType::BID: last_put_bid_ = bmp::cpp_dec_float_50(price); break; case TickType::ASK: last_put_ask_= bmp::cpp_dec_float_50(price); break; case TickType::LAST: qqq_put_trade.last(bmp::cpp_dec_float_50(price)); trade_queue_.push(qqq_put_trade); break; default: break; } } } catch (const std::exception& exception) { std::cerr << "ib_trading_engine::tickPrice() exception: " << exception.what() << "\n"; } } Core was generated by `./atm_call_paper_2.1'. Program terminated with signal SIGSEGV, Segmentation fault. #0 0x00000000004221fd in boost::multiprecision::backends::cpp_dec_float<50u, int, void>::pow2 (p=30) at /usr/include/boost/multiprecision/cpp_dec_float.hpp:2936 2936 cpp_dec_float<Digits10, ExponentType, Allocator> t; [Current thread is 1 (Thread 0x7fc4418027c0 (LWP 20245))] (gdb) bt #0 0x00000000004221fd in boost::multiprecision::backends::cpp_dec_float<50u, int, void>::pow2 (p=30) at /usr/include/boost/multiprecision/cpp_dec_float.hpp:2936 #1 0x00000000004157ba in boost::multiprecision::backends::cpp_dec_float<50u, int, void>::operator=<double> (this=0x7fc440fe2f40, a=2.9500000000000002) at /usr/include/boost/multiprecision/cpp_dec_float.hpp:2290 #2 0x0000000000411c17 in boost::multiprecision::backends::cpp_dec_float<50u, int, void>::cpp_dec_float<double>(double, std::enable_if<std::is_floating_point<double>::value&&(!std::is_same<double, __float128>::value), void>::type*) (this=0x7fc440fe2f40, val=2.9500000000000002) at /usr/include/boost/multiprecision/cpp_dec_float.hpp:249 #3 0x000000000040fcb6 in boost::multiprecision::number<boost::multiprecision::backends::cpp_dec_float<50u, int, void>, (boost::multiprecision::expression_template_option)1>::number<double>(double const&, std::enable_if<std::is_convertible<boost::multiprecision::detail::canonical<double, boost::multiprecision::backends::cpp_dec_float<50u, int, void> >::type, boost::multiprecision::backends::cpp_dec_float<50u, int, void> >::value&&(!boost::multiprecision::detail::is_restricted_conversion<boost::multiprecision::detail::canonical<double, boost::multiprecision::backends::cpp_dec_float<50u, int, void> >::type, boost::multiprecision::backends::cpp_dec_float<50u, int, void> >::value), void>::type*) (this=0x7fc440fe2f40, v=@0x7fc440fe1d60: 2.9500000000000002) at /usr/include/boost/multiprecision/number.hpp:64 #4 0x0000000000447332 in ib_trading_engine::tickPrice (this=0x1dd0650, tickerId=1002, field=BID, price=2.9500000000000002, attribs=...) at ../src/ib_trading_engine.cpp:700 #5 0x000000000049c5c4 in EDecoder::processTickPriceMsg (this=0x1dd30c0, ptr=0x7fc43c0077a6 "00%", endPtr=0x7fc43c0077a6 "00%") at ../src/client/EDecoder.cpp:65 #6 0x00000000004a7ea6 in EDecoder::parseAndProcessMsg (this=0x1dd30c0, beginPtr=@0x7fc440fe33e8: 0x7fc43c007790 "1", endPtr=0x7fc43c0077a6 "00%") at ../src/client/EDecoder.cpp:2247 #7 0x00000000004bee93 in EReader::processMsgs (this=0x1dd30b0) at ../src/client/EReader.cpp:282 #8 0x0000000000444630 in ib_trading_engine::process_messages (this=0x1dd0650) at ../src/ib_trading_engine.cpp:405 #9 0x000000000044465f in ib_trading_engine::current_time (this=0x1dd0650) at ../src/ib_trading_engine.cpp:410 #10 0x0000000000447086 in ib_trading_engine::tickPrice (this=0x1dd0650, tickerId=1002, field=BID, price=2.96, attribs=...) at ../src/ib_trading_engine.cpp:666

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Crash in async_handshake function
by Ales Mulej 08 Feb '22

08 Feb '22

Hi All, I'm writing TLS client/server and my server is continuously crashing in the async_handshake function. I'm running out of ideas of what I'm doing wrong or how to solve the issue. I'm using VS 2022 and the latest boost from github. Tested with 1.78.0 as well. Using OpenSSL 3.0.1. Code is compiled as x64, /std:c++20. Using a single thread. Simplified function call: on_accept: auto server = boost::make_shared<cserver_session_ws>(std::move(socket), m_ioc, m_ctx); server->run(); run: boost::asio::dispatch(m_ws.get_executor(), boost::beast::bind_front_handler(&cserver_session_ws::on_run, shared_from_this())); on_run: m_ws.next_layer().async_handshake(boost::asio::ssl::stream_base::server, boost::beast::bind_front_handler(&cserver_session_ws::on_handshake, shared_from_this())); on_handshake function never gets called, due to the crash in async_handshake function. m_ws is defined as: boost::beast::websocket::stream<boost::beast::ssl_stream<boost::beast::tcp_stream>> m_ws; Exception call stack: Unhandled exception thrown: read access violation. **this** was 0x1. boost::asio::detail::scheduler::post_immediate_completion(boost::asio::detail::scheduler_operation ...... Line 349 boost::asio::detail::select_reactor::schedule_timer<boost::asio::detail::chrono_time_traits<std::chrono ..... Line 66 boost::asio::detail::deadline_timer_service<boost::asio::detail::chrono_time_traits ..... Line 273 boost::asio::basic_waitable_timer<std::chrono::steady_clock,boost::asio::wait_traits ...... Line 806 boost::asio::detail::completion_handler_async_result<boost::beast::basic_stream ..... Line 485 boost::asio::async_initiate<boost::beast::basic_stream<boost::asio::ip ..... Line 865 ..... Here are only the last few functions from the call stack. I can share the entire call stack if requested. I would appreciate any help on this as I can't figure out what caused the crash. Regards, A

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Boost SSL handshake(http_server_sync_ssl) : still reachable memory keeps increasing
by Sandeep Bhardwaj 03 Feb '22

03 Feb '22

Hi all, I am using boost 1.76.0 version. I have slightly modified the example program http_server_sync_ssl.cpp to just dump the payload it receives and i have used certificates with ssl context. When I run the program with valgrind, the "still reachable" memory keeps increasing with time. This is one example: ==17719== 38,880 bytes in 60 blocks are still reachable in loss record 740 of 740 ==17719== at 0x4C312EF: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so) ==17719== by 0x567F438: CRYPTO_zalloc (in /usr/lib64/libcrypto.so.1.1) ==17719== by 0x52AA5CA: SSL_SESSION_new (in /usr/lib64/libssl.so.1.1) ==17719== by 0x52AAE22: ??? (in /usr/lib64/libssl.so.1.1) ==17719== by 0x52C8A06: ??? (in /usr/lib64/libssl.so.1.1) ==17719== by 0x52B7FF6: ??? (in /usr/lib64/libssl.so.1.1) ==17719== by 0x52A3F43: SSL_do_handshake (in /usr/lib64/libssl.so.1.1) ==17719== by 0x419630: boost::asio::ssl::detail::engine::do_accept(void*, unsigned long) (engine.ipp:316) ==17719== by 0x4193E3: boost::asio::ssl::detail::engine::perform(int (boost::asio::ssl::detail::engine::*)(void*, unsigned long), void*, unsigned long, boost::system::error_code&, unsigned long*) (engine.ipp:248) ==17719== by 0x418F6D: boost::asio::ssl::detail::engine::handshake(boost::asio::ssl::stream_base::handshake_type, boost::system::error_code&) (engine.ipp:148) ==17719== by 0x419778: boost::asio::ssl::detail::handshake_op::operator()(boost::asio::ssl::detail::engine&, boost::system::error_code&, unsigned long&) const (handshake_op.hpp:47) ==17719== by 0x424DB8: unsigned long boost::asio::ssl::detail::io<boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::any_io_executor>, boost::asio::ssl::detail::handshake_op>(boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::any_io_executor>&, boost::asio::ssl::detail::stream_core&, boost::asio::ssl::detail::handshake_op const&, boost::system::error_code&) (io.hpp:38) ==17719== by 0x421332: boost::asio::ssl::stream<boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::any_io_executor>&>::handshake(boost::asio::ssl::stream_base::handshake_type, boost::system::error_code&) (stream.hpp:389) ==17719== by 0x41D5FC: boost::beast::ssl_stream<boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::any_io_executor>&>::handshake(boost::asio::ssl::stream_base::handshake_type, boost::system::error_code&) (ssl_stream.hpp:344) ==17719== by 0x406971: do_session(boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::any_io_executor>&, boost::asio::ssl::context&, std::shared_ptr<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const> const&) (boost_server.cpp:219) I have attached the test program. Can anyone point out what needs to be done here? Thanks & Regards, Sandeep

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Boost DLL shared library handling
by Nicholas Yue 02 Feb '22

02 Feb '22

Hi, I am learning about <boost/dll/shared_library.hpp> So far I have manage to follow along with the tutorial I believe https://www.boost.org/doc/libs/1_77_0/doc/html/boost_dll/tutorial.html Using tutorial 5 as an illustration https://github.com/apolukhin/Boost.DLL/blob/develop/example/tutorial5/load_… On this line, I will have the ability to reference the object of my_api_sum I believe https://github.com/apolukhin/Boost.DLL/blob/develop/example/tutorial5/load_… I have the following questions: 1. If I have a class that is e.g. a shape, say rectangle (of different sizes), what approach may I use to create different instances of the class from the plugin? 2. If my class requires parameters for it's construction, how do I pass it via the shared library loading mechanism ? Or have I been looking to use boost dll shared_library wrongly and that I might look at the plugin being some sort of factory design approach ? Thank you in advance. Cheers -- Nicholas Yue https://www.linkedin.com/in/nicholasyue/

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boost placeholders help
by Hariharan.A.S 25 Jan '22

25 Jan '22

Hi, I am trying to build my catkin workspace for Ros Noetic in my raspberry pi 400 running Buster. I get the following message while building roscpp Scanning dependencies of target roscpp_generate_messages Scanning dependencies of target roscpp [ 31%] Built target roscpp_generate_messages [ 36%] Building CXX object CMakeFiles/roscpp.dir/src/libros/master.cpp.o [ 36%] Building CXX object CMakeFiles/roscpp.dir/src/libros/network.cpp.o [ 36%] Building CXX object CMakeFiles/roscpp.dir/src/libros/subscriber.cpp.o [ 37%] Building CXX object CMakeFiles/roscpp.dir/src/libros/common.cpp.o [ 38%] Building CXX object CMakeFiles/roscpp.dir/src/libros/publisher_link.cpp.o In file included from /home/pi/ros_catkin_ws/src/ros_comm/roscpp/include/ros/node_handle.h:32, from /home/pi/ros_catkin_ws/src/ros_comm/roscpp/src/libros/subscriber.cpp:29: /home/pi/ros_catkin_ws/src/ros_comm/roscpp/include/ros/publisher.h: In member function ‘boost::function<void(const boost::shared_ptr<ros::SubscriberLink>&)> ros::Publisher::getLastMessageCallback()’: /home/pi/ros_catkin_ws/src/ros_comm/roscpp/include/ros/publisher.h:174:70: error: ‘boost::placeholders’ has not been declared return boost::bind(&Impl::pushLastMessage, impl_.get(), boost::placeholders::_1); ^~~~~~~~~~~~ In file included from /home/pi/ros_catkin_ws/src/ros_comm/roscpp/src/libros/subscriber.cpp:29: /home/pi/ros_catkin_ws/src/ros_comm/roscpp/include/ros/node_handle.h: In member function ‘ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, void (T::*)(M), T*, const ros::TransportHints&)’: /home/pi/ros_catkin_ws/src/ros_comm/roscpp/include/ros/node_handle.h:406:91: error: ‘boost::placeholders’ has not been declared ops.template initByFullCallbackType<M>(topic, queue_size, boost::bind(fp, obj, boost::placeholders::_1)); ^~~~~~~~~~~~ /home/pi/ros_catkin_ws/src/ros_comm/roscpp/include/ros/node_handle.h: In member function ‘ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, void (T::*)(M) const, T*, const ros::TransportHints&)’: /home/pi/ros_catkin_ws/src/ros_comm/roscpp/include/ros/node_handle.h:417:91: error: ‘boost::placeholders’ has not been declared ops.template initByFullCallbackType<M>(topic, queue_size, boost::bind(fp, obj, boost::placeholders::_1)); ^~~~~~~~~~~~ /home/pi/ros_catkin_ws/src/ros_comm/roscpp/include/ros/node_handle.h: In member function ‘ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, void (T::*)(const boost::shared_ptr<const M>&), T*, const ros::TransportHints&)’: /home/pi/ros_catkin_ws/src/ros_comm/roscpp/include/ros/node_handle.h:470:73: error: ‘boost::placeholders’ has not been declared ops.template init<M>(topic, queue_size, boost::bind(fp, obj, boost::placeholders::_1)); ^~~~~~~~~~~~ /home/pi/ros_catkin_ws/src/ros_comm/roscpp/include/ros/node_handle.h: In member function ‘ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, void (T::*)(const boost::shared_ptr<const M>&) const, T*, const ros::TransportHints&)’: /home/pi/ros_catkin_ws/src/ros_comm/roscpp/include/ros/node_handle.h:480:73: error: ‘boost::placeholders’ has not been declared ops.template init<M>(topic, queue_size, boost::bind(fp, obj, boost::placeholders::_1)); ^~~~~~~~~~~~ /home/pi/ros_catkin_ws/src/ros_comm/roscpp/include/ros/node_handle.h: In member function ‘ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, void (T::*)(M), const boost::shared_ptr<U>&, const ros::TransportHints&)’: /home/pi/ros_catkin_ws/src/ros_comm/roscpp/include/ros/node_handle.h:533:97: error: ‘boost::placeholders’ has not been declared ops.template initByFullCallbackType<M>(topic, queue_size, boost::bind(fp, obj.get(), boost::placeholders::_1)); ^~~~~~~~~~~~ /home/pi/ros_catkin_ws/src/ros_comm/roscpp/include/ros/node_handle.h: In member function ‘ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, void (T::*)(M) const, const boost::shared_ptr<U>&, const ros::TransportHints&)’: /home/pi/ros_catkin_ws/src/ros_comm/roscpp/include/ros/node_handle.h:544:97: error: ‘boost::placeholders’ has not been declared ops.template initByFullCallbackType<M>(topic, queue_size, boost::bind(fp, obj.get(), boost::placeholders::_1)); I am not sure how to fix this problem. Any help is much appreciated Thank you Hariharan -- Hariharan.A.S

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Vector values gradients for vector -> scalar function
by Amit Gupta 25 Jan '22

25 Jan '22

I am currently exploring boost as autodiff framework for my application. I would like to calculate the derivative of a vector->scalar function. However I could not find a way to evaluate the same, rather I always get total gradient. Example: How to get the following program yield output equivalent to JAX fwd? #include <boost/math/differentiation/autodiff.hpp> #include <iostream> #include<vector> template <typename T> T power_sum(double p, std::vector<T> &z){ T y=0.0; for (int i=0; i<6;i++){ y += pow(z[i], p); } return y; } int main() { using namespace boost::math::differentiation; constexpr unsigned Order = 2; std::vector<double> z_v = {1.,2.,3.,4.,5.,6.}; std::vector<autodiff_fvar<double, Order> > z; for (int i=0; i<6;i++){ z.push_back(make_fvar<double, Order>(z_v[i])); } auto y = power_sum(2.0,z); std::cout<<y<<"\n"; std::cout<<y.derivative(1)<<"\n"; return 0; } JAX output: import jax as jx import jax.numpy as jnp x = jnp.array([1.0, 2.0, 3.0, 4.0, 5.0, 6.0]) def power_sum(x, p): y = x[0] ** p + x[1] ** p + x[2] ** p + x[3] ** p + x[4] ** p + x[5] ** p return y f_prime = jx.jacfwd(power_sum)(x,2.0) f_prime # DeviceArray([ 2., 4., 6., 8., 10., 12.], dtype=float32) I understand I can do it by send array 6 times with all other vvector values being zero. Is there a better way?

1 0

Re: [Boost-users] casually blocked UDP port
by Alexander Carôt 17 Jan '22

17 Jan '22

Hello again, I'd consider using boost asio SO_REUSEPORT option in order to reuse the port if already taken according to this thread: https://stackoverflow.com/questions/34596638/boost-asio-so-reuseport I will try it asap but please let me know if you have concerns or better solutions. Thanks and best Alex P.S.: see below – I now know how to reproduce the issue: When my application does receive UDP streaming data I spontaneously quit the application. Then doing: "netstat -p UDP" shows me the following Proto Recv-Q Send-Q Local Address Foreign Address (state) udp4 1026 0 *.50050 *.* So, basically the receive queue for this socket is not empty and the previous bind port is indeed still there. If anyone has an idea how to proceed from here on please let me know but now I might be able to fix it myself already. Best Alex Thanks for the swift response, Andreas ! In fact I am aware of what you wrote but with regard to the conditions my app works under it is extremely unlikely that some other process is taking this port. However, the next step for me is to identify which process actually has taken it. In that regard a follow-up question: Once an application (which uses boost sockets) has shut down (for crash or other reasons) the local bind port is also automatically released, right ? In other words: Can the OS stick a port although the corresponding application is not existent anymore ? I've been assuming no so far but maybe I am mistaken so I just need confirmation. Thank you, best Alex -- http://www.carot.de Email : Alexander(a)Carot.de Tel.: +49 (0)177 5719797 > Gesendet: Samstag, 15. Januar 2022 um 23:46 Uhr > Von: "Andreas Wehrmann via Boost-users" <boost-users(a)lists.boost.org> > An: boost-users(a)lists.boost.org > Cc: "Andreas Wehrmann" <a.wehrmann(a)yandex.com> > Betreff: Re: [Boost-users] casually blocked UDP port > > Am 14.01.2022 um 22:50 schrieb Alexander Carôt via Boost-users: > > Hello all, > > > > I have a problem with a a casually blocked UDP bind port: My application uses UDP port 50050 and initiates the socket this way: > > > > So I am basically using bind port 50050 and if it fails I am increasing it by one until the bind suceeds. In most cases the bind to port 50050 works fine but casually after a relaunch of the app or a crash the bind port 50050 appears to be blocked which is why it increases to higher numbers. > > > > Hi, > be aware that UDP sockets may are opened and closed for sending a single > request only by many applications/services. > If the sending application doesn't care about the local port and leaves > it up to the OS to assign a local port number, > you may run into the situation that another application/service/daemon > is opening a UDP socket, > not caring about the local port and the OS happens to assign the port > number that you want to bind your own socket to. > > All the best, > Andreas > > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > https://lists.boost.org/mailman/listinfo.cgi/boost-users >

2 2

Re: [Boost-users] casually blocked UDP port
by Alexander Carôt 16 Jan '22

16 Jan '22

P.S.: see below – I now know how to reproduce the issue: When my application does receive UDP streaming data I spontaneously quit the application. Then doing: "netstat -p UDP" shows me the following Proto Recv-Q Send-Q Local Address Foreign Address (state) udp4 1026 0 *.50050 *.* So, basically the receive queue for this socket is not empty and the previous bind port is indeed still there. If anyone has an idea how to proceed from here on please let me know but now I might be able to fix it myself already. Best Alex Thanks for the swift response, Andreas ! In fact I am aware of what you wrote but with regard to the conditions my app works under it is extremely unlikely that some other process is taking this port. However, the next step for me is to identify which process actually has taken it. In that regard a follow-up question: Once an application (which uses boost sockets) has shut down (for crash or other reasons) the local bind port is also automatically released, right ? In other words: Can the OS stick a port although the corresponding application is not existent anymore ? I've been assuming no so far but maybe I am mistaken so I just need confirmation. Thank you, best Alex -- http://www.carot.de Email : Alexander(a)Carot.de Tel.: +49 (0)177 5719797 > Gesendet: Samstag, 15. Januar 2022 um 23:46 Uhr > Von: "Andreas Wehrmann via Boost-users" <boost-users(a)lists.boost.org> > An: boost-users(a)lists.boost.org > Cc: "Andreas Wehrmann" <a.wehrmann(a)yandex.com> > Betreff: Re: [Boost-users] casually blocked UDP port > > Am 14.01.2022 um 22:50 schrieb Alexander Carôt via Boost-users: > > Hello all, > > > > I have a problem with a a casually blocked UDP bind port: My application uses UDP port 50050 and initiates the socket this way: > > > > So I am basically using bind port 50050 and if it fails I am increasing it by one until the bind suceeds. In most cases the bind to port 50050 works fine but casually after a relaunch of the app or a crash the bind port 50050 appears to be blocked which is why it increases to higher numbers. > > > > Hi, > be aware that UDP sockets may are opened and closed for sending a single > request only by many applications/services. > If the sending application doesn't care about the local port and leaves > it up to the OS to assign a local port number, > you may run into the situation that another application/service/daemon > is opening a UDP socket, > not caring about the local port and the OS happens to assign the port > number that you want to bind your own socket to. > > All the best, > Andreas > > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > https://lists.boost.org/mailman/listinfo.cgi/boost-users >

1 0

casually blocked UDP port
by Alexander Carôt 16 Jan '22

16 Jan '22

Hello all, I have a problem with a a casually blocked UDP bind port: My application uses UDP port 50050 and initiates the socket this way: udp::resolver resolver(dFC->myIoService); int port = 50050; bool failed; do{ failed = false; udp::resolver::query query(udp::v4(), IPAddress, port); try { dFC->s = new udp::socket( dFC->myIoService, udp::endpoint(*resolver.resolve(query))); } catch (std::exception &e) { failed = true; int intPort = this->intConverter(port); intPort++; ostringstream conv; conv << intPort; port = conv.str(); cout << "new port: " << port << endl; } while (failed); So I am basically using bind port 50050 and if it fails I am increasing it by one until the bind suceeds. In most cases the bind to port 50050 works fine but casually after a relaunch of the app or a crash the bind port 50050 appears to be blocked which is why it increases to higher numbers. Now I wonder how the port can still be taken although the app has terminated and if there is way to force the app / the OS using port 50050 ? So far I have seen this on OSX only – on Windows and Linux I haven't noticed it yet. Thanks in advance for any pointer how to resolve my isse, best Alex -- http://www.carot.de Email : Alexander(a)Carot.de Tel.: +49 (0)177 5719797

2 2

exception on boost serialization
by Alessio Mochi 13 Jan '22

13 Jan '22

Hello, I can't resolve my exception when I compile my qt project with visual studio 2022. Error C2039 'throw_exception': is not a member of 'boost' DentalCad E:\boost_1_78_0\boost\serialization\throw_exception.hpp 30 I tried a compile a small example and work correctly without exception. I don't understand how solve the problem. Have you a suggest? Thanks in advance.

4 10

Communicating with MS SQL Server.
by Senthil Cheetancheri 12 Jan '22

12 Jan '22

Hi, Is there a Boost library to communicate with Microsoft SQLServer? I see there is a proposal for MySQL (https://anarthal.github.io/boost-mysql-docs/index.html) but can't seem to find anything for MS SQLServer. Any pointers would be appreciated. Thanks, Senthil.

1 0

Clarification on statechart post_event vs process_event within react()
by John McCabe 10 Jan '22

10 Jan '22

Hi, Apologies if this has already been answered/clarified, but my search of the internet to try to get a definitive answer, at least one I recognised as being definitive, was unsuccessful. Below I have posted some source code, based on the stopwatch example from the tutorial, but using an 'external' object to delegate the actual handling of event stuff to and using the state, rather than simple_state base class, and some other tweaks. This is a cut down version of something that someone I work with has devised, but I just wanted to get a clear answer on whether process_event() should be getting called in cases like this. I think it probably should not since, in the code below, you change state (with a state object's destructor being executed) whilst you're executing that state's react(EvStartStop) function. If someone can confirm this is the correct interpretation that would be very much appreciated. Any questions, feel free to ask (BTW - I'm compiling for C++17) John PS - In case it's of any use, the output from running this code is: ------ Entered Active Entered Stopped Stopped - payload2 m_charValue: a Exited ~Stopped <<<--- This is the bit I don't like the look of because... Entered Running Active - payload2 m_charValue: a <<<--- ... this happens from the forward_event() call payload1 value1: 20 payload1 value2: 200.2 Exited ~Running Entered Stopped Exiting Program Exited ~Stopped Exited ~Active ------ If I swap the //*** comments to the doProcess() lines instead of doPost(), the output seems more sensible ------ Entered Active Entered Stopped Stopped - payload2 m_charValue: a Exited ~Stopped Entered Running Active - payload2 m_charValue: a payload1 value1: 20 payload1 value2: 200.2 Exited ~Running Entered Stopped Exiting Program Exited ~Stopped Exited ~Active ------ ========== code =========== #include <boost/statechart/event.hpp> #include <boost/statechart/state_machine.hpp> #include <boost/statechart/state.hpp> #include <boost/statechart/transition.hpp> #include <boost/statechart/custom_reaction.hpp> #include <boost/mpl/list.hpp> #include <iostream> #include <string> namespace sc = boost::statechart; namespace mpl = boost::mpl; // Forward declare a handler 'class' that's going to have activity delegated to it struct Handler; // Normal example start/stop and reset events struct EvStartStop : sc::event<EvStartStop> {}; struct EvReset : sc::event<EvReset> {}; // A couple of events that carry data with them struct EvPayload1 : sc::event<EvPayload1> { EvPayload1(int value1, double value2) : m_value1 { value1 }, m_value2 { value2 } {}; int m_value1 { 0 }; double m_value2 { 0.0 }; }; struct EvPayload2 : sc::event<EvPayload2> { EvPayload2(const char& charValue) : m_charValue { charValue } {}; char m_charValue { false }; }; // Back to the example bits struct Active; struct StopWatch : sc::state_machine<StopWatch, Active> { typedef sc::transition<EvReset, Active> reactions; // The extra 'handler' stuff void setHandler(Handler* handler) { m_handler = handler; }; Handler* getHandler() const { return m_handler; }; Handler* m_handler { nullptr }; // Used to make post_event() accessible from an external class...seems unpleasant, but... using sc::state_machine<StopWatch, Active>::post_event; }; // The implementation of the Handler class; created with a reference to a StopWatch object struct Handler { Handler(StopWatch& stopWatch) : m_stopWatch { stopWatch } {}; void doPost() { m_stopWatch.post_event(EvStartStop()); } void doProcess() { m_stopWatch.process_event(EvStartStop()); } StopWatch& m_stopWatch; }; struct Stopped; struct Active : sc::state<Active, StopWatch, Stopped> { Active(my_context ctx) : my_base { ctx } { std::cout << "Entered Active" << std::endl; }; ~Active() { std::cout << "Exited ~Active" << std::endl; }; typedef mpl::list<sc::custom_reaction<EvPayload1>, sc::custom_reaction<EvPayload2>, sc::transition<EvReset, Active>> reactions; sc::result react(const EvPayload1& payload1) { std::cout << "payload1 Event NOT HANDLED" << std::endl; return discard_event(); } sc::result react(const EvPayload2& payload2) { std::cout << "Active - payload2 m_charValue: " << payload2.m_charValue << std::endl; return discard_event(); } }; struct Running : sc::state<Running, Active> { Running(my_context ctx) : my_base { ctx } { std::cout << "Entered Running" << std::endl; }; ~Running() { std::cout << "Exited ~Running" << std::endl; }; typedef mpl::list<sc::custom_reaction<EvPayload1>, sc::transition<EvStartStop, Stopped>> reactions; sc::result react(const EvPayload1& payload1) { std::cout << "payload1 value1: " << payload1.m_value1 << std::endl; std::cout << "payload1 value2: " << payload1.m_value2 << std::endl; //***context<StopWatch>().getHandler()->doPost(); context<StopWatch>().getHandler()->doProcess(); return discard_event(); } }; struct Stopped : sc::state<Stopped, Active> { Stopped(my_context ctx) : my_base { ctx } { std::cout << "Entered Stopped" << std::endl; }; ~Stopped() { std::cout << "Exited ~Stopped" << std::endl; }; typedef mpl::list<sc::custom_reaction<EvPayload2>, sc::transition<EvStartStop, Running>> reactions; sc::result react(const EvPayload2& payload2) { std::cout << "Stopped - payload2 m_charValue: " << payload2.m_charValue << std::endl; //***context<StopWatch>().getHandler()->doPost(); context<StopWatch>().getHandler()->doProcess(); return forward_event(); } }; int main() { StopWatch myWatch; Handler myHandler(myWatch); myWatch.setHandler(&myHandler); myWatch.initiate(); myWatch.process_event(EvPayload2 { 'a' }); myWatch.process_event(EvPayload1 { 20, 200.2 }); std::cout << "Exiting Program" << std::endl; return 0; }

1 1

boost.gil build failed with GCC11 and -std=c++20
by Qiang Ren 10 Jan '22

10 Jan '22

Hi, I am on ubuntu 20.04, I have GCC9.4 and 10.3 and 11.1 installed. I found that when set "-std=c++20", with gcc11, boost.gil will failed to build. Here is the simple test cpp to reproduce the issue: #include <sstream> #include <boost/gil.hpp> #include <boost/gil/extension/io/png.hpp> namespace gil = boost::gil; int main() { gil::rgb8_image_t img; std::stringstream buf(std::ios::in | std::ios::out | std::ios::binary); gil::read_and_convert_image(buf, img, gil::png_tag{}); return 0; } the build command is: g++ -o test test_gcc11_gil.cc -std=c++20 -I${THIRD_PARTY}/boost/boost_1_78_0 -L${THIRD_PARTY}/libpng/1.6.37/lib/ -lpng If replaced '-std=c++20' with '-std=c++17', the build would be OK, but with 'c++20', gcc 11 failed with the following errors: In file included from /data/lin/ThirdParty/boost/boost_1_78_0/boost/gil/extension/io/png/read.hpp:13, from /data/lin/ThirdParty/boost/boost_1_78_0/boost/gil/extension/io/png.hpp:11, from test_gcc11_gil.cc:3: /data/lin/ThirdParty/boost/boost_1_78_0/boost/gil/extension/io/png/tags.hpp:576:32: error: expected unqualified-id before ‘)’ token 576 | image_read_info< png_tag >() | ^ /data/lin/ThirdParty/boost/boost_1_78_0/boost/gil/extension/io/png/tags.hpp:711:36: error: expected unqualified-id before ‘)’ token 711 | image_read_settings< png_tag >() | ^ In file included from /data/lin/ThirdParty/boost/boost_1_78_0/boost/gil/extension/io/png/read.hpp:21, from /data/lin/ThirdParty/boost/boost_1_78_0/boost/gil/extension/io/png.hpp:11, from test_gcc11_gil.cc:3: /data/lin/ThirdParty/boost/boost_1_78_0/boost/gil/io/make_reader.hpp: In instantiation of ‘typename boost::gil::get_reader<String, FormatTag, ConversionPolicy>::type boost::gil::make_reader(Device&, const FormatTag&, const ConversionPolicy&, typename std::enable_if<typename boost::mp11::detail::mp_and_impl<boost::mp11::mp_list<boost::gil::detail::is_adaptable_input_device<FormatTag, Device, void>, boost::gil::is_format_tag<FormatTag> >, void>::type::value>::type*) [with Device = std::__cxx11::basic_stringstream<char>; FormatTag = boost::gil::png_tag; ConversionPolicy = boost::gil::detail::read_and_convert<boost::gil::default_color_converter>; typename boost::gil::get_reader<String, FormatTag, ConversionPolicy>::type = boost::gil::reader<boost::gil::detail::istream_device<boost::gil::png_tag>, boost::gil::png_tag, boost::gil::detail::read_and_convert<boost::gil::default_color_converter> >; typename std::enable_if<typename boost::mp11::detail::mp_and_impl<boost::mp11::mp_list<boost::gil::detail::is_adaptable_input_device<FormatTag, Device, void>, boost::gil::is_format_tag<FormatTag> >, void>::type::value>::type = void;typename boost::mp11::detail::mp_and_impl<boost::mp11::mp_list<boost::gil::detail::is_adaptable_input_device<FormatTag, Device, void>, boost::gil::is_format_tag<FormatTag> >, void>::type =std::integral_constant<bool, true>]’: /data/lin/ThirdParty/boost/boost_1_78_0/boost/gil/io/read_and_convert_image.hpp:263:34: required from ‘void boost::gil::read_and_convert_image(Device&, Image&, const FormatTag&, typename std::enable_if<typename boost::mp11::detail::mp_and_impl<boost::mp11::mp_list<boost::gil::detail::is_read_device<FormatTag, Device, void>, boost::gil::is_format_tag<FormatTag> >, void>::type::value>::type*) [with Device = std::__cxx11::basic_stringstream<char>; Image = boost::gil::image<boost::gil::pixel<unsigned char, boost::gil::layout<boost::mp11::mp_list<boost::gil::red_t, boost::gil::green_t, boost::gil::blue_t> > >, false, std::allocator<unsigned char> >; FormatTag = boost::gil::png_tag; typename std::enable_if<typename boost::mp11::detail::mp_and_impl<boost::mp11::mp_list<boost::gil::detail::is_read_device<FormatTag, Device, void>, boost::gil::is_format_tag<FormatTag> >, void>::type::value>::type = void; typename boost::mp11::detail::mp_and_impl<boost::mp11::mp_list<boost::gil::detail::is_read_device<FormatTag, Device, void>, boost::gil::is_format_tag<FormatTag> >, void>::type = std::integral_constant<bool, true>]’ test_gcc11_gil.cc:11:30: required from here /data/lin/ThirdParty/boost/boost_1_78_0/boost/gil/io/make_reader.hpp:193:30: error: no matching function for call to ‘boost::gil::image_read_settings<boost::gil::png_tag>::image_read_settings()’ 193 | return make_reader(file, image_read_settings<FormatTag>(), cc); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from /data/lin/ThirdParty/boost/boost_1_78_0/boost/gil/extension/io/png/read.hpp:13, from /data/lin/ThirdParty/boost/boost_1_78_0/boost/gil/extension/io/png.hpp:11, from test_gcc11_gil.cc:3: /data/lin/ThirdParty/boost/boost_1_78_0/boost/gil/extension/io/png/tags.hpp:718:5: note: candidate: ‘boost::gil::image_read_settings<boost::gil::png_tag>::image_read_settings(const point_t&, const point_t&)’ 718 | image_read_settings( const point_t& top_left | ^~~~~~~~~~~~~~~~~~~ /data/lin/ThirdParty/boost/boost_1_78_0/boost/gil/extension/io/png/tags.hpp:718:5: note: candidate expects 2 arguments, 0 provided /data/lin/ThirdParty/boost/boost_1_78_0/boost/gil/extension/io/png/tags.hpp:707:8: note: candidate: ‘constexpr boost::gil::image_read_settings<boost::gil::png_tag>::image_read_settings(const boost::gil::image_read_settings<boost::gil::png_tag>&)’ 707 | struct image_read_settings< png_tag > : public image_read_settings_base | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /data/lin/ThirdParty/boost/boost_1_78_0/boost/gil/extension/io/png/tags.hpp:707:8: note: candidate expects 1 argument, 0 provided /data/lin/ThirdParty/boost/boost_1_78_0/boost/gil/extension/io/png/tags.hpp:707:8: note: candidate: ‘constexpr boost::gil::image_read_settings<boost::gil::png_tag>::image_read_settings(boost::gil::image_read_settings<boost::gil::png_tag>&&)’ /data/lin/ThirdParty/boost/boost_1_78_0/boost/gil/extension/io/png/tags.hpp:707:8: note: candidate expects 1 argument, 0 provided Only gcc 11 will fail with '-std=c++20', gcc9 and gcc 10 worked fine. I guess that gcc11 has implemented more c++20 features than gcc9 and gcc10. Since the boost project updates more quickly than gcc, I hope this issue might be fixed in the next boost version. Thanks, Qiang Ren

2 2

Dimension conversion for free?
by KL 08 Jan '22

08 Jan '22

1 0

TypeTraits
by Gero Peterhoff 27 Dec '21

27 Dec '21

Hello John, Some time ago I asked whether further type traits would be included in boost. Unfortunately that somehow fizzled out. Because based on this, many useful functions and classes can first be defined that behave correctly. But the problems are much deeper and I would like to show a solution here. 1) For some types there are feature-tesing-macros (e.g. __cpp_char8_t, __cpp_unicode_characters), but not for most. So this is incomplete. So we need this (plus the __cpp_lib-macros): - __cpp_char8/16/32_t, __cpp charw_t, __cpp_char_t - __cpp_int8/16/32/64/128_t - __cpp_float16/32/64/80/128_t, __cpp_float16b_t - __cpp_bool_t 2) Building on this, we can then query, e.g. struct has_float80: bool_constant < #if defined (__cpp_float80_t) true #else false #endif > {}; template <typename Type> struct is_float80: bool_constant < #if defined (__cpp_float80_t) is_same_v<Type, float80> #else false #endif > {}; This has to be done for all types. 3) Then we can further classify; plus is_X_v and concepts: character: template <typename Type> struct is_character: bool_constant < #if defined (__cpp_char32_t) is_same_v<Type, char32_t> || #elif defined (__cpp_char16_t) is_same_v<Type, char16_t> || #elif defined (__cpp_char8_t) is_same_v<Type, char8_t> || #elif defined (__cpp_charw_t) is_same_v<Type, wchar_t> || #endif is_same_v<Type, char> > {}; template <typename Type> struct is_unsigned_character: bool_constant < is_unsigned_v<Type> && character_v<Type> > {}; template <typename Type> is_signed_character: bool_constant < is_signed_v<Type> && character_v<Type> > {}; float: template <typename Type> struct is_floating_point: bool_constant < #if defined (__cpp_float128_t) is_same_v<Type, float128_t> || #elif defined (__cpp_float80_t) is_same_v<Type, float80_t> || #elif defined (__cpp_float64_t) is_same_v<Type, float64_t> || #elif defined (__cpp_float32_t) is_same_v<Type, float32_t> || #elif defined (__cpp_float16b_t) is_same_v<Type, float16b_t> || #elif defined (__cpp_float16_t) is_same_v<Type, float16_t> || #endif false > {}; integer: template <typename Type> struct is_unsigned_integer: bool_constant < #if defined (__cpp_int128_t) is_same_v<Type, uint128_t> || #elif defined (__cpp_int64_t) is_same_v<Type, uint64_t> || #elif defined (__cpp_int32_t) is_same_v<Type, uint32_t> || #elif defined (__cpp_int16_t) is_same_v<Type, uint16_t> || #elif defined (__cpp_int8_t) is_same_v<Type, uint8_t> || #endif false > {}; template <typename Type> struct is_signed_integer: bool_constant < #if defined (__cpp_int128_t) is_same_v<Type, int128_t> || #elif defined (__cpp_int64_t) is_same_v<Type, int64_t> || #elif defined (__cpp_int32_t) is_same_v<Type, int32_t> || #elif defined (__cpp_int16_t) is_same_v<Type, int16_t> || #elif defined (__cpp_int8_t) is_same_v<Type, int8_t> || #endif false > {}; template <typename Type> struct is_integer: bool_constant < is_unsigned_integer_v<Type> || is_signed_integer_v<Type> > {}; logic: template <typename Type> struct is_logic: bool_constant < is_same_v<Type, bool> > {}; With that we would have created the basics to be able to continue working properly at all. 4) 3 more steps to make things easier #define bitsof(ARG) (size_t(sizeof(ARG) * CHAR_BIT)) Like std::numbers with std::strings with various constantans namespace strings { constexpr static auto empty = ""; constexpr static auto nullptr = "nullptr"; constexpr static auto Void = "void"; constexpr static auto True = "true"; constexpr static auto False = "false"; constexpr static auto indeterminate = "indeterminate"; constexpr static auto overdeterminate = "overdeterminate"; constexpr static auto underdeterminate = "underdeterminate"; constexpr static auto bin = "bin"; constexpr static auto oct = "oct"; constexpr static auto dec = "dec"; constexpr static auto hex = "hex"; constexpr static auto literal_bin = "0b"; constexpr static auto literal_oct = "0o"; constexpr static auto literal_dec = "0d"; constexpr static auto literal_hex = "0x"; } and more and for streams so that you don't have to fumble with the flags namespace detail { using format_flags_t = typename std::ios_base::fmtflags; static inline constexpr format_flags_t defaultfloat = format_flags_t{}, hexfloat = std::ios_base::fixed | std::ios_base::scientific; inline format_flags_t get_flags (const std::ios_base & stream, const format_flags_t & fieldmask) noexcept { return stream.flags () & fieldmask; } } // detail inline bool is_boolalpha (const std::ios_base & stream) noexcept {return (stream.flags () & stream.boolalpha) == stream.boolalpha; } inline bool is_showbase (const std::ios_base & stream) noexcept {return (stream.flags () & stream.showbase) == stream.showbase; } inline bool is_showpoint (const std::ios_base & stream) noexcept {return (stream.flags () & stream.showpoint) == stream.showpoint; } inline bool is_skip (const std::ios_base & stream) noexcept {return (stream.flags () & stream.skipws) == stream.skipws; } inline bool is_uppercase (const std::ios_base & stream) noexcept {return (stream.flags () & stream.uppercase) == stream.uppercase; } inline bool is_lowercase (const std::ios_base & stream) noexcept {return! is_uppercase (stream); } inline bool is_float_bin (const std::ios_base & stream) noexcept {return false; } inline bool is_float_hex (const std::ios_base & stream) noexcept {return detail::get_flags (stream, stream.floatfield) == detail::hexfloat; } inline bool is_float_fixed (const std::ios_base & stream) noexcept {return detail::get_flags (stream, stream.floatfield) == stream.fixed; } inline bool is_float_default (const std::ios_base & stream) noexcept {return detail::get_flags (stream, stream.floatfield) == detail::defaultfloat; } inline bool is_float_scientific (const std::ios_base & stream) noexcept {return detail::get_flags (stream, stream.floatfield) == stream.scientific; } inline bool is_integer_bin (const std::ios_base & stream) noexcept {return false; } inline bool is_integer_oct (const std::ios_base & stream) noexcept {return detail::get_flags (stream, stream.basefield) == stream.oct; } inline bool is_integer_dec (const std::ios_base & stream) noexcept {return detail::get_flags (stream, stream.basefield) == stream.dec; } inline bool is_integer_hex (const std::ios_base & stream) noexcept {return detail::get_flags (stream, stream.basefield) == stream.hex; } 5) And now we can finally get correctly working functions, e.g. template <integer Type, unsigned_integer Bits> inline constexpr Type shl(const Type& arg, const Bits& bits) noexcept { using unsigned_type = make_unsigned_t<Type>; const type res {Type(arg << unsigned_type(bits))}; return (bits < bitsof(Type)) ? res : Type{0}; } template <integer Type, unsigned_integer Bits> inline constexpr Type shr(const Type& arg, const Bits& bits) noexcept { using unsigned_type = make_unsigned_t<Type>; const type ovl {is_signed_integer_v<Type> ? ((arg < Type{0})? Type(-1) : Type{0}) : Type{0}}, res {Type(arg >> unsigned_type(bits))}; return (bits < bitsof(Type)) ? res : ovl; } and classes, e.g. constexpr bool2/3/4 with template <> struct is_logic<bool4>: true_type {}; template <> struct is_logic<bool3>: true_type {}; template <> struct is_logic<bool2>: true_type {}; (I am happy to send it to you, because boost::tribool does not meet the requirements). PS: I could have used the days multi-array/multi-index; but that's done because all of these libs are not constexpr. Will these be updated again? thx Gero

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Boost geometry: 3d difference and union?
by KL 13 Dec '21

13 Dec '21

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Question on boost shared memory allocators
by Da Xu 08 Dec '21

08 Dec '21

Hi folks, got a couple of questions about using shared memory allocators. Please see below. I have the following code template <typename T> using CAP_Alloc = cached_adaptive_pool<T, segment_manager_t>; using CAP_Shmem_String = basic_string<char, std::char_traits<char>, CAP_Alloc<char> >; using CAP_Shmem_String_Alloc = CAP_Alloc<CAP_Shmem_String>; using CAP_Shmem_Void_Alloc = CAP_Alloc<void>; class MyDataBlock{ using pointer = CAP_Shmem_String_Alloc::pointer; pointer strData; float extraData; MyDataBlock(): strData(nullptr), extraData(0.0) {} MyDataBlock(const CAP_Shmem_Void_Alloc& alloc) { /* My question is how do I convert CAP_Shmem_Void_Alloc to type CAP_Shmem_String_Alloc to call allocate? And do I pass in the void allocator as a construction argument? Is there a difference between allocate and construct? */ } ~MyDataBlock() { /* To delete the memory, do I need to keep around a copy of the original allocator, so I can call deallocate or destroy? Or can that be derived or converted from somewhere, like calling strData->alloc() ? */ } } Any help would be greatly appreciated. Thank you.

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[release] Boost 1.78.0
by Marshall Clow 08 Dec '21

08 Dec '21

Release 1.78.0 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 numerous enhancements and bug fixes for existing libraries. For details, including download links, see <http://www.boost.org/users/news/version_1.78.0> You can also download directly from: <https://boostorg.jfrog.io/artifactory/main/release/1.78.0/> 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, Glen Fernandes

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