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Installing (in the b2 sense) boost under windows
by Chris Stankevitz 24 Aug '13

24 Aug '13

Hello, I was recently tasked with installing boost binaries under windows. I used this command: C:\boost_1_49_0>b2 --build-dir=\boost-build toolset=gcc --build-type=complete stage --prefix=c:\boost-prefix\ install I was expecting the directory c:\boost-prefix to contain boost header and library files; however, that directory contained no files whatsoever. Did I do something wrong? PS: The c:\boost-build directory was filled with intermediate build files. Thank you, Chris

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[asio] Infinite loops
by Michael Chisholm 24 Aug '13

24 Aug '13

I have found that when (ab)using asio in a particular way, it causes a hang in my app, which I think is caused by an infinite loop in asio. I'll state up front that the usage is pretty underhanded, so I may not get much sympathy here :) But it also seems reasonable to not hang. The hang happens only on the two linux platforms I tested, which were centos 5.9 and 6.4. I built it on win7 and mingw 4.6.3 (with slight code changes), and it doesn't hang. The simplified test app demonstrating the hang is pasted at the bottom of this email. I basically just wanted an API to smooth over platform network API differences and also give me a nice iostream class backed by a socket. So there's none of the fancy proactor stuff. There is a need to "reset" the app after socket connections have been established, and one thread is blocked on a socket read. So I needed a way to unblock the thread. Closing the socket seemed like a reasonable way to do it, but I found that simply calling a close() method from a different thread doesn't work; it causes race conditions and crashes, since asio classes seem not to be thread-safe. So I got more devious, and decided to just grab the raw handle and call close() directly on it. That's the underhanded part. I thought asio would figure out that the socket's no longer valid, and propagate an error up to the caller, thus unblocking the thread. But it doesn't, the thread just stays blocked. After doing some gdb tracing, it looked to me like asio is repeatedly polling the socket with epoll/select (I tried the latter by defining BOOST_ASIO_DISABLE_EPOLL) and a timeout, and never breaking out of its loop even though the socket is no longer valid. So, does it seem reasonable for asio to break out of its polling loop when someone (underhandedly) closes the socket out from under it? :) Andy #include <cstdio> #include <boost/system/error_code.hpp> #include <boost/chrono.hpp> #include <boost/thread.hpp> #include <boost/asio.hpp> using namespace std; namespace bs = boost::system; namespace bc = boost::chrono; namespace ip = boost::asio::ip; boost::asio::io_service iosvc; ip::tcp::socket clientSocket(iosvc); ip::tcp::iostream serverStream; #define TEST_PORT 2000 void connectToServer() { bs::error_code ec; clientSocket.connect( ip::tcp::endpoint(ip::address_v4::loopback(), TEST_PORT), ec); if (ec) cout << "Client couldn't connect: " << ec.message() << endl; else cout << "Client connected!" << endl; } void waitForClient() { ip::tcp::acceptor acceptor(iosvc, ip::tcp::endpoint(ip::address_v4::loopback(), TEST_PORT)); bs::error_code ec; acceptor.accept(*serverStream.rdbuf(), ec); if (ec) cout << "Server couldn't accept: " << ec.message() << endl; else cout << "Server accepted!" << endl; } void serverReadAByte() { int b = serverStream.get(); if (serverStream) cout << "Got byte: " << b << endl; else cout << "Error reading byte: " << serverStream.error().message() << endl; } int main(int, const char **) { boost::thread serverThread(waitForClient); // wait a second for the server socket to open... boost::this_thread::sleep_for(bc::seconds(1)); connectToServer(); serverThread.join(); int sd = serverStream.rdbuf()->native_handle(); // this will block, since we won't write anything // to the client socket. boost::thread readThread(serverReadAByte); // wait a second for the socket read to block... boost::this_thread::sleep_for(bc::seconds(1)); // close the server socket out from under our stream! // Does readThread unblock? if (close(sd) == -1) { perror("close"); return 1; } cout << "Waiting for read thread..." << endl; readThread.join(); clientSocket.close(); serverStream.close(); return 0; }

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[multiprecision] mpfi_sqr function
by Александров Петр 24 Aug '13

24 Aug '13

Hello. Is mpfi_sqr (square) function supported by Boost.Multiprecision? This function may give better results (interval with less length) than simple multiplication. Kind regards, Petr.

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Do I need a seperate boost_python lib for python 3?
by Neal Becker 24 Aug '13

24 Aug '13

If I already built against python2.7, do I need to build again against python 3? This is on Fedora 19 linux.

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Re: [Boost-users] boost::any_range with an abstract class reference
by Sergey Zhuravlov 24 Aug '13

24 Aug '13

Hi, you wrote: > typedef boost::any_range< Try use reference to value as value_type template parameter for boost::any_range. Also you can use boost::indirected_range instead.

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Boost Logging File Rotation
by Bryan Pham 24 Aug '13

24 Aug '13

Hi I'm trying to use boost logging rotation and I'm not seeing any output nor file is being written. The old method of using boost trivial seems to output to stdout just fine. My setup: void boost_log_setup(int level) { //boost::log::core::get()->set_filter(boost::log::trivial::severity >= level); boost::shared_ptr< boost::log::core > core = boost::log::core::get(); boost::shared_ptr< boost::log::sinks::text_file_backend > backend = boost::make_shared< boost::log::sinks::text_file_backend >( boost::log::keywords::file_name = "cloutenna_%5N.log", boost::log::keywords::rotation_size = 5 * 1024 * 1024, boost::log::keywords::time_based_rotation = boost::log::sinks::file::rotation_at_time_point(12, 0, 0) ); // Wrap it into the frontend and register in the core. // The backend requires synchronization in the frontend. typedef boost::log::sinks::synchronous_sink< boost::log::sinks::text_file_backend > sink_t; boost::shared_ptr< sink_t > sink(new sink_t(backend)); core->set_filter(severity >= level); core->add_sink(sink); } enum severity_level { trace, debug, notification, warning, error, fatal }; BOOST_LOG_ATTRIBUTE_KEYWORD(severity, "Severity", severity_level) BOOST_LOG_INLINE_GLOBAL_LOGGER_DEFAULT(logger, boost::log::sources::severity_logger_mt<>) //Common loggin define #define CM_TRACE BOOST_LOG_SEV(logger::get(), trace) #define CM_DEBUG BOOST_LOG_SEV(logger::get(), debug) #define CM_INFO BOOST_LOG_SEV(logger::get(), notification) #define CM_WARN BOOST_LOG_SEV(logger::get(), warning) #define CM_ERROR BOOST_LOG_SEV(logger::get(), error) #define CM_FAIL BOOST_LOG_SEV(logger::get(), fatal) int main(int argc, char* argv[]) { boost_log_setup(severity_level::debug); CM_INFO << "starting ... " }

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boost::any_range with an abstract class reference
by voivoid 23 Aug '13

23 Aug '13

Consider the following code: #include <vector> #include <boost\range\any_range.hpp> #include <boost\range\adaptors.hpp> struct IFooBar { virtual void func() = 0; }; typedef boost::any_range<IFooBar, boost::random_access_traversal_tag, const IFooBar&, std::ptrdiff_t> FooBarRange; int main() { std::vector<std::unique_ptr<IFooBar>> vec; FooBarRange range = vec | boost::adaptors::indirected; return 0; } Compilation fails with the following error ( looks like any_range value is supposed to be copy-constructable? ) Is there any workaround? boost_1_54_0, MSVC 2010 1>c:\users\voivoid\libs\boost_1_54_0\boost\range\detail\any_iterator_interface.hpp(90): error C2259: 'IFooBar' : cannot instantiate abstract class 1> due to following members: 1> 'void IFooBar::func(void)' : is abstract 1> c:\users\voivoid\projects\cpptestapp\cpptestapp\main.cpp(9) : see declaration of 'IFooBar::func' 1> c:\users\voivoid\libs\boost_1_54_0\boost\range\detail\any_iterator_interface.hpp(93) : see reference to class template instantiation 'boost::range_detail::any_single_pass_iterator_interface<Reference,Buffer>' being compiled 1> with 1> [ 1> Reference=IFooBar, 1> Buffer=boost::any_iterator_buffer<64> 1> ] 1> c:\users\voivoid\libs\boost_1_54_0\boost\range\detail\any_iterator_interface.hpp(101) : see reference to class template instantiation 'boost::range_detail::any_single_pass_iterator_interface<Reference,Buffer>' being compiled 1> with 1> [ 1> Reference=const IFooBar &, 1> Buffer=boost::any_iterator_buffer<64> 1> ] 1> c:\users\voivoid\libs\boost_1_54_0\boost\range\detail\any_iterator_interface.hpp(123) : see reference to class template instantiation 'boost::range_detail::any_forward_iterator_interface<Reference,Buffer>' being compiled 1> with 1> [ 1> Reference=const IFooBar &, 1> Buffer=boost::any_iterator_buffer<64> 1> ] 1> c:\users\voivoid\libs\boost_1_54_0\boost\range\detail\any_iterator_interface.hpp(151) : see reference to class template instantiation 'boost::range_detail::any_bidirectional_iterator_interface<Reference,Buffer>' being compiled 1> with 1> [ 1> Reference=const IFooBar &, 1> Buffer=boost::any_iterator_buffer<64> 1> ] 1> c:\users\voivoid\libs\boost_1_54_0\boost\range\detail\any_iterator.hpp(452) : see reference to class template instantiation 'boost::range_detail::any_random_access_iterator_interface<Reference,Difference,Buffer>' being compiled 1> with 1> [ 1> Reference=const IFooBar &, 1> Difference=ptrdiff_t, 1> Buffer=boost::any_iterator_buffer<64> 1> ] 1> c:\program files (x86)\microsoft visual studio 10.0\vc\include\xutility(385) : see reference to class template instantiation 'boost::range_detail::any_iterator<Value,Traversal,Reference,Difference,Buffer>' being compiled 1> with 1> [ 1> Value=IFooBar, 1> Traversal=boost::random_access_traversal_tag, 1> Reference=const IFooBar &, 1> Difference=ptrdiff_t, 1> Buffer=boost::any_iterator_buffer<64> 1> ] 1> c:\users\voivoid\libs\boost_1_54_0\boost\detail\iterator.hpp(83) : see reference to class template instantiation 'std::iterator_traits<_Iter>' being compiled 1> with 1> [ 1> _Iter=boost::range_detail::any_iterator<IFooBar,boost::random_access_traversal_tag,const IFooBar &,ptrdiff_t,boost::any_iterator_buffer<64>> 1> ] 1> c:\users\voivoid\libs\boost_1_54_0\boost\iterator\iterator_traits.hpp(30) : see reference to class template instantiation 'boost::detail::iterator_traits<Iterator>' being compiled 1> with 1> [ 1> Iterator=boost::range_detail::any_iterator<IFooBar,boost::random_access_traversal_tag,const IFooBar &,ptrdiff_t,boost::any_iterator_buffer<64>> 1> ] 1> c:\users\voivoid\libs\boost_1_54_0\boost\range\iterator_range_core.hpp(141) : see reference to class template instantiation 'boost::iterator_value<Iterator>' being compiled 1> with 1> [ 1> Iterator=boost::range_detail::any_iterator<IFooBar,boost::random_access_traversal_tag,const IFooBar &,ptrdiff_t,boost::any_iterator_buffer<64>> 1> ] 1> c:\users\voivoid\libs\boost_1_54_0\boost\range\any_range.hpp(95) : see reference to class template instantiation 'boost::iterator_range<IteratorT>' being compiled 1> with 1> [ 1> IteratorT=boost::range_detail::any_iterator<IFooBar,boost::random_access_traversal_tag,const IFooBar &,ptrdiff_t,boost::any_iterator_buffer<64>> 1> ] 1> c:\users\voivoid\projects\cpptestapp\cpptestapp\main.cpp(19) : see reference to class template instantiation 'boost::range_detail::any_range<Value,Traversal,Reference,Difference>' being compiled 1> with 1> [ 1> Value=IFooBar, 1> Traversal=boost::random_access_traversal_tag, 1> Reference=const IFooBar &, 1> Difference=ptrdiff_t 1> ] Thanks. -- View this message in context: http://boost.2283326.n4.nabble.com/boost-any-range-with-an-abstract-class-r… Sent from the Boost - Users mailing list archive at Nabble.com.

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[units] "Simple" conversion from Kelvin to Celsius
by Michael Powell 22 Aug '13

22 Aug '13

Hello, It's been a couple of years since I've done any work with Boost.Units, and I am finding that I want to make a dimensionally-safe conversion from Kelvin to Celsius. I've got an I2C controller that reports in Kelvin, but I want to report it to the end-user in Celsius. The examples I am finding seem to "almost" fit the bill, but I am having a difficult time extrapolating a sane conversion. First, would help if I understood what the Boost.Units SI (my assumed base-system) base-temperature units were. I gather Fahrenheit? Or is it indeed Kelvin? I could be mistaken. Thank you... Regards, Michael Powell

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Trouble building 1.5.4 on OS X 10.6
by Jo Meder 22 Aug '13

22 Aug '13

Hi, I'm having trouble building 1.5.4 on OS X 10.6 for Intel only Universal builds (32 and 64 bit). This is my command line for b2: ./b2 macosx-version=10.6 macosx-version-min=10.6 threading=multi architecture=x86 address-model=32_64 I've also tried a simpler command line just specifying the architecture and address model, same results. Originally I was having trouble building all the libraries, in particular the thread lib wasn't building. Now mysteriously it is. However the libraries are being built with the ppc and ppc64 architectures as well as i386 and x86_64, which doesn't seem right given the options I'm specifying. You can see the unwanted archs in the build lines too, for example: "g++-4.0" -ftemplate-depth-128 -arch x86_64 -arch i386 -arch ppc64 -arch ppc -O3 -finline-functions -Wno-inline -Wall -gdwarf-2 -fexceptions -Wno-long-double -isysroot /Developer/SDKs/MacOSX10.6.sdk -mmacosx-version-min=10.6 -arch i386 -arch x86_64 -DBOOST_ALL_NO_LIB=1 -DNDEBUG -I"." -c -o "bin.v2/libs/context/build/darwin-4.0/release/address-model-32_64/architecture-x86/link-static/macosx-version-min-10.6/macosx-version-10.6/threading-multi/unsupported.o" "libs/context/src/unsupported.cpp" There are 4 arch flags near the start for x86_64, i386, ppc64 and ppc. There are also two more for x86_64 and i386 further on, which I assume are the ones the darwin.jam file has added based on my options passed to b2. I'm guessing these build lines are only being shown when there's a problem as there certainly isn't one for every file, but I assume they're representative. Now the libs seem to be building but I'm getting link errors from libboost_thread: Undefined symbols: "boost::thread_detail::enter_once_region(boost::once_flag&)", referenced from: boost::detail::set_current_thread_data(boost::detail::thread_data_base*)in libboost_thread.a(thread.o) boost::detail::get_current_thread_data() in libboost_thread.a(thread.o) _thread_proxy in libboost_thread.a(thread.o) _thread_proxy in libboost_thread.a(thread.o) boost::(anonymous namespace)::make_external_thread_data() in libboost_thread.a(thread.o) "boost::thread_detail::commit_once_region(boost::once_flag&)", referenced from: boost::detail::set_current_thread_data(boost::detail::thread_data_base*)in libboost_thread.a(thread.o) boost::detail::get_current_thread_data() in libboost_thread.a(thread.o) _thread_proxy in libboost_thread.a(thread.o) _thread_proxy in libboost_thread.a(thread.o) boost::(anonymous namespace)::make_external_thread_data() in libboost_thread.a(thread.o) "boost::thread_detail::rollback_once_region(boost::once_flag&)", referenced from: boost::detail::set_current_thread_data(boost::detail::thread_data_base*)in libboost_thread.a(thread.o) boost::detail::get_current_thread_data() in libboost_thread.a(thread.o) _thread_proxy in libboost_thread.a(thread.o) _thread_proxy in libboost_thread.a(thread.o) boost::(anonymous namespace)::make_external_thread_data() in libboost_thread.a(thread.o) ld: symbol(s) not found collect2: ld returned 1 exit status I saw there was a problem building the thread lib on OS X so I've added: #define BOOST_THREAD_DONT_USE_ATOMIC to boost/config/user.hpp. That seems related because in the headers that appears to control which file with the enter_once_region and so on functions gets included. If anyone has any insight I'd appreciate it. Regards, Jo Meder

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memory used by vector<int> vs vector<char>
by Lloyd 21 Aug '13

21 Aug '13

Hi, If I create a vector<int> of 100 elements and a vector<char> of 100 elements, will there be any difference in the total memory used by them? or which is more efficient? Thanks, Lloyd

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