February 2018 - Boost-users

compilation error
by Dk Jack 21 Feb '18

21 Feb '18

Hi, I am getting a compilation error when trying to compile my app. I've detailed my issue on stack overflow. https://stackoverflow.com/questions/48897103/compile- error-in-boost-header-file-fails-on-centos-7-compiles-on-ubuntu-16-04 Would appreciate if someone here can provide some guidance on how to resolve it. Thanks. D.

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Serialization of optional<std::string>
by Chardrazle 21 Feb '18

21 Feb '18

As part of upgrading a product to a later version of boost the compilation has tripped up on serialization of a boost::optional<std::string>. The /optional.hpp/ header now has the comment: ...and this fires for std::string. What, if any, is the recommended way forward for this? An example code snippet to illustrate: Previous version of boost: 1.50; new: 1.6x Compiling with g++ 4.6.4 (although same problem with 4.8.5): -W -Wall -std=c++0x... (The real code is actually using the portable_binary_archive, but let's avoid muddying the waters at this stage :) -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Users-f2553780.html

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Math and numerics: Odeint - problem with adaptive step size
by William Heitler 20 Feb '18

20 Feb '18

Hello, I'm a moderately experienced C++ programmer using Visual Studio 2017, but I'm new to using the boost odeint library. I'm trying to integrate the Hodgkin-Huxley equations, which are a set of ODEs that describe the generation of nerve impulse. The output should be a time-series waveform which is mainly flat but with occasional spikes in it. I have a functor HH which works fine with a standard fixed-step Runge-Kutta routine runge_kutta4< state_type > stepper; integrate_const(stepper, HH, x, 0.0, 20.0, 0.04,trace_observer()); This code produces exactly the right waveform However, I would like to use an adaptive step size because the waveform is pretty flat between the spikes. I tried the following: integrate_adaptive(make_dense_output(1.0e-6, 1.0e-6, runge_kutta_dopri5< state_type >()), hh, x, 0.0, 10.0, 0.04, trace_observer()); This works up to about the peak of the first spike, but then crashes with the error message: Debug Assertion Failed! ... Expression: vector iterator not incrementable It dies in the Visual Studio vector library code _Vector_const_iterator& operator++() in a call from boost::norm_inf where iterator first1 reports as first1 {2.105352686232e-314#DEN} std::_Vector_const_iterator<std::_Vector_val<std::_Simple_types<double> > > I certainly don't understand how the boost code works under the hood, but I wondered if anyone could suggest a change in my calling code that might make it work? I have hand-crafted some adaptive step size code which works OK (and does run faster than the fixed step size), but it is a bit of a kludge and I would rather use code developed by people who actually understand the maths. For reasons of brevity I haven't put the HH code in this message, but could do if it would help. Thanks for any help Dr W J Heitler School of Biology University of St Andrews 01334 463490 www.st-andrews.ac.uk/~wjh<http://www.st-andrews.ac.uk/~wjh>

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[Iostreams] Known issue with 32-bit and iostreams::file_descriptor_sink?
by Tim Landscheidt 19 Feb '18

19 Feb '18

Hi, I'm trying to debug several issues in ledger (https://www.ledger-cli.org/) under Fedora 26 (boost 1.63; https://github.com/ledger/ledger/issues/534) and Debian Stretch (boost 1.62; https://github.com/ledger/ledger/issues/539) These issues occur only on 32-bit architectures (i386/i686), and on Fedora 26 (boost 1.63) some segmentation faults can be /fixed/ by executing: | std::ostream *dummy = new iostreams::stream<iostreams::file_descriptor_sink>(2, iostreams::never_close_handle); but this does not "work" on Debian Stretch (boost 1.62). Does that ring a bell for anyone? (NB: I don't want to im- ply that there is a bug in Boost, but maybe someone recog- nizes the scenario and can suggest where the real issues probably lie.) TIA, Tim

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Compiling boost for Intel compiler on Windows
by Boaz Barnea MTH 19 Feb '18

19 Feb '18

Hi, I followed the steps<https://software.intel.com/en-us/articles/building-boost-with-intel-c-compi…> (with adjustments for intel compiler version 18) to build boost using Intel compiler. I have Intel i7 processor, with windows 7 64-bit version, therefore I run compilervars.bat batch with intel64 flag. I run b2 with address-model=32, yet in boost libboost_log-iw-mt-gd-x32-1_66.lib is created as an x64 binary (I see it using 'dumpbin /HEADERS libboost_log-iw-mt-gd-x32-1_66.lib') I guess the library is built by default as x64 for some reason.... any idea? Thanks, Boaz. *********************************************************************************************** Please consider the environment before printing this email ! The information contained in this communication is proprietary to Israel Aerospace Industries Ltd. and/or third parties, may contain confidential or privileged information, and is intended only for the use of the intended addressee thereof. If you are not the intended addressee, please be aware that any use, disclosure, distribution and/or copying of this communication is strictly prohibited. If you receive this communication in error, please notify the sender immediately and delete it from your computer. Thank you. Visit us at: www.iai.co.il

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[Container] flat_multimap::erase crash on OSX 10.13.3/AppleClang Release mode
by Ho Cheung 19 Feb '18

19 Feb '18

Hi all, Please see attached CMakeLists and cpp file for minimal reproducible example. The throw seems to not always trigger (roughly 20-30% failure rate for me). Compiler: hoc$ clang --version Apple LLVM version 9.0.0 (clang-900.0.39.2) Target: x86_64-apple-darwin17.4.0 Thread model: posix InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin hoc$ system_profiler SPSoftwareDataType | grep Version System Version: macOS 10.13.3 (17D47) Kernel Version: Darwin 17.4.0 -- This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited.

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[boost] Yap's formal review is starting now!
by Louis Dionne via Boost 16 Feb '18

16 Feb '18

Dear Boost community, The formal review of Zach Laine's Yap library starts Monday, February 5th and ends on Wednesday, February 14th. Yap is a C++14-and-later library to build expression templates. Yap uses new features introduced in C++14/17 to make the library simpler to use and compile faster than existing solutions, such as the well known Boost.Proto library. The documentation is available here: https://tzlaine.github.io/yap/doc/html/index.html The GitHub repository is available here: https://github.com/tzlaine/yap We encourage your participation in this review. At a minimum, please state: - Whether you believe the library should be accepted into Boost - Your name - Your knowledge of the problem domain You are strongly encouraged to also provide additional information: - What is your evaluation of the library's: * Design * Implementation * Documentation * Tests * Usefulness - Did you attempt to use the library? If so: * Which compiler(s)? * What was the experience? Any problems? - How much effort did you put into your evaluation of the review? All issues discussed during this review will be tracked on the library's GitHub issue tracker at https://github.com/tzlaine/yap/issues. Regards, Louis Dionne P.S.: I've been having trouble posting to this list. If this ends up being a duplicate post, let's make this one the official one. _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

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I search information about directory_iterator
by Andy 16 Feb '18

16 Feb '18

I have: #include <boost/filesystem.hpp> namespace fs=boost::filesystem; for (auto& de : fs::directory_iterator("D:\\prog\\alg\\Diff")) { fs::path p = de.path(); auto ext = fs::extension(p); } directory_iterator is object or non-objective method? How can I write something similar, but database iterator. I want get information from mySQL. The simplest way is add everything returning by select to vector of vector of string. But I prefer database iterator. How it write? How is in general directory_iterator as a iterator model?

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We need more mentors for GSoC
by David Bellot 14 Feb '18

14 Feb '18

Hi Boost community, we have already a few mentors, but we need more. If you're interested working with top-level C++ students from all around the world, please contact me and I'll add you to the list of mentors. We need more mentors now ! Best regards, David

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Boost C++ is a mentoring organization for GSoC'18 !
by David Bellot 12 Feb '18

12 Feb '18

We just received this message from Google. It says it all ! *Congratulations! Boost C++ Libraries has been selected as a Google Summer of Code 2018 mentor organization.* This year again, we will be a mentoring organization for the Google Summer of Code. If you want to be a mentor, please contact me right now and register on the Google Summer of Code website too. Best regards, David

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