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[Release 1.70] Master branch is now closed for the beta
by Marshall Clow 07 Mar '19

07 Mar '19

Except with explicit permission by a release manager. Do whatever you want on develop, just don't change master. We'll re-open master after the beta. As always, check the calendar at https://www.boost.org/development 6-Mar: Boost 1.70.0 closed for all changes 13-Mar: Boost 1.70.0 beta; master branch re-opened 2-Aug: Release closed for all changes, except by permission of a release manager. 3-Apr: Boost 1.70.0 closed for all changes 10-Apr: Boost 1.70.0 release -- The release managers

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[build] Boost.Build/develop broken with msvc?
by John Maddock 07 Mar '19

07 Mar '19

Currently I see: D:/data/boost/boost/tools/build/src/tools\msvc.jam:1388: in configure-really *** argument error * rule generate-setup-cmd ( version : command : parent : options * : cpu : global-setup ? : default-global-setup-options : default-setup ) * called with: ( 14.16.27023 14.11.25503 : D:/compilers/visual studio/2017/VC/Tools/MSVC/14.11.25503/bin/HostX64/x64 : D:\compilers\visual studio\2017\VC\Tools\MSVC\14.11.25503\bin\HostX64 : <command>D:\compilers\visual studio\2017\VC\Tools\MSVC\14.16.27023\bin\Hostx64\arm\cl.exe <command>D:/compilers/visual studio/2017/VC/Tools/MSVC/14.11.25503/bin/HostX64/x64/cl.exe : i386 : : x86 : vcvars32.bat ) * extra argument 14.11.25503 D:/data/boost/boost/tools/build/src/tools\msvc.jam:1003:see definition of rule 'generate-setup-cmd' being called D:/data/boost/boost/tools/build/src/tools\msvc.jam:393: in configure D:/data/boost/boost/tools/build/src/tools\msvc.jam:345: in msvc.init D:/data/boost/boost/tools/build/src/build\toolset.jam:44: in toolset.using D:/data/boost/boost/tools/build/src/build\project.jam:1104: in using C:\cygwin64\home\John Maddock\user-config.jam:46: in modules.load D:/data/boost/boost/tools/build/src\build-system.jam:255: in load-config D:/data/boost/boost/tools/build/src\build-system.jam:453: in load-configuration-files D:/data/boost/boost/tools/build/src\build-system.jam:607: in load D:\data\boost\boost\tools\build\src/kernel\modules.jam:295: in import D:\data\boost\boost\tools\build\src/kernel/bootstrap.jam:139: in boost-build D:\data\boost\boost\boost-build.jam:17: in module scope Master is fine BTW. Best, John. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

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[interprocess] support for a new synchronisation mechanism
by Dudi Likvornik 06 Mar '19

06 Mar '19

Hi, My name is David, I would like to suggest a new synchronisation mechanism based on linux futex. as far as I saw, its not being supported as of now with in the interprocess communication library. One suggestion is to support a mutex, here is an example, possible partial implementation, based upon the following paper: http://dept-info.labri.fr/~denis/Enseignement/2008-IR/Articles/01-futex.pdf Mutex::Mutex(): m_word(UNLOCK) {} void Mutex::lock() { int lockState = UNLOCK; if(std::atomic_compare_exchange_strong(&m_word, &lockState, static_cast<int>(LOCK_SINGLE)) == false) { if(lockState != LOCK_MANY) lockState = std::atomic_exchange(&m_word, static_cast<int>(LOCK_MANY)); while(lockState != UNLOCK) { #if defined(__linux) syscall(SYS_futex, &m_word, FUTEX_WAIT, LOCK_MANY, nullptr, nullptr, 0); #else throw Exception(__CORE_SOURCE, "wait is not being supported by current platform"); #endif lockState = std::atomic_exchange(&m_word, static_cast<int>(LOCK_MANY)); } } } void Mutex::unlock() { if(std::atomic_fetch_sub(&m_word, 1) == LOCK_SINGLE) return; m_word = UNLOCK; #if defined(__linux) syscall(SYS_futex, &m_word, FUTEX_WAKE, 1, nullptr, nullptr, 0); #else throw Exception(__CORE_SOURCE, "wake is not being supported by current platform"); #endif } bool Mutex::try_lock() { int lockState = UNLOCK; return std::atomic_compare_exchange_strong(&m_word, &lockState, static_cast<int>(LOCK_SINGLE)); } ————————————————————————————————————————————————————————— And a conditional variable: Condition::Condition(): m_command(SLEEP), m_waitersCount(0){} void Condition::signal(Command command) { m_wakeLock.lock(); if(m_waitersCount == 0) { m_wakeLock.unlock(); return; } m_command.store(command, std::memory_order_relaxed); #if defined(__linux) syscall(SYS_futex, &m_command, FUTEX_WAKE, command == NOTIFY_ONE ? 1 : std::numeric_limits<int>::max(), nullptr, nullptr, 0); #else throw Exception(__CORE_SOURCE, "wake is not being supported by current platform"); #endif while(m_command.load(std::memory_order_relaxed) != SLEEP && m_waitersCount.load(std::memory_order_relaxed) != 0){} m_wakeLock.unlock(); } void Condition::wait(std::unique_lock<core::Mutex> &lock) { m_waitersCount++; lock.unlock(); while(true) { while(m_command.load(std::memory_order_relaxed) == SLEEP) #if defined(__linux) syscall(SYS_futex, &m_command, FUTEX_WAIT, SLEEP, nullptr, nullptr, 0); #else throw Exception(__CORE_SOURCE, "wait is not being supported by current platform"); #endif int fromCommand_one = NOTIFY_ONE; if(m_command.compare_exchange_strong(fromCommand_one, static_cast<int>(SLEEP), std::memory_order_relaxed)) { m_waitersCount--; lock.lock(); return; } else if(m_command.load(std::memory_order_relaxed) == NOTIFY_ALL) { if(m_waitersCount.fetch_sub(1, std::memory_order_relaxed) == 1) m_command.store(SLEEP, std::memory_order_relaxed); lock.lock(); return; } } } ConditionVariable::ConditionVariable() {} void ConditionVariable::wait(std::unique_lock<core::Mutex> &lock) { m_condition.wait(lock); } void ConditionVariable::notify_one() { m_condition.signal(Condition::NOTIFY_ONE); } void ConditionVariable::notify_all() { m_condition.signal(Condition::NOTIFY_ALL); } class ConditionVariable { public: ConditionVariable(); ConditionVariable(const ConditionVariable&) = delete; ConditionVariable& operator=(const ConditionVariable&) = delete; void wait(std::unique_lock<Mutex>& lock); template<typename Predict> void wait(std::unique_lock<Mutex>& lock, const Predict& predict) { while(predict() == false) m_condition.wait(lock); } void notify_one(); void notify_all(); private: Condition m_condition; }; Your thoughts of the idea, if any. p.s. Please be soft, its my first post ever :).

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Boost.uBLAS [gsoc19]
by Sarthakag 06 Mar '19

06 Mar '19

Hello, I am Sarthak Agarwal, 3rd-year undergraduate student from Birla Institute of Technology and Science, Pilani - Goa, India currently pursuing a double major MSc. Mathematics and B.E. Computer Science and Engineering. I am an active Competitive Programmer on various online judges for the last 4 years. I am comfortable in C/C++(STL) and Python(Django). I wish to contribute to Boost.uBLAS, specifically to Project 4 on implementing non-negative matrix factorization(NMF). I would also like to know if there are any upcoming ideas to implement in Boost.intrusive. I have completed the Boost Competency test and learned a lot while doing it. How can I share it for valuable feedback? I look forward to your guidance. Sarthak Agarwal -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Dev-f2600599.html

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Regarding GSOC'19
by Keshav Gupta 05 Mar '19

05 Mar '19

Hi I am Keshav Gupta from India and wanted to work with Boost during GSOC 2019 on the major topic of Boost GIL. So can you tell me how to proceed with? Regards Keshav Gupta

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[variant2] Need rationale for never-empty guarantee
by Andrzej Krzemienski 04 Mar '19

04 Mar '19

Hi Peter, Thank you for writing and sharing this implementation of variant. I am sorry if I am bringing back an issue that has been already discussed and solved before, but I do not understand the rationale behind doing compromises in order to provide the never-empty guarantee. The short rationale provided in Boost.Variant library: https://www.boost.org/doc/libs/1_69_0/doc/html/variant/design.html#variant.… was provided before we got C++11 the moved-from state in the language. Today, it should come as no surprise to programmers that a type might be in a "moved from" state where only a limited interface of an object can be used. The guarantee provided by variant's assignment is not a strong exception safety guarantee: it is possible that my variant has value A, I want to assign value B, and (due to an exception) I end up with value C. If this happens, the only thing I can reasonably do is to either abandon whatever I was doing or reset the variant to the state that I need. So the guarantee that it is not left empty does not seem to be of much use. But the cost to be paid is noticeable. I think that this question should be addressed in the documentation. Regards, Andrzej

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[gsoc19][astronomy] Code for review
by Avinal Kumar 04 Mar '19

04 Mar '19

where should I submit my code for programming competency test ??

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Mentors invitations
by David Bellot 04 Mar '19

04 Mar '19

Dear Boost C++ mentors, it seems we only have 5 mentors this year. It's not a lot. Usually, we have one student per mentor, but we also have 6 to 8 students as well. We need at least one or two mentors more. I've just sent the invite from the GSOC website to become a mentor. If you didn't receive it yet, it's surely because I forgot your name. Can you please send me a reminder now with your correct email address? If you didn't propose to become a mentor but want to now, please let me know as well. Cheers, David

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GSoC 2019 Introduction|Boost.Python-C++-Python Integration Project
by Roopkatha Samanta 04 Mar '19

04 Mar '19

Hi, I am Roopkatha Samanta, studying in 2nd year CSE (undergrad) at Jadavpur University, Kolkata, India. I am very well versed with programming languages like C, C++, Python and Java. I am very much into mathematics too and also interested in machine learning and deep learning. Presenly I am working on two projects in domain of Image Processing as my undergrad project and also trying to develop games on my own. I would like to contribute toBoost.Python-C++-Python Integration Project as my GSoC 2019 Project. Kindly guide me through the process on how to start. Regards, Roopkatha Samanta

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[gsoc19] Logo
by Cem Bassoy 04 Mar '19

04 Mar '19

Hi, is there a chance to change the current logo on the organization list https://summerofcode.withgoogle.com/organizations/?sp-page=5 with https://de.wikipedia.org/wiki/Boost_(C%2B%2B-Bibliothek)#/media/File:Boost.… The current image on the google summer of code page does not look too good and all other organization have smooth ones. Best Cem

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GSoC 2019
by Shourya IIT B 04 Mar '19

04 Mar '19

Respected Sir, I am Parashuram Shourya from India. Currently, I am doing my Master’s in Geoinformatics from Centre of Studies in Resources Engineering(CSRE), Indian Institute of Technology Bombay(IITB). I have a Bachelor's degree in Computer Science and Engineering. Currently, I am learning Machine Learning and High-Performance Computing. I have vast programming experience in C, C++, Python I would love to contribute to The Qt Project in the upcoming Google Summer of Code 2019. I would be very grateful to get any directions to start with so that I can pursue and participate in GSoC 2019 with your organization.

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GSoC 2019: we're in again!
by David Bellot 04 Mar '19

04 Mar '19

Dear Boost community, this year again, Boost C++ has been accepted as a mentor organization for the Google Summer of Code 2019. We are very happy to be part of this program every year because it brings talented students and a substantial amount of money to our organization to support our work toward the best libraries in C++. If you want to be a mentor, please propose your project now here: https://github.com/boostorg/boost/wiki/Google-Summer-of-Code:-2019 It's very important to write your proposal as soon as possible to attract the best students. If you have any questions, please contact me immediately. If you happen to be in Sydney, come and have a chat with me directly. Happy coding, David

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Regarding project idea for GSOC 2019
by Syed Souban 04 Mar '19

04 Mar '19

Hi guys! I am a machine learning enthusiast looking forward to work in implementing some machine learning algorithms in c++ as a gsoc 2019 project. I know that a similar project has been done last year. So in a way I want to extend to that idea. I needed some suggestions and or pointers on which algorithms are feasible to implement. Regards, Souban

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(no subject)
by Roopkatha Samanta 04 Mar '19

04 Mar '19

I want to contribute to boost C++-Python integration project for my GSoC 2019 project.

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[Boost.Intrusive]
by PREET THAKKAR 03 Mar '19

03 Mar '19

I am a 2nd year computer science student. I want to contribute to Boost.Intrusive as part of GSoC '19. I have some ideas to enhance Boost.Intrusive and also add more features to previous year's project in Intrusive. I am new to Boost. Any help regarding getting started with the library would be appreciated. Regards, Preet Thakkar

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Re: [boost] Review request for variant2, review manager wanted
by Peter Dimov 03 Mar '19

03 Mar '19

> If anyone would like to step forward to manage the review, please do. Michael Caisse was the first to graciously offer his services (via Slack) and I'll be glad to have him manage the review. Thanks to Niall who also volunteered. :-) With respect to Niall's request for compile time and run time measurements, I've added a benchmark https://github.com/pdimov/variant2/blob/develop/benchmark/benchmark1.cpp and the results from compiling and running it on my machine are at https://github.com/pdimov/variant2/blob/develop/benchmark/benchmark1.md This is not a cherry-picked example that makes variant2 look good, so it loses to std::variant here and there. :-)

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Runtime code generation
by VIKRAM LODHI 03 Mar '19

03 Mar '19

I am trying to write a grammar based code but can't seems to find starting point. Is there anything I should go through first. Grammar based . All the functions are written in string formats by user and parsed into binary at runtime and are able to use that function.

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[release][multi_index] Permission to merge to master
by Joaquin M López Muñoz 03 Mar '19

03 Mar '19

I'm asking permission to merge the following fairly trivial changes to master: https://github.com/boostorg/multi_index/compare/bbb915bd344463ba767aebe7988… Travis and AppVeyor tests are passing. BTW, the conditions for allowed commits at this release stage ("closed for major changes") are not clear to me. Do I really need to ask for permission if the change (as is this case) is deemed minor? Joaquín M López Muñoz

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Re: [boost] [Boost-testing] Running regression tests for msvc-14.2 (preview)
by Tom Kent 02 Mar '19

02 Mar '19

On Tue, Feb 26, 2019 at 7:13 AM Mateusz Loskot via Boost-Testing < boost-testing(a)lists.boost.org> wrote: > On Tue, 26 Feb 2019 at 14:02, Tom Kent via Boost-Testing > <boost-testing(a)lists.boost.org> wrote: > > I was hoping to start running regression tests for the upcoming Visual > Studio 2019 (toolset 14.2) and got stumped by an issue. > > I've set a user-config.jam: > > using msvc : 14.2 ; > > Is this toolset even supported? > > As I explained in > https://lists.boost.org/Archives/boost/2019/02/245143.php, > I had to 'fake' it as 14.1 in project-config.jam: > > using msvc : 14.1 : "C:\\Program Files (x86)\\Microsoft Visual > > Studio\\2019\\Preview\\VC\\Tools\\MSVC\\14.20.27323\\bin\\HostX64\\x64\\cl.exe" > I was able to get the regression tests to run using this workaround in user-config.jam. Here's what the config_info is: https://www.boost.org/development/tests/develop/developer/output/teeks99-te… I'm disappointed that we can't have general support for future versions of msvc. We don't seem to have this problem with pre-release versions of GCC/Clang. https://www.boost.org/development/tests/develop/developer/output/teeks99-02… Tom

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Gsoc 2019 Boost.GIL project
by fady faragallah 02 Mar '19

02 Mar '19

Hi,I am fady faragallah 4th year student at faculty of computer engineering. I am interested in Boost.GIL and would like to contribute to the project. I have good experience in C++ programming and image processing algorithms and I am currently working on image processing and deep learning projects using convolutional neural networks. I need to know where I can deliver the competency test and how to contact the mentors. Thanks

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Interested in working on Boost.GIL
by AvZ NaV 01 Mar '19

01 Mar '19

Hello, I am Arnav Tiwari, a sophomore year undergraduate student of IIT Kharagpur. I am interested in working on Boost.GIL. I have prior experience in image processing and C++ so I feel I will be able to pick up the project and get to work quickly. I would really appreciate it if someone can point me in the right direction to get started. I hope I'm not spamming the mailing list, apologies if that is the case. -- Regards, Arnav Tiwari

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Re: [boost] [variant2] Need rationale for never-empty guarantee
by Nikita Kniazev 01 Mar '19

01 Mar '19

> This reply actually addresses my question: visitation on boost::variant2 is > faster than on std::variant because it does not have to account for the > valueless state. I would not expect perfomance differences on CPUs with branch predictor or if visitation translated into jump table (variant uses switch for this?). > For example, resizing a std::vector implements the strong guarantee that > state will be restored to before the resize if an exception is thrown in > the middle of the resize. Probably one should use different container type if a data types move/copy can throw. There even a vector implementation that will not copy/move on resize https://www.youtube.com/watch?v=Ke1mJiGO-pU (for CPU with virtual memory).

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[appveyor] basic question
by Raffi Enficiaud 01 Mar '19

01 Mar '19

Hi Boost, Can somebody explain me like I am 5 what I need to do in order to activate Appveyor builds for boost.test? I am not admin of the repository. Thanks! Raffi

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Review request for variant2, review manager wanted
by Peter Dimov 28 Feb '19

28 Feb '19

I'd like to request a formal Boost review for the Variant2 library, https://github.com/pdimov/variant2. Variant2 contains an implementation of a variant<T...> type that is an almost conforming std::variant, except it doesn't require C++17 and supports C++11 and above. It's also never valueless and has a few other extensions. The same library also contains an expected<T, E...> type, which is like the proposed std::expected<T, E>, but supports more than one error type. expected<> is not yet production-ready and has no test suite, but I will finish it if the library is accepted. The documentation for the variant<T...> class is at https://pdimov.github.io/variant2/index.html. If anyone would like to step forward to manage the review, please do.

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Contributing to Boost.Algorithm
by Juho Lauri 28 Feb '19

28 Feb '19

Hello all, I'd be interested in contributing towards Boost.Algorithm - what's the appropriate way forward? Or perhaps this question has already been asked somewhere and I'd appreciate if you could point me to the right place. Thanks

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