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Boost MSM parallel behavior with delayed self-transitions?
by Christophe Henry 22 Mar '17

22 Mar '17

Hi Danylo, >Hi community, > > I am using Boost MSM (basic and functor front-ends) and am trying to >implement the following state machine (https://i.stack.imgur.com/K79qk.png ): Ok, State1 is itself a state machine (also called composite). See: http://www.boost.org/doc/libs/1_63_0/libs/msm/doc/HTML/ch02s02.html#d0e151 and: http://www.boost.org/doc/libs/1_63_0/libs/msm/doc/HTML/ch03s02.html#d0e529 Then you have 2 active states, which are called orthogonal regions. See: http://www.boost.org/doc/libs/1_63_0/libs/msm/doc/HTML/ch03s02.html#d0e577 >I am using Boost MSM (basic and functor front-ends) and am trying to >implement the following state machine: enter image description here > >In words: < snip > > >I would like to know the way to create this state machine in Boost MSM. The above link has an example. >There are two tricks here which I cannot figure out how to do: > > - Execution in parallel (i.e. running action_A does not stop running >action_B at the same time) It depends what you mean with "in parallel". Having 2 active states means that the actions execute only logically at the same time, meaning within the same process_event call. But as you have just one thread, they will execute after each other. If you mean in different threads, then no, the library does not support this. But my next library, Asynchronous does ( https://github.com/henry-ch/asynchronous) I have examples with state machines, timer, etc. >- Delayed transition (i.e. the transitions which happen after 2 >seconds for state A and after 5 seconds for state B). Neither delay >should be blocking! The transitions should just "fire" after this time. Sorry, this is out of scope of the library as it would involve threads. You can do one of the following: - use your own timer (Boost.Asio offers one) and handle thread safety yourself. - have a look at Asynchronous. Sorry if it looks like advertising, but the library was written for this kind of things. >Thank you very much for helping, > >Danylo. HTH, Christophe

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Re: [boost] [gsoc17] Project1: Static map: Can I implement the competency test in g++-7?
by Vic Luo 22 Mar '17

22 Mar '17

Hi, In the last few days I finished a toy implementation with continuous integration at https://github.com/htfy96/gsoc-static-map, which has been tested on g++5/6 and clang++3.8/3.9. Current test failure is as expected due to g++-5's incomplete constexpr optimization. Besides, my proposal draft has been submitted which includes a very tiny benchmark with boost::hana on compile-time lookup performance on map<int, int> structure. Any kind of suggestion is welcomed at https://gist.github.com/htfy96/0bd9b3200d9a0e67f449edc40bfa43b5*. * Thanks,* * -- --------------------------------- Vic Luo Shanghai Jiaotong University Key fingerprint 0x98809ca08bf5662a

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Re: [boost] [release] 1.64.0 please test master snapshot
by Olaf van der Spek 22 Mar '17

22 Mar '17

On Wed, Mar 22, 2017 at 12:45 PM, Andrey Semashev <andrey.semashev(a)gmail.com> wrote: >> Right, boostorg doesn't have tickets enabled though.. where should I >> open a ticket? > > > Probably, in Trac: I hate Trac. > https://svn.boost.org/trac/boost/newticket?component=algorithm;version=Boos… > > Although since it's fixed in develop and there is a PR for merge to master, > I'm not sure there's much point in a ticket. I meant in general. -- Olaf

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Re: [boost] [release] 1.64.0 please test master snapshot
by Andrey Semashev 22 Mar '17

22 Mar '17

And once again, this went to Olaf directly instead of the list. Re-sending. On 03/22/17 14:45, Andrey Semashev wrote: > On 03/22/17 13:45, Olaf van der Spek wrote: >> On Wed, Mar 22, 2017 at 11:05 AM, Andrey Semashev via Boost >> <boost(a)lists.boost.org> wrote: >>> On 03/22/17 11:59, Olaf van der Spek via Boost wrote: >>>> >>>> VC2015 /std:c++latest: >>>> >>>> struct to_lowerF : public std::unary_function<CharT, CharT> >>>> >>>> boost\algorithm\string\detail\case_conv.hpp(33): error C2143: syntax >>>> error: missing ',' before '<' >>> >>> >>> This seems to be fixed in develop but not merged to master. I've >>> created a >>> PR to do the merge: >>> >>> https://github.com/boostorg/algorithm/pull/34 >>> >>>> https://github.com/mclow/String-Algo/issues/7 >>> >>> >>> That ticket is for a fork, not the boostorg repo. >> >> Right, boostorg doesn't have tickets enabled though.. where should I >> open a ticket? > > Probably, in Trac: > > https://svn.boost.org/trac/boost/newticket?component=algorithm;version=Boos… > > > Although since it's fixed in develop and there is a PR for merge to > master, I'm not sure there's much point in a ticket. >

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Re: [boost] GSoC proposal
by Vissarion Fisikopoulos 22 Mar '17

22 Mar '17

Hi Rasul, thanks for your interest in Boost.Geometry. I guess you have already read this https://svn.boost.org/trac/boost/wiki/SoC2017 There are two possibilities: either you provide a library (with some standards described in the webpage) or you do the test. My opinion is that doing the test (even if not needed) will first strengthen your application and second will give you a good overview of the problem you are going to work on, if selected. >From your repo what is the library that you propose for your application and meets the requirements described in the webpage above (e.g. no coursework, more than 6 months old etc)? The tests are described here: https://svn.boost.org/trac/boost/wiki/SoC2017#a3.Boost.Geometry Depending on what (?) project you prefer to pursue there is a corresponding test. Best, Vissarion ps. I copy the message to boost list so the community can follow and provide feedback if needed On 22 March 2017 at 12:00, Rasul Kerimov <rkerimov(a)std.qu.edu.az> wrote: > Hey Mr. Fysikopoulos, > > I'm really interested in Boost GSoC 2017 project proposal, but I don't > know how to pass Programming competency Test. > > I have a github repo with all my codes that I wrote in C++, but I > don't know if it's enough to pass test. > > Github page: https://github.com/CoderINusE/ > Github repo: https://github.com/CoderINusE/Algorithms-data-structues > > I will be grateful for any response. Thank you!

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[release] 1.64.0 Delayed because of Microsoft (version numbers)
by Rene Rivera 21 Mar '17

21 Mar '17

Sorry to say the beta release of 1.64.0 is hereby going to be delayed for at least another week. The confusion of VS2017 version numbers and the communities inability to address this issue after the beta is to blame. To address the situation the beta release will be published when one of the two tasks below are completed: (A) Boost Config changes to use 1410 as the autolink version to match what the currently working generated libs are taggeg with. Or: (B) The community decides what version number we should be using and the appropriate PRs are filed and applied and tested for all the repos involved. Which means: 1. The community has until 12:00 CDT US March 18 to decide on what the vc version number and tag should be. 2. The community must post PRs for the places where we reference VS2017 version numbers to the new number. Those are at least: <https://github.com/boostorg/config> <https://github.com/boostorg/build> <https://github.com/boostorg/boost> <https://github.com/boostorg/website> People have until 17:00 CDT Monday March 20 to submit those PRs. 3. The community can test the resulting master snapshot when available at the latest 24:00 Monday March 20. 4. If all goes well we can have a beta release on Wednesday March 22 (ie one week late). -- -- Rene Rivera -- Grafik - Don't Assume Anything -- Robot Dreams - http://robot-dreams.net -- rrivera/acm.org (msn) - grafikrobot/aim,yahoo,skype,efnet,gmail

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[stacktrace] Review
by Peter Dimov 21 Mar '17

21 Mar '17

I think that the Stacktrace library should be ACCEPTED. The design is good. It's unfortunate that to get a stacktrace class that stores the capture internally in a fixed-size array, as the first iteration did, one has to write a special allocator, more so because such an allocator isn't readily available (we don't have one in Boost, for instance). This could easily be addressed by templating basic_stacktrace on a container (default std::vector<frame>) instead, which would allow boost::container::static_vector to be used. The implementation is good. The main problem here, as already discussed in detail, is that under Windows clients of the library that don't make use of the facilities that require windows.h and COM headers to be included still suffer the penalty of this inclusion. Fixing this will be a significant increase in usability. The documentation is adequate, although it could use some editing by a native speaker. The library is potentially very useful. Assert handlers, exceptions and termination handlers can (and should) all make use of it. Wide use under Windows is however hampered by the limitation described above. I tested the library under Windows with msvc-14.0, 14.1, Cygwin g++/clang++. Under Cygwin there is no libbacktrace, but defining BOOST_STACKTRACE_USE_ADDR2LINE worked. I invested a fair chunk of time into my evaluation of the library, and am reasonably knowledgeable about the problem domain.

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Re: [boost] [smart_ptr] Is there any interest in unique_ptr with type erased deleter?
by Andrey Davydov 21 Mar '17

21 Mar '17

On Tue, Mar 21, 2017 at 4:11 PM, Andrey Semashev <andrey.semashev(a)gmail.com> wrote: > On 03/21/17 14:54, Andrey Davydov wrote: > >> On Tue, Mar 21, 2017 at 2:15 PM, Andrey Semashev via Boost >> <boost(a)lists.boost.org <mailto:boost@lists.boost.org>> wrote: >> >> On 03/21/17 12:54, Andrey Davydov via Boost wrote: >> >> On Tue, Mar 21, 2017 at 12:00 PM, Richard Hodges >> <hodges.r(a)gmail.com <mailto:hodges.r@gmail.com>> wrote: >> >> What is required, more than simply creating a type-erased >> deleter? >> >> >> Also deleter must capture pointer, because pointer which was >> passed to >> constructor can differ from the pointer which will be deleted. >> For example, >> >> struct Base { /* ... */ }; >> struct Derived : Base { /* ... */ }; >> >> ptr<Derived> p1(new Derived); >> void * raw_p1 = p1.get(); >> ptr<Base> p2 = std::move(p1); >> void * raw_p2 = p2.get(); >> assert(raw_p1 != raw_p2); >> >> >> The above piece of code strikes me as very unsafe and better be >> avoided in the first place. Designing new tools to handle this case >> is IMHO misguided. >> >> Why this code is very unsafe? If change `ptr` to `shared_ptr` this will >> become perfectly valid and widely used pattern. >> > > Because comparing the void pointers is not safe in general. The above code > in particular will probably work (although not sure if even that's > guaranteed, depending on whether Base and Derived qualify as standard > layout classes), but if the class hierarchy is different, that code will > silently break. I agree, I wrote this code just to demonstrate that deleter must capture pointer because it can be changed due to upcasting. > But, of course, nothing stops you from saving the state in the deleter. > > struct poly_deleter > { > template< typename T > > poly_deleter(T* p) : m_p(p), m_delete(&poly_deleter::do_delete< T >) > { > } > > void operator() (void*) const noexcept > { > m_delete(m_p); > } > > private: > template< typename T > > static void do_delete(void* p) noexcept > { > delete static_cast< T* >(p); > } > > void* m_p; > void (*m_delete)(void*); > }; > > This will work even if you form std::unique_ptr<void, poly_deleter> (i.e. > don't have a universal base class). > Your poly_deleter implementation is the same as I used inside my smart pointer implementation, but there is an issue with std::unique_ptr<T, poly_deleter>, namely it is not constructible from std::unique_ptr<T, std::default_delete<T>> because poly_deleter must capture pointer and so it is not constructible from std::default_delete. -- Andrey Davydov

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[smart_ptr] Is there any interest in unique_ptr with type erased deleter?
by Andrey Davydov 21 Mar '17

21 Mar '17

It is widely known that deleter type is part of std::unique_ptr type. It is the most effective decision, but sometimes not very convenient. The most important use cases (for me) when std::unique_ptr<T, std::default_delete<T>> doesn't work are following: 1. unique_ptr to incomplete class struct MyClass; unique_ptr<MyClass> create(); auto ptr = create(); // compilation error 2. upcast to base without polymorphic destructor struct Base { // ... // no virtual ~Base() here }; struct Derived : Base { // ... }; unique_ptr<Base> ptr = make_unique<Derived>(); // compiles by leaks! 3. unique_ptr with non-default deleter unique_ptr<FILE, int (FILE *)> open_file(std::string const & path) // works but looks ugly, why should the fact that fclose returns `int` be visible from the signature of the function `open_path`? { return { std::fopen(path, "r"), &std::fclose }; } Of course, all this examples could be fixed if unique_ptr would be replaced by shared_ptr, but the semantic of the shared ownership is not desirable often. I have implemented smart pointer with semantics of unique ownership and type erased deleter (https://github.com/AndreyG/unnamed) It has size of 3 pointers and it doesn't require additional memory allocations for the case when deleter is empty class (for example, std::default_delete or non-capturing lambda) and for the case when deleter is known at compile time function (for instance, fclose). The are some simple examples of usage and tests in the repo. Why don't just use unique_ptr<T, function<void (void *>>? The main reason is that due to the small object optimization std::function has rather big size. For instance, sizeof(unique_ptr<T, function<void (void *>>) == 72 for MSVC x64! Results for the other platforms can be found in the repo README. Does it seem useful? -- Andrey Davydov

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[GSOC17] Regarding project Boost.uBLAS
by SHIVAM MITTAL 21 Mar '17

21 Mar '17

Hi, I am *Shivam Mittal*, a sophomore student of *Computer Science & Engineering *discipline of *Indian Institute of Technology, Ropar, India.* I wish to contribute to *Boost.uBLAS*, and develop cool and useful things with the community in GSOC 17. While going through the ideas list, I found the project *Data.Frames in boost.uBlas *very interesting and suitable for me. I think I am well prepared for the task as described in the requirement section. I am very comfortable in C/C++ and fairly comfortable in MATLAB, Python, HTML, CSS, PHP, SQL. I have more than 6 years of experience coding in C++. I have been developing data structures, algorithms, hardware simulators, artificial intelligence programs, and miscellaneous things in C++. The coursework (relevant to this project) which I have completed is : 1. Introduction to computing (in C++) 2. Data structures (in C++) 3. Linear Algebra Some of my selected projects are uploaded on github: https://github.com/shivam5 Please have a look at them. Some projects which I have implemented in C++ are: 1. Simple_RISC plagiarism checker 2. Simple_RISC functional and pipeline simulator 3. Pattern matching system by implementing hash tables. 4. Implementing graphs 5. Implementing AVL and Red black trees 6. Solcvng combinatorial auctions 7. Room booking system 8. Sudoku Solver I have implemented the programming competency test and sent the mentor on personal mail. Can you guide me further on how should I proceed and increase my chances of getting selected. Thank You, Shivam Mittal B.Tech Computer Science & Engineering, IInd Year Indian Institute of Technology Ropar Phone: +91-9888927245, +91-9899461223

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Boost MSM parallel behavior with delayed self-transitions?
by Danylo Malyuta 21 Mar '17

21 Mar '17

Hi community, This is my first post, so I'm sorry for any mistakes in style. I have also posted this question on StackOverflow: http://stackoverflow.com/questions/42920777/boost-msm-parallel-behavior-wit…. I am using Boost MSM (basic and functor front-ends) and am trying to implement the following state machine (https://i.stack.imgur.com/K79qk.png) enter image description here I am using Boost MSM (basic and functor front-ends) and am trying to implement the following state machine: enter image description here In words: 1. Enter state State1 2. Enter state A and execute action_A. After 2 seconds, print "Trying again..." and re-execute state A (i.e. call its entry action). This loops forever... 3. At the same time as 2 (i.e. "in parallel"), enter state B and execute action_B. After 5 seconds, print "Trying again..." and re-execute state B (i.e. call its entry action). This loops forever... I would like to know the way to create this state machine in Boost MSM. There are two tricks here which I cannot figure out how to do: - Execution in parallel (i.e. running action_A does not stop running action_B at the same time) - Delayed transition (i.e. the transitions which happen after 2 seconds for state A and after 5 seconds for state B). Neither delay should be blocking! The transitions should just "fire" after this time. Thank you very much for helping, Danylo.

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Fwd: [gsoc17] Regarding Boost.Geometry
by Aditya Gupta 21 Mar '17

21 Mar '17

Hi I am Aditya Gupta, IInd Yr. B. Tech. Computer Science at IIT Ropar and I wish to work on Project 3 of Boost.Geometry (Nearly antipodal points distance accuracy improvement.) I have completed the competency test <https://github.com/adityagupta1089/earth-geometry>, but I think maybe it was too small or have I misinterpreted, anyways. I have an initial draft of my [GSoC proposal](https://gist.github. com/adityagupta1089/39863577e1716c55d86c98ff57623893) I have also attached my CV.

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Re: [boost] [smart_ptr] Is there any interest in unique_ptr with type erased deleter?
by Andrey Semashev 21 Mar '17

21 Mar '17

For some reason my email went directly to Andrey instead of the mailing list. I'm re-sending the message below. PS: This has happened to me multiple times now after we moved the ML infrastructure. Is there a way to protect oneself from such mistakes? Am I the only one so inattentive to have this problem? On 03/21/17 16:11, Andrey Semashev wrote: > On 03/21/17 14:54, Andrey Davydov wrote: >> On Tue, Mar 21, 2017 at 2:15 PM, Andrey Semashev via Boost >> <boost(a)lists.boost.org <mailto:boost@lists.boost.org>> wrote: >> >> On 03/21/17 12:54, Andrey Davydov via Boost wrote: >> >> On Tue, Mar 21, 2017 at 12:00 PM, Richard Hodges >> <hodges.r(a)gmail.com <mailto:hodges.r@gmail.com>> wrote: >> >> What is required, more than simply creating a type-erased >> deleter? >> >> >> Also deleter must capture pointer, because pointer which was >> passed to >> constructor can differ from the pointer which will be deleted. >> For example, >> >> struct Base { /* ... */ }; >> struct Derived : Base { /* ... */ }; >> >> ptr<Derived> p1(new Derived); >> void * raw_p1 = p1.get(); >> ptr<Base> p2 = std::move(p1); >> void * raw_p2 = p2.get(); >> assert(raw_p1 != raw_p2); >> >> >> The above piece of code strikes me as very unsafe and better be >> avoided in the first place. Designing new tools to handle this case >> is IMHO misguided. >> >> Why this code is very unsafe? If change `ptr` to `shared_ptr` this will >> become perfectly valid and widely used pattern. > > Because comparing the void pointers is not safe in general. The above > code in particular will probably work (although not sure if even that's > guaranteed, depending on whether Base and Derived qualify as standard > layout classes), but if the class hierarchy is different, that code will > silently break. > >> Now, I can understand the need to perform casts on smart-pointers, >> but they should still provide some level of safety, at least the >> same level that is provided by pointer casts in the core language. >> But supporting casts should not require a new smart-pointer. And >> indeed it doesn't: >> >> template< typename U, typename T, typename D > >> std::unique_ptr< U, D > static_pointer_cast( >> std::unique_ptr< T, D >&& p) >> { >> D d = p.get_deleter(); >> return std::unique_ptr< U, D >( >> static_cast< U* >(p.release()), >> std::move(d)); >> } >> >> What is `D`? If it is std::default_delete<T> then function result type >> will be std::unique_ptr<U, std::default_delete<T>> and unlikely this >> type is very useful (even if it compiles). > > Ok, that won't work with std::default_delete<T>. But it will work with > this deleter: > > struct static_polymorphic_deleter > { > template< typename T > > void operator() (T* p) const noexcept > { > std::default_delete<T>()(p); > } > }; > > And it should work with a runtime polymorphic deleter that can be > written to implement your proposal (see below). > >> The other part of your proposal, which is polymorphic behavior with >> a deleter knowing the type to call the destructor on, can be solved >> by a custom deleter. I'm not sure a generalized version of such >> deleter would have a large demand, given that there is the >> alternative TONGARI J suggested, but I'm not opposed to a proposal. >> >> May be I doesn't understand what TONGARI J suggested, but >> how can `unique_ptr<T, void(*)(T*)>` hold stateful deleter? > > It doesn't, unless the required state is contained within the object > itself. But just to implement runtime polymorphism, no additional state > is required. > > struct base > { > protected: > ~base() = default; > }; > > struct derived : base > { > }; > > template< typename T > > void poly_deleter(base* p) noexcept > { > delete static_cast< T* >(p); > } > > template< typename T > > using poly_unique_ptr = std::unique_ptr< T, void(*)(base*) >; > > template< typename T > > poly_unique_ptr< T > make_poly_unique() > { > T* p = new T(); > return poly_unique_ptr< T >{ p, &poly_deleter< T > }; > } > > poly_unique_ptr< derived > pd1 = make_poly_unique< derived >(); > poly_unique_ptr< base > pb1 = std::move(pd1); > poly_unique_ptr< derived > pd2 = > static_pointer_cast< derived >(std::move(pb1)); > > But, of course, nothing stops you from saving the state in the deleter. > > struct poly_deleter > { > template< typename T > > poly_deleter(T* p) : m_p(p), m_delete(&poly_deleter::do_delete< T >) > { > } > > void operator() (void*) const noexcept > { > m_delete(m_p); > } > > private: > template< typename T > > static void do_delete(void* p) noexcept > { > delete static_cast< T* >(p); > } > > void* m_p; > void (*m_delete)(void*); > }; > > This will work even if you form std::unique_ptr<void, poly_deleter> > (i.e. don't have a universal base class). >

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Problem with using matrix library with unit test library
by SHIVAM MITTAL 21 Mar '17

21 Mar '17

Hi everyone, I have been developing something, and basically it requires the two boost libraries - the matrix library and unit test library. I have a file test.cpp : #include <boost/numeric/ublas/matrix.hpp> #include <boost/numeric/ublas/io.hpp> #include <boost/test/included/unit_test.hpp> #define BOOST_TEST_DYN_LINK #define BOOST_TEST_MODULE test BOOST_AUTO_TEST_SUITE(Integer_matrices) BOOST_AUTO_TEST_CASE(Constructors) { BOOST_CHECK(2 == 2); } BOOST_AUTO_TEST_SUITE_END() I am compiling this with: g++ -I <path to boost_1_63_0> test.cpp I'm getting the following error: /tmp/ccnxRzsf.o: In function `main': test.cpp:(.text+0x18aa1): undefined reference to `init_unit_test_suite(int, char**)' collect2: error: ld returned 1 exit status Any help will be greatly appreciated. Thanks.

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[Convert] std::isspace requires unsigned #28
by Olaf van der Spek 21 Mar '17

21 Mar '17

Hi, > boost\convert\base.hpp(112): warning C6330: 'const char' passed as _Param_(1) when 'unsigned char' is required in call to 'isspace'. > boost\convert\base.hpp(115): warning C6330: 'const char' passed as _Param_(1) when 'unsigned char' is required in call to 'isspace'. https://github.com/boostorg/convert/issues/28 IMO the code should be fixed and it's not a documentation issue. What do you think? -- Olaf

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Re: [boost] [release] 1.64.0 Delayed because of Microsoft (version numbers)
by Tom Kent 20 Mar '17

20 Mar '17

Sorry all, I meant to send this to the list but only replied to Daniel. This adds an option 4 and 5. On Sun, Mar 19, 2017 at 3:58 PM, Tom Kent <lists(a)teeks99.com> wrote: > > > On Sun, Mar 19, 2017 at 10:17 AM, Daniel James <dnljms(a)gmail.com> wrote: > >> On 19 March 2017 at 13:10, Tom Kent via Boost <boost(a)lists.boost.org> >> wrote: >> > >> > Option 1 - 14.10 Use microsoft toolset version based on cl.exe version >> -5. >> > This is the official version of the c++ toolset that microsoft has been >> > pushing (somewhere). The new $(VCToolsVersion) macro is "14.10.25017", >> this >> > macro is not available in previous versions of visual studio. >> > >> > build bootstrap would use bootstrap.bat vc1410 >> >> [snip] >> >> > Option 2 - 14.1 Use the abbreviated toolset version that microsoft uses >> for >> > their toolset version. The $(PlatformToolsetVersion) macro is "141". In >> > VS2015 this was "140". >> >> [snip] >> >> > I *think* that is all the reasonable options. Let the consensus form! >> >> I disagree, I think we should limit ourselves to values that Microsoft >> actually uses. As far as I'm aware, they don't use 1410, and they >> don't use 14.1. There are already too many ways of writing the version >> number, adding more will just add to the confusion. >> > > So 2-a would meet these requirements. However, I did overlook the mixed > options: > > Option 4 (141 and 14.10) - > build bootstrap would use bootstrap.bat vc141 > build of source would use b2 toolset=msvc-14.10 > build would generat libraries of the format libboost_NAME_vc141-OPTIONS-1_ > 64.lib > config would auto-link libraries of the same format > (4-a is the same as 2-a) > > Option 5 (1410 and 14.1) - > build bootstrap would use bootstrap.bat vc1410 > build of source would use b2 toolset=msvc-14.1 > build would generat libraries of the format libboost_NAME_vc1410-OPTIONS- > 1_64.lib > config would auto-link libraries of the same format > (5-a is the same as 1-a) > > Tom > >

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About all these metaprogramming libraries
by Louis Dionne 20 Mar '17

20 Mar '17

Dear Boost, We've seen two metaprogramming libraries ask for a formal review on the list recently. I expect a third (Brigand) might join the party soon, and maybe even a fourth (Eric Niebler's meta). I think it would be wise to have a plan for how we're going to deal with this. Before going further, I'd also like to clear something out. Some people have asked whether "classic" metaprogramming libraries still had their place given that we now have Hana. As the author of Hana, I think the answer is yes. While Hana is (IMHO) easier to use and more powerful, it also has an important shortcoming. Hana is too slow when dealing with very large inputs. This is due to the fact that it can also handle values, which is much heavier than dealing with types only. This can be alleviated to some extent, but the truth is that our execution model (the compiler) simply has to do more work when handling values. Hence, I think Boost does need a modern classic TMP library to handle these cases where a library writer needs to handle gigantic type lists. I think marketing such a library as an advanced tool for library writers would be a service to the overall C++ community, but that's an orthogonal concern. However, Boost needs one such library, not four. I think we can't just do 4 reviews and include all the libraries that pass in Boost; that would be a huge disservice to our users, who will be left with the burden of choosing. Heck, if we can't even make our mind, how can they? So, how do we pick? Have we ever been in a similar situation where we have multiple competing libraries solving _exactly_ the same problem? Louis -- View this message in context: http://boost.2283326.n4.nabble.com/About-all-these-metaprogramming-librarie… Sent from the Boost - Dev mailing list archive at Nabble.com.

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Newcomer Contributor to Boost C++ Libraries
by Aman Gupta 20 Mar '17

20 Mar '17

Hello everyone, I am Aman Kumar Gupta, an undergraduate 1st year student from International Institute of Information Technology, Bhubaneswar, India. I'm a newcomer to Boost C++ community. I have ,what i think, medium to good C++ coding background as i've been coding in C++ since past 5-6 years and have won some coding competitions as well. I have a good C++ STL knowledge and am very keen and interested in contributing to Boost's STL libraries. But as i'm a newbie to this community, i'm little confused where and how to start. I would be very glad and thankful if anyone would please help me and guide me through.

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Re: [boost] [gsoc17]The implement of Programming competency test From Ruoyun Jing
by Ruoyun Jing 20 Mar '17

20 Mar '17

Hi Vissarion, 2017-03-20 20:29 GMT+08:00 Vissarion Fisikopoulos <fisikop(a)gmail.com>: > Hi Ruoyun, > > > - The main work I should do during GSoC about project 1 is just to > improve > > the algorithms of compare two distances of two point pairs or try to > > consider different situations which used compare distance predicates to > > avoid calculation? > > the project is about algorithms that does not compute the actual distance > but an approximation (as rough as possible) that suffices to accurately > compare the lengths of two geodesic segments on the ellipsoid > > Thanks for your answer, I have the correct point of these project and will continue to write my proposal. > > - Do "In some algorithms there is the need to compare two distances of > two > > point pairs" this means compare two points distances on Earth? Or on > every > > ellipsoid model? > > the later (see answer above) > > > - Do I need to find the approaches of filter by myself? Could you please > > help me get more information about these? Like the implement detail about > > the predicate compare_distance function, mathematical calculation papers > > about compare distance on ellipsoid? > > Well we give one approach on the website (there is another proposal of > another > candidate on the list). My opinion is that if you understand these > approaches > (pos and cons, differences etc) that will help you towards a solid > application. > Having another idea for an approach will definitely strengthen you > application. > Thanks for your help. I can get the point of those approaches and will try to have new ideas. :) > > - In my view, just like compute the shortest distance between two given > > points on Earth, the background approach can be used. And I used > cartisian > > coordinate to avoid many trigonometric function calculation, but I can > not > > find more improve with my lacking knowledge, could you give me some > aspects > > to get more approaches? > > Please see answer above > > At this point I think it is better to jump to boost list because our > discussion > could interest more people. I will not copy anything of our private > conversation > there but feel free to do the jump and I will continue answering there. > > Btw, any news from you test and comparison with Boost.Geometry. > > I reply you and jump to boost with your advice. Hope this will help more people. :) Vissarion > > ps. you can send questions whenever you want, I will answer them a.s.a.p. > my zone is UTC+2 > > Thanks for your answer. Best regards. Ruoyun -- Northwest University of China Software Engineering jingry0321(a)gmail.com <jingry0321(a)163.com>

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Re: [boost] [geometry] [gsoc17] boost.geometry
by Vissarion Fisikopoulos 20 Mar '17

20 Mar '17

Hi Aman, thanks for your interest in Boost.Geometry and projects 1, 3 in particular. Do you have particular preference between 1 and 3? I think you should specify in your application. Regarding you idea, indeed that could be an option. Do you expect that would be faster or more accurate than the one proposed in the boost GSoC ideas webpage? How would you compare the two approaches? To be clear, I am not testing you but answering that questions could lead to a stronger application. Regarding application there are two options, either you do the competency test or you send a link of a project of you. Please read https://svn.boost.org/trac/boost/wiki/SoC2017 (and links therein) also for details on how to proceed, that is on how to write your proposal. Best, Vissarion. ps. I copy to the boost list for potential feedback from the community On 20 March 2017 at 13:07, Aman Gupta via Geometry <geometry(a)lists.boost.org > wrote: > Respected sir/ma'am > I, Aman Gupta, want to contribute in Boost.Geometry; mainly in Project 1(Filtering > of compare distance predicates) and Project 3( Nearly antipodal points > distance accuracy improvement) . > I have good knowledge in geometry and want to learn more . > > For the problem given in Project 1, another approach I can suggest is to > get 2 intersections of plane (which would be ellipse) with the help given > points and compute the respective distances using those ellipses. > > I hope to get selected for the project work. > > Thanking You. > AMAN GUPTA > resume: https://drive.google.com/open?id=0B9HCqOWnVVvDcm9PQkYtczFjVmM > > _______________________________________________ > Geometry mailing list > Geometry(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/geometry > >

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[gsoc17] boost.geometry
by Aman Gupta 20 Mar '17

20 Mar '17

Respected sir/ma'am I, Aman Gupta, want to contribute in Boost.Geometry; mainly in Project 1(Filtering of compare distance predicates) and Project 3( Nearly antipodal points distance accuracy improvement) . I have good knowledge in geometry and want to learn more . For the problem given in Project 1, another approach I can suggest is to get 2 intersections of plane (which would be ellipse) with the help given points and compute the respective distances using those ellipses. I hope to get selected for the project work. Thanking You. AMAN GUPTA resume: https://drive.google.com/open?id=0B9HCqOWnVVvDcm9PQkYtczFjVmM

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Formal Review Request: mp11
by Peter Dimov 19 Mar '17

19 Mar '17

I'd like to request a review for mp11, a simple C++11 metaprogramming library. The library implements the approach outlined in my two articles http://pdimov.com/cpp2/simple_cxx11_metaprogramming.html http://pdimov.com/cpp2/simple_cxx11_metaprogramming_2.html and is available at https://github.com/pdimov/mp11/ It supports g++ 4.9 and above, clang 3.6 and above, msvc-12.0, 14.0, 14.1. The library is in Boost format and is intended to be placed in libs/mp11 in a Git clone of Boost. There is documentation in doc/html/mp11.html, it can be viewed locally, or with https://htmlpreview.github.io/?https://github.com/pdimov/mp11/master/doc/ht… Please excuse the lack of .css in that link. Thanks in advance for any interest, comments or suggestions.

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[safe_numerics] review results
by Andrzej Krzemienski 19 Mar '17

19 Mar '17

Hi Everyone, This is to inform you that safe_numerics library by Robert Ramey is *CONDITIONALLY ACCEPTED* to Boost. The list of conditions can be found down below. I would like to congratulate Robert for getting the library into Boost, and thank him for the effort to develop a useful library for the community. I also would like to thank everyone who participated in the review and shared their useful feedback. I recorded five reviews with a yes/no vote: - Paul A. Bristow (yes with conditions) - Steven Watanabe (yes with conditions) - John Maddock (yes with conditions) - Antony Polukhin (yes) - Barrett Adair (yes) And three without a vote: - Vicente J. Botet Escriba - John McFarlane - Peter Dimov We also got some feedback from an individual nicknamed "scatters" at Reddit (https://www.reddit.com/r/cpp/comments/5x1z67/boostsafe_ numerics_formal_review_starts_today/deew1kq/), and from Tomasz Kaminski in private conversation. There was a general consensus that the problem of surprises with C++ ints deserves a solution. Some people observed that there are other ways to approach the same problem, but it was agreed that the approach taken by safe_numerics is sound. The acceptance conditions mostly revolve around documenting micro-decisions made by the library, and fixing bugs. They apply to the reviewed GIT commit 3bcfabe1cafb8ef6edf08d3bd8730a1555b1c45d, but I know Robert is already working on fixing them, and has most of them fixed locally. *Acceptance conditions:* - Comply with Boost formal requirements: 1. index.html in root directory that redirects to doc/. 2. all headers in folder include/boost/numeric/. 3. Macro safe_literal: either remove it or let it follow Boost macro naming conventions: BOOST_NUMERIC_SAFE_LITERAL(). - Automatic promotion policy: either just remove it, or fix it so that: - it can see the range of safe_base in order to allow for slower increase in sizeof(), - it is clear from documentation how the promotion mechanism works. - in particular, what type gets selected for bit-wise operators &, | - The division bug (see below) is fixed. - Decide and document up front how the library addresses each of the following different situations: - overflow upon arithmetical operation, - unexpected promotion to unsigned when comparing signed with unsigned number, - arithmetic operation on unsigned int with negative value versus a signed value (-1 + 1u). - bit-wise operation on negative signed integers (unless they are removed), or that would produce one as the result. - division by zero, - operations upon default-constructed int type with indeterminate value, - conversion from float to int, when float contains non-integral value. - conversion from float to int, when float contains an integral value that would overflow upon native conversion - operator% where one operand is negative (for native ints it is implementaiton-defined) - leftshift by 32 bits (on 32-bit int) - Decide and document what safe's default constructor does. - Document upon which operations safe<> throws exceptions (or, signals arithmetic error at run-time). IOW, document in which cases safe<> never throws exceptions (signals run-time failure) because it is able to say that the operation will always succeed. - Document what happens when you invoke an operation on two instances of safe<> with different policies. - Resolve name conflict with interval, which already exists in namespace boost::numeric::interval. Either use a different namespace or a different name. - Remove anonymous namespaces from the header files. Use namespace detail and inline functions instead. - Improve test cases, so that they also check if numeric values of computations are correct (not only whether an operation throws or not). - Use enable_if (or similar) tricks to constrain the overload resolution for your arithmetical operations, so that they only work for numeric types rather than "any type T". - Fix the division bug: safe<signed, automatic> a {-1}; safe<unsigned, automatic> b {2}; auto c = a / b; // this returns 2147483647 <%28214%29%20748-3647> - Either document that safe<T> only works for scalar types (rather than any T that models concept Integer<T>), or provide alternate implementation of safe_base, as described in https://github.com/robertramey /safe_numerics/issues/44 - Fix linker errors when building a program from two cpp files that include safe_numerics headers. The error is caused by non-inline full specializations of operator<<. - Either entirely remove the support for bit-wise ops on signed types (make it a compiler error), or provide a consistent implementation that detects any UB or surprising results. - `++i` should return by reference; `i--` should return by value. *Other important issues* The following are *not *conditions for library acceptance, but I still recommend addressing them before the initial release. - Concepts: what do you need them for? Any other type except built-in scalars does not work anyway. Do you want to show how close safe<T> resembles T? In this case, they need to be changed. If you want to extend safe<T> to other T's, they need to be fixed: https://github.com/robertramey/safe_numerics/issues/46 <https://github.com/robertramey/safe_numerics/issues/46> - IOStreams interoperability needs fixes: - Move to a separate header, so that it does not affect compilation times when not needed (but provide forward declarations, so that implicit conversions to int do not make IOStreams work with unintended semantics) - Fix other problems as per https://github.com/robertramey /safe_numerics/pull/35 - safe<>'s interface is not documented - Make the library compile with -fno-exceptions: https://github.com/robertramey/safe_numerics/pull/31 <https://github.com/robertramey/safe_numerics/pull/31> - Some people fail to see how this library is better than just using rar ints but compiling with a UB-sanitizer. Address this in the documentation. - Prevent inadvertent ADL by putting safe into a nested namespace boost::numeric::save_types, and then in boost::numeric import: `using boost::numeric::save_types::safe`. This way boost::numeric::safe still works, but inadvertent ADL of everything inside namespace boost::numeric is prevented. - Does it make sense to apply bitwise operations on two different types? If so, document the semantics. - Fix header names and paths in documentation. - Consider adding support for saturation policy upon overflow. - Expression `safe<int>{4} ^ 1` does not compile due to overload resolution ambiguity. - Fix constexpr usages. - If possible, make workarounds in order to make the library work with MSVC. - Document that operations on safe<> do not thorw exceptions other than these thrown by exception policy. *Suggestions* The following summarizes other useful suggestions for improving the library in the future. - operation `safe<signed>{INT_MIN} + safe<unsigned>{UINT_MAX}` throws even though the mathematical result would fit in either signed or unsigned int. This is correct according to what policies describe, but is at the same time surprising, given that comparison `safe<signed>{INT_MIN} < safe<unsigned>{UINT_MAX}` just gives a mathematically correct answer rather than throwing an exception. Document this behavior explicitly. - Remove underflow_error from the policies: it sends the wrong message, that som form of an underflow is checked in this library. - Expose functions like add(), divide() in public interface, they might be useful on their own. - Expose the constructor with check disabled in the public interface, like `safe<int>{1, checks_sisabled{}}` this helps to locally disable the checks where the user knows that certain chain of operaitons will not overflow, and checks are redundant, but the library cannot see it. - Issues reported with bit-shift operators - unary operator- on unsigned type with pormotion policy `automatic` could return a signed type. - Use BOOST_NORETURN wherever possible, e.g. in throwing policies. - Use BOOST_LIKELY, BOOST_UNLIKELY for the policy tests. - Add support for statful policies. - Maybe drop the support for automatic type widening, to simplify the interface and the scope of the library, and let some other library handle the widening, maybe BigInt. Regards, Andrzej Krzemienski

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[release] 1.64.0 Decision on VS2017 version number?
by Rene Rivera 19 Mar '17

19 Mar '17

> (B) The community decides what version number we should be using and the > appropriate PRs are filed and applied and tested for all the repos > involved. Which means: > 1. The community has until 12:00 CDT US March 18 to decide on what the vc > version number and tag should be. > It's now past that time.. Is there consensus on what version number Boost should use for identifying the VS2017 toolset? If there is.. People need to start submitting PRs for the changes ASAP.. > 2. The community must post PRs for the places where we reference VS2017 > version numbers to the new number. Those are at least: > <https://github.com/boostorg/config> > <https://github.com/boostorg/build> > <https://github.com/boostorg/boost> > <https://github.com/boostorg/website> > People have until 17:00 CDT Monday March 20 to submit those PRs. Thanks. -- -- Rene Rivera -- Grafik - Don't Assume Anything -- Robot Dreams - http://robot-dreams.net -- rrivera/acm.org (msn) - grafikrobot/aim,yahoo,skype,efnet,gmail

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Project R-tree Serialisation
by Kabir Sahni 19 Mar '17

19 Mar '17

Hi everyone, I am midway through my competency test.I wanted to know whether working of serialisatjon for n dimensional point is the only thing to be demonstrated in main.cpp file. Thanks

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