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[gsoc15] Please help rank GSoC 2015 student projects
by Niall Douglas 28 Mar '15

28 Mar '15

Dear Boost Community, The Google Summer of Code 2015 proposals for Boost are in, and we would deeply appreciate the community's help in ranking the proposals according to merit before the 6th of April. To vote, the process is easy: 1. Go to this page https://www.google-melange.com/gsoc/homepage/google/gsoc2015 and click the "Log in" button under Mentors and Administrators. 2. Now click "Create Profile" on the same page. Note that even if you registered last year, you must register again in 2015. Fill in the form. Note that after submitting it drops you at "Edit Profile", which is confusing. 3. Click "My Dashboard", then "Connect with organisations". 4. Choose "Boost C++ Libraries". 5. In the message box, write this: "I am a member of the Boost community and the email(s) I normally post to boost mailing lists with is <email>" filling in the email address(es) you normally use to post to boost mailing lists. This lets us verify that you are indeed a long standing member of the Boost community. 6. Once we approve your request, you will get an email with the subject "Welcome as organisation member". You can now return to the Dashboard on the GSoC website where there will be a new item "Proposals". 7. Work your way through as many of the 33 proposals as you can. You can score them using the stars at the bottom of each proposal page, taking care to read any comments by the mentors and students if present. PLEASE try to rank some of the lowest scored proposals, every year we get a lot of people who only rank the top five and don't bother with the rest. Try to score on the priority basis of: (i) ability to write quality C++, using the programming competency test or samples of programming the student supplied. (ii) proposal quality and your best estimate of the student's understanding of how best to solve the problem at hand. Bear in mind a gifted programmer with a strong work ethic but poor English may appear to not understand the problem as well as native English speakers, this is why we have asked for examples of their programming competency. (iii) if the student came early to the mailing lists to ask for help writing the proposal (the mentors who helped them with their proposals have usually indicated this in the private comments). (iv) usefulness/appropriateness of the feature or work being proposed. Remember a good GSoC is more about getting promising new engineers into Boost and C++ than necessarily getting code to pass Boost peer review in a single summer. 8. Optional: If a proposal looks especially great to you and you feel able to mentor a student this year, please slide the "wish to mentor" button. Just because a proposal already has willing mentors does NOT mean you should not add yourself - if you can substitute for an existing mentor, that may mean we use that mentor for another proposal. As you know, Google Summer of Code is usually worth $42,000 - $48,000 to Boost each year, and a successful GSoC raises our visibility and reputation in the wider open source community. Our thanks to you in advance for taking the time to vote. Niall Douglas Boris Schäling --- Boost C++ Libraries Google Summer of Code 2015 admin https://svn.boost.org/trac/boost/wiki/SoC2015

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problems using boost::polygon::get_rectangles
by TomDrummond 28 Mar '15

28 Mar '15

Hello I'm trying to use the function get_rectangles to return a list of rectangles however I can' get the code to compile. code #include <boost/polygon/polygon.hpp> std::vector< boost::polygon::rectangle_data<int> > rects; typedef boost::polygon::polygon_90_with_holes_data<int> Polygon90; Polygon90 poly; typedef boost::polygon::polygon_traits<Polygon90>::point_type MyPoint; MyPoint pts[] = { boost::polygon::construct<MyPoint>(0, 0), boost::polygon::construct<MyPoint>(0, 10), boost::polygon::construct<MyPoint>(30, 10), boost::polygon::construct<MyPoint>(30, 20), boost::polygon::construct<MyPoint>(10, 20), boost::polygon::construct<MyPoint>(10, 0) }; boost::polygon::set_points(poly, pts, pts + 6); boost::polygon::get_rectangles(rects, poly ); which gives the error 1>c:\lib\boost\1.57.0\boost\polygon\detail/rectangle_formation.hpp(261): error C2784: 'boost::rational<IntType> boost::abs(const boost::rational<IntType> &)' : could not deduce template argument for 'const boost::rational<IntType> &' from 'int' 1> C:\lib\boost\1.57.0\boost/rational.hpp(104) : see declaration of 'boost::abs' 1> c:\lib\boost\1.57.0\boost\polygon\polygon_90_set_data.hpp(180) : see reference to function template instantiation 'void boost::polygon::form_rectangles<output_container,std::_Vector_iterator<std::_Vector_val<std::_Simple_types<std::pair<int,std::pair<int,int>>>>>,boost::polygon::rectangle_concept>(output_container &,iterator_type,iterator_type,boost::polygon::orientation_2d,rectangle_concept)' being compiled 1> with 1> [ 1> output_container=std::vector<boost::polygon::rectangle_data<int>,std::allocator<boost::polygon::rectangle_data<int>>> 1> , iterator_type=std::_Vector_iterator<std::_Vector_val<std::_Simple_types<std::pair<int,std::pair<int,int>>>>> 1> , rectangle_concept=boost::polygon::rectangle_concept 1> ] 1> c:\lib\boost\1.57.0\boost\polygon\polygon_90_set_concept.hpp(86) : see reference to function template instantiation 'void boost::polygon::polygon_90_set_data<int>::get_rectangles<output_container_type>(output_container &) const' being compiled 1> with 1> [ 1> output_container_type=std::vector<boost::polygon::rectangle_data<int>,std::allocator<boost::polygon::rectangle_data<int>>> 1> , output_container=std::vector<boost::polygon::rectangle_data<int>,std::allocator<boost::polygon::rectangle_data<int>>> 1> ] 1> c:\lib\boost\1.57.0\boost\polygon\polygon_90_set_concept.hpp(86) : see reference to function template instantiation 'void boost::polygon::polygon_90_set_data<int>::get_rectangles<output_container_type>(output_container &) const' being compiled 1> with 1> [ 1> output_container_type=std::vector<boost::polygon::rectangle_data<int>,std::allocator<boost::polygon::rectangle_data<int>>> 1> , output_container=std::vector<boost::polygon::rectangle_data<int>,std::allocator<boost::polygon::rectangle_data<int>>> 1> ] 1> TerrainDispatcher.cpp(185) : see reference to function template instantiation 'void boost::polygon::get_rectangles<std::vector<boost::polygon::rectangle_data<int>,std::allocator<_Ty>>,Polygon90>(output_container_type &,const polygon_set_type &)' being compiled 1> with 1> [ 1> _Ty=boost::polygon::rectangle_data<int> 1> , output_container_type=std::vector<boost::polygon::rectangle_data<int>,std::allocator<boost::polygon::rectangle_data<int>>> 1> , polygon_set_type=Polygon90 1> ] I'm quite new to both boost and templates so any help would be appreciated. -- View this message in context: http://boost.2283326.n4.nabble.com/problems-using-boost-polygon-get-rectang… Sent from the Boost - Users mailing list archive at Nabble.com.

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[geometry] Buffer multi-linestring with different distances
by Renato Silveira 27 Mar '15

27 Mar '15

Is it possible to buffer a multi-linestring where each linestring has his own distance to buffer? Something like this: http://docs.qgis.org/2.2/en/_images/variable_buffer.png Thank you in advance -- *Renato Silveira* Ph. D. Student Informatics Institute - UFRGS Porto Alegre - RS - Brazil http://www.inf.ufrgs.br/~rsilveira

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[Serialization] serialization of shared_ptr with custom deleter
by Elizabeta 27 Mar '15

27 Mar '15

Hi I am using boost 1.49. There is problem with serialization of shared_ptr with custom deleter, it doesnot preserve the deleter. After deserialization of shared_ptr with custom deleter, when using boost::get_deleter on the deserialized shared_ptr it returns null. Here is code example struct DetachTest { ~DetachTest() { int debug =0; } friend class boost::serialization::access; template<class Archive> inline void serialize(Archive & ar, const unsigned int file_version) { } }; { boost::shared_ptr<DetachTest> ss(new DetachTest,SmartDeleter<DetachTest>()); std::ofstream ofs("C:\\detach.xml"); boost::archive::xml_oarchive oa(ofs); oa & boost::serialization::make_nvp("detach",ss); } { DetachTest* test = 0; boost::shared_ptr<DetachTest> ss (test,SmartDeleter<DetachTest>()); //del is nonnul here SmartDeleter<DetachTest>* del = boost::get_deleter<SmartDeleter<DetachTest> , DetachTest>(ss); std::ifstream ifs("C:\\detach.xml"); boost::archive::xml_iarchive ia(ifs); ia & boost::serialization::make_nvp("detach",ss); //de2 is null after deserialization SmartDeleter<DetachTest>* de2 = boost::get_deleter<SmartDeleter<DetachTest> , DetachTest>(ss); } -- View this message in context: http://boost.2283326.n4.nabble.com/Serialization-serialization-of-shared-pt… Sent from the Boost - Users mailing list archive at Nabble.com.

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Cannot build libboost_mpi.so
by Patrick Begou 26 Mar '15

26 Mar '15

Hi, I'm a new user of boost library, as it is requested by fellpp that I'm trying to install. I'm compiling boost 1.57 with the basic commands: tar xvfz boost_1_57_0.tar.gz cd boost_1_57_0 ./bootstrap.sh --prefix=/share/apps/boost_1_57_0-GCC48 ./b2 But I never get the requested libboost_mpi.so ? Even if the begining of the script tells me: Component configuration: - atomic : building - chrono : building - container : building - context : building - coroutine : building - date_time : building - exception : building - filesystem : building - graph : building - graph_parallel : building - iostreams : building - locale : building - log : building - math : building - mpi : building ...... and libboost_mpi.so is requested for Fellpp.... Thanks for your advices. Patrick -- =================================================================== | Equipe M.O.S.T. | | | Patrick BEGOU | mailto:Patrick.Begou@grenoble-inp.fr | | LEGI | | | BP 53 X | Tel 04 76 82 51 35 | | 38041 GRENOBLE CEDEX | Fax 04 76 82 52 71 | ===================================================================

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Re: [Boost-users] [asio] wrap lambda async_receive call
by Cheng Mo 25 Mar '15

25 Mar '15

Hi Gravin: >The compiler will build the code for a lambda only once regardless of >how many times it's called. But it also won't let you create a >recursive lambda, which is what you would need if you wanted to have a >read operation repeat itself when it completes (which is the most common >case). I supposed that which would be built once durning compiling time but multi time in running time, wasn't it ? It will implement every time when async_xxx be invoded. Although I was not do test for proving that. >Well, actually that's not quite true -- you can type-erase a lambda via >std::function or similar and then call it recursively. But AFAIK you >can only do this when capturing by reference, and you can't safely do >that with a locally declared lambda when making async calls. So it's >not really useful in this context. Private member function or std::function type various and transmitted as reference could be better in this case. >> It's better that build a function object in static. What do you think ? >Function objects have a similar lifetime issue, and making one static is >potentially dangerous if you could have multiple operations or >connections running concurrently. It's usually simplest to use a >private method of the containing class, which is what most of the >example code does. You are right, the static is dangerous in multiple op and concurrence, Thanks. (If you really want to hide it from clients of your class, then use the PIMPL idiom.) Cheer~ 程墨 PBI―北京加维通讯电子技术有限公司地址：北京市海淀区西北旺镇丰智东路3号院邮编：100094 Mail: mcheng(a)pbicn.com

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[Boost Graph Library][Serialization] adjacency_list serialization crashes.
by Hardik Soni 24 Mar '15

24 Mar '15

Hi All, I am facing a core dump while serializing adjacency_list class object of BGL. I am using <boost/graph/adj_list_serialize.hpp> file for serialization. Following is the stack trace. I have highlighted the types used for boost::adjacency_list on frame number 19. I am using bundled property method to assign property to nodes and vertices. I tried with no_poperty, the outcome was the same. Does anyone have any idea, why is it crashing? The exception name is "output stream error". #0 0x0000003908e359e9 in raise () from /lib64/libc.so.6 #1 0x0000003908e370f8 in abort () from /lib64/libc.so.6 #2 0x000000390d660565 in __gnu_cxx::__verbose_terminate_handler() () from /lib64/libstdc++.so.6 #3 0x000000390d65e6c6 in ?? () from /lib64/libstdc++.so.6 #4 0x000000390d65e6f3 in std::terminate() () from /lib64/libstdc++.so.6 #5 0x000000390d65e91f in __cxa_throw () from /lib64/libstdc++.so.6 #6 0x000000000040de72 in boost::serialization::throw_exception<boost::archive::archive_exception> (e=...) at /usr/local/include/boost/serialization/throw_exception.hpp:36 #7 0x000000000040dce7 in boost::archive::basic_text_oprimitive<std::ostream>::save_impl<int> (this=0x7fffffffd5b0, t=@0x7fffffffd188: 6) at /usr/local/include/boost/archive/basic_text_oprimitive.hpp:122 #8 0x000000000040dc24 in boost::archive::basic_text_oprimitive<std::ostream>::save<int> (this=0x7fffffffd5b0, t=@0x7fffffffd188: 6) at /usr/local/include/boost/archive/basic_text_oprimitive.hpp:176 #9 0x000000000040db91 in boost::archive::xml_oarchive_impl<boost::archive::xml_oarchive>::save<int> (this=0x7fffffffd580, t=@0x7fffffffd188: 6) at /usr/local/include/boost/archive/xml_oarchive.hpp:75 #10 0x000000000040daeb in boost::archive::save_access::save_primitive<boost::archive::xml_oarchive, int> (ar=..., t=@0x7fffffffd188: 6) at /usr/local/include/boost/archive/detail/oserializer.hpp:88 #11 0x000000000040d9d1 in boost::archive::detail::save_non_pointer_type<boost::archive::xml_oarchive>::save_primitive::invoke<int> (ar=..., t=@0x7fffffffd188: 6) at /usr/local/include/boost/archive/detail/oserializer.hpp:232 #12 0x000000000040d595 in boost::archive::detail::save_non_pointer_type<boost::archive::xml_oarchive>::invoke<int> (ar=..., t=@0x7fffffffd188: 6) at /usr/local/include/boost/archive/detail/oserializer.hpp:308 #13 0x000000000040cccb in boost::archive::save<boost::archive::xml_oarchive, int const> (ar=..., t=@0x7fffffffd188: 6) at /usr/local/include/boost/archive/detail/oserializer.hpp:525 #14 0x000000000040c678 in boost::archive::detail::common_oarchive<boost::archive::xml_oarchive>::save_override<int const> (this=0x7fffffffd580, t=@0x7fffffffd188: 6) at /usr/local/include/boost/archive/detail/common_oarchive.hpp:69 #15 0x000000000040be67 in boost::archive::basic_xml_oarchive<boost::archive::xml_oarchive>::save_override<int> (this=0x7fffffffd580, t=...) at /usr/local/include/boost/archive/basic_xml_oarchive.hpp:112 #16 0x000000000040b5bc in boost::archive::detail::interface_oarchive<boost::archive::xml_oarchive>::operator<< <boost::serialization::nvp<int> const> (this=0x7fffffffd580, t=...) at /usr/local/include/boost/archive/detail/interface_oarchive.hpp:63 #17 0x000000000040b021 in boost::serialization::save<boost::archive::xml_oarchive, boost::vecS, boost::vecS, boost::directedS, std::string, std::string, std::string, boost::listS> (ar=..., graph=...) at /usr/local/include/boost/graph/adj_list_serialize.hpp:48 #18 0x000000000040aa65 in boost::serialization::free_saver<boost::archive::xml_oarchive, boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, std::string, std::string, std::string, boost::listS> >::invoke (ar=..., t=..., file_version=0) at /usr/local/include/boost/serialization/split_free.hpp:45 #19 0x000000000040a6e2 in boost::serialization::split_free<boost::archive::xml_oarchive, boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, std::string, std::string, std::string, boost::listS > > (ar=..., t=..., file_version=0) at /usr/local/include/boost/serialization/split_free.hpp:74 #20 0x000000000040a2cf in boost::serialization::serialize<boost::archive::xml_oarchive, boost::vecS, boost::vecS, boost::directedS, std::string, std::string, std::string, boost::listS> (ar=..., graph=..., file_version=0) at /usr/local/include/boost/graph/adj_list_serialize.hpp:109 Thanks, Hardik Soni

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try_numeric_convert (akin to try_lexical_convert)
by Chris Franz 24 Mar '15

24 Mar '15

We're using the new try_lexical_convert function in our code so we can encapsulate errors in the standard manner used in our project. A counterpart for numeric_cast would be useful. Is any such thing in the works?

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Re: [Boost-users] [range] functor defined result_type with no &, causing temporary variable warnings on VS
by Nick Stokes 24 Mar '15

24 Mar '15

This question is a followup from a multi_index discussion at http://lists.boost.org/boost-users/2015/03/84028.php. Joaquin explained the situation very accurately, so I am including his explanation following my summary below for context (I hope this does not constitute top posting :) In summary the problem is: struct Foo { int i; } struct GetIntMem { typedef int result_type; const int& operator()(const Foo& f) const { return f.i ; } }; aFooRange | boost::adaptors::transformed( GetIntMem() ); yields "warning C4172: returning address of local variable or temporary" in VS 2012 and 2013, with Boost 1.49. There is no warning with Boost 1.56. Is this construct safe with Boost 1.49? In the context of multi_index, the key extractor type is the "GetIntMem". Please see below for details. On Fri, Mar 20, 2015 at 5:33 AM, Joaquin M Lopez Munoz <joaquin(a)tid.es> wrote: > > Please don't top-post: > > http://www.boost.org/community/policy.html#quoting > > Sure. Sorry. Thanks for the link, useful info. > So, to sum up the top-posted chain of posts of yours, > boost::multi_index::member<Class,Type,PtrToMember> publicizes its > result type as > > typedef Type result_type; > > yet its call operator overloads return Type& or const Ttype&, and this > results in some warnings in VS 12 / Boost 1.49 when used in combination > with boost::adaptors::transform. > > So, whatever the problem is, it does not belong in Boost.MultiIndex, > since member merely defines result_type in accordance with the > requirements of the Key Extractor model: > > http://www.boost.org/libs/multi_index/doc/reference/ > key_extraction.html#key_extractors > > I mean, defining result_type in whatever way (or not defining it > at all) is not an error per se; it is Boost.Range assumptions on > this typedef that might be problematic. Unfortunately, the documentation > for boost::adaptors::tranform(rng,fun) > > http://www.boost.org/libs/range/doc/html/range/reference/ > adaptors/reference/transformed.html > > do not mention what the requirements on fun are, whether it is > mandatory that a result_type be present and how this is handled by > Boost.Range. I suggest you initiate a new discussion with [range] > in the subject line showing the problem you found. I suspect this > is related to boost:result_of > > http://www.boost.org/libs/utility/utility.htm#result_of > > which Boost.Range seems to use internally, but only the author can > tell. Also, if the problem does not show in Boost 1.56 you might be > encouraged to simply upgrade and move on. > > Thanks Joaquin. I could not describe the problem any better than what you have above, so I hope you don't mind that I re-purposed this thread. The question is possibly is rather moot at this point, as the issue does not manifest in Boost 1.56 (possibly earlier). However, it'd be interesting to understand why, and at least make sure using 1.49 this way is safe (I am stuck with that version for the time being). Thanks very much if you followed along this far, and sorry as I fear this post ended up more convoluted that it needs to be :P Nick

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Re: [Boost-users] [asio] wrap lambda async_receive call
by Cheng Mo 23 Mar '15

23 Mar '15

Hi Gavin: >Having said this, using lambdas can get tricky in real-world code, as >it's common to want to start the same read operation when the first >completes, and so on. Just like you said, will the code build a lambda expression when async_read() invoked ? So that "[=](const error_code& ec, size_t count" will be built servial times, it is kind of lavish for contructing the lambda expression, isn't ? It's better that build a function object in static. What do you think ? Cheers~ Cheer~ 程墨 PBI―北京加维通讯电子技术有限公司地址：北京市海淀区西北旺镇丰智东路3号院邮编：100094 Mail: mcheng(a)pbicn.com

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