February 2014 - Boost - lists.preview.boost.org

Fwd: possible bug: retrieve data using associative property maps with boost::bimaps - failed
by Aniket Pugaonkar 10 Feb '14

10 Feb '14

Hi, I am not sure whether this email got sent to the list because I received an email that I have to subscribe to the list before asking any question through email. Apologies for sending it again. thanks! I am facing compilation error in the following code. I do understand why the error is, but I could not find a good solution. Here is my code and question explained in detail *What I want to do:* I want to store a key- value pair where both key and its respective values is unique. But After I create a map, I want to use the VALUE and get the corresponding key. Essentially the best way is a bimap. So I do the following using associative property maps. *What I did:* 1. define a bimap (my_bimap ) 2. define associative property map for left view of bimap ( right_asso_bimap ) 3. define associative property map for right view of bimap ( left_asso_bimap ) 4. fill the bimap using *left* view associative property map. i.e. *use boost::put( left_asso_bimap, key, value )* 5. Now using *right* view associative property map, retrieve key for given value i.e. use *boost::get( right_asso_bimap, value )* My main motive is to use GET and PUT helper functions for insertion and retrieval from a bimap. Use PUT to insert in LEFT BIMAP. and Use GET to retrieve from RIGHT BIMAP. I know the error is because of non-const-ness of the iterators because of which I cannot de-reference using iterators. But what would be the alternative to this ? This link here explains how to define parameters for bimap in order for iterators to be mutable. http://www.boost.org/doc/libs/1_55_0/libs/bimap/doc/html/boost_bimap/the_tu… *But I get the error below: * In file included from main.cpp:2:0: /usr/local/include/boost/property_map/property_map.hpp: In instantiation of 'boost::associative_property_map<UniquePairAssociativeContainer>::value_type& boost::associative_property_map<UniquePairAssociativeContainer>::operator[](const key_type&) const [with UniquePairAssociativeContainer = boost::bimaps::views::list_map_view<boost::bimaps::relation::member_at::right, boost::bimaps::detail::bimap_core<int, boost::bimaps::list_of<long unsigned int>, mpl_::na, mpl_::na, mpl_::na> > boost::associative_property_map<UniquePairAssociativeContainer>::reference = const int&; boost::associative_property_map<UniquePairAssociativeContainer>::value_type = const int; boost::associative_property_map<UniquePairAssociativeContainer>::key_type = long unsigned int]': /usr/local/include/boost/property_map/property_map.hpp:357:54: required from 'Reference boost::get(const boost::put_get_helper<Reference, PropertyMap>&, const K&) [with PropertyMap = boost::associative_property_map<boost::bimaps::views::list_map_view<boost::bimaps::relation::member_at::right, boost::bimaps::detail::bimap_core<int, boost::bimaps::list_of<long unsigned int>, mpl_::na, mpl_::na, mpl_::na> > > Reference = const int&; K = int]' main.cpp:41:35: required from here /usr/local/include/boost/property_map/property_map.hpp:502:20: error: no match for 'operator[]' (operand types are 'boost::associative_property_map<boost::bimaps::views::list_map_view<boost::bimaps::relation::member_at::right, boost::bimaps::detail::bimap_core<int, boost::bimaps::list_of<long unsigned int>, mpl_::na, mpl_::na, mpl_::na> > >::C {aka boost::bimaps::views::list_map_view<boost::bimaps::relation::member_at::right, boost::bimaps::detail::bimap_core<int, boost::bimaps::list_of<long unsigned int>, *mpl_::na, mpl_::na, mpl_::na> >}' and 'const key_type {aka const long unsigned int}')* *return (*m_c)[k];* ^ Here my code. You can also see the code here on this website link:* http://coliru.stacked-crooked.com/a/59cbf2c564bf22b2 <http://coliru.stacked-crooked.com/a/59cbf2c564bf22b2>* #include <boost/bimap.hpp> #include <boost/property_map/property_map.hpp> #include <boost/bimap/property_map/set_support.hpp>#include <boost/bimap/list_of.hpp>#include <iostream> using namespace boost; int main() {typedef int vertex_descriptor_t;namespace bm = boost::bimaps;typedef bm::bimap< vertex_descriptor_t, bm::list_of<size_t> > vd_idx_bimap_t;typedef boost::associative_property_map<vd_idx_bimap_t::left_map> Lasso_vd_idx_bimap_t;typedef boost::associative_property_map<vd_idx_bimap_t::right_map> Rasso_vd_idx_bimap_t; // define bimap and assoc prop map for itvd_idx_bimap_t my_bimap;Lasso_vd_idx_bimap_t Lmy_asso_bimap(my_bimap.left );Rasso_vd_idx_bimap_t Rmy_asso_bimap(my_bimap.right); typedef typename vd_idx_bimap_t::value_type value_type; my_bimap.insert( value_type( 1, 100 ) ); my_bimap.insert( value_type( 2, 200 ) ); int z = 1; std::cout << "value = " << get ( my_bimap.left, z ) << std::endl; // prints correctly value = 100 // use left asso bimap for inserting to bimap boost::put( Lmy_asso_bimap, 3, 300 ); // correct // print bimap using *left view*for(auto t = my_bimap.left.begin(); t != my_bimap.left.end(); ++t) std::cout << t->first << " " << t->second << "\n"; int y = 2;*z **= boost::get( Lmy_asso_bimap, y ); // CORRECT OUTPUT for left view * std::cout << "value = " << z << std::endl; // Use right asso bimap to get key based on supplied value y = 100;*z = boost::get( Rmy_asso_bimap, y );* *// -->> ERROR HERE for right view* std::cout << "value = " << z << std::endl; // print map again. (*right view*)for(auto t = my_bimap.right.begin(); t != my_bimap.right.end(); ++t) std::cout << t->first << " " << t->second << "\n"; } Please let me know whether this is a potential bug, or the code semantics is incorrect. Or the current library cannot support this. ? Regards, Aniket Pugaonkar -- Thanks and regards, Aniket Pugaonkar -- Thanks and regards, Aniket Pugaonkar -- Thanks and regards, Aniket Pugaonkar

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[GSOC] Generalized Hypergeometric Functions.
by Anton Bikineev 10 Feb '14

10 Feb '14

Hi all. I just added a quick and naive implementation of Pade approximation for 1f1 and 2f1 hypergeometric functions based on Luke's book. You can find code here: https://github.com/AntonBikineev/math/blob/hypergeometric/ include/boost/math/special_functions/detail/hypergeometric_pfq_pade.hpp I also want to thank Christopher Kormanyos for many advices and help. Best regards, Anton.

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Attn: We need GSoC 2014 mentors for Boost!
by Niall Douglas 10 Feb '14

10 Feb '14

Dear Boost community, We are now just five days away from the closing date for Google Summer of Code 2014 registration. Last year's GSoC was a huge success, with Google funding work on Boost to the tune of $35,000 and paying over $8,000 in costs for three representatives of Boost to attend the GSoC mentor's summit at Google HQ. As part of filling in our application for 2014, we must supply to Google a list of potential GSoC mentors and potential GSoC projects for summer 2014. We do NOT want a repeat of 2012 when our application was rejected due to an insufficiently long list of prospective mentors and projects! At the time of writing, we have just *eight* prospective mentors, and we need more to be sure of being approved by Google! Therefore, if you think yourself able to mentor a student doing some work on Boost this summer, *please* consider adding a description of the proposed work item and your name to the list at https://svn.boost.org/trac/boost/wiki/SoC2014. If you want to know more about mentoring a Google Summer of Code funded student work before you nominate yourself, please feel free to ask on the main Boost developers mailing list boost(a)lists.boost.org. Thank you in advance for your time. Niall Douglas (Boost Google Summer of Code admin) Boris Schäling (Boost Google Summer of Code backup admin)

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[program_options] comma separated options
by Alain Miniussi 10 Feb '14

10 Feb '14

Hi, Someone asked me if it was possible to "easily" specify an option that would allow to specify a vector of values. The first options that came in mind was to use "multitoken". But that solution had to drawback in that situation: - ambiguous with respect to positional parameters - clumsy when you want to allow options to be specified in files, since you have to write: option 12 option 42 ... instead of: option 12 42 19 So I though about using a custom validator, which implies introducing a new type too, if I understand correctly. Something along the lines of: ======================= ... template<typename T> struct option_sequence { std::vector<T> values; }; template<typename T> void validate(boost::any& v, const std::vector<std::string>& values, option_sequence<T>* target_type, int) { namespace po = boost::program_options; namespace alg = boost::algorithm; std::vector<T> result; typedef std::vector<std::string> strings; for ( strings::const_iterator iter = values.begin(); iter != values.end(); ++iter ) { strings tks; alg::split(tks, *iter, alg::is_any_of(":")); for( strings::const_iterator tk = tks.begin(); tk != tks.end(); ++tk) { result.push_back(boost::lexical_cast<T>(*tk)); } } v = option_sequence<T>(); boost::any_cast<option_sequence<T>&>(v).values.swap(result); } int main(int argc, char* argv[]) { .... desc.add_options() ("values,v", po::value<option_sequence<int> >(), "a vector of ':' separated values as in \"12:42:-20\"."); =================== Obviously, one could think that some flexibility could be added (separators for starters) but you get the idea. Is that the right way to go (the intermediate option_sequence template seems clumsy for the user (but you need to distinguish from std::vector's) and if yes, could such a thing be added to the library ? (if yes a could propose a patch for consideration). Cheers -- ===================================== Alain Miniussi DSI/Pôle Génie Logiciel Scientifique Observatoire de la Côte d'Azur

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[Fibers] Performance
by Hartmut Kaiser 10 Feb '14

10 Feb '14

Oliver, Do you have some performance data for your fiber implementation? What is the (amortized) overhead introduced for one fiber (i.e. the average time required to create, schedule, execute, and delete one fiber which runs an empty function, when executing a larger number of those, perhaps 500.000 fibers)? It would be interesting to see this number when giving 1..N cores to the scheduler. Thanks! Regards Hartmut --------------- http://boost-spirit.com http://stellar.cct.lsu.edu

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GSoC 2014 - Full Text Search
by Nikhar Agrawal 09 Feb '14

09 Feb '14

Hi everyone, I'm Nikhar Agrawal, currently pursuing my B.Tech. in Computer Science and Engineering from IIIT-H. I was a GSoC student last time for Boost C++ under the mentorship of Christopher Kormanyos and advisory mentorship of John Maddock and Paul Bristow for the Boost.Math Bernoulli numbers project. It was a wonderful experience to have successfully managed to contribute to Boost. And it was a great learning process. I would love to participate this year as well. I was going through the ideas page and saw 'Full Text Search' listed in tiny letters near the bottom of the page. As part of our coursework on Information Retrieval and Extraction in college, we have built a project on searching for queries on a 42 gb wikipedia xml dump. So, I got a little excited at seeing 'Full Text Search' being listed. I skimmed through the Boost mailing list archives but couldn't find any information on this. Could someone kindly elaborate what exactly is expected from this? And if there's any interest from anyone in mentoring this project? Thanks.

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GSoC
by Utsav Tiwary 09 Feb '14

09 Feb '14

Are there existing libraries for the implementation of finite difference method to solve boundary value problems ? I've been working on it lately using MPI.

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[Move] BOOST_NO_RVALUE_REFERENCES - or so it thinks
by John M. Dlugosz 08 Feb '14

08 Feb '14

Real-world software projects don't always get to use the latest stuff in a timely manner. I'm working on some code that needs to work across several platforms, which generally means programming to the least-common-denominator. What I want to bring up in particular is the issue that the compiler may be more up to date with C++11 than the libraries. Someone trying to use Boost on Android (IIRC) trying to change the Boost config to tell it that C++11 support is available said it was like playing "Whack-a-Mole", in that each change caused more problems elsewhere. It seems that the overall issue is Compiler vs Library. Saying that rvalue references are available doesn't mean that std::move, std::forward, etc. are available. I threw together a move.h file that contains forward, move, and a few others taken exactly from the standard â all one-liners. That lets people who know that the compiler really does know what to do with && write code that uses them, just so long as they remember to use the project's namespace and not std, or the multi-platform build coughs it back out. I also successfully crossbred the unique_ptr implementation from libcxx-3.4 with Boost + my own move.h namespace. Now try putting a (real) move-only object into a boost::container::vector when Boost is built with BOOST_NO_RVALUE_REFERENCES. Might I convince the powers-that-be to reconfigure Boost with that #define removed? That could be done when upgrading Boost anyway, but it seems to not work! Whack-a-mole. I didn't do it personally, but it appears that at the very least Boost would need its own move.h and whatever odds and ends it assumes are present. That would be quite easy since these little functions are just fancy casts and you can mix code that calls different "implementations" of them. So Boost could always use boost::move which turns into static_cast<typename boost::remove_reference<T>::type&&>(t); (as opposed to just 'using' the std::move) and other code doesn't care. That is, it would not be necessary to configure "has std::move vs not have std::move" but just don't rely on std::move at all. In short, I don't know if it's just me, but most of the company jobs I've worked have lagged behind, with upgrading the compiler and/or libs being a Big Deal, especially if using outside code that's already compiled. So, I want to raise the possibility that making Boost work with native rvalue references but legacy (C++03) standard library would be useful to some significant population of developers. #undef'ing BOOST_NO_RVALUE_REFERENCES in the config ought to just work, at least on a lib by lib basis. I mean, it might be fine if some libs didn't handle that as many people don't use every single lib in every project. Boost.Container is interesting though because it is used to overcome legacy std::map etc. as one of its stated goals. It's also good for avoiding platform compatibility issues when all platforms use the same map class (e.g. the master build doesn't spit out failures as erase is void on some platform but returned an iterator on the platform used to try the code before checking it in). The current version of Clang as used for Mac and iPhone/iPad development has && working even if you don't enable the C++11 dialect. So sneaking in some &&'s in a program doesn't require any reconfiguration of the projects. âJohn

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Fwd: [Boost-users] Attn: We need GSoC 2014 mentors for Boost!
by Antony Polukhin 08 Feb '14

08 Feb '14

2014-02-08 7:15 GMT+04:00 Niall Douglas <s_sourceforge(a)nedprod.com>: <...> Therefore, if you think yourself able to mentor a student doing some > work on Boost this summer, *please* consider adding a description of > the proposed work item and your name to the list at > https://svn.boost.org/trac/boost/wiki/SoC2014. > I'm in! How about the following projects: * Running regression tests on Android/RaspberyRI/Qemu, writing a documentation about crosscompiing Boost libraries. + Adding automated TravicCI testing scripts to all the Boost libraries * Library for basic integration with spreadsheet applications Excel/LibreOfficeCalc/OpenOfficeCalc and OfficePrograms (Modifying cell, getting results from cells, saving documents, saving in PDF) * Program protection and obfuscation tools (marking part of assembly at compilation, encrypting/decrypting part of the binary on-the-fly, detecting debuggers, detecting emulators and virtual machines, computer identification and gathering hardware specific identifiers...) If there is an interest in those projects, I'll add some description to the GSOC wiki page. -- Best regards, Antony Polukhin

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Odd regression test results
by Peter Dimov 08 Feb '14

08 Feb '14

Something's not right with this result (among others): http://www.boost.org/development/tests/develop/developer/output/teeks99-02e… It says "Rev 906385497d1f3de04bb8391c5af87e563fd4c0f7". Revision 906385 updates config, and the preceding revision that updates smart_ptr is https://github.com/boostorg/boost/commit/891371e4ba8edf7dd21dc828841f5eab56… which brings it up to +Subproject commit e1f170cd494d2e7ce5e6e7d3f0fe016aceb88048 Rev. e1f170 of smart_ptr is a relatively recent one, as can be seen here: https://github.com/boostorg/smart_ptr/commits/develop The error messages in the report, however: C:\local\teeks99-02\e\boost_root\boost/smart_ptr/detail/shared_count.hpp(276) : error C2903: 'rebind' : symbol is neither a class template nor a function template C:\local\teeks99-02\e\boost_root\boost/smart_ptr/make_shared_object.hpp(174) : see reference to function template instantiation 'boost::shared_ptr<int>::shared_ptr<T, ... seem to suggest that neither shared_count.hpp nor make_shared_object.hpp have been updated to e1f170.

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