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GSoC 2010 : BigInt
by Mario Ynocente Castro 28 Mar '10

28 Mar '10

Hi, I'm a engineering student from Peru. I'm really interested in the BigInt project for GSoC 2010, but there's a part for which I would like a better explanation, the description says : "A successful proposal will include a discussion of licensing concerns". What does it mean? I must choose the license under which the code will be released and indicate it when I submit the aplication? -- Mario Ynocente Castro 20074016B FIIS - UNI

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About Boost XML
by Qingli Ma 28 Mar '10

28 Mar '10

Hi! My idea about XML is listed below: 1.I have experience on processing larege scale xml files(database files).So I feel having boost proccess large xml files in SAX model will be useful and I've make that in Java before. 2.Reading spec about all kinds of XML APIs, and improve current Boost interfaces in Boost to support all kinds of processing without thinking about the backend implemention.By this, interfaces is independent from the backend, thus dynamic backend bindings is possible. 3.Maybe we need a new backend that serves for the API interface,like libxml2.It can parse,tranverse,writer and search(XPath) the document. 4.I am graduating this summer and I'll have enough time. Have you any sugguestions for me?

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[GSoC 2010] Sweepline algorithm
by Marcin Fatyga 28 Mar '10

28 Mar '10

Hello, My name is Marcin Fatyga and I am doing double degree program in computer science and mathematics on Warsaw University. I would like to participate in GSoC 2010 - I would like to implement the sweepline algorithm and use it to solve the problems related to it. In my project I would like to implement the sweepline and then use Fortune's Algorithm to solve the Voronoi Diagram's problem. Then I would provide some modifications to solve the two remaining connected problems : Delanuay triangulation and medial axis. All of these problems have many applications in differnet fields of science and solving them could be useful to may users. Though I don't have quite much experience with the boost library itself, I am particularly interested in algorithms and have some experience with both C++ and generic programming. Though there is no geometry library in current release, I can see it is in development phase. Should the project be integrated with it/use it? Best wishes Marcin Fatyga

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[preprocessor] Computational complexity analysis
by Lorenzo Caminiti 28 Mar '10

28 Mar '10

Hello all: Is there a computational complexity analysis of Boost.Preprocessor data structures? This would be in terms of preprocessing time. For example: Does BOOST_PP_SEQ_ELEM() run* in O(n)? Do BOOST_PP_TUPLE_ELEM() and BOOST_PP_ARRAY_ELEM() run* in O(1)? (*) "Run" within the preprocessor so maybe "expand" is a better term... Thank you. Lorenzo

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[GSoC] Some Ideas about the Boost.Process
by Felipe Tanus 27 Mar '10

27 Mar '10

Hello, I have been studying the project idea about Boost.Process for a while. Some ideas/opinions poped up in my mind and I feel like to share. Please, comment. IMHO, the best design for the library is not to split the APIs from Windows and POSIX. I Believe that boost should provide a higher abstraction level, and get rid of the platform problems. 1.The current implementation of Boost.Process library has the class boost::process::child, and two classes that inherit it, win32_child and posix_child. I don't believe that this is the best solution. There is only one concept of child in both APIs; some resources are different, it is true, but the concept is only one. For example, the call "boost::process::win32_launch()" is defined to launch a process "the windows API way", with the Win32 context. I don't see why can't we create a process with this call in a POSIX system ignoring what don't apply to it (or find some similar concept and use it instead, as named pipes<->fifos). After all, if you are using a Win32 only class, there is no way to run in linux, so if the code works or don't, it does not matter. By doing this way, we could easy a possibly port to another system. This could be done with programming practices as suggested by Vicente Botet, in a previous topic [1] 2.The wait() method, to wait a process (child actually, but this is another problem) to die, is not asynchronous. Sometimes programmers want a synchronous wait() method, so there is no motive for we to remove this. We should implement a new asynchronous wait() method. This method should not be in the asio library, because it's process specific. It may require the asio library, or the asynchronous piece should be implemented in the boost.process. I'm not sure about this, both seems good for me, so please comment. 3.About the process creation, I think the following practice from the documentation should be avoided: “Another important requirement is to always pass at least one argument to the executable. This must be the name of the executable itself”. There is no motive to require a parameter that you can deduce by yourself. The first parameter, in this case, should be implicit. 4.Would really be nice boost::process::launch() be able to receive any kind of string? This tend to let the programmer go for a single platform solution. As a multiplatform library, this may be avoided. I'm not sure about this matter as well, but if the library is here to provide a higher abstraction level, should it also accept API related types? I believe it should not. There is also another points that I would like to discuss in my GSoC proposal; They are well known problems so I'll just cite they: List and access other processes functionality Named pipes and FIFO (following the item #1, would be the same thing? Something would change? Something to be researched yet) move wait from child to process (as well as future asynchronous wait) Deal with process killing bugs (as well as any other known issue) Test platform issues. Should this be enough for a GSoC proposal? Do you have any other suggestion about what could I discuss in it? Thank you for your time, []'s [1] http://thread.gmane.org/gmane.comp.lib.boost.devel/188736 -- Felipe de Oliveira Tanus E-mail: fotanus(a)gmail.com Blog: http://www.itlife.com.br Site: http://www.inf.ufrgs.br/~fotanus/ ----- "All we have to decide is what to do with the time that is given us." - Gandalf

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GSOC query for Heaps and Que
by Chirag 27 Mar '10

27 Mar '10

Hello Sir The Boost C++ library has mutable_heap and mutable_que and the current container works perfectly for basic datatypes like double , int etc but for datatypes like pointers it requires that user should have knowledge of property_map types. Sir for making mutable heaps , can we ask user for a hash function from the user for the data type he want to make the heap. This way we can hash each newly added value to heap and store pointer for that which will point to its location in the original heap. Here two problem i am facing 1) Can user provide a hash function for all data types 2) Worst case of hashing search would be O(n) though it chances are very low . I know O(n) case is not wat we are aiming to achieve but for users who dont want to get into understanding of property map they can use this heap instead , and I am thinking of giving it as a option to the already available mutable que in boost. This is just a idea I am proposing and its definately not final , I am thinking on other ways to improve it . I just want to know if it is a good option to give or not. Thanks Chirag IIT guwahati -- Life is short live it happily

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Stability: More on 3 level Boost libraries
by vicente.botet 27 Mar '10

27 Mar '10

Hi, I would like to come back to the 3 level proposition but from a different point of view (stability and quality) 1st level: stable Libraries belonging to this level must be very stable, any modification on the public interface must be reviewed. The goal been that changes in these libraries don't break user code, even if they will need to recompile. Libraries can pretent to be in this level if the library use only libraries at this level, has not introduced breaking changes for a given amount of time and of course if the author wants to be constrained to have a review for changes on the public interface and to correct quicky the possible tickets. 2nd level: quite stable Libraries at this level, even if stable, introduce breaking changes from time to time. Libraries can go to this level if the library use only libraries at this level or the 1st level, after a deep review of the of the interfaces, the documentation, the implementation and the test coverage and have a reduced number of tickets since a to be defined period. 3rd level: unstable It is assumed that young libraries will have a lot of breaking changes at the public interface level. Libraries can go to this level after a review of the interfaces and the documentation. Comments are welcome, _____________________ Vicente Juan Botet Escribá

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Help with GSoC; BigInt and Heaps & Queue
by Lucas Gambarra 27 Mar '10

27 Mar '10

Hi, I'm very interested in participating in GSoC. While watching the list of ideas proposed by the boost C++ Libraries, I was really interested in two of them: 'Heaps & Queues' and 'BigInt'. I am a student of Computing Sciences of the Federal University of Paraíba - Brazil. I wanted information on how to contact the mentortes of such projects. Could someone help me? Forgive me for my English. ------------ --------- --------- --------- --------- --------- --------- --------- -------- Lucas Lucena Gambarra Estagiário no Laboratório de Sistemas Digitais (LASID - UFPB) Projeto Brazil-IP 2010 email: lucas.ufpb(a)gmail.com.br MSN: lucas_gambarra@hotmail. com

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The problems with Boost development
by Vladimir Prus 27 Mar '10

27 Mar '10

Hello, in a recent post, Dave listed a few things that he thinks are wrong with Boost development, at present, quoting: I know I'm not the first person to notice that, as Boost has grown, it has become harder and harder to manage, Subversion is getting slow, our issue tracker is full to overflowing, and the release process is a full-time job. It seems to be important, right now, to discuss whether this problems are real, and what problems are most important. So, I would like to ask that everybody who is somehow involved in *development* -- whether in writing code, triaging bugs, sending patches, or managing thing, list three most important problems with Boost now. Please keep the items to a sentence or two, so that we can easily collect the problems. Here's my take: - Unmaintained components. Many authors are no longer active, and we have no procedures for taking over. - Reviews that are getting rare and, IMO, less interesting then before. - Turnaround time of test results Thanks, Volodya

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[variant] compatibility with move-constructible objects
by Zachary Turner 26 Mar '10

26 Mar '10

I have the following rough sequence of typedefs: struct empty {}; typedef std::unique_ptr<foo> foo_ptr; typedef std::unique_ptr<bar> bar_ptr; typedef std::vector<foo_ptr> foo_ptr_vec; typedef std::vector<bar_ptr> bar_ptr_vec; typedef std::variant<empty, foo_ptr_vec, bar_ptr_vec> my_variant; I then declare an instance of my_variant in a class, and make the class moveable and noncopyable. class my_class { my_class(const my_class&); my_class& my_class(const my_class&); my_variant v_; public: my_class(my_class&& other) : v_(std::move(other.v_)) { } }; I cannot get this to compile under MSVC 10 and boost 1.42. In theory I don't see why this shouldn't be ok. Even though the objects are not copy-constructible due to unique_ptr, they are move constructible. The errors are quite long, but you can see it's trying to invoke vector::operator= from within the variant code. Is this just a technical limitation of variant, or a bug? 1> behavior_collection.cpp 1>C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include\xutility(2144): error C2248: 'behavior_collection::behavior_impl<Output>::operator =' : cannot access private member declared in class 'behavior_collection::behavior_impl<Output>' 1> with 1> [ 1> Output=kinematic_output 1> ] 1> c:\users\zach\documents\visual studio 2010\projects\dxdemo\dxdemo\behavior_collection.h(15) : see declaration of 'behavior_collection::behavior_impl<Output>::operator =' 1> with 1> [ 1> Output=kinematic_output 1> ] 1> C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include\xutility(2165) : see reference to function template instantiation '_OutIt std::_Copy_impl<_InIt,_OutIt>(_InIt,_InIt,_OutIt,std::_Nonscalar_ptr_iterator_tag)' being compiled 1> with 1> [ 1> _OutIt=behavior_collection::behavior_impl<kinematic_output> *, 1> _InIt=behavior_collection::behavior_impl<kinematic_output> * 1> ] 1> C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include\vector(719) : see reference to function template instantiation '_OutIt std::_Copy_impl<behavior_collection::behavior_impl<Output>*,behavior_collection::behavior_impl<Output>*>(_InIt,_InIt,_OutIt)' being compiled 1> with 1> [ 1> _OutIt=behavior_collection::behavior_impl<kinematic_output> *, 1> Output=kinematic_output, 1> _InIt=behavior_collection::behavior_impl<kinematic_output> * 1> ] 1> C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include\vector(709) : while compiling class template member function 'std::vector<_Ty> &std::vector<_Ty>::operator =(const std::vector<_Ty> &)' 1> with 1> [ 1> _Ty=behavior_collection::behavior_impl<kinematic_output> 1> ] 1> C:\dev\boost\1.42.0\boost/type_traits/is_pod.hpp(34) : see reference to class template instantiation 'std::vector<_Ty>' being compiled 1> with 1> [ 1> _Ty=behavior_collection::behavior_impl<kinematic_output> 1> ] 1> C:\dev\boost\1.42.0\boost/type_traits/is_pod.hpp(129) : see reference to class template instantiation 'boost::detail::is_pod_impl<T>' being compiled 1> with 1> [ 1> T=std::vector<behavior_collection::behavior_impl<kinematic_output>> 1> ] 1> C:\dev\boost\1.42.0\boost/type_traits/has_trivial_constructor.hpp(27) : see reference to class template instantiation 'boost::is_pod<T>' being compiled 1> with 1> [ 1> T=std::vector<behavior_collection::behavior_impl<kinematic_output>> 1> ] 1> C:\dev\boost\1.42.0\boost/type_traits/has_trivial_constructor.hpp(36) : see reference to class template instantiation 'boost::detail::has_trivial_ctor_impl<T>' being compiled 1> with 1> [ 1> T=std::vector<behavior_collection::behavior_impl<kinematic_output>> 1> ] 1> C:\dev\boost\1.42.0\boost/type_traits/has_nothrow_constructor.hpp(23) : see reference to class template instantiation 'boost::has_trivial_constructor<T>' being compiled 1> with 1> [ 1> T=std::vector<behavior_collection::behavior_impl<kinematic_output>> 1> ] 1> C:\dev\boost\1.42.0\boost/type_traits/has_nothrow_constructor.hpp(32) : see reference to class template instantiation 'boost::detail::has_nothrow_constructor_imp<T>' being compiled 1> with 1> [ 1> T=std::vector<behavior_collection::behavior_impl<kinematic_output>> 1> ] 1> C:\dev\boost\1.42.0\boost/mpl/not.hpp(41) : see reference to class template instantiation 'boost::has_nothrow_constructor<T>' being compiled 1> with 1> [ 1> T=std::vector<behavior_collection::behavior_impl<kinematic_output>> 1> ] 1> C:\dev\boost\1.42.0\boost/mpl/aux_/preprocessed/plain/and.hpp(25) : see reference to class template instantiation 'boost::mpl::not_<T>' being compiled 1> with 1> [ 1> T=boost::has_nothrow_constructor<std::vector<behavior_collection::behavior_impl<kinematic_output>>> 1> ] 1> C:\dev\boost\1.42.0\boost/mpl/aux_/preprocessed/plain/and.hpp(55) : see reference to class template instantiation 'boost::mpl::aux::and_impl<C_,T1,T2,T3,T4>' being compiled 1> with 1> [ 1> C_=true, 1> T1=boost::mpl::apply1<boost::mpl::protect<boost::detail::variant::find_fallback_type_pred>,boost::mpl::l_iter<boost::mpl::l_item<boost::mpl::long_<2>,std::vector<behavior_collection::behavior_impl<kinematic_output>>,boost::mpl::l_item<boost::mpl::long_<1>,std::vector<behavior_collection::behavior_impl<dynamic_output>>,boost::mpl::l_end>>>>, 1> T2=boost::mpl::true_, 1> T3=boost::mpl::true_, 1> T4=boost::mpl::true_ 1> ] 1> C:\dev\boost\1.42.0\boost/mpl/iter_fold_if.hpp(46) : see reference to class template instantiation 'boost::mpl::and_<T1,T2>' being compiled 1> with 1> [ 1> T1=boost::mpl::not_<boost::is_same<boost::mpl::l_iter<boost::mpl::l_item<boost::mpl::long_<2>,std::vector<behavior_collection::behavior_impl<kinematic_output>>,boost::mpl::l_item<boost::mpl::long_<1>,std::vector<behavior_collection::behavior_impl<dynamic_output>>,boost::mpl::l_end>>>,boost::mpl::l_iter<boost::mpl::l_end>>>, 1> T2=boost::mpl::apply1<boost::mpl::protect<boost::detail::variant::find_fallback_type_pred>,boost::mpl::l_iter<boost::mpl::l_item<boost::mpl::long_<2>,std::vector<behavior_collection::behavior_impl<kinematic_output>>,boost::mpl::l_item<boost::mpl::long_<1>,std::vector<behavior_collection::behavior_impl<dynamic_output>>,boost::mpl::l_end>>>> 1> ] 1> C:\dev\boost\1.42.0\boost/mpl/aux_/preprocessed/plain/apply_wrap.hpp(49) : see reference to class template instantiation 'boost::mpl::aux::iter_fold_if_pred<Predicate,LastIterator>::apply<State,Iterator>' being compiled 1> with 1> [ 1> Predicate=boost::mpl::protect<boost::detail::variant::find_fallback_type_pred>, 1> LastIterator=boost::mpl::l_iter<boost::mpl::l_end>, 1> State=boost::mpl::int_<1>, 1> Iterator=boost::mpl::l_iter<boost::mpl::l_item<boost::mpl::long_<2>,std::vector<behavior_collection::behavior_impl<kinematic_output>>,boost::mpl::l_item<boost::mpl::long_<1>,std::vector<behavior_collection::behavior_impl<dynamic_output>>,boost::mpl::l_end>>> 1> ] 1> C:\dev\boost\1.42.0\boost/mpl/aux_/preprocessed/plain/apply.hpp(63) : see reference to class template instantiation 'boost::mpl::apply_wrap2<F,T1,T2>' being compiled 1> with 1> [ 1> F=boost::mpl::protect<boost::mpl::aux::iter_fold_if_pred<boost::mpl::protect<boost::detail::variant::find_fallback_type_pred>,boost::mpl::l_iter<boost::mpl::l_end>>>, 1> T1=boost::mpl::int_<1>, 1> T2=boost::mpl::l_iter<boost::mpl::l_item<boost::mpl::long_<2>,std::vector<behavior_collection::behavior_impl<kinematic_output>>,boost::mpl::l_item<boost::mpl::long_<1>,std::vector<behavior_collection::behavior_impl<dynamic_output>>,boost::mpl::l_end>>> 1> ] 1> C:\dev\boost\1.42.0\boost/mpl/aux_/preprocessed/plain/iter_fold_if_impl.hpp(62) : see reference to class template instantiation 'boost::mpl::apply2<F,T1,T2>' being compiled 1> with 1> [ 1> F=boost::mpl::protect<boost::mpl::aux::iter_fold_if_pred<boost::mpl::protect<boost::detail::variant::find_fallback_type_pred>,boost::mpl::l_iter<boost::mpl::l_end>>>, 1> T1=boost::mpl::int_<1>, 1> T2=boost::mpl::l_iter<boost::mpl::l_item<boost::mpl::long_<2>,std::vector<behavior_collection::behavior_impl<kinematic_output>>,boost::mpl::l_item<boost::mpl::long_<1>,std::vector<behavior_collection::behavior_impl<dynamic_output>>,boost::mpl::l_end>>> 1> ] 1> C:\dev\boost\1.42.0\boost/mpl/aux_/preprocessed/plain/iter_fold_if_impl.hpp(102) : see reference to class template instantiation 'boost::mpl::aux::iter_fold_if_forward_step<Iterator,State,ForwardOp,Predicate>' being compiled 1> with 1> [ 1> Iterator=boost::mpl::l_iter<boost::mpl::l_item<boost::mpl::long_<2>,std::vector<behavior_collection::behavior_impl<kinematic_output>>,boost::mpl::l_item<boost::mpl::long_<1>,std::vector<behavior_collection::behavior_impl<dynamic_output>>,boost::mpl::l_end>>>, 1> State=boost::mpl::int_<1>, 1> ForwardOp=boost::mpl::protect<boost::mpl::next<boost::mpl::na>>, 1> Predicate=boost::mpl::protect<boost::mpl::aux::iter_fold_if_pred<boost::mpl::protect<boost::detail::variant::find_fallback_type_pred>,boost::mpl::l_iter<boost::mpl::l_end>>> 1> ] 1> C:\dev\boost\1.42.0\boost/mpl/iter_fold_if.hpp(94) : see reference to class template instantiation 'boost::mpl::aux::iter_fold_if_impl<Iterator,State,ForwardOp,ForwardPredicate,BackwardOp,BackwardPredicate>' being compiled 1> with 1> [ 1> Iterator=boost::mpl::l_iter<boost::mpl::l_item<boost::mpl::long_<3>,behavior_collection::null_behavior,boost::mpl::l_item<boost::mpl::long_<2>,std::vector<behavior_collection::behavior_impl<kinematic_output>>,boost::mpl::l_item<boost::mpl::long_<1>,std::vector<behavior_collection::behavior_impl<dynamic_output>>,boost::mpl::l_end>>>>, 1> State=boost::mpl::int_<0>, 1> ForwardOp=boost::mpl::protect<boost::mpl::next<boost::mpl::na>>, 1> ForwardPredicate=boost::mpl::protect<boost::mpl::aux::iter_fold_if_pred<boost::mpl::protect<boost::detail::variant::find_fallback_type_pred>,boost::mpl::l_iter<boost::mpl::l_end>>>, 1> BackwardOp=boost::mpl::na, 1> BackwardPredicate=boost::mpl::always<boost::mpl::false_> 1> ] 1> C:\dev\boost\1.42.0\boost/mpl/iter_fold_if.hpp(102) : see reference to class template instantiation 'boost::mpl::iter_fold_if<Sequence,State,ForwardOp,ForwardPredicate>::result_' being compiled 1> with 1> [ 1> Sequence=boost::mpl::l_item<boost::mpl::long_<3>,behavior_collection::null_behavior,boost::mpl::l_item<boost::mpl::long_<2>,std::vector<behavior_collection::behavior_impl<kinematic_output>>,boost::mpl::l_item<boost::mpl::long_<1>,std::vector<behavior_collection::behavior_impl<dynamic_output>>,boost::mpl::l_end>>>, 1> State=boost::mpl::int_<0>, 1> ForwardOp=boost::mpl::protect<boost::mpl::next<boost::mpl::na>>, 1> ForwardPredicate=boost::mpl::protect<boost::detail::variant::find_fallback_type_pred> 1> ] 1> C:\dev\boost\1.42.0\boost/variant/variant.hpp(170) : see reference to class template instantiation 'boost::mpl::iter_fold_if<Sequence,State,ForwardOp,ForwardPredicate>' being compiled 1> with 1> [ 1> Sequence=boost::mpl::l_item<boost::mpl::long_<3>,behavior_collection::null_behavior,boost::mpl::l_item<boost::mpl::long_<2>,std::vector<behavior_collection::behavior_impl<kinematic_output>>,boost::mpl::l_item<boost::mpl::long_<1>,std::vector<behavior_collection::behavior_impl<dynamic_output>>,boost::mpl::l_end>>>, 1> State=boost::mpl::int_<0>, 1> ForwardOp=boost::mpl::protect<boost::mpl::next<boost::mpl::na>>, 1> ForwardPredicate=boost::mpl::protect<boost::detail::variant::find_fallback_type_pred> 1> ] 1> C:\dev\boost\1.42.0\boost/variant/variant.hpp(1079) : see reference to class template instantiation 'boost::detail::variant::find_fallback_type<Types>' being compiled 1> with 1> [ 1> Types=boost::mpl::l_item<boost::mpl::long_<3>,behavior_collection::null_behavior,boost::mpl::l_item<boost::mpl::long_<2>,std::vector<behavior_collection::behavior_impl<kinematic_output>>,boost::mpl::l_item<boost::mpl::long_<1>,std::vector<behavior_collection::behavior_impl<dynamic_output>>,boost::mpl::l_end>>> 1> ] 1> c:\users\zach\documents\visual studio 2010\projects\dxdemo\dxdemo\behavior_collection.h(39) : see reference to class template instantiation 'boost::variant<T0_,T1,T2>' being compiled 1> with 1> [ 1> T0_=behavior_collection::null_behavior, 1> T1=behavior_collection::kinematic_behaviors, 1> T2=behavior_collection::dynamic_behaviors 1> ]

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Re: [boost] Library dependencies and intrer-library code reuse
by Brian Wood 26 Mar '10

26 Mar '10

Dave Abrahams writes: At Fri, 26 Mar 2010 03:45:51 -0700 (PDT), Vicente Botet Escriba wrote: <snip whole thread> > > > > > > > Please don't top post. > > Vicente Please don't overquote. just-for-symmetry-ly y'rs, Dave, are you aware your messages are being duplicated on the list? I've seen that a few times with others, but often it is the case with your messages. I would also appreciate it if people would stop with the top posting and excessive quoting. -- Brian Wood Ebenezer Enterprises http://webEbenezer.net (651) 251-9384

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GSoC Parallel BGP implementation
by Naresh Reddy Sankapelly 26 Mar '10

26 Mar '10

hi, I am naresh, a student pursuing B.Tech 4th year from Indian Institute of Information Technology- Allahabad, India. I am keen to get involved in open source project development as part of GSoC 2010 with Boost. I went though the ideas list provided in the site. I'm interested to work on parallel graph algorithms for BGL in particular with graph connectives project. I took this because I have worked on parallelizing graph algorithms as a part of my Parallel Computing course. I would be happy to know few things. 1. Can I work on library of my own for parallel computing like Intel's TBB ?or should I use MPI only? 2. It would be helpful for me if I can have one more student working on sequential part of graph algorithms. Is it allowed? If it is, and any one interested please reply me back. 3. Can I get few more details of Computer Vision algorithms? I look forward to your replies soon. Thanks

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Is there anyone can tell me who is in charge of the Google Summer of Code in boost community for this year
by Qingli Ma 26 Mar '10

26 Mar '10

Hello , I want to take part in the Google Summer of Code( http://socghop.appspot.com/site/home/site) but can not find who I should contact. XML is very useful.I have used Jdom,dom and SAX for XML.Therefor,I want get the boost library support XML operations better. So ,is there anyone can tell me who should I contact with to tell my ideas and ask for suggestions.

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Should Boost adopt pimpl/d-pointer as much as it can?
by Artyom 26 Mar '10

26 Mar '10

Hello, There are recently lots of discussions about current development issues. I would like to point to one small but extremely important issue (from user point of view). Boost has too many logic in header part of library, by meaning too much I mean painfully too much. I think that Boost should adopt as policy: 1) All implementation related code **should** be put in sources. 2) Any non-template based class should have opaque/d/pimpl pointer in its body. Why? I give you a simple example: one of the pearls of Boost: Boost.Asio is one of most painful libraries to use. I created a simple example of echo server written with Boost.Asio and written with a small pimpl-wrapped Boost.Asio (I had written myself as proof of concept - that uses boost.asio in implementation): http://art-blog.no-ip.info/files/asio_pimpl.tar.gz These are results of compilation times with gcc-4.3 (seconds): -O0 -O2 -O3 -O2+link asio 2.56 4.65 4.96 4.75 pimpl 0.59 0.85 0.89 0.94 diff *4.3 *5.5 *5.6 *5.05 And this is trivial echo server. When the code gets larger and bigger it becomes even more painful. For me, compilation of components based on Asio is total nightmare because of unacceptable compilation times. Another issue is executable size. I had took same echo sever placed in 10 object compiled under different namespaces once I did it with Boost.Asio and then I did it with pimpl-ed Asio. Result (liked executable size with gcc-4.3): Build Size (-Os stripped) Asio: 245K Pimpl: 190K ---------------------------- Conclusions: ============ There are too many good libraries (Asio as good example) that use headers too much or headers only, this terribly increases compilation times and makes executable sizes much bigger (this is especially relevant for embedded systems). Should Boost wellcome pimpled libraries more? I think yes. It would solve two problems: 1. It would give faster compilation times. 2. It would allow to provide changes easily without breaking compatibility (even would allow to provide backward ABI compatibility) Dear Boosters. What do you think about? Artyom

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Re: [boost] GSOC query for Heaps and Que
by Andrew Sutton 26 Mar '10

26 Mar '10

Hi Chirag, 1) Relaxed Fibbonacci Heaps by Chandrasekhar Boyapati C. Pandu Rangan > 2) Relaxed Weak Que by Amr Elmasry Claus Jensen Jyrki Katajainen > 3) Soft Heap by Bernand Chazelle > > Please tell can I add these datastuctures to my proposal for GSOC . > I think those data structures are in the spirit of the proposal. It would not be a bad idea. > I also want to add radix tree and generalized version of union find > datastructure into my proposal. > Will it be a good proposal ? > That might be a little ambitious for a 3 month project. I would try to keep your proposal a little more focused. Andrew Sutton andrew.n.sutton(a)gmail.com

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Re: [boost] [gil] Can not open test.jpg
by Mariusz Kwiczala 26 Mar '10

26 Mar '10

Christian, >>This file needs to be swapped out. Will do that next week. >Done. Thank you. >Marius, do you wanna try out it the new gil::io? It's located here: >http://gil-contributions.googlecode.com/svn/trunk/gil_2/boost/gil/extension / Will it be available in 1.43? >Let me know if you have questions, problems, etc. I have one suggestion: Gil::Io extensions do not work without required libjpeg libpng, libtiff ... There is no way to run examples from "boost_1_42_0\libs\gil\example" without required libs. There are problems to match boost::gil and "external graphlibs" i.e. http://stackoverflow.com/questions/2442335/libpng-boostgil-png-infopp-null-n ot-found I think that libjpeg libpng, libtiff libs should be included into boost and compiled with use bjam. Regards, Mariusz

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Re: [boost] [transact] code in sandbox
by vicente.botet 26 Mar '10

26 Mar '10

----- Original Message ----- From: <strasser(a)uni-bremen.de> To: "vicente.botet" <vicente.botet(a)wanadoo.fr> Sent: Friday, February 12, 2010 2:00 AM Subject: Re: Re:[boost] [transact] code in sandbox > Zitat von "vicente.botet" <vicente.botet(a)wanadoo.fr>: >> IMO the transaction must be accesible during the handling of the exceptions. > > why? I see one reason in your examples (although I don't understand > force_to_abort, maybe that's another one, see below), and that is > committing on exception: > >>>> #define BOOST_TRANSACT_BASIC_RETHROW(TXMGR, TX, E) \\ >>>> catch (E&) {(TX).commit(); throw;} > > why can't the user create his own try/catch block for that?: > (using your syntax) > BOOST_TRANSACT_ATOMIC(_) { > try{ > ... > }catch(my_exc &){ > _.commit(); > } > }BOOST_TRANSACT_COMMIT(); Yes this is always possible. However, transactions and exception handling are used for the same goal, recover from errors. Thus it is interesting to handle them in the same way and in a single try-cactch block. >> _.force_to_abort(); > > what does this do? retry the transaction but make sure it fails? why? > why don't you just go ahead and throw an exception that is not caught > inside the transaction scope? When the user wants to undo whatever the transacton block did, the simple way is to abort the transaction. Don't forget that transactions can be used in a single-threaded application to make exception-safe code. >>> at some point I think the macros loose their benefit and you might >>> just as well write the loop yourself. e.g. if you need to execute >>> custom code on retry. >> >> You are right. The specific macros are not important. What is >> important is that the provided macros can be extended naturaly. > > that's what I'm not so sure of. if you need to control the number of > retries or execute custom code on retry, why don't you just write this > instead of using macros: > > for(int c=0;c<10;++c){ > try{ > transaction tx; > ... > tx.commit(); > break; > }catch(isolation_exceotion &e){ > e.unwind(); > std::cerr << "my custom retry code\n"; > } > } > > doesn't seem a whole lot more verbose to me. > but I'm not against adding more macros for convenience. the one thing > I would like is not complicating the simplest use case. the user > shouldn't have to to add something like "(_)" if he doesn't need it > and has no idea what it is there for. the default use case should be > as simple as possible. I would like also to don't need to add a transaction variable name. I need the name of the transaction variables to implement break and continue in a language-like. From my side, the inclusion of the macros is to be close to what the user will write if the language provided some specific transaction constructs. The user is always free to use directly the class interface. The question is what is the simple case. for an INNER transaction Boost.STM provides a macro #define BOOST_STM_USE_ATOMIC(TX) \ for (boost::stm::transaction TX; \ ! TX.committed() \ && TX.restart(); \ TX.commit()) that the user ca use like BOOST_STM_USE_ATOMIC(_) { // transaction statement } In this case every exception scape the transaction block, and will be managed by the outer transaction block. This is simple, recall a possible language statement transaction { // transaction statements } The parameter is needed only if we want to return from the transaction block. If needed we can add a simple #define BOOST_STM_INNER_TRANSACTION \ for (boost::stm::transaction __TX; \ ! __TX.committed() \ && __TX.restart(); \ __TX.commit()) use as follows BOOST_STM_INNER_TRANSACTION { // transaction statement } As I said in a preceding post, we can provide initialy both sets of macros and see which set the users use more often. Best, Vicente

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About adding XML API in the boost.
by Qingli Ma 26 Mar '10

26 Mar '10

Hello,everyone! I am from china and want to take part in the boost commnnity. Support for XML is limited in boost, so I want to do something about this. Also I see some information at https://svn.boost.org/trac/boost/wiki/SoC2010. I wish to take part in the Google Summer of Code(http://socghop.appspot.com/). Can you give me some ideas about that?Who should I contact with? Thank you for your sugguestion!

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GSOC - Boost.XML
by Shrinidhi Hudli 26 Mar '10

26 Mar '10

Hello, I am interested to send a proposal to work on Boost.XML for GSOC 2010. I have a couple of questions: 1. Would it make sense to provide C++ binding for XML using XSD? This would make it much more convenient that using parsers explicitly. 2. Is the project mostly to develop an abstraction for the backend parsers so that different parsers can be "plugged-in"? Thanks for the clarification. -- Shrinidhi Hudli

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Re: [boost] [lexical_cast] A non-throwing lexical cast? [Was: 5Observations - My experience with the boost libraries]
by pete＠pcbartlett.com 26 Mar '10

26 Mar '10

On Fri 26/03/10 01:25 , Gennadiy Rozental <rogeeff(a)gmail.com> wrote: > Rene Rivera writes: > > > > Tom Brinkman wrote: > > > boost::lexical_cast_no_throw() > > > > Or.. > > > > template > > T lexical_cast(const S & arg, const T & error_default_value); > > > I've implemented later in my own version of lexical cast. In 99% of > the time > this is exactly what I need: either convert string to number or take > this > default value. Another good consequence is that I do not need > template parameter > anymore. > Gennadiy Looking at the various threads it seems like three different behaviours in the event of conversion failure have been requested. - Default Value - boost::system::error_code - throw custom exception. So this would suggest an interface like template< typename T , typename S, typename FailureHandler > lexical_cast(S const& arg , FailureHandler fh) with specializations if FailureHandler = T or FailureHandler = boost::system::error_code&. You do lose your "good consequence" with this formulation though. As I said in another message, the original author of lexical_cast has said several times over the years that doing something like this is too far from the spirit of a *_cast, though, so if it gets into Boost I think it will have to be in the StringConvert library.

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[lexical_cast] A non-throwing lexical cast? [Was: 5 Observations - My experience with the boost libraries]
by pete＠pcbartlett.com 26 Mar '10

26 Mar '10

On Wed 24/03/10 03:40 , Jonathan Franklin <franklin.jonathan(a)gmail.com> wrote: > On Tue, Mar 23, 2010 at 9:31 PM, Tom Brinkman wrote: > > ... All I'm saying is that in the real world, most > > projects are mixed C/C++ and that the needs of both communities > need > > to be addressed if boost is going to remain relevent. > For the sake of not arguing, let's assume that your assertion is > true. > Let's hear your *actionable* proposal for improving boost. E.g. > show > us the better interface for <insert Boost library here> Taking an example from way back at the start othis thread, in my personal experience a non-throwing version of lexical_cast<> would be very nice. If I look at the cases where I pass user data through my libraries into boost libraries without some pre-validation, there are very few, and naturally these are the cases where the validation would as difficult as the "parse": - boost::spirit::phrase_parse - Just returns a true/false, and I build a nice context-driven error message myself if necessary. - boost::lexical_cast - throws. Almost always needs to be caught and re-thrown.

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Re: [boost] [lexical_cast] A non-throwing lexical cast? [Was: 5 Observations - My experience with the boost libraries]
by Pete Bartlett 25 Mar '10

25 Mar '10

Kim Barrett wrote: > On Mar 24, 2010, at 5:20 PM, Bruno Santos wrote: >>boost::bad_lexical_cast is not derived from >>my_project::invalid_user_input o or whatever. This happens a lot with >>boost::lexical_cast. >> >If the user data is data that comes from a file or user interface, I >agree in your assertion. > >However, if it's from someone using your library, it's an obvious >programming error, doing exception translation in this case is >pointless. Agreed, but the source of data in a text format that should be a numeric format is much more likely to be end-user systems and inputs rather than that created within a client application, IME. >Anyway, in my opinion, passing a boost::system::error_code as the second >parameter for a non throwing version would be the best solution. As Jeff points out, others have been here before us, and it looks like the proposed Boost.StringConvert is the result of prior discussions. Perhaps our energies would be best spent making sure that library meets our needs by being reviewers or even the review manager [one is still needed, according to the schedule]. Pete

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GSOC 2010 Boost-Graph
by Chinmaya Poswalia 25 Mar '10

25 Mar '10

Hi Myself Chinmaya Poswalia Computer Science an Engineering B.Tech, Indian Institute of Technology, Guwahati I am finding all the graph topic(my favorite topic to work on) very interesting that's why i asked a lot of questions regarding all in one mail. - i want to work on semantic graph - how about maintaining an adjacency list, denote V as nodes and E as edges, so the space complexity will be O(V+E). - Also we can employ pointers of type void* to point to edges/vertices of different types so as to maintain the graph of different edge and vertex types. - rather than employing a vector in each node and edge either we should allocate space during insertion or we maintain the size of vector array by ourself. - Through generic programming, all the operations being implemented on graph up till now will be made applicable on these new members of the library. - various functions that can be induced on these graphs are 1. Distribution of node degree 2. finding clustering co-efficient of semantic graph 3. relevance of a link and node 4. scale on semantic graph 5. disparity of connected types/dispersion co-efficient. - Semantic graph are generating huge level of importance in networking (network semantics on web), video screening, statistical analysis of data,etc so it will be a great thing to work on it. Can you suggest some more links to read on for these I am working on my proposal about the graph and your help is crucial for me. With regards Chinmaya

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[log] Boost.Log formal review result
by Vladimir Prus 25 Mar '10

25 Mar '10

First of all, I would like to thank Andrey for this submission and the active discussion during the review. I also would like to thank everybody who participated in the review. The comments on the library were generally positive. Several reviewers have tried it in practical projects already, and found it superior to other libraries. It clearly will benefit the users of Boost right away. Therefore, the library is accepted. Congratulations, Andrey! On the other hand, some concerns about the ease of use and performance and implementation details were raised. Of those, some can be easily addressed as part of normal maintenance, while some seem to require significant rework and may change the library quite consirably. Therefore, the library is accepted subject to several conditions -- listed below under "Critical issues". Because the changes can be large, I think a mini-require is required when those issues are addressed. To avoid delays, it's probably not necessary to formally schedule and conduct a mini-review -- just posting a email asking for discussion will be sufficient. Statistics ========== There were roughly 300 emails during formal review (I have a mbox archive if anybody needs it). The following persons submitted a review with a vote. Some of votes are "provisional", this is not reflected below, but affects the list of critical issues below. - Boris Schaeling (yes) - Roland Bock (yes) - Ralf Globisch (yes) - Sean Chittenden (yes) - Darryl Green (no) - Tom Brinkman (no) - Barend (yes) - Sam Gundry (yes) - Vicente Botet (yes) - Robert Stewart (yes) - Alexander Arhipenko (yes) - "M-Square" (yes) Critical issues =============== These issues must be addressed, and be passed through informal mini-review, before the library can be added to SVN. - It appears that the 'trivial' logging is not sufficiently good to just take and use. The library should provide an out-of-the-box mechanism that: - supports channel/severity attributes, without creating new logger for each severity. It also should be possible to filter out specific channel by essentially poking at some "map", and without manually composing a new filter that checks for a set of allowed channels sequentally. I believe that at least Christian, Roland, Robert and myself requested this. - has no observable effect on compile time. One second (or more) that trivial.hpp imposes is not acceptable. - outputs to console by default, but permits changing that - outputs only component/severity/message by default, but probably permits changing that. - By default, the library should try hard to continue working no matter what errors happen during processign a log record -- including things like invalid attribute names or types, or other exceptions. - The library should not reinvent wheels. In particular, custom implementations of TSS and RW mutex seems like a very bad idea. Use of a custom lambda implementation was pointed by many as not great -- we already have a couple, so let's not add more to the mix. - Library interface is too geared towards lambda. In particular, implementing formatters/filters as free-standing functions appears to require considerably more code. In particular, it should be possible to access an attribute using a single function call. Also, logging::extract taking a lambda for callback complicates matters, it's desirable to have a more direct variant. Important issues ================ These issues are important enough to be mentioned here, but can be addressed as convenient. - The reported run-time performance can be improved. In particular the performance with date attributes seems scary and 2x slowdown relative to some other library in the 'most records are filtered out' case is also concerning. - I don't think it was satisfactory explained why 'attr' exists in two namespaces, as opposed to being a single type that is used for both formatting and filtering. Other notes =========== These issues seem important and should be considered, but might not even be fixable within the current design. - Several reviewers said the library is "too flexible" and this makes it harder to understand. Probably nothing can be done about that at this point, but interesting data point notwithstanding. - It was suggested that the library include an API that another Boost log may use in a way that permits plugging another logging library should end user of a Boost so desire. This seems a good idea, but I think it's up to Andrey to implement such API or not. - Alternative design approaches were proposed, in particular (i) permitting user log records and templating/basing other components on a user-defined record type and (ii) using compile-time indexing to access attributes. Also, it was proposed that named parameters not be necessary to use the library, and a more conventional interface be available. It does not seem that implementing those suggestions is fully possible without writing a different library from scratch, so it's up to Andrey to consider those proposals. - It was suggested to use newer Spirit to address poor compile times for the library itself. Thanks, Volodya

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[log] How to derive from a logger
by Andreas Huber 25 Mar '10

25 Mar '10

Hi Andrey As discussed earlier, we're kind of desperate to add functionality to a logger class provided by Boost.Log. Instead of duplicating severity_channel_logger_mt, I'm wondering whether it's a good idea to derive from it, as follows: class Logger : public ::boost::log::sources::severity_channel_logger_mt< Severity > { public: typedef ::boost::log::sources::severity_channel_logger_mt< Severity > logger_base; BOOST_LOG_FORWARD_LOGGER_CONSTRUCTORS(Tracer) void SetMinimumSeverity(Severity severity); Severity GetMinimumSeverity(); private: Severity minimumSeverity; }; Elsewhere we'd use this class as follows: BOOST_LOG_DECLARE_GLOBAL_LOGGER_INIT(Whatever, Logger) { // ... } It seems to work, but is this a good idea? Thanks & Regards, -- Andreas Huber When replying by private email, please remove the words spam and trap from the address shown in the header.

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