March 2010 - Boost - lists.preview.boost.org

[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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