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GSoC: Student application deadline in less than 24 hours
by Boris Schaeling 02 May '13

02 May '13

Students interested in applying for a GSoC project should submit their application as soon as possible. The deadline is in less than 24 hours. Click here to apply: <https://google-melange.appspot.com/gsoc/homepage/google/gsoc2013> Boris

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[gsoc-2013] Boost.Expected
by Pierre T. 02 May '13

02 May '13

Hello, My name is Pierre Talbot, I participated to GSoC 2011 and began the implementation of the Boost.Check library (for checking the validity of any number having a check digit — credit card number, ISBN, …). It was two years ago and the design is still evolving due to many variation points in the code. One of the function looks like : template <typename check_algo, typename range> boost::optional<typename check_algo::checkdigit_type> compute_checkdigit(const range &x); Using boost::optional tell us that: "A check digit should be computed if 'x' is a valid sequence". Since 'x' has many reasons to be incorrect, many errors could be raised. Based on a policy template class, it launches exception or returns with an empty optional . Then I though a lot about a better way to do it, allowing the user to get an exception or an error code. But it was quite complex for a so little part of my library… I decided that the policy "throw exception or nothing" should be enough. Yesterday, I watched the video of Mr. Alexandrescu on Boost.Expected and I think it would be a very useful library. It could mainly be useful in system programming (where many error codes can arise from a single call), but in any code where many exception errors can be thrown (like in Boost.Check). As you suspected, I'm interested in coding Boost.Expected during the summer as a GSoC student. Firstly, it could be very useful to list the resources on the subject (aside the talk), I have several articles that I will talk about later. Secondly, and hoping you'll debate, I would like to ask your opinion about several ideas and facts: 1) In the Boost project description, we can read: "adding a class expected-or-error_code". Obviously, the main design decision made by Alexandrescu is to consider that error code are exception. Do we need an abstraction of exception/error code ? Why do you think a "expected-or-error_code" class is interesting ? 2) Consider this code (from Alexandrescu slides) : // Caller string s = readline(); auto x = parseInt(s).get(); // throw on error auto y = parseInt(s); // won’t throw if (!y.valid()) { // handle locally if (y.hasException<std::invalid_argument>()) { // ------------------ < The flagged line. // no digits ... } y.get(); // just "re"throw } The flagged line has some tastes of "return to the past" flavor. Back to the C procedural language, the basic error code handling system was a lot criticized because: * Readability of the code decrease ; * Error handling occurs in the middle of the execution flow ; * <Add your favourite reason here>. Several links on the subjects (if you have others, I'm interested) http://www.joelonsoftware.com/articles/Wrong.html http://www.joelonsoftware.com/items/2003/10/13.html http://blogs.msdn.com/b/oldnewthing/archive/2005/01/14/352949.aspx http://nedbatchelder.com/text/exceptions-vs-status.html Basically, only the last one is clearly for exception. The main argument against the procedural approach is the readability. I would say that the Expected approach just differ by allowing to rethrow exception. But if you want to handle it, you must code multiple if-than-else statements. So I considered a complementary approach working with Expected to handle multiple error cases: string visa_number = readline(); expected<char> expected_checkdigit = compute_checkdigit<visa>(visa_number); if(expected_checkdigit.valid(visa_error_resolver)) { visa_number += expected_checkdigit.get(); std::cout << visa_number << std::endl; } With this code, there is only a if statement, and no more multiple error cases handles. But what is this error_resolver ? It may be declared as : // Somewhere in visa.hpp. A type list. typedef error_list<size_error_exception, unknown_character_exception, checkdigit_encoding_exception, …> visa_errors; // Somewhere in the user code. error_resolver<visa_errors, expected_type> visa_error_resolver; // in this case, expected_type is a char. // Initialize error handler on specific exception/errors. visa_error_resolver.on<size_error_exception>(size_error_handler) .on<unknown_character_exception>(unknown_character_exception) ... Now we are agree that visa_error_resolver can be reused everywhere we want to resolve an error on a visa number. What are the handlers ? There are [Function|Functor|Lambda] (pick up your favourite) with this form : expected<ExpectedType> size_error_handler(const size_error_exception&) expected<ExpectedType> unknown_character_exception(const unknown_character_exception&) Now you can understand for what the type list "error_list" stands for, we can store these handlers into the error_resolver and call them without any virtual cost. Why the return type of error handler is expected<ExpectedType> ? Consider this size_error_handler code : expected<ReturnType> size_error_handler(const size_error_exception& e) { std::cout << "The number you gave has a bad size." << std::endl; std::cout << "Enter it again : " << std::endl; return read_visa_checkdigit(); } read_visa_checkdigit can call recursively valid() until it's valid. Though there are some ways to make this treatment iterative. A basic treatment could be to print an warning message and just returns (in this case, valid returns false): expected<ReturnType> size_error_handler(const size_error_exception& e) { std::cout << "Warning: the VISA field is incorrect." << std::endl; return expected<ReturnType>::fromException(e); } Results: * The error code handling is delegated to specific functions ; * The readability is still excellent ; * You can easily re-use your error handler function ; * If you don't like it, you can still throw exception on failure with "get()". I can code a "proof of concept" if you think this is a good idea. Do not hesitate to comment it, point out programming pitfalls, request further clarification, or anything you judge useful. Thank you for reading it ! Pierre Talbot

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Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
by Niall Douglas 02 May '13

02 May '13

> > I have just read N3388 - Using Asio with C++11 and a think I start to > > understand the ASIO design. > > Could we say the completion handlers are continuations? > > And that the user use to master which thread executes the continuation by > > calling the io_service::run() function? > > Pretty much, except that multiple threads can call io_service::run > concurrently. Basically Boost.Asio is a work sharing queue plus a > collection of waitqueues to wait for specific events. Far clearer than my explanation. Thanks. > That's orthogonal. Boost.Asio provides the funding blocks. A nicer > interface that doesn't require an explicit continuation passing style > transformation can be built with Boost.Context or a similar library. > But it probably needs a future implementation that integrates with > ASIO, which is one of the point of Niall Douglas. Spot on. Especially as parts of ASIO are due to enter with TR2. I worry that a thread pool designed without ASIO in mind would become an orphan isolate. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

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[testing] run.py and cross compilation
by Antony Polukhin 02 May '13

02 May '13

Hi, Is there some possibility to compile sources on one platform (x86) and then run compiled tests on other platform (ARM/Android) using run.py script? This is required, because Android SDK exists only for x86 so there is no way to compile tests on ARM Android device. -- Best regards, Antony Polukhin

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[GSoC2013] My updated proposal to the XML library project
by Amos Ji 02 May '13

02 May '13

Hi, I have updated my proposal to the XML library project. If you're interested in it, you can review it at http://www.google-melange.com/gsoc/proposal/review/google/gsoc2013/amosji/3… And there is also a pdf version: https://www.dropbox.com/s/3zgxkpb9bx45auo/Boost_XML_library.pdf Any comments are appreciated. Thanks a lot. Regards, Mingchao

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[reference_wrapper] Overloading operator() in reference_wrapper
by Nathan Crookston 02 May '13

02 May '13

Hi all, std::reference_wrapper includes an overload of operator()[1] which allows a wrapped function object to be called without needing to first unwrap: #include <boost/ref.hpp> #include <functional> #include <iostream> int main() { auto f = [](int i) { std::cout << i * 2 << std::endl; }; std::ref(f)(5);//change this to boost::ref and it will not compile. } I think it would be valuable to update boost::ref to match the standard version. On compilers which support variadic templates and rvalue references the code is obvious. Those which support one or neither could still have overloads for some number of arguments. This would be handy in a few places, notably boost::gil::for_each_pixel[2]. I know that boost::bind + reference wrapper could be used instead (boost::bind(boost::ref(f), 5)). Given that implementing operator() is relatively simple, and that the standard object based on boost::reference_wrapper has it (rather than requiring std::bind), I'd argue that this change is desirable. Thanks, Nate [1] http://en.cppreference.com/w/cpp/utility/functional/reference_wrapper/opera… [2]http://comments.gmane.org/gmane.comp.lang.c%2B%2B.isocpp.general/513

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Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
by Niall Douglas 02 May '13

02 May '13

> Le 01/05/13 20:39, Niall Douglas a ?crit : > >> I don't see the term "central asynchronous dispatcher" used in any of > >> the links. Could you clarify what it is? > > I have to admit I'm struggling to see where your block is, but Dave Abrahams > > often found the same with me, so it must be me. > It is just that I don't know the term. > As I don't know the domain (the words) you are talking about we can stop > the exchange here if you prefer, or you could continue to explaining me > the things I don't know/understand. Don't worry, it's almost certainly me as native English speakers rarely understand me either. Besides when I lived in Spain I remember only too well the problem with domain terminology, like when a dentist told me I had a "del gasto" which I took to him wanting money because he had high rent :). I'll keep going as long as you need. We'll get there eventually. > > The central means one execution context does the dispatch. The asynchronous > > means that callbacks are processed by recipients asynchronous to the > > dispatcher. And dispatcher, well that dispatches. > In order to be sure I understand what you say could you tell me how a > decentralized asynchronous dispatcher behaves? What are the differences? A centralized dispatcher dispatches from one execution context to many. A decentralized dispatcher dispatches from many execution contexts to one or more contexts. An example of the latter is cloud apps actually, where millions of apps will dispatch events to a load balanced core cluster of servers i.e. many => few. By execution context I mean a thread, a fibre, a coroutine, a handler or even a closure. Generally if it's got its own distinct stack separate from other stacks, it's an execution context. > > I'd take a reasonable guess that MCAS will benefit centralized kernel-based > > threading primitives architectures such as Windows NT more than > > decentralized threading primitive architectures such as POSIX. That said, I > > could see Linux using TM for batch multi-kernel-futex ops, though I'd have > > to say implementing that without breakage would be daunting. > > > Are you saying that current TM technology should be much more useful for > centralized than decentralized asynchronous dispatchers? I'm saying my suspicion is that. Others on SG5 may disagree (they disagree with me about most of my opinions). It's still very early days for TM in C++. > Does this means that the whole application would improve its > performances using always centralized asynchronous dispatchers? I'm saying it's a likely optimization case. Other than a recompile, application need not know the difference. > > You may find N3562 Executors and schedulers coproposed March 2013 for > > Bristol by Google and Microsoft of use to you in understanding the relation > > between thread pools and Boost.ASIO > > (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3562.pdf) > I know this proposal. Could you explain me how it is related to > Boost.Asio? Could you point me where in the Asio documentation could I > find related information? I think your other post is more relevant, so I'll answer there. But agreed that Asio's documentation assumes the user already understands how it works. If you come from a NT kernel or VMS or libuv programming background, it's obvious. But much less so for everyone else. > > My > > proposed Boost.AFIO library is an implementation of that same N3562 idea, > > albeit I extend Boost.ASIO which is IMHO more C++-y whereas Google and > > Microsoft have gone with proprietary implementations. Also, they include > > timing and many other more general purpose features, and mine does not > > (currently) as it's mainly aimed at maximising input/ouput with highly > > jittery random latency storage. > > > Thanks Niall for all the explanations and sorry if all this is trivial > for you. These types of discussion always add to the collective good. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

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[testing] run.py and cross compilation
by Niall Douglas 02 May '13

02 May '13

> Is there some possibility to compile sources on one platform (x86) and > then run compiled tests on other platform (ARM/Android) using run.py > script? > > This is required, because Android SDK exists only for x86 so there is > no way to compile tests on ARM Android device. I believe we have a related or similar problem with unit testing Boost on BB10. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

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[gsoc2013] Proposal for Boost.Math Bernoulli numbers and special functions project
by Artemy Margaritov 02 May '13

02 May '13

Hi folks! I want to provide my proposal for Boost.Math Bernoulli numbers and special functions poject to the Boost community. Please, lets discuss it! I will be grateful for your advices. -- Best regards, Artemy Margaritov

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Re: [boost] [gsoc-13][proposal] Boost.uBLAS
by Aditya Avinash 02 May '13

02 May '13

On Thu, May 2, 2013 at 1:24 AM, Aditya Avinash <adityaavinash143(a)gmail.com>wrote: > I have updated the proposal. Here it is. > > > On Thu, May 2, 2013 at 1:21 AM, Aditya Avinash <adityaavinash143(a)gmail.com > > wrote: > >> Hi, this is my GSOC 13 proposal on Boost uBLAS. >> >> >> On Wed, May 1, 2013 at 3:15 PM, David Bellot <david.bellot(a)gmail.com>wrote: >> >>> Great. I'm looking forward to it. >>> >>> Best, >>> David >>> >>> >>> On Tue, Apr 30, 2013 at 11:06 PM, Aditya Avinash < >>> adityaavinash143(a)gmail.com >>> > wrote: >>> >>> > I'll upload in 16 hrs. >>> > >>> > On Wed, May 1, 2013 at 2:55 AM, David Bellot <david.bellot(a)gmail.com> >>> > wrote: >>> > >>> > > Hi Aditya, >>> > > >>> > > yes, please send me a written proposal, so that I can help you on >>> that. >>> > > It's definitively something we want to do for ublas. >>> > > >>> > > Best, >>> > > David >>> > > >>> > > >>> > > On Mon, Apr 29, 2013 at 6:56 PM, Aditya Avinash >>> > > <adityaavinash143(a)gmail.com>wrote: >>> > > >>> > > > Hi, I have a proposal for boost in gsoc-13 under boost.ublas >>> > > > >>> > > > *Proposal: SIMD abstraction for uBlas.* >>> > > > >>> > > > >>> > > > - I want to develop SIMD abstraction for uBlas. >>> > > > >>> > > > >>> > > > Goal 1: Develop the Intel SSE & AVX backend for SIMD abstraction in >>> > > uBLAS. >>> > > > >>> > > > Goal 2: Develop AMD SSE backend for SIMD abstraction in uBLAS. >>> > > > >>> > > > Goal 3: Develop frontend for SIMD abstraction in C++. >>> > > > >>> > > > Goal 4: Joining of frontend and backend, so the the code is >>> flexible to >>> > > > implement on both AMD and INTEL. >>> > > > >>> > > > Goal 5: Develop the ARM-NEON backend for SIMD abstraction in >>> uBLAS. >>> > (if >>> > > > time permits). >>> > > > >>> > > > -- >>> > > > ---------------- >>> > > > Atluri Aditya Avinash, >>> > > > India. >>> > > > >>> > > > _______________________________________________ >>> > > > Unsubscribe & other changes: >>> > > > http://lists.boost.org/mailman/listinfo.cgi/boost >>> > > > >>> > > >>> > > _______________________________________________ >>> > > Unsubscribe & other changes: >>> > > http://lists.boost.org/mailman/listinfo.cgi/boost >>> > > >>> > >>> > >>> > >>> > -- >>> > ---------------- >>> > Atluri Aditya Avinash, >>> > India. >>> > >>> > _______________________________________________ >>> > Unsubscribe & other changes: >>> > http://lists.boost.org/mailman/listinfo.cgi/boost >>> > >>> >>> _______________________________________________ >>> Unsubscribe & other changes: >>> http://lists.boost.org/mailman/listinfo.cgi/boost >>> >> >> >> >> -- >> ---------------- >> Atluri Aditya Avinash, >> India. >> > > > > -- > ---------------- > Atluri Aditya Avinash, > India. > -- ---------------- Atluri Aditya Avinash, India.

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[gsoc 2013] draft proposal for chrono::date
by Anurag Kalia 02 May '13

02 May '13

I have prepared a draft proposal for Boost.chrono/date implementation. Could you kindly go through it and tell me of any errors and suggestions? Regards, Anurag Kalia.

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Proposal for Bernoulli numbers
by Gaurav Deshmukh 02 May '13

02 May '13

Mentors for Boost.Math, please review my proposal at the melange site. http://www.google-melange.com/gsoc/proposal/review/google/gsoc2013/gaurav42… Shall I include details about the templates of functions I will have to implement? Or are there any corrections or details needed? Thanking you, Gaurav Deshmukh

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Re: [boost] [GSOC] Are we going to participate?
by Stefan Seefeld 02 May '13

02 May '13

Hi Boris, I just noticed today someone inquiring about Boost.XML as a GSoC project. Being the one who originally suggested that idea almost ten (!) years ago (and who then also implemented a simple sandbox project as a proof-of-concept), I would love to see such a project being successful. Do you think it's still time to work on a proposal ? Where should I register to be an eligible mentor with boost.org ? (I'm already registered with GSoC - my ID is 'stefan'.) Thanks, Stefan -- ...ich hab' noch einen Koffer in Berlin...

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[Log] Plans to use std::thread?
by Rich E 01 May '13

01 May '13

Hi all, As I've been testing out the newly added Boost.Log library, I noticed it is relying on Boost.Thread even when the C++11 <thread> library is present. Are there any plans to allow the native <thread> library to be used when it is available? I think this can be done with Boost.Config's BOOST_NO_CXX11_HDR_THREAD macro. Thanks, Rich

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Re: [boost] GSoC Boost.Multiprecision project
by Jyotesh Choudhari 01 May '13

01 May '13

Hello, > Hi Jyotesh. >>>> Looking at the project description, I think >>>> I have understood what needs to be implemented >>>> in this project. > Yes, you seem to have a good grasp of the issues. > Good work. >>>> I have also gone through the current >>>> code cpp_bin_float.hpp and I have understood some >>>> part of it. I want to know how >>>> detailed should my proposal be? What details >>>> should I include in my proposal? >>>> What should be the deliverables for the project? > Go ahead and add some details from cpp_bin_float > if you like. You can mention that this is a potential > solution method. Thank you for your valuable feedback. I have written project proposal for the first time in my life. So, I did not know what details to include. I have made some changes to my proposal as per your suggestions. > Other than that, I believe you have found > the right level of detail, with a few more suggestions > from my side below. >> I have attached my proposal with this mail. >> Please have a look at it and let me know your feedback. >> Thanks and regards, > I suggest you move the FFT algorithms to an optional > part, add a bit more time for the elementary transcendental > functions, and add some time for testing the various > milestones in the project. > After that, you should start submitting your proposal. > As far as I know, you can modify your proposal up > to May 03. I have written FFT algorithm as an optional algorithm now and made some changes to schedule. Please let me know if it is fine now. > Keep up the good work. > Sincerely, Chris I was studying the code for cpp_bin_float and I have some doubts in my mind. 1. What are eval_ops_signed_type, eval_ops_unsigned_type and eval_ops_float_type? 2. What is the use of following lines? typedef mpl::list<eval_ops_signed_type> signed_types; typedef mpl::list<eval_ops_unsigned_type> unsigned_types; typedef mpl::list<eval_ops_float_type> float_types; These are not used in the class elsewhere. Similar lines are present in cpp_dec_float.hpp also and not used elsewhere in the class. 3. In the function from_float_type, I think the variable number_of_digits should be initialized to zero before using it in while loop. Lastly, I have seen on mailing list, that some of the students are submitting code samples. As I am busy with my end-semester exams and R&D project, I am not able to send any sample code. As soon as I get free, I will send it. Thanks and regards, Jyotesh Choudhari

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[gsoc-13][proposal] Boost.uBLAS
by Aditya Avinash 01 May '13

01 May '13

Hi, I have a proposal for boost in gsoc-13 under boost.ublas *Proposal: SIMD abstraction for uBlas.* - I want to develop SIMD abstraction for uBlas. Goal 1: Develop the Intel SSE & AVX backend for SIMD abstraction in uBLAS. Goal 2: Develop AMD SSE backend for SIMD abstraction in uBLAS. Goal 3: Develop frontend for SIMD abstraction in C++. Goal 4: Joining of frontend and backend, so the the code is flexible to implement on both AMD and INTEL. Goal 5: Develop the ARM-NEON backend for SIMD abstraction in uBLAS. (if time permits). -- ---------------- Atluri Aditya Avinash, India.

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Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
by Niall Douglas 01 May '13

01 May '13

> Le 29/04/13 21:35, Niall Douglas a ?crit : > > No major changes to the C++11 futures API is needed. Rather that a > > different, but compatible, optimized implementation of future<> gets > > returned when used from a central asynchronous dispatcher. So the C++ > > standard remains in force, only the underlying implementation is more > > optimal. > > Could you explain me what a central asynchronous dispatcher is? An asynchronous procedure call implementation. Here's Microsoft's: http://msdn.microsoft.com/en-us/library/windows/desktop/ms681951(v=vs.85).as px. Here's QNX's: http://www.qnx.com/developers/articles/article_870_1.html. Boost.ASIO is the same thing for Boost and C++ but implemented by application code. It is *not* like asynchronous POSIX signals which are a nearly useless subset of APCs. > If not, please could you elaborate what kind of optimizations can be > obtained? If you have transactional memory in particular, you gain multi-CAS and the ability to (un)lock large ranges of CAS locks atomically, and a central dispatcher design can create batch lists of threading primitive operations and execute the batch at once as a transaction. Without TM, you really need the kernel to provide a batch syscall for threading primitives to see large performance gains. > > Futures come in because you'd naturally use std::packaged_task<> with > > Boost.ASIO. It returns a future. > Could you point me to the Networking paper proposal that has > packaged_task<> on its user interface. I would expect this to be an > implementation detail. You misunderstand me. *If* you want Boost.ASIO to dispatch unknown std::function<>, *then* std::packaged_task<> is the most obvious route forwards. And the correct way to pass a value from one execution context to another is std::future<>. This includes the single threaded case e.g. when going through a C++ -> C -> C++ transition as a stack unwinds. > > For reference, the AFSIO/AFIO project is *not* a threadpool. It's a batch > > asynchronous execution engine based on Boost.ASIO that lets you chain, in > > vast numbers, huge arrays of std::function<> whose returns are fetched using > > std::future<> to be executed asynchronously according to specified > > dependencies e.g. if A and B and C, then D, then E-G. That sort of thing. > So the thread pool you need is an internal one that is adapted to you > particular needs, isn't it? I think you don't understand what Boost.ASIO is or how it works. Boost.ASIO's core is boost::asio::io_service. That is its dispatcher implementation which each dispatch execution context being executed via boost::asio::io_service::run() which is effectively an event loop. Third parties then enqueue items to be dispatched using boost::asio::io_service::post(). You don't have to run Boost.ASIO using multiple threads: it can be single threaded. So is my thread pool an internal one adapted to my particular needs? In the sense I need not use threads at all, yes. In the sense that boost::asio::io_service's use scenario is inviolate, no. Boost.ASIO has its API, and you have to use it. And Boost.ASIO's API will be similar to the TR2 networking API. There is nothing stopping a person merging a Boost.ASIO managed thread pool with a traditional thread pool. I would struggle to see the use case though - this would an excellent thought project actually which would benefit any Boost.ThreadPool. > > One thing presently implemented on that engine is asynchronous file i/o, but > > in the next month or two you'll hopefully see batch parallel SHA256 using > > 4-SHA256 SSE2 and NEON implementations also added to the asynchronous > > engine. The idea is that the engine is fairly generic for anywhere where you > > do need to chain lots of coroutine type items together (not that it supports > > Boost.Coroutine yet). v1 isn't particularly generic nor optimal, but I'm > > hoping with feedback from Boost that v2 in a few years' time would be much > > improved. > > > As Oliver noted you could take a look at Boost.Fiber and Boost.Task. Right now anything Boost.Context based can't have multiple contexts simultaneously entering the kernel apart from on QNX and possibly Hurd. Therefore, for the time being, full fat threads are the only thing being considered. If kernel support ever includes coroutines or fibres, that will be eagerly added (I like coroutines, I use them a lot on Python). Note that on async i/o capable platforms multiple threads are solely used for non-async APIs like batch directory creation and batch chmod. Normal i/o gets multiplexed using completion handlers. Currently on Windows for example, threads are barely used at all. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

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Re: [boost] [operators] moving forward use return by reference for compilers with proper support?
by Andrew Ho 01 May '13

01 May '13

> They do NOT apply to this scenario: > > X&& func(X&& x) { return std::move(x); } > const X& r3 = func(temporary()); // DANGLING REFERENCE > X&& r4 = func(temporary()); // DANGLING REFERENCE Hmm, I see. sub-clause of 12.2 clause 5: > The lifetime of a temporary bound to the returned value in a function return statement (6.6.3) is not extended; the temporary is destroyed at the end of the full-expression in the return statement. I presume there must be some implementation detail on why a returned temporaries' lifetime can't be extended. Too bad, looks like return by value is the best option available.

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[operators] moving forward use return by reference for compilers with proper support?
by Andrew Ho 01 May '13

01 May '13

Following some feedback I got from MS about the disparity between VS2012 and GCC/Clang in how some the lifetimes of temporaries are handled, it appears that going forward (possibly C++14) overloading operators in the same fashion as Dfrey operators should be safe. For reference, these overloads for a single argument commutative operator are: T operator OP(const T&, const T&); T&& operator OP( T&& lhs, const T& rhs); T&& operator OP( const T& lhs, T&& rhs); T&& operator OP( T&& lhs, T&& rhs); They referred me to http://www.open- std.org/jtc1/sc22/wg21/docs/papers/2012/n3337.pdf (draft of C++ standard), which in section 12.2, clause 5 says that a temporary's lifetime is extended to the lifetime of the reference it is bound to. I checked draft n3376 (latest publicly available draft as of today), and the same clause was present. This is the current behavior in VS2012 and it's likely that future compilers will support this as well. Should we start tracking which compilers do exhibit this behavior in Boost.Config and use the return by rvalue ref code if proper compiler support is available? I know these are just working drafts and can change in the future, but I can't think of a reason why they would remove this clause from the C++14 standard, or of any test cases which would cause a program to fail assuming this clause is properly implemented. We'll have to provide an implementation which supports return by value as well for compilers which don't support this clause, and possibly a third implementation for compilers which don't support move semantics at all, though I have demonstrated that Boost.Move can be used to merge these latter cases.

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GSoC 2013
by Anoop C S 30 Apr '13

30 Apr '13

I wish to participate in GSoC 2013 along with the Boost C++ libraries. I plan to take up the problem of Unified Representation of Vector and Matrix into a unique matrix class. Which of the Boost libraries are to be studied thoroughly inorder to achieve the goal. I already started reading Boost Documentation.

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[GSoC 2013] Boost.Math Bernoulli Numbers and Applications to Special Functions
by Łukasz Marecik 30 Apr '13

30 Apr '13

Hi, My name is Lukasz Marecik, I am fifth year student of Mathematics and fourth year student of Computer Science at Warsaw University. I would like to apply to Google Summer of Code 2013 project. I am interested in Bernoulli Numbers and their applications. While thinking about this project and doing some research, I collected some questions and issues, which I would like to discuss with my (potential) mentors. The answers can have strong influence at my official proposal. 1. Is (one of) the goal of this project to implement FROM SCRATCH completely new boost library, which will calculate Bernoulli Numbers ? I have already found two great C++ open-source programs: - http://www.bernoulli.org/ - http://web.maths.unsw.edu.au/~davidharvey/papers/bernmm/ They are already extremely efficient and fast (the funny thing is that they use completely different approach). Can boost project include and adapt one of them ? Why not ? 2. Are we going to implement only precise calculation of Bernoulli numbers or also Bernoulli numbers modulo p (where p is prime) ? 3. How the implementation of method of computing Bernoulli numbers will look like? Will it be a big template which works with all (reasonable) types (built-in, multiprecision) in the same way ? I was thinking for a while about this and I think it would be better to implement separately computing rational Bernoulli numbers (e.g. gmp_rational type) in a modern way: compute B_n modulo a lot of small primes and then reconstruct B_n via Chinese Remainder Theorem. This algorithm is one of the faster for this concrete type: precise rational numbers, but (in my opinion) it will be inefficient, when we want the output be built-in types. I do not know if I express precise what I want. For example: naive Akiyama–Tanigawa algorithm does not assume the type of output: the calculation can be performed at any type. Will our library work with all types in the same manner, or will our library run different algorithms and choose which one is better in this concrete case ? 4. Do I need to make my own research, reads papers about Bernoulli numbers, find the best practical algorithm and then propose it to my mentor or my mentor will help me to find and choose algorithm ? (so: Can I rely on myself only ?). Until now I have found three interesting approach: - use Chinese Remainder Theorem (described above) - use Euler's formula and the zeta-function algorithm - use completely new subquadratic algorithm (the paper was "submitted to publication", but it was not published in magazine until now ; it is online) The first two of them all already implemented and work (I think) in O(n^(2+eps)) time (it is good to mention that we need \theta(n log n) bits to represent precise number). The third one had (asymptotically) better complexity, but it goes throw a lot of complicated Maths, p-adic numbers etc and it has been not implemented yet - so it can turn out that the constant hidden in Big O notation is so big, that it is unpractical. But who knows. Do I need to discuss in my proposal different approach ? 5. Do I need to include in my proposal some words about applications to boost function: - theoretical view: where bernoulli numbers appear - practical view: how those functions are implemented now and how there will be implemented - and why they will be better ? I am sorry, that I am writing so late, but I was not sure for a long time if I want to apply ; I hope I finish my proposal in time. Kind regards, Lukasz Marecik

2 1

[type_traits] boost::decay vs std::decay
by Agustín K-ballo Bergé 30 Apr '13

30 Apr '13

Hello, It has been pointed out before that `boost::decay` and `std::decay` are not exactly the same. The standard does remove CV qualifiers while boost doesn't. See https://svn.boost.org/trac/boost/ticket/7760 I would like to know if there is a resolution on this issue. If the difference is intentional, then I suggest a note be added to the documentation. I could prepare a patch either way. Regards, -- Agustín K-ballo Bergé.- http://talesofcpp.fusionfenix.com

1 0

GAL (Generic Audio Library) based on GIL
by Brendon Costa 30 Apr '13

30 Apr '13

I am looking into the possibility of developing a library based on the same concepts and a similar interface to Boost.GIL call Boost.GAL. The idea is simply to define something very similar to GIL but for audio processing instead of image processing. Most of the concepts in GIL map almost 1 to 1 to audio processing as well. What are peoples thoughts on such a project? Is there anything in Boost.GIL that we have learn't from that should be done differently? --- Basic Premise --- The base concepts for GAL are described below and shown are the direct equivalents in the GIL library: * GAL.Sample ~= GIL.Channel Represents the amplitude of a single audio sample (float32, int16, ...) * GAL.SampleTime ~= GIL.Point Identifies the "time" a sample was taken (in units of the SampleRate) * GAL.Channel ~= GIL.Colour Identifies an audio channel location (FRONT_LEFT, or FRONT_RIGHT might be a channel for example) * GAL.ChannelMapping ~= GIL.Colour-space Maps channels to specific layout in memory (offset 0 is FRONT_LEFT, ...) * GAL.Frame ~= GIL.Pixel Identifies a single time slice (multiple channels for single sample point in time) * GAL.Block ~= GIL.Image Identifies a 1D sequence of Frame's * GAL.SampleRate ~= GIL.PPI I don't think GIL has this concept at the moment, but would be similar to Pixels Per Inch in the image world * GAL.Layout ~= GIL.?? This is the same in GIL and GAL the memory layout can be interleaved or not (planar for GIL) * GAL.Format ~= GIL.?? I don't think GIL has this concept at the moment but it represents the format of data without actually storing any data. It contains: - Sample type - ChannelMapping (implicitly identifies count of channels) - SampleRate - Layout

4 6

[Boost.FixedPoint] Choose notation
by Dmitriy Gorbel 30 Apr '13

30 Apr '13

Hello, community! I propose extending the Boost Libraries to provide binary fixed-point arithmetic, within GSOC project. Fixed-point library will provide nonnegative and negatable class templates for fractional arithmetic, and cardinal and integral for integer arithmetic. In total, four class templates. Fixed-point arithmetic use more than one notation, and I want to provide several notation to make happy all. Now I plan to implement two notations - Q notation and notation from C++1y proposal. Examples: C++1y proposal notation: cardinal<16> 0 <= n < 65536 integral<4> -16 < n < 16 nonnegative<8,-4> 0 <= n < 256 in increments of 2^-4 = 1/16 negatable<16,-8> -65536 < n < 65536 in increments of 2^-8 = 1/256 Q notation: cardinal<16> 0 <= n < 65536 integral<4> -16 < n < 16 nonnegative<8, 4> 0 <= n < 256 has 4 bit for fractional part negatable<16, 8> -65536 < n < 65536 has 8 bit for fractional part Please, help me to choose default notation, propose other notation, or just make any feedback. Sincerely, Dmitriy. -- View this message in context: http://boost.2283326.n4.nabble.com/Boost-FixedPoint-Choose-notation-tp46462… Sent from the Boost - Dev mailing list archive at Nabble.com.

8 16

[GSoC 2013] Moving to Boost to Boost.Move
by Vicente J. Botet Escriba 30 Apr '13

30 Apr '13

Hi, In case there are some students that are looking for a last idea. There a re a lot of Boost libraries that don't support move semantics. It would be nice if one student propose to adapt the some of the existing libraries. The idea is to use Boost.Move so that an emulation is provided for compilers not supporting rvalue references. Some of the libraries (let me know if I'm wrong are). My priority is given between [], lower numbers means higher priority. Of course others would have others priorities: C++11 * [0] Tuple or * Fusion/tuple (it seems that it support or will support c++11 move semantics but don't use Boost.Move) * [0] Bind * [1] Function * [2] SmartPtr * [8] Array ? Accepted for C++14 * [5] optional Having an active proposal for C++1y * [3] Heaps * [6] Any * [7] Variant Other * [4] LockFree * [9] Parameters * [10] Signals? Please help me to complete this list. Adding constexpre and noexcept would be welcome also. Best, Vicente

3 4

Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
by Niall Douglas 30 Apr '13

30 Apr '13

> > There are many ways systemically of implementing futures. The way you > > and Anthony have taken to date is a non-intrusive approach such that > > futures stand alone. This is great for not forcing design onto third > > parties and is a decentralised POSIX-y approach, but it comes with > > significant performance and memory costs because it's hard to get > > standalone, non-intrusive futures to batch themselves without > > sacrificing performance. > > I have no merit here. This is the approach the standard has defined futures. No major changes to the C++11 futures API is needed. Rather that a different, but compatible, optimized implementation of future<> gets returned when used from a central asynchronous dispatcher. So the C++ standard remains in force, only the underlying implementation is more optimal. > > An alternative approach is to assume a central dispatcher/event loop > > which can optimize then() chaining because it knows of all futures and > > their relationships currently in flight (this is a much more > > centralized statist NT-y approach, and it you can see that philosophy > > clearly in Microsoft's N3428). You can see an example of this approach > > to implementing future chaining with multiple dependencies which > > extends Boost.ASIO in > > https://github.com/ned14/TripleGit/blob/master/triplegit/include/async > > _file_ io.hpp#L785. I also went ahead and implemented N3428's > > when_all() which returns a future chained to multiple input futures, > > not that I claim the implementation mature yet. > > I don't know ASIO enough to understand the advantages or liabilities. > While a central dispatcher/event loop could be useful for some applications > other need more concurrency. > I'll need to take a deep look at ASIO when I would have enough time. I know you'll have studied Microsoft's N3428 in depth. Their proposal is quite trivial to implement when you have an NT kernel to hand where the kernel directly manages all multithreading primitives and there is a top quality APC implementation. Implementing N3428 without a NT kernel to hand is very considerably harder, indeed there are many, many gotchas as I know you know. Even then() is tricky, because code called from then() needs two main call forms, asynchronous and synchronous (i.e. the original object completes only after type B then() completes, whereas type A then() lets the original complete first). Not introducing race conditions is quite hard (for me at least). > > My concern with Boost.ThreadPool right now is that it could get in the > > way of the latter approach. I have zero objection to a formulation > > which embraces both approaches, but when you ask why a thread pool > > isn't in the standard, I think it's because until we've fixed futures > > implementation and all the composibility and chaining we're sure we > > need, and made sure that interops smoothly with the forthcoming TR2 > > networking proposal, then and only then is it wise to proceed with > > threadpool design. > > I'm not aware of the TR2 networking proposal needs respect to futures or > thread pool. Again I'll take a look to the current proposals. Futures come in because you'd naturally use std::packaged_task<> with Boost.ASIO. It returns a future. > > All that said, this is purely a cautious opinion of mine. You're one > > of the Boost.Thread maintainers, so I happily defer to your judgment > > on this. If you think we need a threadpool now, you'll find no > > opposition from me. > > If IIUC you are not suggesting that the student uses the ASIO approach, but that > it is not time to solve the thread_pool now. Could you confirm? > If yes, could you tell me what is blocking that we can not try to solve? We ought to finish N3428 for pure POSIX first. During implementation, you will find many areas where significant optimization using a central dispatcher become possible. Specialisations of N3428 for some arbitrary central dispatcher might be worth prototyping as a thought exercise. After that I see no reason to hesitate on thread_pool as it now has the type inferences available to it to have an optimal design. > I was not aware that there was a AFSIO GSoC project as described here > https://svn.boost.org/trac/boost/wiki/SoC2013#Boost.ASIO and that this > project propose also thread pool. I understand better now your concerns. I hadn't announced it to this list for various reasons. Hopefully I'll have news there soon. For reference, the AFSIO/AFIO project is *not* a threadpool. It's a batch asynchronous execution engine based on Boost.ASIO that lets you chain, in vast numbers, huge arrays of std::function<> whose returns are fetched using std::future<> to be executed asynchronously according to specified dependencies e.g. if A and B and C, then D, then E-G. That sort of thing. One thing presently implemented on that engine is asynchronous file i/o, but in the next month or two you'll hopefully see batch parallel SHA256 using 4-SHA256 SSE2 and NEON implementations also added to the asynchronous engine. The idea is that the engine is fairly generic for anywhere where you do need to chain lots of coroutine type items together (not that it supports Boost.Coroutine yet). v1 isn't particularly generic nor optimal, but I'm hoping with feedback from Boost that v2 in a few years' time would be much improved. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

3 2

[iterator] Is there general const_iterator adaptor?
by TONGARI 30 Apr '13

30 Apr '13

Hi folks, I wonder if there's a general const_iterator adaptor that transforms any iterator to a const one: template<class Iterator> struct const_iterator : iterator_adaptor < const_iterator<Iterator>, Iterator , typename iterator_value<Iterator>::type const > { const_iterator() {} const_iterator(Iterator const& base) : const_iterator::iterator_adaptor_(base) {} }; Which is simple but handy for use in that we don't have to make 2 versions for both const & non-const iterators each time we make a container. Does Boost offer this which I missed somewhere, or would you think it's a good idea to add? Thanks

3 5

GSOC 2013
by Razvan Florea 29 Apr '13

29 Apr '13

Hello, I'm a student interested in working on odeint project this summer in GSOC. In the last weeks I spoke with Mario Mulansky about my ideas. After he gave me a task in order to accustom with odeint project, I started building my proposal. He suggested me to put my first version of proposal on the mailing list to get feedback or some advice about what should I change. Is this the right mailing list to share my proposal? If yes, how should I share my proposal with you? Should I put on melange or can I put it on a google doc and give you a link to it? Have a nice day, Razvan

3 3

Re: [boost] hi
by dominic ibeme 29 Apr '13

29 Apr '13

http://expecthead.com/wp-content/plugins/wp-plugin-repo-stats/china.php?ygf… \\\\\\ The improver of knowledge absolutely refuses to acknowledge authority, as such. For him, skepticism is the highest of duties, blind faith the one unpardonable sin. -- Thomas Huxley (1866)

1 0

Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
by Niall Douglas 29 Apr '13

29 Apr '13

> > I'm not ruling out the merit of a Boost.Thread threadpool. For me > > personally though, the hurdle is very significantly raised: you need > > to strongly prove to me why your proposed thread pool is much superior > > to a Boost.ASIO based threadpool. Otherwise I will zero score the GSoC > > proposal, because in the end we need other proposed projects more. > This is your right, but I don't know how the fact you can write easily the thread > pool you need to diminish a generic thread pool working well with futures. > [snip] > Hopping this helps you to understand the project I'm looking for. There are many ways systemically of implementing futures. The way you and Anthony have taken to date is a non-intrusive approach such that futures stand alone. This is great for not forcing design onto third parties and is a decentralised POSIX-y approach, but it comes with significant performance and memory costs because it's hard to get standalone, non-intrusive futures to batch themselves without sacrificing performance. An alternative approach is to assume a central dispatcher/event loop which can optimize then() chaining because it knows of all futures and their relationships currently in flight (this is a much more centralized statist NT-y approach, and it you can see that philosophy clearly in Microsoft's N3428). You can see an example of this approach to implementing future chaining with multiple dependencies which extends Boost.ASIO in https://github.com/ned14/TripleGit/blob/master/triplegit/include/async_file_ io.hpp#L785. I also went ahead and implemented N3428's when_all() which returns a future chained to multiple input futures, not that I claim the implementation mature yet. My concern with Boost.ThreadPool right now is that it could get in the way of the latter approach. I have zero objection to a formulation which embraces both approaches, but when you ask why a thread pool isn't in the standard, I think it's because until we've fixed futures implementation and all the composibility and chaining we're sure we need, and made sure that interops smoothly with the forthcoming TR2 networking proposal, then and only then is it wise to proceed with threadpool design. All that said, this is purely a cautious opinion of mine. You're one of the Boost.Thread maintainers, so I happily defer to your judgment on this. If you think we need a threadpool now, you'll find no opposition from me. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

3 2

[interprocess] [container] Can iterator hold raw-pointer instead of offset_ptr?
by TONGARI 29 Apr '13

29 Apr '13

Hi there, When putting containers in shared memory, offset_ptr is used internally, and IIUC, the iterator of the container will also use offset_ptr. But it seems to me that in most cases we only use iterator locally rather than putting those iterators in shared memory as well, so the plain-old-raw-pointer is sufficient and hopefully more efficient for iterator's usage. What do you think?

3 4

[gsoc 2013] Approximate string matching
by Jan Strnad 29 Apr '13

29 Apr '13

Hi, I'm Jan Strnad, currently a Master's student at CTU in Prague, Czech Republic. This summer, I would like to participate in GSOC and I believe that approximate string matching is a good match for me, since my background i this area is quite strong. Now more specifically. I would like to implement approximate string matching algorithm(s) based on the NFA. I would like to support various approximate distances, such as Hamming distance [1], Levenstein distance [2], Damerau-Levenstein distance [3], Delta distance, Gamma distance and finally (delta, gamma) distance. Sorry no explanation of the last three found on the Web, but I can provide one if interested. In the matter of NFA implementation, I would probably choose dynamic programming approach, but I'm thinking of shift-or algorithm as well. Can I ask you for any kind of thoughts or feedback regarding this topic? Best regards, Jan Strnad [1] http://en.wikipedia.org/wiki/Hamming_distance [2] http://en.wikipedia.org/wiki/Levenstein_distance [3] http://en.wikipedia.org/wiki/Damerau%E2%80%93Levenshtein_distance

7 19

[Property Map] put_get_helper, keys are passed by value
by ilker 29 Apr '13

29 Apr '13

Hello, I require a pm which returns passed key (itself or a 'part' of it) as mapped value. For this purpose I wrote another helper since boost::put_get_helper's put function passes keys by value. // Pasted as a reminder template <class PropertyMap, class Reference, class K, class V> inline void put(const put_get_helper<Reference, PropertyMap>& pa, K k, const V& v) { static_cast<const PropertyMap&>(pa)[k] = v; } Is there any way to accomplish this by not introducing another custom helper ? (may be there already something similar exists in boost) Thanks. -- View this message in context: http://boost.2283326.n4.nabble.com/Property-Map-put-get-helper-keys-are-pas… Sent from the Boost - Dev mailing list archive at Nabble.com.

1 0

[operators] What is the correct overload set for a binary operator?
by Daniel Frey 28 Apr '13

28 Apr '13

Hi, after some more experiments, I convinced myself that I should explore the option of returning an rvalue (not an rvalue reference) in all cases when implementing operator+ based on operator+= (as an example). But I wonder what the most efficient overload set would look like. With this post I'll concentrate on same-type operations (T+T). Given a class T with operator+= like this: T& T::operator+=( const T& ); T& T::operator+=( T&& ); // if useful the class provides it and it should be used if applicable I think the following is currently the best overload set for operators: T operator+( T lhs, const T& rhs ) { lhs += rhs; return lhs; // no std::move needed } T operator+( T&& lhs, T&& rhs ) { lhs += std::move( rhs ); return std::move( lhs ); } T operator+( const T& lhs, T&& rhs ) { #ifdef COMMUTATIVE rhs += lhs; return std::move( rhs ); #else T nrv( lhs ); nrv += std::move( rhs ); return nrv; #endif } I tested this with the following expressions with both COMMUTATIVE defined and not defined: T a, b, c; // initialized to something T r1 = a + b + c; T r2 = a + ( b + c ); T r3 = ( a + b ) + ( b + c ); and with both GCC 4.7.3 and Clang 3.2. Could someone please test this with VC++? (complete code below) Generally: Any thoughts? Examples of expressions where and how it could be improved? Theoretical improvements are also welcome, but please mark them as such and always test your code to prevent pessimizations in practice! One remarks about the proposed full version of operators2.hpp: Andrew, I really appreciate your work and enthusiasm, but please understand that IMHO this needs to be done step-by-step and much more slowly than you probably hope for. Let's figure out the proper overload set for T+T first, then T+U/U+T (again both commutative and non-commutative), noexpect-specifier for all overloads, etc. After that, we need to decide on whether or not to improve the existing operator library or to provide an independent V2. This might include rethinking the grouped templates. Using Boost.Move might help with the implementation or not, depending on what overload set we want/need. It all needs tests and documentation and it will be quite some work… hope you and others are still with me on this :) Best regards, Daniel Here's the complete test code I used: #include <iostream> #include <utility> struct MyClass { MyClass() { std::cout << "MyClass::MyClass()" << std::endl; } MyClass( const MyClass& ) { std::cout << "MyClass::MyClass( const MyClass& ) COPY" << std::endl; } MyClass( MyClass&& ) { std::cout << "MyClass::MyClass( MyClass&& ) move" << std::endl; } ~MyClass() { std::cout << "MyClass::~MyClass()" << std::endl; } MyClass& operator+=( const MyClass& ) { std::cout << "MyClass::operator+=( const MyClass& ) +=" << std::endl; return *this; } MyClass& operator+=( MyClass&& ) { std::cout << "MyClass::operator+=( MyClass&& ) += &&" << std::endl; return *this; } }; MyClass operator+( MyClass lhs, const MyClass& rhs ) { lhs += rhs; return lhs; } MyClass operator+( MyClass&& lhs, MyClass&& rhs ) { lhs += std::move( rhs ); return std::move( lhs ); } // #define COMMUTATIVE MyClass operator+( const MyClass& lhs, MyClass&& rhs ) { #ifdef COMMUTATIVE rhs += lhs; return std::move( rhs ); #else MyClass nrv( lhs ); nrv += std::move( rhs ); return nrv; #endif } int main() { MyClass a, b, c; std::cout << "--- r1" << std::endl; MyClass r1 = a + b + c; std::cout << "--- r2" << std::endl; MyClass r2 = a + ( b + c ); std::cout << "--- r3" << std::endl; MyClass r3 = ( a + b ) + ( b + c ); std::cout << "--- done" << std::endl; }

3 8

GSOC 2013
by Dmitriy 28 Apr '13

28 Apr '13

Hi folks! I am Dmitriy Gorbel, a computer science student at the Kharkiv Polytechnic University from Ukraine. I browsed Boost C++ Libraries home page for GSoC and I want to propose a project to implement of a Fixed Point library. I read open standard on open-std.org http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3352.html and tried implementation by Vicente J. Botet Escriba at the https://svn.boost.org/svn/boost/sandbox/fixed_point/ Now I prepare my proposal. So I will take implementation by Vicente J. Botet Escriba in the first place, and I found few more simple implementations, but can anyone advise me other implementations of Fixed Point arithmetic, which I must pay attention? Not necessarily in C++, pure C also would be good. Thanks

5 29

Re: [boost] [GSOC] XML library of Boost
by Amos Ji 28 Apr '13

28 Apr '13

On Apr 28, 2013, at 12:11 PM, Andrey Semashev <andrey.semashev(a)gmail.com> wrote: > On Monday 29 April 2013 02:08:01 Amos Ji wrote: >> Hi All, >> >> I'm a graduate student from Fudan University in China. And I hope to >> contribute some code to Boost during the GSOC. >> >> I've scanned the idea page. The ideas in the page are all very interesting >> and challenging. But what I'm interested in most is XML library, which is >> at the bottom of page. I think the XML format is the most popular standard >> for storing information so it's important for Boost to have a good XML >> library. > > Agreed, a good and fast XML library would be most useful. >> In my opinion, an XML parser must be able to do these things: >> >> 1. To Iterate over DOM nodes tree; >> 2. To access the values of nodes and their attributes quickly; >> 3. To insert or delete nodes or attribute of an exact node easily; >> 4. To generate new XML from the structure which stores XML in the >> library. > > IMHO, support for SAX is also mandatory. I would even say that SAX should be > the first and the primary thing to be implemented in Boost.XML, as DOM can be > added later on top of it if the time for GSOC allows. > I agree. SAX parser will use less memory than DOM parser. I'll add it into my proposal. > You also listed support for encodings in the optional features. I agree with > it being optional with exception for Unicode. At least UTF-8 should be > supported from the very start. But that should not be a problem now that we > have Boost.Locale. I know little about Boost.Locale. I'll see how it can help support other encodings when I need. Thanks a lot for your suggestions. _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

1 0

Google Summer of Code 2013
by sskytyba＠gmail.com 28 Apr '13

28 Apr '13

I’m student from Ukraine. My name is Skytyba Sergij. I want to get some information. I’m interested in such projects as Boost.uBLAS, Boost.Math Bernoulli Numbers and Applications to Special Functions (very) , Boost.Multiprecision (very) , Boost.Thread/SyncQueue, Moving Boost to Boost.Move. To whom can I send my proposal and how can I contact with mentors of these projects?

2 1

[GSoC] Boost.Multiprecision project
by Віталій Мельник 28 Apr '13

28 Apr '13

Hi! I am a second year student in Computer Science and I`m very interested in Boost.Multiprecision project on GSoC. What can I do to be invited to this project? I have some achievements in sport programming, so I can tell you that I know algorithms and I like to solve algorithmic problems. -- Vitalii Melnyk

2 1

Re: [boost] GSoC Boost.Multiprecision project
by Jyotesh Choudhari 28 Apr '13

28 Apr '13

> 2013/4/21 Jyotesh Choudhari <jyoteshrc_at_[hidden]>: > <...> >> Looking at the project description, I think I have understood what needs to >> be implemented in this project. I have also gone through the current code >> cpp_bin_float.hpp and I have understood some part of it. I want to know how >> detailed should my proposal be? What details should I include in my >> proposal? What should be the deliverables for the project? > Hi, and welcome! > Start from writing a proposal according to this link > https://svn.boost.org/trac/boost/wiki/SoCSubmissionTemplate<https://svn.boost.org/trac/boost/wiki/SoCSubmissionTemplate>. > This link may also help https://svn.boost.org/trac/boost/wiki/SoCHints I have attached my proposal with this mail. Please have a look at it and let me know your feedback. Thanks and regards, Jyotesh Choudhari > After it is done, mail it ti this mailing list with title starting > from [boost] GSOC. > I also recommend to read this mailing list first, because there is a > lot of interesting discussions and useful information about GSOC and > some comments about Boost.Multiprecision. > One more advice: there are already two or three students that want to > work on Boost.Multiprecision. Try to describe in your proposal why do > you suit for that task better than others. > -- > Best regards, > Antony Polukhin

2 1

[GSOC-2013]-boost.odeint implicit routines
by preethamsreenivas 28 Apr '13

28 Apr '13

Hi all, I am preetham sreenivas, a sophomore at computer science and engineering, IIT Bombay(Indian Institute of Technology, Bombay). I am very much interested in the project of adding support to implicit routines to the boost.odeint library. I have recently completed a course on numerical analysis and i've used all the common numerical methods as part of the course including euler methods , runge-kutta routines etc. I've also used the boost.odeint for algorithmic analysis assignments for this course. I've gone through the articles linked from the project description and also snippets of odeint code at codeproject.com I would like to get through to mario mulansky or Karsten Ahnert , the mentors for this project to provide me with further pointers and any assignments they would like to give me. I am sorry that i couldn't start on it earlier as i've just completed my exams for the spring semester. please reply as soon as possible. kindly oblige, regards, preetham sreenivas, sophomore, CSE IIT Bombay -- View this message in context: http://boost.2283326.n4.nabble.com/GSOC-2013-boost-odeint-implicit-routines… Sent from the Boost - Dev mailing list archive at Nabble.com.

2 1

GSoC uBLAS algorithms for derterminants, inversion and decomposition
by Ganesh Prasad 28 Apr '13

28 Apr '13

As inversion involves steps that use the determinant of the matrix, it's better to develop an algorithm that evaluates the determinant of the matrix faster than the conventional recursive way. I think extending the rule of Sarrus does the trick. So far we have used rule of sarrus as a light weight formula for evaluating determinants of 2x2 and 3x3 matrices. But extending it in the following way makes it applicable for higher order matrices too. And this algorithm has a time complexity O(2*n^2) for nxn matrices. // a is a n x n matrix Det_a=0 Sum1=0 Sum2=0 For count=0 to n-1 do For i=1 to n do J=i+count Val=(j>n)?n:0 j-=val product*=a[i][j] sum1+=product For count=0 to n-1 do For i=1 to n do J=n-count-(i+1) Val=(j<1)?n:0 J+=val product*=a[i][j] sum2+=product det_a=sum1-sum2 return det_a I want to use this algorithm in my GSoC project to evaluate determinants, and based on this implementation I'll develop algorithms for inversion and decomposition. But I think if we can make some changes to this algorithm, this may run faster. As you can see, this thing traverses the matrix twice. If we can achieve the goal in only one traversal calculating sum1 and sum2 simultaneously, then it'd be a bit faster, but here I lack ideas. So please provide me with some help in this regard. ~Ganesh Prasad

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[Boost][GSOC] proposal for Trie
by Hardy Huang 28 Apr '13

28 Apr '13

Hi, this is my proposal for GSOC 2013, please read it and give me some useful information on it, thanks == Personal Details == * Name: Zhe(Hardy) Huang * College/University: Peking University * Course/Major: Computer Science * Degree Program: M.Sc. * Email: hzithlony(a)gmail.com * Homepage: not yet * Availability: * How much time do you plan to spend on your GSoC? I will spend the most part time of the semester(till late June), and then the whole summer on my GSoC project. * What are your intended start and end dates? I basically will obey the rules of GSoC, and I will also listen to mentor’s advice on it. * What other factors affect your availability (exams, courses, moving, work, etc.)? I am having my courses now, and I will have my final exams in June. Since I am not having many courses, I have enough time to do something for the project before exams. And in summer I could almost work full time on it. == Background Information == Please summarize your educational background (degrees earned, courses taken, etc.). I majored in Computer Science in Zhongshan University from 2008 to 2012, by which I earned my bachelor’s degree. During the four years, I learned many basic courses on Computer Science, like algebra, logic, data structure, algorithms, operating system, Compilers, databases, networks. >From 2012 till now, I am studying Computer Science in Peking University pursuing my master’s degree. My research field is information retrieval. Please summarize your programming background (OSS projects, internships, jobs, etc.). GSoC is the first time that I get involved with a real and large OSS project. Besides, I’ve developed many things in C and C++. I developed a simplified B-tree data structure in C during my intership for a small company. Later a system in C to extract and evaluate the content of webpages for my research, and I am still on it. An implementation of a search system in C++. A webpage template system in C for my lab to generating webpages in order to do some research on them. Please tell us a little about your programming interests. I like to write codes for the basic and general use. I am pursuing well-framework of design and code, and high reusability when I think of develop the project. Please tell us why you are interested in contributing to the Boost C++ Libraries. Boost is widely used by programmers and famous for its powerful and efficient. It is an honor to contribute to such a lib, and have my codes used and reviewed by so many programmers. I like the reusability of well-designed lib, so it also will be a good chance for me to improve my skill of design and programming. And a good chance to communicate with good guys as well. I want to be a good programmer with many good programmers as my friends. What is your interest in the project you are proposing? Because I have participated in many competitions of algorithm, I have a good knowledge of algorithms and data structures. I have also implement many, but for the sake of winning, the codes usually can not be well-reused. Meanwhile the STL in C++, which I’ve used many times during the competitions, such as set, map, priority_queue, sort are good examples of well-reused algorithms and data structures. So I’ve been expecting to develop some general libraries of algorithms and data structures. Boost is a well-formed organization, and Boost lib is a widely-used lib, so I also want to learn some skills to develop a good lib from developing the project with mentors in Boost. Have you done any previous work in this area before or on similar projects? I am good at data structure and algorithm, and I wrote codes of various algorithms and data structures for many times. I am very familiar with the Trie data structure, and as I list above, I've develop a simplified general B-tree data structure in C, which is a good experience when I develop Trie for Boost. What are your plans beyond this Summer of Code time frame for your proposed work?. I will dedicate my summer to my work. And taking the experience as a good beginning, I will be feeling happy to contribute more to Boost, and other OSS projects. Please rate, from 0 to 5 (0 being no experience, 5 being expert), your knowledge of the following languages, technologies, or tools: - C++ 3 - C++ Standard Library 3 - Boost C++ Libraries 2 - Subversion 3 What software development environments are you most familiar with (Visual Studio, Eclipse, KDevelop, etc.)? I use Visual Studio in my lab, and vim + gcc for myself. What software documentation tool are you most familiar with (Doxygen, !DocBook, Quickbook, etc.)? I’ve used Doxygen before, it is simple and efficient. == Project Proposal == Please provide a description of your proposed work. Trie(Radix Tree) is an efficient in memory data structure to deal with string storing and searching. It can be used in many applications, and in comparison to hashtables, it has better expandability and stability. It will be an data structure of great importance and wide usage. == Proposed Milestones and Schedule == Please provide estimated milestones and schedule for completing the proposed work. Before May 27: To familiarize with the Boost lib, with reading the codes and discussing about it in mailing list. To have a better knowledge of lib, with reading some books of STL and Boost, and comparing Boost with STL. To setup us a proper environment for development. Study deep into Trie, reading some others’ good implementations. May 27 – June 17: Keep in touch with the Boost organization and have good communications with my mentor. Get involved with the development of boost. Try some toys about Boost, and discuss them with mentor, in order to know better about mentor and how the development goes on. June 17 – July 15(Coding period begins): Discuss the detail of the design with mento, develop an alpha version of Trie, and have it tested in small scale. July 15 – July 29(To mid-term evaluation): Refine my alpha codes, analyze the performance, and try to improve it. Write an initial report of the project and document of Trie. July 29 – September 23: Refine my codes, and have some thorough tests on it, make it robust. Reorganize codes and improve documents.

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[result_of] Allow result_of to work with C++11 lambdas
by Nathan Crookston 27 Apr '13

27 Apr '13

Hi all, Using C++11 lambda functions with several boost components. For example, the following code snippet will not work with VC10, nor with g++ up to 4.8: #include <boost/assign.hpp> #include <boost/range/adaptors.hpp> #include <boost/range/algorithm.hpp> #include <iostream> int main() { std::vector<int> v; for(int i = 0; i < 10; ++i) v.push_back(i); boost::for_each(v | boost::adaptors::transformed([](int i) { return i * 2; }), [](int i) { std::cout << i << std::endl; }); } g++4.5 gives around 34k of error messages, while VC10 has a mere 22k. The root of these problems is that lambda functions don't conform to the tr1::result_of protocol -- there is no nested result_type member, nor nested result struct. The standard doesn't mandate this case since decltype may be used to deduce the return type on C++11-conforming compilers. boost::result_of disables the use of decltype on many compilers in favor of tr1-style deduction due to weaknesses in the implementation of decltype. While it is important to use tr1-protocol result_of to allow code involving incomplete types to compile, it would be very convenient to fall back to a decltype approach when it's detected that the tr1 protocol is not being followed. Jeff Hellrung suggested[1] a fallback to decltype *only* for compilers which had nonconforming decltype operators. Thus the only behavioral change would be that some code which before would produce an error would now compile and run correctly. A ticket[1] with a patch (including tests and docs) was created. Daniel Walker suggested further discussion on the list, which this attempts to provoke. I think this would be a nice improvement for a set of often-used compilers -- the list of boost-users questions whose problems could be addressed by this patch is extensive (and can be provided, if desired). Thanks, Nate [1] http://boost.2283326.n4.nabble.com/Range-amp-c-0x-Lambdas-Can-this-be-done-…<http://boost.2283326.n4.nabble.com/Range-amp-c-0x-Lambdas-Can-this-be-done-…> [2] https://svn.boost.org/trac/boost/ticket/7753

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[type_erasure] Using any with iterator Concept.
by Adam Wulkiewicz 27 Apr '13

27 Apr '13

Hi, I'm trying to use type-erased iterator in STL algorithms, e.g. copy but get errors like this one: error C2039: 'iterator_category' : is not a member of 'boost::type_erasure::any<Concept>' c:\program files (x86)\microsoft visual studio 10.0\vc\include\xutility 373 of course any doesn't define iterator_category. I'm using MSVC2010 and doing something like this: typedef boost::type_erasure::any< boost::type_erasure::iterator< boost::single_pass_traversal_tag > > iterator; // ... iterator first = return_some_iterator(...); iterator last = return_some_iterator(...); // BAM! std::copy(first, last, std::back_inserter(result)); // BAM! typedef iterator::iterator_category C; I simply tried to add it to the iterator<> Concept defined in iterator.hpp but this didn't help: template<...> struct iterator< ::boost::single_pass_traversal_tag, ...> : iterator< ::boost::incrementable_traversal_tag, ...> { typedef ValueType value_type; typedef typename iterator_reference< Reference, ValueType >::type reference; typedef DifferenceType difference_type; typedef std::input_iterator_tag iterator_category; }; Am I doing something wrong or is it an error in Boost.TypeErasure? Regards, Adam Wulkiewicz

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Bernoulli Numbers Implementation With More Precision and Boost.Test
by Gaurav Deshmukh 27 Apr '13

27 Apr '13

I have further improved the implementation of 'bernoulli' function for Math.Bernoulli project idea of GSoC-2013. In my previous update, I made the return type generic. But, there was lack of precision as I had mentioned. For achieving greater accuracy, I implemented the Akiyama-Tanigawa algorithm using 'cpp_rational' data type. As there is no approximation in intermediate steps, it gives best accuracy. It can be casted to the data types of 'cpp_dec_float'. But, I think this implementation may be slower than the previous implementations. So, there is trade-off between running time and precision. We may implement 'bernoulli' function in two ways. If priority is running time than the accuracy of precision, then we can use previous implementation. If priority is the precision, then we can use this implementation. I have attached the 3 files. 1) bernoulli.hpp : It contains the function fr calculating bernoulli number. 2) example.cpp : It contains the program to test bernoulli.hpp 3) test.cpp : This is the Boost.Test comparing the values calculated by benoulli.hpp with some of the published values.

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[gsoc 2013] Approximate string matching proposal
by Jan Strnad 27 Apr '13

27 Apr '13

Hi, I've already posted this but it probably got buried. My proposal for GSOC 2013 is also available at http://webdev.fit.cvut.cz/~strnaj11/gsoc/. Regards, Jan Strnad GSOC 2013 Proposal - Approximate string pattern matching ======================================================== Abstract -------- My name is Jan Strnad and this is my proposal for GSOC 2013. I would like to implement a set of approximate string matching algorithms. There are two categories of these algorithms. A representative of the first category takes two strings and computes so-called distance between those two strings. A member of the second category takes some text and a pattern and finds all approximate matches of the pattern in the text according to some given distance. I'm planning to support various distances, such as Hamming, Levenstein, Damerau–Levenshtein, Jaro, Delta, Gamma ... I'm proposing to implement a general solution that supports multiple string containers, not only std::string. There are many possible applications such as spell checking. Personal Details ---------------- Name: Jan Strnad University: Czech Technical University in Prague, Faculty of Information Technology, The Czech Republic Major: Theoretical Informatics / System Programming - studying both in parallel Degree program: MSc. Email/XMPP: hanny.strnad(a)gmail.com ICQ: 335127474 homepage: none Mailing address: Okružní 508, 788 13 Vikýřovice, Czech Republic Availability: * Start: at worse by 17th June but probably earlier * End: 21st September * I have no other duties during this period but I may take a one week vacation. * I'm planning to spend 40-45 hours per week. Background ---------- Please summarize your educational background I'm first year master's student at CTU in Prague with major in Theoretical Informatics and System Programming. At this university I also gained my BSc. degree (Software Engineering, with honors) in June 2012. Here's an incomplete list of courses I have taken so far: Data structures and algorithms, Graph theory, Complexity theory, Automata and grammar theory, Compiler design course, Software engineering courses (including practical ones), various programming languages (C, C++, Java, Scala, Common Lisp, Haskell, Erlang, SML), various programming paradigms (imperative, object-oriented, functional, logical), math & statistics courses, Data compression, String pattern matching course, Computer architecture related courses, Parallel algorithms course and many others. I also spent 4 months as an exchange student in Uppsala University, Sweden where I took Constraint programming and Software verification courses. Please summarize your programming background I'm able to code in many languages, but I'm most experienced in C++ (5 years) and Scala languages (1.5 years). My C++ experience is gained mostly from school's projects an my small own projects (usually some kind of small tweaks of third party programs). I have an experience with C++ templates, multi-threading using both POSIX threads and openMP, STL and with some of the Boost libraries (Program Options, Smart Ptr). I definitely not know everything that would be needed for my GSOC project, but I'm quick learner. Please tell us a little about your programming interests. Please tell us why you are interested in contributing to the Boost C++ Libraries. What is your interest in the project you are proposing? As you may have guested, my professional interests are programming languages (especially their paradigms), concurrent & parallel programming and finally everything related to theoretical informatics. That includes things such as data compression or pattern matching. This is also one of the reasons why I want to contribute to Boost. I want to share my knowledge of pattern matching algorithms and I believe that the Boost project is the right place. I'm seeking for an off the school programming experience. Another reason is that since I'm a long time user of various open source software, I believe that it is time to start to contribute to community as well. From this program I mostly expecting gaining some real world experience. My C++ and especially Boost knowledge should improve significantly. Have you done any previous work in this area before or on similar projects? I think I have everything that is needed to successfully complete this project. I have a theoretical foundations of approximate string matching algorithms from my university courses as well as I'm able to implement them using C++ without any major issues. What are your plans beyond this Summer of Code time frame for your proposed work?. I know that it may take a long time for a project to become a part of Boost library. So, if selected, my intentions after the summer is over are: 1. Release my project as an open-source, not necessary as a standard part of Boost library. 2. Do everything necessary to include my work as a part of standard part of Boost library eventually. 3. Further development: adding support of more distances, implementing another string algorithms such as repetitions searching. This heavily depends on users' interest. I know that my work won't end by the end of summer. I'm willing to spend a couple of hours per week (say 2 or 3) to keep my project updated and most importantly alive. Languages, technologies, tools My regular C++ development environment is consisted of Linux, git, CMake, Sublime text, gdb and valgrind. I have also used Eclipse and svn before. For documentation purposes I'm most familiar with Doxygen. Here is a self-evaluation of desired skills: C++ 3 STL 4 Boost libraries 1 Subversion 3 Proposal -------- Approximate string matching is used in many areas. To name some of them, there are spell checking and DNA processing. I can also imagine many applications in human-to-computer interaction. I'm proposing an extension of Boost String algorithms library. I would like to implement algorithms of two categories: 1. Compute distance of two strings. Imagine a function that takes two strings a returns a number describing their distance (various distances are described below). 2. Find all approximate matches of a pattern in some text using given distance. Example of this can be found in API interface usage example. Distance is defined as a number (or a tuple of numbers) describing similarity of two strings. Here is a list of all distances I'm planning to implement: 1. Hamming - a number of replace (single character only) operations needed so that the strings match exactly. 2. Levenstein - a number of insert, delete and replace operations. 3. Generalized Levenstein (Weighted Levenstein) - same as before but each operation may have different cost. 4. Damerau-Levenstein - a number of insert, delete, replace and transpose (of two adjacent characters) operations. 5. Weigted Damerau-Levenstein - same as before but each operation may have different cost. 6. Jaro - please see [1] 7. Jaro-Winkler - also see [1] (following assumes we can compute distance of two characters, eg. c - a = 2) 8. Delta - the maximum number of distance between two characters, eg. Delta(aaa,bbb) = Delta(aaa,aab) = 1. 9. Gamma - a cumulative distance between two characters, Gamma(aaa,bbb) = 3. 10. (Delta, Gamma) - a combination of two preceding distances. Distance 10 is not exactly needed, but I included it because it is quite common to compute both Delta and Gamma distances at the same time, so I provided efficient algorithm for this. As noted, when using distances 8-10 we must be able to compute distance between two characters. This behavior should be customizable as well. Simple API definition follows. It's very immature and it will change but it should give you general idea: ~~~~ {.cpp} namespace boost{ template <typename TRange> std::size_t hamming_dist(TRange first, TRange second); template <typename TRange> std::size_t levenstein_dist(TRange first, TRange second); template <typename TRange, typename Type> Type weighted_levenstein_dist(TRange first, TRange second, Type replace_cost, Type insert_cost, Type delete_cost); template <typename TRange> std::size_t damerau_levenstein_dist(TRange first, TRange second); template <typename TRange, typename Type> Type weighted_damerau_levenstein_dist(TRange first, TRange second, Type replace_cost, Type insert_cost, Type delete_cost, Type transpose_cost); template <typename TRange> std::size_t delta_dist(TRange first, TRange second); template <typename TRange> std::size_t gamma_dist(TRange first, TRange second); template <typename TRange> float jaro_dist(TRange first, TRange second); template <typename TRange> float jaro_winkler_dist(TRange first, TRange second, float weight); template <typename TRange> std::pair<std::size_t, std::size_t> deltagamma_dist(TRange first, TRange second); template <typename Type> class approximate_distance { // ... }; class hamming_distance : public approximate_distance<std::size_t>{}; template <typename Type, typename TRange> class approx_pattern { public: approx_pattern(approximate_distance<Type>& distance, Type max_allowed, TRange pattern); }; template <typename Type, typename TRange> class sapprox_match_iterator { public: sapprox_match_iterator(TRange text, approx_pattern<Type, TRange>); // overloaded ++ and * operators }; template <typename Type, typename TRange> class sapprox_match_result { public: Type distance() const; std::size_t startIndex() const; std::size_t endIndex() const; TRange str() const; }; } ~~~~ Here is an example of usage: ~~~~ {.cpp} string a = "aaabc"; string b = "aaacb"; cout << boost::hamming_dist(a, b) << endl; // prints 2 cout << boost::damerau_levenstein_dist(a, b) << endl; // prints 1 string pattern = "acbdef"; string text = "aacdefbcdefabccef"; boost::approx_pattern ap(boost::hamming_distance, 1, pattern ); boost::sapprox_match_iterator begin( text, ap ); boost::sapprox_match_iterator end; std::for_each( begin, end, []( const boost::sapprox_match_result& what ) { cout << what.str() << " starting at " << what.startIndex() << endl; } ); // aacdef at 0 , fbcdef at 5, abccef at 11 ~~~~ As you can see, I would like my implementation to be general so that other string containers can be used instead of std::string. A will also take care of proper design in a way that further distances can be easily added later. There are multiple implementation approaches that can be used: NFA simulation, Shift-or algorithm and dynamic programming approach. I will probably choose the dynamic programming - it has low time and space complexity as well as it does not require any kind of preprocessing. Thus searching all occurrences of pattern in a text has O(m*n) complexity, m is length of pattern, n is length of text. Related work There is currently only one C++ library I know of: Flamingo [2]. From my point of view, its usage is a kind of complicated. You can also find implementations of single functions on-line, but they lack of multiple distances support as well as they are not general (eg. designed for C-like strings only). Another related project is stringmetrics [3]. This project is written in Scala so it is not related to C++ programmers. Schedule -------- This is an approximate schedule I would like to keep on. Since I will probably hit many unexpected issues I have reserved some time for it. 17th June : start 17th June - 27th June : prototyping and designing API interface as well as auxiliary functions / classes 28th June - 30th June : setting up testing environment, writing basic unit tests 1st July - 14th July : implementation of general dynamic programming model that will be used by most distances 15th July - 28th July : implementation of distances 1 - 5 29th July - 4th August : implementation of distances 8 - 10 5th August - 11th August : implementation of distances 6,7 12th August - 1st September : implementation of approximate pattern search in a text for all distances 2nd September - 15th September : wrapping up, end user documentation 16th September - 21st September : reserved During all implementation phases I'll be also performing testing and source code documentation. References ---------- [1] http://en.wikipedia.org/wiki/Jaro-Winkler_distance [2] http://flamingo.ics.uci.edu/releases/4.1/ [3] http://rockymadden.com/stringmetric/

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[gsoc 2013] chrono::date
by Anurag Kalia 27 Apr '13

27 Apr '13

After going through related docs and general information, I have some questions regarding the chrono::date library. What is the origin of the name 'chrono'? I have assumed till now, it has something to do with chronology, but I am not sure.Why is date a part of 'chrono' at all? As I understand, chrono::date library is supposed to be based on the counts of sunrises. I am in favour of it because it elegantly circumvents the complications of leap seconds which are unnecessary with date-related arithmetic. But if we want it to be compatible with the rest of chrono library, complications arise:If we use a definition in line with principles of chrono (i.e. not using sunrises for a moment), a date really becomes a time-interval defined by the 00:00:00 of that date + a duration of 1 day, if we follow the rules of chrono library. But the length of a day can be changed today due to insertion/deletion of leap seconds to the conventional 24-hour day, if needed. Moreover, this change is arbitrary, since leap seconds are used to keep the time in sync with earth's rotations, which changes without a fixed pattern.The length of month and year similarly are complicated, not only by the length of days in it (see above) but also by the variable number of days. For example January has 31 days, April has 30 days and February has 28 or 29 days depending upon common year or leap year respectively. Due to the latter, length of year also varies between 365 and 366 days.In essence, there is no fixed duration of day, month or year; unlike the rest of chrono library which fundamentally is based on 'duration' class.Now if we revert to our original definition, our library basically becomes a count of sunrises since epoch. Aren't we forming an independent library from chrono then?What does one mean when one says the chrono::date library interoperates with rest of chrono library? This question is an offshoot of previous question. I am confused as to how far can both parts interoperate given the above-mentioned complications. Subtraction of dates yields us theoretically a duration of a number of days. But since actual time duration of a day is ill-defined (see above), we have to return the answer in resolution of seconds, if we use 'duration' at all. I am unable to think of more possibilities of cross-pollination between the two parts. Am I correct in my reasoning? I am genuinely stuck at this clubbing up of unrelated (to me) classes. Even more so because Boost already supplies such a vast number of header files with least number of interdependencies. A smaller self-contained date library seems (to me) more in line with its principles. Thanks,Anurag Kalia.

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Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
by Niall Douglas 27 Apr '13

27 Apr '13

> > [1] http://danlincan.3owl.com/gsoc/Proposal.pdf > > > I have some questions: > > * Why the submit function of all the thread pools doesn't returns the same? > * What is the advantage of returning future from submit call? > .... My personal big issue with a Boost.Thread threadpool is why adding one is necessary when forty lines of C++11 code using Boost.ASIO implements you one: /*! \class thread_pool \brief A very simple thread pool based on Boost.ASIO and std::thread */ class thread_pool { class worker { thread_pool *pool; public: explicit worker(thread_pool *p) : pool(p) { } void operator()() { pool->service.run(); } }; friend class worker; std::vector< std::unique_ptr<thread> > workers; boost::asio::io_service service; boost::asio::io_service::work working; public: //! Constructs a thread pool of \em no workers explicit thread_pool(size_t no) : working(service) { workers.reserve(no); for(size_t n=0; n<no; n++) workers.push_back(std::unique_ptr<thread>(new thread(worker(this)))); } ~thread_pool() { service.stop(); for(auto &i : workers) i->join(); } //! Returns the underlying io_service boost::asio::io_service &io_service() { return service; } //! Sends some callable entity to the thread pool for execution template<class F> future<typename std::result_of<F()>::type> enqueue(F f) { typedef typename std::result_of<F()>::type R; // Somewhat annoyingly, io_service.post() needs its parameter to be copy constructible, // and packaged_task is only move constructible, so ... auto task=std::make_shared<boost::packaged_task<R>>(std::move(f)); // NOTE to self later: this ought to go to std::packaged_task<R()> service.post(std::bind([](std::shared_ptr<boost::packaged_task<R>> t) { (*t)(); }, task)); return task->get_future(); } }; ... and you're done. Moreover, this thread pool integrates seamlessly with Boost.ASIO ioservice callback dispatch which is a huge plus. I took that example from some page on the internet, so I don't claim I wrote most of the above. Do bear in mind before you respond that parts of Boost.ASIO are scheduled to enter the standard in TR2, therefore no you won't need Boost.ASIO as a dependency soon. I'm not ruling out the merit of a Boost.Thread threadpool. For me personally though, the hurdle is very significantly raised: you need to strongly prove to me why your proposed thread pool is much superior to a Boost.ASIO based threadpool. Otherwise I will zero score the GSoC proposal, because in the end we need other proposed projects more. By the way, I actually don't object at all if your proposed Boost.Thread threadpool is a thin wrapper of Boost.ASIO. That, actually, is just fine with me, though I'd doubt Google would feel it substantial enough for GSoC funding seeing as it would be finished within a week. Niall

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[operators] v2 test code
by Andrew Ho 26 Apr '13

26 Apr '13

I took a some time re-working the operators header based on previous feedback provided. Hopefully this will allow us to get a rough base worked out and we can work through some of the details. Most of the general idea is the same as v1, but there are a few changes and in general is not backwards-compatible. As far as I know this should be usable and support at least all of the features provided by v1 or something equivalent (see notes). codepad link: http://codepad.org/F2LrIUD2 notes: 1. Rather than using op1/op2, this version uses template specialization to make the distinction between the two. 2. All math operators have commutative and non-commutative versions, as well as left versions. Distinction is made by struct name, i.e. op is non- commutative, op_commutative is commutative, and op_left is the left variation. Note that there isn't any hard checks to prevent op_left<T, T> (which obviously makes no sense, may even result in a compiler error regardless), but the internal composite operators all use template partial specialization which don't have op_left if U = T. 3. I opted for the return-by-value only method to safely handle move semantics (see other discussion Daniel started for why). Changing this to the unsafe version is as simple as replacing the basic operator definition macro (I have that code, too. Let me know if I should post this, too). 4. Pretty much all code which alluded to a specific compiler bug/support has been removed. This includes NRVO code. I'm still not sure what level of backwards-compatibility or specific compiler code we wanted so I just code to C++03/C++11. 5. I haven't added noexcept yet (mainly because I haven't had the time to learn more about noexcept yet). My testing has nearly all so far been done in VS2012 which has an "illustrious reputation" with standards compliance. I also have access to VS2010 and MinGW (GCC 4.7.2) so I'll try testing these later, but I don't have a setup for testing compilers in Linux/Unix/Mac or any other compilers we may want to support (Clang, Intel, Embarcadero/Borland, etc.). A few questions I have: 1. In v1 operators were always considered commutative/non-commutative. The composite operators take advantage of this fact, and I have the composite operators implemented with the same assumptions. Are there any composite operators we want to provide which make different assumptions (for example, a matrix has commutative add/subtract, but non-commutative multiply)? 2. I'm a little unsure if the <boost/iterator.hpp> include is still required. It compiled fine without it, but I haven't tried out all the features to see if it is indeed required. Anyone know why we should keep this include in v2? Feedback would be appreciated, thanks.

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GSoC : Boost.Math Bernoulli Numbers
by Gaurav Deshmukh 26 Apr '13

26 Apr '13

Hi, I am Gaurav Deshmukh, CSE second year student. I am interested in the idea of adding support to Bernoulli's number to special functions in Boost.Math for GSoC-2013. I have the experience of using Boost libraries and generics in C++. I have experience to use git. I have also learned to use Boost Test upto some extent. I have tried to implement naive Akiyama–Tanigawa algorithm for second Bernoulli numbers using multi-precision boost class *'number' (cpp_dec_float_50**)*. I have attached two files. The header file *bernoulli.hpp* contains the function to calculate second bernoulli number for n<3000. *exampe.cpp *is made to test the bernoulli.hpp .

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[gsoc-2013]Approximate string matching
by Yu Jiang 26 Apr '13

26 Apr '13

Hello, I'm Yu Jiang, currently a master student from Tsinghua University in China. I'm attracted by the idea of "approximate string matching" since it's highly related about my research and also my interest. I have seen in a previous discussion, another student proposed to implement some basic matching functions such as "edit distance" for boost. He said by using dynamic programming, the time complexity is O(m*n). However, if we give a threshold T and only report the exact edit distance if it's no larger than T, the complexity can be O(T * min(m,n)). I think sometimes we just need to decide whether the edit distance is small enough. Furthermore, I'm also interested in approximate string search. That is, given a query string word Q and a candidate word set S, find all the strings in S who have the edit distance no larger than a threshold T with the query string. This is very useful in many area such as data integration, and I have strong knowledge in fast algorithms to solve this. So, is it compatible for gsoc 2013 and for boost? Looking forward to your opinions. Thanks, Yu

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[operators] The future of Boost.Operators
by Daniel Frey 26 Apr '13

26 Apr '13

Hello, for a long time there hasn't been any significant update of Boost.Operators and I had an easy job being its maintainer for the past 10+ years. I guess that will change soon. :) I would like to discuss the future of Boost.Operators, as several issues and options have piled up in the past. Here are some points to take into account: 1) Support for rvalue references to generate fewer temporaries. (where available) 2) Support for noexcept. (where available) 3) Support for constexpr if this is applicable at all. I haven't found the time to properly research it yet. 4) Allow dedicated commutative and non-commutative versions for several operators, leading to fewer temporaries for commutative versions in several cases. 5) Remove work-arounds for ancient compilers, general cleanup. I worked on a clean rewrite (called df.operators) which supports 1), 2) and 4) (and obviously 5)) and published it a few weeks ago on GitHub, see <http://github.org/d-frey/operators/>. It is meant to show one option, but it is not a suitable replacement for Boost.Operators in its current form. If it turns out to be useful as a test-bed for the next version of Boost.Operators, I will be glad to improve it into this direction but the future of Boost.Operators does not depend on it. That said, I'd like to invite anyone interested to have a look. If applicable to the future of Boost.Operators, please provide feedback on this mailing list. If feedback only concerns df.operators but not Boost, please don't spam the list and write to my private email, thanks! Some issues which need to be discussed/solved for Boost.Operators' future: 1.1) Which implementation should be used for maximum performance/compatibility? 1.1.1) Pass-By-Value as suggested by Dave Abrahams' article. (<http://cpp-next.com/archive/2009/08/want-speed-pass-by-value/>) 1.1.2) Overloads for Pass-By-Const-LValue-Reference and Pass-By-RValue-Reference. (as in df.operators) See below for why I decided to create 1.1.2) as an alternative to 1.1.1). 4.1) Decide for a default. 4.1.1) Commutative by default (as the current version of Boost.Operators assumes), non-commutative if explicitly requested by the user. 4.1.2) Non-commutative per default, commutative versions need to be explicitly requested by the user. (as in df.operators) 5.1) The main issue is probably the base-class-chaining. 5.1.1) Keep base-class-chaining, makes VC++ happy. (apply EBO and keep the object size small) 5.1.2) Drop base-class-chaining, stop punishing the rest of the world for VC++'s inability to apply the EBO for multiple inheritance. (I might be a bit biased here…) 5.1.3) Any other option I fail to see? (If a MS-employee would like to provide some information on if/when the EBO-problem will be fixed (here or in private email), I'd be grateful. If it is already fixed, I apologize, but the last information I got about VS2012 suggests EBO is not applied for multiple inheritance.) I think this should be enough to get some discussion going… Best regards, Daniel Why 1.1.2) as an alternative to 1.1.1)? Consider the following test program: #include <iostream> #include <utility> struct A { A() { std::cout << "A::A()" << std::endl; } A( const A& ) { std::cout << "A::A(const A&)" << std::endl; } A( A&& ) { std::cout << "A::A(A&&)" << std::endl; } ~A() { std::cout << "A::~A()" << std::endl; } A& operator+=( const A& ) { std::cout << "+=" << std::endl; return *this; } }; // #define BY_VALUE #ifdef BY_VALUE A operator+( A lhs, const A& rhs ) { lhs += rhs; return lhs; } #else A operator+( const A& lhs, const A& rhs ) { A nrv( lhs ); nrv += rhs; return nrv; } A&& operator+( A&& lhs, const A& rhs ) { lhs += rhs; return std::move( lhs ); } #endif int main() { A a, b, c, d; A r = a + b + c + d; } The above code, compiled with G++ or Clang prints: A::A() A::A() A::A() A::A() A::A(const A&) += += += A::A(A&&) A::~A() A::~A() A::~A() A::~A() A::~A() A::~A() If you define BY_VALUE, it prints: A::A() A::A() A::A() A::A() A::A(const A&) += A::A(A&&) += A::A(A&&) += A::A(A&&) A::~A() A::~A() A::~A() A::~A() A::~A() A::~A() A::~A() A::~A()

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Re: [boost] [gsoc-2013] Boost.Thread/ThreadPool project
by Niall Douglas 26 Apr '13

26 Apr '13

> > I'm not ruling out the merit of a Boost.Thread threadpool. For me personally > > though, the hurdle is very significantly raised: you need to strongly prove > > to me why your proposed thread pool is much superior to a Boost.ASIO based > > threadpool. Otherwise I will zero score the GSoC proposal, because in the > > end we need other proposed projects more. > > Superior in what way? Performance-wise, interface-wise? What advanced > features would you want from a thread pool to make it superior to the > presented implementation? That's for the applicant to decide. Any proposal needs to be very significantly better than something based on existing features to pass muster not just with Boost, but with Google themselves. There is always an assumption against duplication of existing functionality just for the sake of it. Niall

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[type_erasure] error in type-erased iterators
by Adam Wulkiewicz 26 Apr '13

26 Apr '13

Hi, iterator< ::boost::no_traversal_tag, ...> defines constructible<T()> requirement. This however musn't be meet in the case of incrementable and single-pass iterators. It should probably be moved to the iterator< ::boost::forward_traversal_tag, ...> Patch attached. Regards, Adam Wulkiewicz

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Fwd: [gsoc 2013] boost.multiprecision
by Sagar Massand 26 Apr '13

26 Apr '13

Hi, I wanted to submit a proposal but I am not sure right now if I am going in the right direction.It would be great if you could guide me here. I was thinking of implementing karatsuba multiplication in the initial stages, complete with a testing of the implementation, and then move on to Schonhage-Strassen and other fast-fourier transform algorithms in the last one and half months seeing that our primary requirement is for numbers uptil 1000 digits. I was also thinking of the implementation of some other division algorithms like Goldschmidt, Newton-Raphson etc. A complete link to my proposal can be found below: https://docs.google.com/file/d/0B5iapFjtoO7GTVR2eGhJd2dXZHM/edit It would be great if you could give suggestions to improve this.Thanks. Regards, Sagar Massand

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[gsoc-2013] Boost.Thread/ThreadPool project
by Dan Lincan 26 Apr '13

26 Apr '13

Hello, My name is Dan Lincan. I'm a 4th year undergratuate student in Computer Science at the "Politehnica" University of Bucharest and I'm interested in the project "Boost.Thread/ThreadPool". I have studied the documents provided as resouces and I would really appreciate if you helped me better understand this project. Are there any tasks that are meant to get solved for the proposal? How do I start? I am aware that it will not be an easy task at all, especially because I don't have much experience with boost, but I'm willing to learn and work as much as it is needed to get it done. Thank you for your time, Dan Lincan

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[Runtime Parameters Reference]Command Line Argument
by Hemanth Choudary M V (RBEI/ETA1) 26 Apr '13

26 Apr '13

Hi, I would like to run selected test cases from multiple tests suits. Pl let me know the command line argument to be passed. Mit freundlichen Grüßen / Best Regards, Hemanth Choudary MV RBEI/ETA1

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Re: [boost] Live read-only GIT mirrors of Boost trunk SVN
by Niall Douglas 25 Apr '13

25 Apr '13

> >The live GIT mirrors of Boost trunk SVN have become a bit stale in recent > >months [...] > > I tried making a mercurial mirror of the Boost trunk SVN and found > that it took so long to do the conversion process, that I could never > get it to complete on my home computer with cable modem internet > access, but I could get it to complete on a shell account with faster > trunk access. I simply allocated an OpenVZ container on my cloud with 64Mb of RAM and 128Mb of swap. > I also found the resulting repository was *huge* because I had *every* > revision of boost ever recorded in the svn repository. Github reckons the entire mirror consumes 700.40Mb. No idea if that's good or bad. > I'm curious if you had different experiences when making a git > repository. To be honest, the process was very straightforward. I configured it as per subgit's instructions. I set it running. It OOMed a few times, but hardly unsurprising with 64Mb of RAM for the VM. I simply restarted when it did. And after a day or two it completed (note that the cloud hardware is a 2Ghz Core 2 without SSD). Better hardware would be far faster. > I am more familiar with mercurial than git, and I wanted to make a > local mercurial repository so that I could work on my changes locally > and checkpoint them using the version control system instead of manual > backups. AFAIK, there's no way to record local changes with > versioning using subversion, there's only committing to the remote > server. Ah, getting subversion commits to match git commits that's subgit's problem :). Subgit gives you three sync options, "safe", "somewhat safe" and "not safe". "safe" locks both subversion and git repos during the sync, however long that takes, and during which no pushes nor pulls nor checkouts may happen. So long as you can live with that (I can), the live two way mirroring works well, but it could be frustrating for users of busy repos. Niall

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Re: [boost] [operators] The future of Boost.Operators
by Andrew Ho 25 Apr '13

25 Apr '13

> Maybe we're talking past each other. I have 3 overload set variants in > mind: > > (A) > T operator?(T, T); > > (B) > T operator?(T const &, T const &); > ... > T operator?(T&&, T&&); > > (C) > T operator?(T const &, T const &); > ... > T&& operator?(T&&, T&&); > > AFAICT, neither (A) nor (B) have any safety issues. Oh, but now I see the > problem with (C): T&&'s are implicitly convertible to T&'s...that's what I > was missing before. Sorry for being dense. > > So if you do > > T& a = b + c; > This succeeds in VS2012 with all (no compile or runtime problems, oddly VS2012 extends the lifetime of ref returned by C to be valid), and fails with all in gcc 4.7.2 (compiler error) :P > invalid initialization of non-const reference of type 'T&' from type 'T&&' Yep, this is what happens in gcc for me. > > I swear I just tried a T& y = static_cast<T&&>(x) on gcc and finding it > compiled fine. This gave a compiler error for me. > Now you can ask the same question with T const& instead... Compile succeeds, with only two operands the called overload returns a T, not T&& so there's no problems. If you had: const T& r = a + b + c; (A) and (B) are perfectly safe, but (C) will have runtime issues. Same goes for: T&& a = b + c; T&& r = a + b + c; First line doesn't have any problems with (A), (B), or (C) because of which overload is used. The second line (A) and (B) have no problems but (C) will have runtime issues. Of course, (C) will have a few extra temporaries created (which may or may not be optimized away). The question originally posed is do we: 1. Ignore this problem with (C) to get better performance and just document the problem? 2. Implement (B) to take advantage of move semantics with no internal problems, albeit with a few temporaries being created (if they aren't optimized away by the compiler)? 3. Implement a user-accessible macro switch to let the user decide globally As Jeff said, (3) is ugly especially when linking different codes together, but does provide the most options to the user. (2) isn't necessarily the most efficient but is completely safe. It may also end up being just as efficient as (1) if compilers support the optimization to remove unnecessary temporaries. Daniel's argument is that the problems which occur with (C) are typically a result of user error, and (C) in general guarantees the least amount of temporaries being used. Are there any cases where the problems described above with (C) would be a result of intended behavior with no acceptable work-around? Hopefully we're on the same page now.

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Google Summer of Code Proposal Feedback
by Niall Douglas 25 Apr '13

25 Apr '13

> aware of GSOC until recently. I had strongly considered writing a proposal > for Boos.ASIO, but I fear my lack of experience with Linux, POSIX, and > concurrency in general might prove to be too great of an obstacle. If the > subject matter can be learned relatively quickly, I would love to discuss > what such a project would require with the mentor, Niall Douglas, or a > community member who has is familiar with the project. I'm hardly "the" mentor in Boost.ASIO. I'm probably just the only one to have registered as a potential mentor so far. It's still early days. A lot more potential mentors will register in time, then depending on project scoring and people's availability and of course Google's preferences, we'll see what turns out. > My original proposal probably isn't unique, and much to my chagrin as I > read the hints for successful proposals it seems a popular topic. I am of > course suggesting a project dealing with Trees. Rather than suggest > building a generic tree, I am suggesting the start of a tree library, or > the addition of several types of trees to existing libraries, as I am not > sure which is more appropriate. An awful lot of students expose their ignorance of what Boost, or indeed the C++ standard library, provides during GSoC. It really doesn't help them to be scored well which is why Boost strongly recommends that students discuss their ideas here first before submission. 95% of the time their idea is already implemented. For example, there are multiple tree implementations in the C++ STL and Boost. Look into Boost.Intrusive for example. > Because trees are such a fundamental data type in computer science, I have > found it difficult to understand why there are no explicit tree classes in > the c++ standard. They generally don't have "tree" in their name ;) > tested in an afternoon, while implementing a Red Black Tree would take > considerably longer, yet the C++ standard has linked lists and not Red > Black Trees. Red-black trees are called std::map<>, std::set<> et al. in C++ since 1998. Of course std::map<> et al. doesn't *have* to be implemented as red-black, but most implementations do since the SGI STL defined std::map<> using stl_tree<>. > The library I am proposing should eventually be able to satisfy almost > anyone requiring the use of a tree. It should have many different types of > trees, Binary trees, AVL Trees, Red Black Trees, Treeps, B-Trees, > Skip-Lists, etc. It should support common methods of traversal, inorder, > preorder, postorder, and user defined traversal methods. Eventually, the > library should support an n-ary trees and their operations. Trees in the > library should also be performant, fail gracefully, be well documented, > unit and integration tested, as exception safe as possible, and, someday, Look into Boost.Intrusive. They're the most appropriate category for what you propose. Niall

1 0

Discussion Policy
by Rob Stewart 25 Apr '13

25 Apr '13

If you're relatively new to this list, you may not have taken the time to read Boost's discussion policies[1]. Even if you've been on the list for a while, reviewing the policies may be educational. Thanks for your efforts to make discussions easier and more consistent for all. ___ Rob (Sent from my portable computation engine) [1] http://www.boost.org/community/policy.html

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Re: [boost] Going forward with Boost.SIMD
by Niall Douglas 25 Apr '13

25 Apr '13

> A GPU is an accelerator for large regular computations, and requiring sending > memory and receiving it back. It's also programmed with a very constrained > programming model that cannot express efficiently all kinds of operations. > > A CPU, on the other hand, is a very flexible processor and all memory is already > there. You can make it do a lot of complex computations, irregular, sparse or > iterative, can do dynamic scheduling and work stealing, and have fine-grained > control on all components and how they work together. :) You're actually wrong on that, and it's one of the first big surprises anyone who sits on ISO committees experiences: the change in scope of definitions. When you're coming at things from the level of international engineering standards, a computer's CPU is not defined as anything approximating what any of us use on a regular basis. It includes large NUMA clusters, it includes Cray supercomputers all of which don't do SIMD anything like how a PC does. It *also* includes tiny embedded 8-bit CPUs, the kind you find in watches, inlined in wiring, that sort of thing. Some of those tiny CPUs, believe it or not, do SIMD and have done SIMD for donkey's years, but it's in a very primitive way. Some of those CPUs, for example, work in SIMD 3 x 8 bit = 24-bit or even 3 x 9 bit = 27-bit not 32-bit integers, that sort of thing. Yet international engineering standards must *always* target the conservative majority, and PCs or even CPUs designed more recently than the 1990s are always in a minority in that frame of reference. Don't get me wrong: you could standardize desktop class SIMD on its own. But generally you need to hear noise complaining about the costs of lack of standardization, and I'm not aware of much regarding SIMD on CPUs (it's different on GPUs where hedge funds and oil/gas frackers regularly battle lack of interop). > However, SIMD has been here for 25 years and is still in the roadmap of future > processors. Across all this time it has mostly stayed the same. > > On the other hand GPU computing is relatively new and is evolving a lot. > It's also quite trendy and buzzword-y, and is in reality not as fast and versatile as > marketing makes it out to be. > A lot of people seem to be intent on standardizing GPU technology rather than > SIMD technology; that's quite a shame. Thing is, had Intel decided Larrabee was worth pushing to the mass market - and it was a close thing - PC based SIMD would look completely different now and we wouldn't be using SSE/NEON/AVX which is really an explicit prefetch opcode set for directly programming the ALUs and bypassing the out of order logic, not true SIMD (these are Intel's own words, not mine). As it is, convergence will simply take longer. Some of those new ARM dense cluster servers look awfully like Larrabee actually, 1000+ NUMA ARM Cortex A9's in a single rack, and their density appears to be growing exponentially for now. Given all this change going on, I'd still wait and see. Niall

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Google Summer of Code Proposal Feedback
by Paul Kirth 25 Apr '13

25 Apr '13

Hello Boost community, I am a student interested in the Google Summer of Code (GSOC), and have a few proposals in mind. If I have posted this in the wrong place, my apologies, but applicants are encouraged to post to the mailing list, and after some research this seemed like the best list to post to. I have an original proposal for Boost, and strong interest in the Boost.ASIO idea. I've decided to seek some feedback from the community on their feelings about my idea, in the hopes that I can better define them, and increase my chances of success in being selected for the GSOC. I realize it is a bit late to begin discussing proposals, but I wasn't really aware of GSOC until recently. I had strongly considered writing a proposal for Boos.ASIO, but I fear my lack of experience with Linux, POSIX, and concurrency in general might prove to be too great of an obstacle. If the subject matter can be learned relatively quickly, I would love to discuss what such a project would require with the mentor, Niall Douglas, or a community member who has is familiar with the project. *About Me* First, let me begin with a bit about myself. My name is Paul Kirth, and I am currently pursuing a masters in Computer Science. This statement may be a bit misleading, however, as I received my BS in Civil Engineering from UCLA in 2005, and have only recently decided to pursue a course of study in Computer Science. I have for the last two years taken CS classes to prepare for Masters level courses, but am still a bit of a novice in CS. I would say that I am at about a 3rd year level in CS, proficient in C++ and python, and competent in Java, with a limited amount of assembly, and very little work in concurrency. I have not spent much time doing engineering work in the last few years, as my focus has been on my education, but I was fairly good at solving linear systems, and had a good amount of experience with design and collaboration. As an undergraduate I made the mistake of not pursuing summer internships or jobs, and as a result I found that many of my peers had a much easier time with our courses as a result of their work experience. After all, 20-30 hours a week solving engineering problems will generally make you more proficient at solving them than someone who doesn't. I do not wish to make the same mistake with my new career path, and desperately want to gain experience in professional software design, and in working on a collaborative project. I am keenly aware of my lack of experience, and really wish to use this opportunity to push myself, and gain as much expertise as possible during the few months of the summer. *Original Proposal* My original proposal probably isn't unique, and much to my chagrin as I read the hints for successful proposals it seems a popular topic. I am of course suggesting a project dealing with Trees. Rather than suggest building a generic tree, I am suggesting the start of a tree library, or the addition of several types of trees to existing libraries, as I am not sure which is more appropriate. Because trees are such a fundamental data type in computer science, I have found it difficult to understand why there are no explicit tree classes in the c++ standard. I have read the arguments that there is no standard use for a tree, and as such it cannot be made to satisfy enough users. I have read more arguments stating that std::sets and std::map use tree structures underneath their interface. Furthermore I have read in several places that it is common to use Boost.graph to make trees. Trees have myriad uses, and a library implementation should consider this heavily when designing the data structure, but trees are common enough to warrant a standard implementation in the same way as lists, queues, and stacks. I will concede that trees can be considered, and in fact are, graphs, and that many graph algorithms are very powerful tools. But trees don't always need those algorithms, and graphs don't always maintain the tree in the way we wish. Using an std::set or std::map is not the same thing as using a tree, regardless of how they are implemented. Conservatively, a linked list can be fully implemented and tested in an afternoon, while implementing a Red Black Tree would take considerably longer, yet the C++ standard has linked lists and not Red Black Trees. This seems a bit counter intuitive. We have a relativity simple data structure in the standard, and a more complex one is not. I'm sure that linked lists are more common than red black trees, but by how much? If self balancing binary trees are considered a fundamental data structure by every computer science curriculum, why aren't comprehensive, reliable implementations of them part of the standard, or widely available in 3rd party libraries like Boost? The library I am proposing should eventually be able to satisfy almost anyone requiring the use of a tree. It should have many different types of trees, Binary trees, AVL Trees, Red Black Trees, Treeps, B-Trees, Skip-Lists, etc. It should support common methods of traversal, inorder, preorder, postorder, and user defined traversal methods. Eventually, the library should support an n-ary trees and their operations. Trees in the library should also be performant, fail gracefully, be well documented, unit and integration tested, as exception safe as possible, and, someday, concurrency safe/compatible. I'm unsure of the Boost stance on inheritance is, but my initial feeling is that users should be able to use tree classes as base classes if they desire. Proposing a large library as a summer project is ridiculous, hence I am proposing a start to this library, containing a few tree classes that can be implemented, tested, and documented within a few months, and a set of standards for new entries in the library. I don't expect the whole library to immediately be accepted into Boost, but the project will aim to meet those standards, with a long term goal of eventually being included into Boost. My research has found several projects that implement single tree classes, or groups of tree classes, but no tree library. A good c++ example is the rbrees project at https://code.google.com/p/rbtrees/ , or python has a few implementations of trees, such as bintrees 0.3.0, https://pypi.python.org/pypi/bintrees/0.3.0, which is a binary tree library, containing BinaryTree, AVLTree, and RBTree classes. I feel that bintrees 0.3.0 is a good project to mimic in the early stages, as binary trees are fairly easy to implement, test, and maintain with AVL and RB Trees. I am comfortable with binary, AVL and Red Black Trees, and feel very confident in my ability to implement them. I would like to do more, and push myself this summer, but I am not sure how much work unit and integration testing are, how long they take, and how much extra time is required for classes/libraries to be refined to Boost standards. I am sure that this time is non trivial, but as a student I'm very unsure about how much time things take, or how much time they should take. In general I would like to work on a project that would expose me to more new ideas, but I really think the world deserves access to a C++ tree library that can have some guarantees for performance, and is part of a larger, well documented, highly respected library. I understand that this project is virtually guaranteed to take more that one summer's worth of effort, and I am comfortable with staying involved in the project beyond the length of GSOC, or having the work done absorbed into another library/project. Whether or not this project is accepted into GSOC, if there is support for this effort in the community I would love to help as I am able. Obviously if I am working this summer my commitment will not be able to be as substantial, but I do feel strongly about the need for standard, performant, reliable tree classes in c++. Thank you for reading my lengthy first post to the mailing list. I hope to have more discussions with this community in the future, and I am eager to hear your thoughts about how this proposal could be improved. -- Paul Kirth (310) 709-2516

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proposal for date_time implementation
by Shamsher Siddiqui 25 Apr '13

25 Apr '13

hi mentors plz review my project and give me suggestion to improve to my proposal Name :Shamsher Ahmed College/University:University Insititute of Engineering &Technology,Chandigarh,India Course/Major:Computer Science & Engineering Degree Program:Bachelor of Engineering Email:mail.shamshersiddiqui@gmail.com Homepage:Not yet Availability: How much time do you plan to spend on your GSoC? I can work full time to complete this project. What are your intended start and end dates? I will start the project according to GSOC 2013 schedule but i will try to finish the project 2 weeks before so that I can have the necessary time for debugging and for unforeseen situation it occurs. What other factors affect your availability (exams, courses, moving, work, etc.) ? My semester exam will get start from 18 may and it will end on 28 may .So I will have complete time to dedicate. I don’t have any course or work during this summer . Background Information: • Please summarize your educational background (degrees earned, courses ,taken, etc.) I passed out 10+2 from Indian School Certificate in 2010 and I am currently pursing bachelor of engineering from university institute of Engineering & Technology, Chandigarh Till now I mainly focused in learning programming language (C,C++,Java). I have mastered over Java and c++ but scratchy in C.I have also taken course on Algebra, Calculus, Data Structure & Algorithm ,database etc etc. • Please summarize your programming background (OSS projects, internships,jobs, etc.) This will be my first OSS project at such large level. I have developed many things in c++ & Java. During my last summer I have done my internship in slr infotech ,a small software firm . • Please tell us a little about your programming interests : I am programming from 8th grade .In 10 and +2 board exam I obtained 96 and 97 respectively in my computer science subject. I love to code for hours .And most important thing about open-source I like about is sharing, helping and hacking code . • Please tell us why you are interested in contributing to the Boost C++ Libraries? Boost c++ Libraries are one most powerful libraries of c++ used by many well known organizations .It is cross platform library which has high efficiency And it goes together with standard template library in c++. I will get support from boost community and it is documented very well which makes it very easy to understand and if any bugs comes than it is easily recognized and eliminated , lastly while working with bright minds I will be able to learn from them and impart my experience , knowledge to other developers • What is your interest in the project you are proposing? Libraries were mystery for me when I started learning my first programming language c but after some time I was able to perform the same task without using library but there was increase in time and length of code for doing the same program.I want to develop this project because it will increase the reusability of code and in Boost community best minds works together to give the one of the best libraries of c++. Date library will be always used in every development project whether big or small and When I read this project https://svn.boost.org/svn/boost/sandbox/chr ono_date/libs/date/doc/date.html .This is small library but will be most efficient and will be able to perform all task and save time ,reusability of code is very high. • Have you done any previous work in this area before or on similar projects? No ,I haven’t done any project regarding libraries but I am using libraries in my other project. But me and my friend are developing a tagging software which creates a folder on the basis of album,artist,track number etc. We have implemented internal structure but GUI part is left which my friend is working on. and developed small games in c++ as my project assignment. • What are your plans beyond this Summer of Code time frame for your proposed work? After Summer of code ,I will remain involve with the boost c++ community and I would like to add more feature to current project.Secondly I will work with the boost community in building in their library because I love coding for long hour. I enjoy this work. • Please rate, from 0 to 5 (0 being no experience, 5 being expert), your knowledge of the following languages, technologies, or tools:  C++: 4  C++ Standard Library: 3  Boost C++ Libraries: 2  Subversion :2 • What software development environments are you most familiar with (Visual Studio, Eclipse, KDevelop, etc.) I generally use Qt creater or Visual studio depending on the operating system I am using . • What software documentation tool are you most familiar with (Doxygen, DocBook, Quickbook, etc.)? I am familiar with Doxygen Project Proposal Goals & Implemenatations 1) Construction of Date: • Date can be represented in two ways field representation or as an serial representation . In field based representation(YMD) date value is constructed from individual year,month,and day value in three integral value. In serial reprensentation(SERIAL) data values are stroed in intergral number of days from an implementation defiend epoch date, there is third hybrid version to represent the date which implemantd the both representation and it is named HH_YMD_SERIAL_X where x represents the size of types in byte. • Providing support for entering the date in form YDM(year,day,month) which is lacking currently in chrono:date library • No invalid dates can be entered considering range cheaking ,non existent date if entered bad_date exception is thrown . • Constructing constant object for day,week_day. Eg. last/may/2000 represents 31 may 2000 • Construction of meta data for date 1) Leap year flag 2) Nth day of month 3) Nth weekday month 2) Arithematic Operation On date Date airthematic can be done on three units i.e day,month,year.In chrono date ::calendar(Gregorian calendar) length of month and year is not fixed : • day arithematic 1) Adding number of days to date until range doesn’t exceed 2) Implementing last day arithmetic to avoid the bad date excepti Eg. aug/last/2011 +months(1)= sep/30/2011 aug/31/2000 +months(1)=sep/31/2000 //invalid date bad date excep thrown • month arithmetic Month arithmetic is quite complex compared to day arithmetic since number of are not fixed . 1) (month day <=28 || month day =last day ) always add month 2) month day =29 cheak for leap year and than add month 3) Month day>=30 add but don’t add if resulting month is feb 4) Using constant objects for month arithmetic. • year arithematic 1) Always add year to date considering the condition of leap year 2) Reversal of date back to original date 3) Usage of last day during year arithematic During any of the airthematic operation result should not be an invalid date if it occurs than bad_date exception is thrown. 3) InterConversion field representation & serial representation Some operation are quite fast on field but airthematic operation are much faster on serial campared field representation .So it is necessary to provide the inter-coversion so that it can be easily converted from one representation to another. 1) Constructing bi-directional conversion of serial and field by making use of static cache to optimize conversion 4) Building function for week days & date formatting 1) weekday of a date used. 2) nextweek day of date used. 3) previous weekday of date used. 4) finding number of weeks in month 5) formatting of date according of all types 5)Interoperability with other calendar Current chrono::calendar is Gregorian calendar which exist everywhere in date & time library of every programming language.(c,c++,java) and ISO 8601 and POSIX. This section provides conversion of chrono calendar to client calendar. 1) Conversion of chrono ::calendar to Julian Calendar 2) Conversion of chrono :: calendar to Hebrew calendar 3) Conversion of chrono :: calendar to hindu calendar 4) Conversion of chrono :: calendar to Chinese calendar 5) Conversion of chrono :: calendar to Buddhist calendar 6) Conversion of chrono :: calendar to Islamic calendar Hindu ,Chinese ,Buddhist ,Hebrew(Jewish ) calendars are lunisolar calendar with a very little difference. Julian, Gregorian are very much similar except the method of finding the leap year. Islamic calendar is lunar calendar(totally dependent on moon ) which is quite unpredicatable. Hence accurate conversion is rare. TimeLine Until 17 June :Community bonding , understanding boost c++ libraries ,discussing with mentor about the details of proposal . 17 June to 27 June: Construction of date 28 June to 12 july : testing &debugging of construction of date and implementing date arithemetic 13 july to 29 july (Mid term evaluation) : implementation of interconversion of serial and field representation and testing ,debugging and making more efficient the previous code develop. 30 july to 15 August :Implementation of date formatting and developing function on weekday. 16 August to 30 August: testing ,debugging and aadding more feature to weekday and implementation of interconversion of calendar. 31 August to 23 Sept:testing ,debugging ,making efficient the whole code .

2 2

Fwd: [asio]Extension for audio device service
by adrien courdavault 24 Apr '13

24 Apr '13

Hello. I make this new thread to be clearer. There is currently no way to manage audio endpoints cconnection easily. It looks like some people might find this usefull (as I do), and I've been suggested on the boost dev list to try to detail this, as an extension to Boost.ASIO. For this reason I create this thread. I'm trying to make a very basic first draft of the concepts and see if this may be a good idea. I attached here the first things I've written. This is very short and general. I would like to know: * do you think I'm going in the right direction by seing this as Boost.ASIO extension. * do you have suggestions * would someone like to participate ? Thank you

2 3

[gsoc-2013]Boost.multiprecision project
by Sagar Massand 24 Apr '13

24 Apr '13

Hi, I wanted to submit a proposal for the boost.multiprecision project. Please find attached the files:1)Proposal for the project 2)Naive code for karatsuba multiplcation in C. It would be very kind of you if you could give me suggestions, point out flaws etc. in this. Regards, Sagar Massand

1 0

Going forward with Boost.SIMD
by Mathias Gaunard 24 Apr '13

24 Apr '13

Hi, This week I presented a proposal to the C++ standards committee to provide a standard library component for SIMD computation based on the library in development Boost.SIMD (not yet a Boost library). I was hoping to get feedback on the interface and establish an API that would satisfy hardware and compiler vendors. Unfortunately the concurrency/parallelism group has decided that they do not want C++ to provide types representing SIMD registers. I'm afraid I don't quite understand the rationale for such a refusal; proposing more high-level constructs similar to valarray (or to our own library NT2) was suggested, but that's obviously a more complex and limited API, not a basic building block to program portably a specific processor unit. Development of Boost.SIMD will still proceed, aiming for integration in Boost, but standardization appears to be definitely out of the question. Any feedback of the API presented in the proposal is welcome. <http://open-std.org/JTC1/SC22/WG21/docs/papers/2013/n3571.pdf>

7 19

[Runtime parameters reference]Regarding Call Stack Trace
by Hemanth Choudary M V (RBEI/ETA1) 24 Apr '13

24 Apr '13

Hello, We are running a boost unit test using command line (cmd). The command is: C:\> /c "D:\MyExecutable.exe" --run_test=testcase1,testcase2,testcase3, --report_format=xml --report_level=detailed --log_format=xml --log_level=all >test_log.xml 2>test_report.xml The output format is in XML. I would like to have the call stack for the failed test cases. Is it possible to write the call stack trace in test_report.xml or test_log.xml ? Is there any macro or Boost API can help me achieve this? Mit freundlichen Grüßen / Best Regards, Hemanth Choudary MV RBEI/ETA1

1 0

'XPath error : Undefined namespace prefix' when building boost.test docs
by legalize+jeeves＠mail.xmission.com 24 Apr '13

24 Apr '13

[Please do not mail me a copy of your followup] I get this error when I try to build the boost.test documentation and I'm not sure where it's coming from or what to do about it. Since the HTML files are commmitted to the repository, I can't tell if the documentation was actually generated or not. D:\Code\boost\svn-boost-trunk\libs\test\doc>b2 standalone ...found 39 targets... ...updating 1 target... xslt-xsltproc-dir.windows html\standalone_HTML.manifest XPath error : Undefined namespace prefix set XML_CATALOG_FILES=../../../bin.v2/boostbook_catalog.xml "d:/code/boost/boost-tools/bin/xsltproc.exe" --stringparam boost.defaults "Boos t" --stringparam chunk.toc "/D:/Code/boost/svn-boost-trunk/libs/test/doc/src/btl -toc.xml" --stringparam example.dir "file:///D:/Code/boost/svn-boost-trunk/libs/ test/doc/src/examples" --stringparam manifest "standalone_HTML.manifest" --strin gparam manual.toc "/D:/Code/boost/svn-boost-trunk/libs/test/doc/src/btl-toc.xml" --stringparam snippet.dir "file:///D:/Code/boost/svn-boost-trunk/libs/test/doc/ src/snippet" --path "D:\Code\boost\svn-boost-trunk\libs\test\doc/src" --xinclude -o "html/" "D:\Code\boost\svn-boost-trunk\libs\test\doc\src\xsl\html.xsl" "..\. .\..\bin.v2\libs\test\doc\msvc-11.0\debug\utf-boostbook-on\src\btl.docbook" ...failed xslt-xsltproc-dir.windows html\standalone_HTML.manifest... ...failed updating 1 target... D:\Code\boost\svn-boost-trunk\libs\test\doc> Any suggestions? -- "The Direct3D Graphics Pipeline" free book <http://tinyurl.com/d3d-pipeline> The Computer Graphics Museum <http://computergraphicsmuseum.org> The Terminals Wiki <http://terminals.classiccmp.org> Legalize Adulthood! (my blog) <http://legalizeadulthood.wordpress.com>

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Re: [boost] GSOC - Boost.SQL and Boost.Thread interest
by Guillaume Nuel 23 Apr '13

23 Apr '13

Hi Vicente ! > if you are interested on one of these projects, please send as soon as possible to this ML a concrete proposal.> If both subject interest you, you can make two proposals. My main choice for Thread is: Thread.Pool (Proposal n°2 on my homepage: http://immortal-pc.info/Boost.html )General idea: ( Syntax highlighting at: http://immortal-pc.info/Boost.html#threadPool_idea ) int f1( const char* i ) { std::cout << i << ':'; // ... return 'f'+1; } int f2( const char* i ) { //... return 'f'+2; } int f3( const char* i ) { //... return 'f'+3; } int f4() { //... return 20+20+2;// 42 Power ! ^^ } int f5() { //... return 'f'+5; } int main() { // I want 5 threads for my job. Boost::Pool bp(5); // Note: A great option would be to use the "main thread" for calculations. (OpenMP like) // With this idea, 5 threads needed => 4 new theads + the main thread // // Another interesting option would be to provide switch between thread and process (fork) // I love Python multiprocessing: // http://docs.python.org/2/library/multiprocessing.html#using-a-pool-of-worke… // Note: Using, C++11 Brace-Initialization => std::initializer_list // Map function will call f1("Data1"), f1("Data2"), ... // >> ONE CALL PER parameter bp.map(f1, {"Data1","Data2","Data3","Data4","Data5","Data6","Data7"} );//!< WAITING function // "apply_async" will call {f1} with the parameter "Test" five times. // >> 1 CALL for f1 ! // >> 1 CALL for f2 ! // >> 1 CALL for f3 ! // >> f1 // f2 // f3 // -> // = paralell bp.apply_async(f1, "Test"); bp.apply_async(f2, "Test"); bp.apply_async(f3, "Test"); bp.execute();//!< WAINTING function // Or maybe a function who provide a result list for each function // Like this: std::array<int> functionsReturns = bp.get_result<int>();//!< WAITING function // And another great things from https://svn.boost.org/svn/boost/sandbox/async/libs/async/doc/html/toward_bo… // Multi-function without parameter // >> 1 CALL for f4 // >> 1 CALL for f5 // >> f4 // f5 // -> // = paralell // NOTE: same as: // bp.apply_async(f4); // bp.apply_async(f5); // bp.execute();//!< WAITING function bp.call_all(f4, f5);//!< WAITING function // Maybe a function who provide a result list for each function // Like this: std::array<int> functionsReturns = bp.get_result<int>(); return 0; } > The link doesn't worksOups. Sorry for the typo. http://immortal-pc.info/Boost.html Do you keep my proposal for Boost.SQL? Best,Guillaume

2 1

GSoC: Student applications can now be submitted
by Boris Schaeling 23 Apr '13

23 Apr '13

Student applications can now be submitted to <https://google-melange.appspot.com/gsoc/homepage/google/gsoc2013>. The deadline is 3 May. Boris

3 3

[iterator] Code/documentation mismatch in iterator_facade
by Gabriel Redner 23 Apr '13

23 Apr '13

Hi folks, I've stumbled upon an issue with iterator_facade. When creating a random access facade, one must implement the distance_to member function in order for std::distance to work. However, it looks like the arguments passed to this method are reversed from what the documentation states. Specifically, the docs [1] say (paraphrased): a.distance_to(b) is equivalent to distance(a, b). However, when I call std::distance(a, b), I find that b.distance_to(a) is invoked in the facade - the mirror image of what the docs say! This is not a problem if just wrapping some other random access iterator, but in my case the calculation of distance is nontrivial and this issue led to a rather tiresome debugging session and the solution (negating before returning from distance_to, knowing that iterator_facade will re-negate my response) is annoying to explain. Should I file a bug? A test case is appended to this message. -Gabe [1] http://www.boost.org/doc/libs/1_53_0/libs/iterator/doc/iterator_facade.html… ==================== #include <boost/iterator/iterator_facade.hpp> #include <vector> #include <iterator> #include <iostream> class vector_iterator : public boost::iterator_facade< vector_iterator, int, boost::random_access_traversal_tag> { public: vector_iterator(char tag, std::vector<int>::iterator it) : _tag(tag), _it(it) {} private: friend class boost::iterator_core_access; int& dereference() const { return *_it; } bool equal(vector_iterator const& other) const { return _it == other._it; } void increment() { ++_it; } void decrement() { --_it; } void advance(int n) { std::advance(_it, n); } std::vector<int>::iterator::difference_type distance_to(const vector_iterator& other) const { std::cerr << _tag << ".distance_to(" << other._tag << ")\n"; std::vector<int>::iterator::difference_type result = std::distance(_it, other._it); std::cerr << "result = " << result << '\n'; return result; } private: const char _tag; std::vector<int>::iterator _it; }; int main() { std::vector<int> v; v.push_back(1); v.push_back(2); vector_iterator a('a', v.begin()); vector_iterator b('b', v.end()); std::cerr << std::distance(a, b) << '\n'; } ====================

2 2

[REVIEW] Boost.Predef
by Joel Falcou 23 Apr '13

23 Apr '13

Hi all, first, I want to apologize for the delay in getting this review results out. Looks like my last email get lost at some point. Anyway, after the initial review of Rene Riviera Boost.Predef, my decision was to Conditionnally Accept Boost.Predef under the request that the comments raised during the review period were addressed. Since then, Rene worked hard on actually making those changes so I now feel confident to announce that Boost.Predef is ACCEPTED as a Boost library. Regards

1 0

GSOC 2013
by Computer Vision 23 Apr '13

23 Apr '13

Hello, I was very busy with my studies, am I late? Are there any free projects left? Kind Regards

3 2

Going forward with Boost.SIMD
by Niall Douglas 23 Apr '13

23 Apr '13

> Unfortunately the concurrency/parallelism group has decided that they do > not want C++ to provide types representing SIMD registers. > I'm afraid I don't quite understand the rationale for such a refusal; > proposing more high-level constructs similar to valarray (or to our own > library NT2) was suggested, but that's obviously a more complex and > limited API, not a basic building block to program portably a specific > processor unit. As much as a refusal can be heartbreaking, trust me when I say that indecision or indifference is worse. The fact they gave you a definite refusal is actually one of the least worst outcomes from an ISO standards proposal, because you can now move on without uncertainty. > Development of Boost.SIMD will still proceed, aiming for integration in > Boost, but standardization appears to be definitely out of the question. > Any feedback of the API presented in the proposal is welcome. > <http://open-std.org/JTC1/SC22/WG21/docs/papers/2013/n3571.pdf> If I were still part of ISO standards, I'd observe the following: 1. GPU and CPU stream computation technologies are still merging. In other words, it's too soon to standardize this technology lest we accidentally break some novel form of new convergence. Happy to reconsider post-C++14. 2. It's hard to standardize current CPU SIMD implementations due to extremely irritating inconsistencies between vendors. For example, a generic straight port of SSE2 to NEON will have awful performance because SSE2 code does a lot of flipping between SIMD and non-SIMD, and because NEON is a coprocessor on ARM that generates poor performance. Another bug bear of mine on NEON is the lack of an equivalent to _mm_movemask_epi8(), which can be emulated in about eight NEON instructions, but in so doing you'll make code which was very speedy on SSE2 pretty slow in most cases on NEON. My point here is you cannot standardize such non-uniform behavior in a universally performant way, because you'll just get lowest common denominator performance across all SIMD implementations which kinda defeats its purpose. If all vendors were like NEON, or like SSE2, then we still have to see how CUDA and OpenCL pan out long run. 3. I am unsure if C++ is the appropriate language for SIMD standardization when perhaps a meta-form of JIT compiled C++ would be much superior (i.e. you supply LLVM bytecode, and it gets delivered to a GPU/CPU/whatever). We'll have those on the table with LLVM-type compilers. In other words, I would vote to wait and see what the market throws up. I appreciate that none of these three rationale are what you want to hear. Still, I hope my observations are useful to you. None of them suggests you shouldn't proceed with Boost.SIMD. Boost has a much wider remit than just as a testing ground for future C++ standard library features. But I suspect that if SIMD ever does get standardized, it won't look like your library or proposal because it will be based on technologies which don't exist yet. Hope that helps, Niall

3 2

[log] Patch: rotating file collector (Was: Boost.Log: Any Comments?)
by Alexander Arhipenko 23 Apr '13

23 Apr '13

Hi, Just to remind the context, I'm pasting content from previous mail thread. On Tuesday 09 April 2013 18:43:05 Alexander Arhipenko wrote: >> ... >> [snip] >> ... >> >> It would be very nice to have rotation feature work the same way as in e.g. >> python logging library or Apache web server: >> * latest file has the name filename.log >> * previous file has the name filename.log.1 or filename.log.YYYY-MM-DD >> AFAIK, it's impossible to achieve in current implementation. >> >> Andrey, what do you think about this? >The library does not provide this behavior out of the box. But the file sink >uses a file collector object to collect rotated files. This collector can be >implemented by the user (it should derive from sinks::file::collector >interface) and it should be possible to implement it the way you describe. >Would you like to submit such implementation? I've added implementation of rotating file collector - the patch against boost log trunk attached. This is not the final version, I'm going at least to finish most of the TODOs. However, it would be nice to receive feedback and questions from library author as well as from people interested in this feature. Andrey, could you please find several minutes to review the attached patch? Also, I would like to discuss following question with you : rotate_file invocation in ~text_file_backend - I would prefer to have this call during text_file_backend construction phase. Regards

1 0

std::optional<T>
by Fernando Cacciola 23 Apr '13

23 Apr '13

Hi People, I'm pleased to announce that thanks to the outstanding effort of Andrzej Krzemienski who wrote the standard papers, and Ville Voutilainen who champion it during the meetings, we now have std::optional<T> in C++14! Cheers -- Fernando Cacciola www.scisoft-consulting.com

11 15

Plugin/Extension : DLL/so loading?
by Mathias Gaunard 23 Apr '13

23 Apr '13

I remember there were a couple of projects (Boost.Plugin or Boost.Extension) to support dynamic loading of a DLL/so plugin in a portable fashion in Boost. What has happened to these, and is there some code I can use somewhere?

3 4

Boost Graph Library: why are `source()`/`target()` non-member functions?
by Max Moroz 22 Apr '13

22 Apr '13

Why is `source()` not a member function of the graph class? (See http://www.boost.org/doc/libs/1_53_0/libs/graph/doc/index.html for description, and boost/graph/adjacency_list.hpp and boost/graph/adjacency_matrix.hpp for implementation.) I thought the reason was that it was a generic algorithm. But it's not. There's no interface (beyond `source()` itself) exposed by an edge descriptor that would allow `source()` to avoid digging into the implementation. If I interpret the code correctly, `source()` reads directly from the internal data structure of the edge descriptor (`detail::edge_base.m_source`), which I am pretty sure is the implementation detail (`m_source`, despite being strangely exposed as a public member, is not the standard interface; otherwise it would have been defined as such, and `source()` would have been entirely redundant.) I think I'm missing something, but what?

2 3

GSOC
by Flórián Deé 22 Apr '13

22 Apr '13

Personal Details: Name: Flórián Deé University: Budapest University of Technology and Economics Major: Engineering Information Technology Degree Program: B.Sc. Email: deeflorian(a)gmail.com Availability: -starting after the exams, best case: June 10, worst case: June 21 -ending on at the 2nd week at the university: Sept. 15 -planned time spent on GSoC: 32 to 56 hours per week, as needed -other factors: two 3-day long trips - would catch up afterwards with extra work Background information: During my B.Sc. studies I'll already have finished all courses that are related to calculus, linear algebra, number theory, combinatorics and digital technology until summer, so in my opinion, all the educational background needed is present with the exception of the Signals and Systems course in next semester, which would cover digital Fourier transforms in detail. I'd gladly make up for this by reading the needed material. As for my programming background, I've fallen in love with C and C++, which now I consider to be my main languages. I'm currently working on a project as an outsider member of the dorm's Coder team (a poker framework for AIs), and I'm also a "consultant" for students with their C/C++ assignments. As a result, I've seen, written and debugged lots of different (admittedly not so enormous) projects with different coding styles. I'm interested in contributing to the Boost Libraries because two of my friends used a quite a lot of them while researching, and their feedback was always positive. The C++11 implementations also sounded nice, so adding to this codebase as a summer project would be an honor. I wanted to do a Solar System simulator during secondary school because I thought that I could calculate the acceleration (and approximate path) of a pen somehow shot near Earth. Then after the first console-based C++ implementation I realized that doubles aren't sufficiently precise to determine if an object is near or inside a planet, so I tried to write a "double double" class - which was too childish to work both code and mathematicalwise. Since then I know that I'd needed a precise mathematical library, and that radix-2 is my best friend when calculating on CPU-s, so I think that this project would be an ideal fit. Rating of knowledge: C++ - 4 C++ Standard Template Library - 4 Boost C++ Libraries - 2 Subversion - 3 Development environments: Eclipse, Visual Studio Documentation tools: Doxygen Project proposal, schedule and milestones: I'd like to work on the Boost.Multiprecision project described on the wiki page. As the description there is more than detailed, I wouldn't like to copy all that text here, but I'd follow the main steps described. I think that the I/O and the +, - operators should be finished, and the multiplication already started by the end of July. The *, / operators should be finished by the end of August at least with the Karatsuba multiplication, interoperable with Boost.Math, and the FFT multiplication should also be started by then. The final goal would be FFT multiplication, with passed correctness tests of wide variety from the beginning of the project.

1 0

shared_ptr ordering
by Matt Bergin 22 Apr '13

22 Apr '13

Back in 2008, changing shared_ptr operator< to compare by pointer value rather than owner was discussed: http://lists.boost.org/Archives/boost/2008/10/143175.php There seem to be convincing arguments for both implementations (aliasing, consistency with equality operator etc). Is boost::shared_ptr intended to be a compliant C++11 std::shared_ptr? If so, will shared_ptr be changed to comply with [util.smartptr.shared.cmp] or is the ensuing breakage too high a price to pay for 100% compliance? Thanks Matt

2 1

[ublas] GSoC 2013 Proposal - uBLAS Math Library and Performance Optimization
by Sathyam Vellal 22 Apr '13

22 Apr '13

Hello everyone. I've been in touch with Mr. David Bellot and Mr. Nasos Iliopoulos and with their guidance and support I've written this proposal for Boost.uBLAS. The proposal can be viewed here -http://goo.gl/Qo7Ry. (This is a link to a google doc; a pdf version of the proposal). Thank you -- Sathyam M Vellal P.E.S. Institute of Technology, Bangalore, india

1 0

[config][mpl][type_traits][integer] BOOST_STATIC_CONSTANT should use constexpr
by Vicente J. Botet Escriba 22 Apr '13

22 Apr '13

Hi, BOOST_STATIC_CONSTANT could be improved to make use of constexpr. This is needed for instance to make integral_constant compliant with C++11. The patch consists in changing const by BOOST_CONSTEXPR_OR_CONST in boost/config/suffix.hpp // BOOST_STATIC_CONSTANT workaround --------------------------------------- // // On compilers which don't allow in-class initialization of static integral // constant members, we must use enums as a workaround if we want the constants // to be available at compile-time. This macro gives us a convenient way to // declare such constants. # ifdef BOOST_NO_INCLASS_MEMBER_INITIALIZATION # define BOOST_STATIC_CONSTANT(type, assignment) enum { assignment } # else # define BOOST_STATIC_CONSTANT(type, assignment) static *BOOST_CONSTEXPR_OR_CONST* type assignment # endif and in each out of line static constant definition as in template <int b1, int b2> bool *BOOST_CONSTEXPR_OR_CONST* ice_eq<b1,b2>::value; The main problem is that this is a *breaking change*: the list of concerned libraries is quite big (mpl, type_traits/integer_traits, ...) and users of BOOST_STATIC_CONSTANT would need to make this modification also. An alternative is to define a BOOST_STATIC_CONSTANT_11 that includes this modification and update the Boost libraries that could make use of the new macro without introducing a breaking change. Library providing a template class containing a field with such a change that can be specialized by the user would need to either announce a breaking change or just don't use the new macro. While this mean more changes the backward compatibility can be mastered. What do you think, it is worth try to fixing this? Best, Vicente

4 17

GSOC - Boost.SQL and Boost.Thread interest
by Guillaume Nuel 22 Apr '13

22 Apr '13

Hi Boost C++ Team ! My name is Guillaume NUEL. I'm a French student in computer security (fourth year in computer science). I'm actually making a game witch uses Boost (Thread, Signal,...). I also use CouchBase for database. I really would like mixing my game development and Boost development. My project proposal Idea : I'm mainly interesting in adding a new module: Boost.SQL for managing database: MySQL, Couchbase, … If the project proposal is not suitable, I have others interests. I would also be interesting in adding new functions to Thread abilities. So I am interested in the following topics : - Boost.Thread/SyncQueue: Provide boost::sync_bounded/unbounded_queue implementations base on the C++ Concurrent Queues proposal. Trying an adaptation of the Boost.LockFree queues to follow the same interface. - Boost.Thread/ThreadPool:Provide a boost::thread_pool class scheduling arbitrary functions based on Toward Boost Async 0.2 and extend the boost::async function to manage with this new class. Projects mentored by Vicente J. Botet Escriba I'm an expert in C++ and I have good skills in OpenMP and Cuda ( GPU ) and so in parallelization of code. Homepage: http://immmortal-pc.info/Boost.html My CV is available at http://immortal-pc.info/cv.html Thank you for taking the time to read my e-mail, I look forward to receive a response from you. With regards, NUEL Guillaume

2 1

GSoC: More mentors?
by Boris Schaeling 22 Apr '13

22 Apr '13

From Monday on students can apply for GSoC projects. Mentors can already apply at <https://google-melange.appspot.com/gsoc/homepage/google/gsoc2013>. So far we have four possible mentors (for uBLAS, odeint, graph and benchmark). Are there others who would like to mentor? Then please pick a project from <https://svn.boost.org/trac/boost/wiki/SoC2013> or propose your own (like I did a few days ago: <http://article.gmane.org/gmane.comp.lib.boost.devel/240251>). Applying as a mentor doesn't mean that you must mentor a student. Among others it all depends on if and how many student applications we will receive. But having a few more mentors just in case would be nice. :) Thank you, Boris

4 6

media > audio project (gsoc or future boost)
by adrien courdavault 22 Apr '13

22 Apr '13

Hi everyone. I read the project list for the GSOC 2013 and in Ideas I've seen the mention of Audio. I would like to know who is interested in this and if someone could give some details about this line : 'Audio library (OpenAL/FMOD/etc)' see here :https://svn.boost.org/trac/boost/wiki/SoC2013#Media I would like to know if this might be related to this: http://comments.gmane.org/gmane.comp.lang.c%2B%2B.isocpp.proposals/310 Thank you in advance. Adrien

6 11

Writing timer output to file
by Mohamed Nemri 22 Apr '13

22 Apr '13

Hi, I want customize boost::timer::auto_cpu_timer to put results in a logging stream(file, console,...). What is the best way to do that? Thanks --

1 0

[GSoC] Boost.Multiprecision project
by Jyotesh Choudhari 22 Apr '13

22 Apr '13

Hello, My name is Jyotesh Choudhari and I am from India. I am pursuing my Masters in Computer Science and Technology from Indian Institute of Technology (IIT) Bombay. I went through the ideas page for GSoc 2013 and would like to work on Boost.Multiprecision (cpp_bin_float) project. Looking at the project description, I think I have understood what needs to be implemented in this project. I have also gone through the current code cpp_bin_float.hpp and I have understood some part of it. I want to know how detailed should my proposal be? What details should I include in my proposal? What should be the deliverables for the project? Thanking you. Regards, Jyotesh Choudhari

2 1

[GSoC] Boost.multiprecision project
by Flórián Deé 22 Apr '13

22 Apr '13

Hello, I'm Florián Deé from Hungary, studying at Budapest University of Technology and Economics. I'm really interested in the Boost.Multiprecision project for GSoC 2013. A little background on myself, I'm an undergraduate software engineering student mostly into C and C++, with interests in low level programming and maths. I'm currently working on a project as an outsider member of the dorm's Coder team (a poker framework for AIs), and I'm also a "consultant" for students with their C/C++/Maths assignments (mostly calculus and linear algebra). As a result, I don't really have much free time till the exams, but I've planned, seen, written and debugged lots of different projects with different coding styles. Going through the project description, I think my skill set and interests would fit in nicely, with the exception of fast Fourier transforms, which I'm only mildly familiar with, but I'd gladly read any needed extra material till summer. So I kindly seek your guidance to help me go about my application for the GSoC 2013. Looking forward to your reply. Regards, Flórián

2 1

[ublas] bugfix for matrix operation /
by Mario Mulansky 22 Apr '13

22 Apr '13

Hi, I wanted to add an elementwise divide operations for ublas matrices using operator / Unfortunately, there is operator/ defined for matrix and integral types which hides any other operator definition (matrix_expression.hpp l. 3388) and thus makes it impossible to add this functionality. I would like to add an enable_if statement there that checks if the second argument is convertible to matrix::value_type, as is done for other operators. Who would be responsible for this small change? I can provide the according patch, it's almost trivial. Mario

4 7

[gsoc-2013] Physics Library Abstraction Layer
by Preston Hamlin 22 Apr '13

22 Apr '13

I am working on putting together a draft proposal for the project. Is there a preferred format desired? I was going to use a PDF since they are quite portable. I am somewhat confused as to the scope of the project, due to the previous posts in this thread. Is the library to be built upon a specific physics library (PhysX for instance) by utilizing existing code in the respective SDK to abstract away much of the object management? Or is it meant to be built from the ground up to create generic objects, which can then be translated into an arbitrary format for an existing library? Thank-you, -Preston

2 3

library to support async/await pattern
by Valentin Milea 21 Apr '13

21 Apr '13

Is there interest for a coroutine-based library to make asynchronous APIs easier to deal with? Typically, for each task there is cruft: chaining callbacks, managing intermediate state and error codes (since exceptions don't fit this model). The code flow get inverted and becomes difficult to follow. Recent versions of F# and C# solve this problem. They implement an await operator that effectively suspends the executing method until a task completes. The compiler takes care of transforming subsequent code into a continuation. Everything runs on the main thread, with asynchronous methods spending most time awaiting. N3328 proposes resumable functions of this kind in C++. For an immediate solution we could leverage the Boost.Context/Coroutine library. The resulting code may look like this: try { task = do_a_async(...) // yield until task done task.await(); } catch (const some_exception& e) { // exceptions arrive in awaiting context } // normal code flow for (auto& task : tasks1) { task.await(); } taskAny = await_any(tasks2); taskAny.await(); ... There needs to be a representation for Awaitable tasks (similar to std::future but non-blocking). The other requirement is to have a Scheduler (run loop) in order to weave between coroutines. Benefits: - normal code flow: plain conditionals, loops, exceptions, RAII - algorithm state tracked on coroutine stack - async tasks are composable - any async API can be wrapped Cons: - must wrap async APIs (e.g. Boost.Asio) - needs std::exception_ptr to dispatch exceptions - stackful coroutines are sometimes difficult to debug I wrote an open-source library that does this: https://github.com/vmilea/CppAwait. It's far from Boost style but the concept looks sane. For a comparison between async patterns please see: https://github.com/vmilea/CppAwait/blob/master/Examples/ex_stockClient.cpp Making a Boost version would involve serious redesign. So is this worth pursuing? Thanks!

5 9

Re: [boost] GSoC: More mentors?
by Christopher Kormanyos 21 Apr '13

21 Apr '13

> From Monday on students can apply for GSoC projects. > Mentors can already apply at > <https://google-melange.appspot.com/gsoc/homepage/google/gsoc2013>. > So far we have four possible mentors (for uBLAS, odeint, > graph and benchmark). Are there others who would like > to mentor? Then please pick a project from > <https://svn.boost.org/trac/boost/wiki/SoC2013> or propose > your own. > Thank you, Boris Hello, Christopher Kormanyos (who is me) just signed up as a potential mentor for the GSoC projects with Boost.Math and Boost.Multiprecision. We have already had contact with some good candidates. Thank you. Sincerely, Chris.

1 0

GSOC - Boost.uBLAS interest
by deck léa 21 Apr '13

21 Apr '13

Hi Boost C++ Team ! My name is Lea Deck, I'm French and I study in fourth year in computer science (security in computer science), but I really like mathematics. So I look for projects that mix the two. I would be interesting in adding new mathematics properties to your uBLAS libraries, like Hadamard, Toeplitz and Block matrices, the generation of matrices, Strassen multiplications and possibly new algorithms. You also alluded to the Bernoulli numbers, but I don't see any mention in the list of new features. Is the project still available? If so, should its implementation also contain the Bernoulli polynomials? About the question of optimisation, I have some skills in Cuda (GPU) and OpenMP and so in parallelization of code. So I am able to produce a correct parallelized code. Also, my knowledge of C++ is beginning to spread to the use of C++11 ( including unordered structure map). One last question, what do you mean by "Pretty display" in your list of new features? My CV is available here <http://dla.immortal-pc.info/>. ( http://dla.immortal-pc.info/) Thank you for taking the time to read my e-mail, and I look forward to receive a response from you. With regards, DECK Léa

1 0

[GSoC 2013] SVN?
by Vicente J. Botet Escriba 21 Apr '13

21 Apr '13

Hi, would all the GSoC projects be stored under SVN? Best, Vicente

3 5

Qustion about GSOC Project
by Hardy Huang 20 Apr '13

20 Apr '13

Hi, there. I am a graduate student in Peking University. I have known Boost library for long. And I used it for several times. This year I wanted to get involved in GSOC, and I was happy when I see Boost in the list, it is my dream and it will be honor to contribute to such a powerful library. Since I am good at algorithm and data structure, knowing that there are some idea projects relative with algorithm and data structure, like radix sort, trie, I want to know something detail about the plan to develop algorithm and data structure. Thanks, I am expecting to receive some useful replies.

4 6

Re: [boost] [config][mpl][type_traits][integer] BOOST_STATIC_CONSTANT should use constexpr
by Vicente J. Botet Escriba 20 Apr '13

20 Apr '13

Le 20/04/13 14:33, Vicente J. Botet Escriba a écrit : > Le 20/04/13 13:18, Antony Polukhin a écrit : >> 2013/4/20 John Maddock<boost.regex(a)virgin.net>: >> <...> >>> No that's correct as is: >>> >>> * if BOOST_NO_INCLASS_MEMBER_INITIALIZATION is defined, then the constant is >>> really an enum and there should be no out-of-line definitions. >>> * if BOOST_NO_INCLASS_MEMBER_INITIALIZATION is *not* defined, then the >>> constant *should* have the out-of-line definition in case it's address is >>> taken/used. >> Oh, now I see, thanks. >> >>> As for the original question, this is such a pervasive breaking change, I >>> think a new macro is inevitable I'm afraid :-( >> New macro will do exactly what the old macro did, but using C++11 >> feature. Code in all Boost libraries will be changed to use new macro. >> So the old macro will be required only for users code that use macro >> and attempts to take address of constant... >> >> To me, it looks less obscuring to have one macro and a note for users >> to use BOOST_CONSTEXPR_OR_CONST for out-of-line definition; than two >> macro (which one shall be used by default?) that do the same thing but >> very slightly differ in details. >> > Just to add some information about some uses > > grep -r BOOST_NO_INCLASS_MEMBER_INITIALIZATION * | wc -l > 113 > grep -r BOOST_STATIC_CONST * | wc -l > 6598 > The figures are a little bit better :) grep -r BOOST_STATIC_CONSTANT * | grep -v svn | wc -l 3030 grep -r BOOST_NO_INCLASS_MEMBER_INITIALIZATION * | grep -v svn | wc -l 57 Best, Vicente

1 0

Trac: Add ref library
by Vicente J. Botet Escriba 20 Apr '13

20 Apr '13

Hi, Boost.Ref is not included as a library on the Trac system. Coul dit be added? Best, Vicente

1 0

[log] Permission to merge to trunk
by Andrey Semashev 20 Apr '13

20 Apr '13

Hi, I'd like to ask for permission to merge Boost.Log v2 to Boost trunk. The library has passed the review back in 2010 and was provisionally accepted [1]. It has been reworked since then, and in a few recent posts I described the changes [2][3]. [1] http://lists.boost.org/boost-announce/2010/03/0256.php [2] http://thread.gmane.org/gmane.comp.lib.boost.devel/237748 [3] http://thread.gmane.org/gmane.comp.lib.boost.devel/239313

16 43

Google Summer of Code - 2013: Boost C++ Libraries
by Ketan Akade 20 Apr '13

20 Apr '13

Hi, I am Ketan Akade, Graduate student at University of Southern California. I am majoring in Computer Science. I went through the project ideas of Boost C++ Libraries, and would like to work on it. I am particularly interested in the *Boost.uBLAS* project idea which is unifying representation of vector and matrices into a unique matrix class. Could you please let me know further details of the same? What steps should I take to start on this? PFA project proposal in which I have mentioned my academic and technical background. Thanks and regards, Ketan Akade Graduate Student, University of Southern California.

1 0

[gsoc 2013] chrono::date
by Anurag Kalia 19 Apr '13

19 Apr '13

I saw the chrono::date library proposal in the ideas page of gsoc 2013. It already seems quite solid and fleshed out; I am confident that I have understood it and can carry it out. Here it is for reference: <http://tinyurl.com/ct4tc3m> I have a few questions though. 1) Is this proposal in its final stages? The Boost chrono library docs mention in appendices that they intend to implement it in later releases. What I want to ask is if I am allowed to propose changes in the library if I want to. For example, the proposal proposes that adding a year to 'Feb 29' (leap year) should result in 'Feb 28 of next year' (non-leap year). I tend to think this is counter-intuitive. The author already gives the excellent idea of using a syntax like "last/february/2013" which also covers the case of anniversaries falling on 'Feb 29' pretty well. Moreover, it is a pretty big assumption that a person would want to celebrate the 'Feb 29' anniversaries on 'Feb 28' and not on 'Mar 1'. Moreover, adding a month to '31 January' results in an invalid date (31 February). Why shouldn't we mirror the behaviour for years? We can just make a library function to cover this issue. In short, am I allowed to propose such changes? 2) How should I apply for gsoc now that I have found my area of interest? What is the last date of application? Shall I post a draft of my application here first for review before submitting it officially? Am I allowed to? 3) I have my final examinations scheduled during three weeks in the coming month of May after which I am totally free to pursue gsoc internship. Though I will use this time to research for design and implementations of other similar libraries, I would still need to channel much time into my examinations. How am I supposed to circumvent this conflict, given that I do have ample time to dedicate to my internship later on? Thanks.Anurag.

2 1

[fusion] [range] Interest in unified functions
by Antony Polukhin 19 Apr '13

19 Apr '13

Hi, I was playing with Boost.Fusion and wrote this simple function: template <class Sequence> std::string stringize(const Sequence& seq) { std::string result; boost::fusion::for_each(seq, stringize_functor(result)); return result; } Which allows to convert many types to strings: boost::fusion::vector<cat, int, std::string> tup1(cat(), 0, "_0"); boost::tuple<cat, int, std::string> tup2(cat(), 0, "_0"); std::pair<cat, cat> cats; std::cout << stringize(tup1) << '\n' << stringize(tup2) << '\n' << stringize(cats) << '\n' But this example fails to convert the following : std::vector<cat> too_many_cats(20); All we need to do to allow conversions, is just add the following: #include <boost/range/algorithm/for_each.hpp> namespace boost { namespace fusion { template <typename Sequence, typename F> inline typename disable_if< traits::is_sequence<Sequence> , void >::type for_each(Sequence const& seq, F const& f) { ::boost::range::for_each(seq, f); } }} So now std::cout << stringize(too_many_cats) << '\n'; works and boost::fusion::for_each may work with any type, runtime length or compile time. We may also make a lot of other algorithms to make no difference between runtime and compile time classes: accumulate, find, find_if, count, all, none, begin, end, advance, distance, dereference, empty and others... The questions are: Is there interest in such features? Is there interest in adopting other algorithms and which ones? To what library shall those methods belong? -- Best regards, Antony Polukhin

1 0

[signals2] Uncombined signal
by Ivan Le Lann 19 Apr '13

19 Apr '13

Hi, I have a project where I use boost::signals2 in the spirit of the "Signal Return Values (Advanced)" section of the tutorial. That is, I have signals roughly equivalent to : boost::signals2::signal<float (), maximum<float> > sig; // slots produce values accumulated by the combiner Problem comes when I want multiple combiners on the same slots. Especially combiners of different types : You need to duplicate signals, and you need your connection setup code to know about used combiners. IMHO, having a basic signal class with no combiner makes sense. Attached is a POC patch to version 1.50, to add to boost::signals2::signal the method : slot_call_range all (BOOST_SIGNALS2_SIGNATURE_FULL_ARGS(BOOST_SIGNALS2_NUM_ARGS)) const (in boost/signals2/detail/signal_template.hpp) >From there, I think one could use any algorithm/accumulator directly on the signal.all() result. Implementation left aside, any feedback on this ? Regards, Ivan

2 4

GSoC project idea: Directory monitor for Boost.Asio (student wanted)
by Boris Schaeling 18 Apr '13

18 Apr '13

Here's another idea for a GSoC project: Turn the directory monitor from <http://www.highscore.de/boost/dir_monitor.zip> into a full-featured Boost.Asio extension. This includes understanding the source code of the existing directory monitor, getting familiar with Boost.Asio internals, enhancing the current interface, implementing the directory monitor on multiple operating systems, writing test cases and a documentation. This is a project which can be completed within a summer. It could be the right project for a student who is interested in Boost.Asio and wants to go through all steps from designing to documenting. Boris

1 0

bug in boost::container ??
by Olaf Peter 18 Apr '13

18 Apr '13

Hi, the attached example confuses me, I've got: $ g++ -Wall boost_container_bug.cpp -o boost_container_bug && ./boost_container_bug (size=4 [1, 2, 3, 4, 0, 4]) $ LANG=en g++ --version g++ (GCC) 4.6.3 20120306 (Red Hat 4.6.3-2) Copyright (C) 2011 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Did I miss something or is it a bug? Thanks, Olaf

6 6

[variant] Multivisitation patch
by Antony Polukhin 18 Apr '13

18 Apr '13

Hi, There is a ticket #8459 that adds boost::apply_visitor for arbitrary amount of arguments. If there will be no objections and comments, I'll commit it to trunk at the end of next week. -- Best regards, Antony Polukhin

2 1

Using both boost 64 and 32 bit on Windows with CMake
by Klaim - Joël Lamotte 18 Apr '13

18 Apr '13

It appear that this mailing list don't accept cross messages so I'm posting a link to a discussion related to both boost and cmake. Basically I'm looking for guidance to help improving development of one application using boost in 64 and 32 bit modes by finding a way to make the FindBoost cmake module find the right binaries depending on either mode. Currently you have to specify an undocumented CMake variable manually to do this. See the full discussion: http://cmake.3232098.n2.nabble.com/boost-b2-Differenciate-32bit-and-64-bit-… Joel Lamotte

5 15

Interested in working on a project for Boost
by Ganesh Prasad 18 Apr '13

18 Apr '13

I am a Student of 2nd Semester, B.Tech in Computer Science and Engineering from National Institute of Technology, Rourkela, India. I am interested in working on a project on “ Developing Data Structures and related algorithms for a generalized Matrix and Vector Class” for the Boost Libraries as a participant of GSoC. I have some experience in working on algorithm development in C++. And I am positive that I have pretty good knowledge in advanced C/C++.I have participated in various coding contests too. Though I am just a student of Second Semester, I can assure you that I'll be working up to the requirements and expectations. But I am new to this GSoC program. I need advice and help to go on with this project. So, requesting advice and help before I start discussing about my project ideas. :) -Ganesh Prasad

2 1

[range] location of numeric algorithms
by Nathan Ridge 18 Apr '13

18 Apr '13

Hi, Is there any reason the numeric algorithms in Boost.Range (accumulate(), inner_product(), etc.) are located in boost/range/numeric.hpp rather than in files named boost/range/algorithm/<algorithm-name>.hpp like every other algorithm? I think it's confusing for users who expect the uniform file naming convention that Boost.Range applies to other algorithms, to apply to these ones too. Thanks, Nate

2 2

[iostreams] Doc errors
by Richard Hadsell 18 Apr '13

18 Apr '13

I'm just starting to read the Boost.Iostreams documentation and found a couple of minor errors. Perhaps someone would like to make these trivial corrections to help other novices in the future. (1) 2.1.4. In the implementation of container_device::write, the block that writes remaining characters at the end of the container ("if (result < n) { ... }") should insert characters from 's + result', not from 's': "container_.insert(container_.end(), s + result, s + n);". (2) 2.1.4. In the implementation of container_device::seek, there are 3 uses of "ios_bas" instead of "ios_base". -- Dick Hadsell 203-992-6320 Fax: 203-992-6001 Reply-to: hadsell(a)blueskystudios.com Blue Sky Studioshttp://www.blueskystudios.com 1 American Lane, Greenwich, CT 06831-2560 Follow Blue Sky Studios on Facebook <http://www.facebook.com/BlueSkyStudios> and Twitter <http://twitter.com/#%21/blueskystudios>

2 1

GOOGLE sUMMER OF CODE
by kashish jajodia 17 Apr '13

17 Apr '13

Dear sir/ma'am, I am really interested in your project(making libraries for C++) mentioned in google summer of code . I am good in algorithm and acquainted well with c++. What else do you require me to know for being a favourable candidate for this project??? & Do you Have any website/blog where I can get to know about the Boost libraries were included in C++11 standard library Thank you Yours kashish Jajodia B.tech computer science and engineering(second year) National Institute of technology , Trichy India

3 2

About
by Hasit Bhatt 17 Apr '13

17 Apr '13

I am 3rd year student of Computer Science and Engineering from Institute Of Technology, Nirma University, Ahmedabad, one of the best Engineering colleges in Gujarat. I was going through GSoC ideas page and, as I like algorithms, I wish to work on algorithms. So, I just wanted to ask, how can I start working on it. ~ Hasit Bhatt

2 1

[gsoc-2013] Boost.uBLAS
by Jignesh Jain 17 Apr '13

17 Apr '13

I am interested in this project for Gsoc, which involves unification of vector and matrix libraries. I have been browsing boost ublas code, but have no idea about how should I begin as I am totally new to Boost. Can Someone please guide me some approach for getting started in this project. Thank you.

2 1

[log] Segfault in "rotating_file" example
by Jason 16 Apr '13

16 Apr '13

I'm working from SVN trunk revision 83923. I've been experiencing segfaults when trying to set up a file sink that has date/time format specifiers in its file name. I thought I was doing something wrong, but I found that the "rotating_file" example also illustrates the same behavior. Here is a sample backtrace: #0 0x000000000077c0b8 in ?? () #1 0x0000000000415d25 in boost::date_time::microsec_clock<boost::posix_time::ptime>::create_time (converter=0x77c0b8) at /code/env/include/boost/date_time/microsec_time_clock.hpp:100 #2 0x00000000004d628b in boost::log::v2s_mt_posix::sinks::(anonymous namespace)::date_and_time_formatter::operator()(std::string const&, unsigned int) const [clone .isra.401] () #3 0x00000000004d639a in boost::log::v2s_mt_posix::aux::light_function<std::string (unsigned int)>::impl<boost::_bi::bind_t<boost::_bi::unspecified, boost::log::v2s_mt_posix::sinks::(anonymous namespace)::date_and_time_formatter, boost::_bi::list2<boost::_bi::bind_t<boost::_bi::unspecified, boost::log::v2s_mt_posix::sinks::(anonymous namespace)::file_counter_formatter, boost::_bi::list2<boost::_bi::value<std::string>, boost::arg<1> > >, boost::arg<1> > > >::invoke_impl(boost::log::v2s_mt_posix::aux::light_function<std::string (unsigned int)>::impl_base*, unsigned int) () #4 0x00000000004d3c90 in boost::log::v2s_mt_posix::sinks::text_file_backend::consume(boost::log::v2s_mt_posix::record_view const&, std::string const&) () #5 0x00000000004206c6 in boost::log::v2s_mt_posix::sinks::basic_formatting_sink_frontend<char>::feed_record<boost::log::v2s_mt_posix::aux::fake_mutex, boost::log::v2s_mt_posix::sinks::text_file_backend> (this=this@entry=0x783600, rec=..., backend_mutex=..., backend=...) at /code/env/include/boost/log/sinks/basic_sink_frontend.hpp:445 #6 0x000000000042082f in boost::log::v2s_mt_posix::sinks::basic_formatting_sink_frontend<char>::try_feed_record<boost::mutex, boost::log::v2s_mt_posix::sinks::text_file_backend> (this=0x783600, rec=..., backend_mutex=..., backend=...) at /code/env/include/boost/log/sinks/basic_sink_frontend.hpp:489 #7 0x00000000004c1475 in boost::log::v2s_mt_posix::core::push_record_move(boost::log::v2s_mt_posix::record&) () #8 0x000000000040dff1 in push_record (this=<optimized out>, rec=...) at /code/env/include/boost/log/core/core.hpp:308 #9 push_record_unlocked (rec=..., this=<optimized out>) at /code/env/include/boost/log/sources/basic_logger.hpp:268 #10 push_record (rec=..., this=<optimized out>) at /code/env/include/boost/log/sources/basic_logger.hpp:582 #11 ~record_pump (this=0x7fffffffddc0, __in_chrg=<optimized out>) at /code/env/include/boost/log/sources/record_ostream.hpp:279 #12 main (argc=<optimized out>, argv=<optimized out>) at main.cpp:84 Looking at the disassembly of where the segfault happens, it seems to have gone off the rails and is executing invalid code. Specifically, the function pointer "converter" inside the date_time::microsec_clock<>:create_time() function seems to be invalid. Any ideas? I'm using gcc 4.7.2 on Ubuntu 12.10. Jason -- View this message in context: http://boost.2283326.n4.nabble.com/log-Segfault-in-rotating-file-example-tp… Sent from the Boost - Dev mailing list archive at Nabble.com.

3 4

[smart_ptr] No more shared_ptr<T>::value_type?
by Andrew Hundt 16 Apr '13

16 Apr '13

I updated from boost 1.52 to 1.53 and it appears that the typedefs have been removed, I couldn't find any mention of it in the release notes, and I searched the list for shared_ptr value_type and saw no mention of the change there. Was this a deliberate change? This breaks a *lot* of code for me, and will make more difficult for me to convince my team to continue to use boost or upgrade in the future because they are very apprehensive of breaking changes. I understand if it has been removed to be C++11 compliant but I expected some warning before breaking changes like this. boost::thread and boost::filesystem are good examples of changes that were made with solid advance notice. This caught me completely by surprise, did I miss something obvious? Could someone point me to the recommended alternative as well? 1.52 has typedef T value_type: http://www.boost.org/doc/libs/1_52_0/boost/smart_ptr/shared_ptr.hpp 1.53 does not: http://www.boost.org/doc/libs/1_53_0/boost/smart_ptr/shared_ptr.hpp Thanks for your help! Cheers! Andrew Hundt

3 3

Windows Binary Builds
by Tom Kent 16 Apr '13

16 Apr '13

A couple months ago some of us got an e-mail from Dave Abrams saying that since BoostPro was going to be shutting down, there wouldn't be anyone maintaining the windows binary installer that they had been offering. Since I have been making windows binaries available on my site for the last several releases [http://boost.teeks99.com] he suggested that I take this over. I currently have a simple zip file (self extracting though) that just grabs all the 32 bit or 64 bit binaries...and they're huge, 6-8GB installed. So going forward I've built a system to make one installer for each tool/architecture: msvc-8.0-32, msvc-9.0-32, msvc-10.0-32, msvc-11.0-32, msvc-8.0-64, msvc-9.0-64, msvc-10.0-64, msvc-11.0-64. In addition to the binaries for that architecture, I would also include the boost release inside the installer. This way it is a single download/single install for everything an end-user developer would need (for each architecture). If a user wants multiple architectures, he/she can run multiple installers and they will instill on top of each other (with seperate lib directories for each set of binaries...for example: boost_1_53_0/lib_32-msvc-8.0 and boost_1_53_0/lib_64-msvc-11.0). All the scripts I use to build these (assume visual studio pro 8.0, 9.0, 10.0, and 11.0) are on my github account at: https://github.com/teeks99/boost-build If you want to see for yourself, I have the 1.53 installers on my website at: http://boost.teeks99.com/bin/boost_1_53_0-msvc-8.0-32.exe http://boost.teeks99.com/bin/boost_1_53_0-msvc-9.0-32.exe http://boost.teeks99.com/bin/boost_1_53_0-msvc-10.0-32.exe http://boost.teeks99.com/bin/boost_1_53_0-msvc-11.0-32.exe http://boost.teeks99.com/bin/boost_1_53_0-msvc-8.0-64.exe http://boost.teeks99.com/bin/boost_1_53_0-msvc-9.0-64.exe http://boost.teeks99.com/bin/boost_1_53_0-msvc-10.0-64.exe http://boost.teeks99.com/bin/boost_1_53_0-msvc-11.0-64.exe If we like this going forward, I'd be happy to upload these to sourceforge for each release, instead of having to go to my site for them. Thoughts? Tom Kent

5 9

Reading uBLAS Documentation
by Yosef Hamza 16 Apr '13

16 Apr '13

i'm little confused here ... should i read the documentation in the same sequence they are written ?(i started that way and i'm having a hard time but still on it) or should i start from (Storage and Special Containers) and down? Thanks in advance!

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Google Summer of Code 2013 - Boost.org - Boost.Multiprecision
by Saurav 16 Apr '13

16 Apr '13

Hi! I am a CS undergraduate student and I really want to work on Boost.Multiprecision<https://svn.boost.org/trac/boost/wiki/SoC2013#Boost.Multiprecision>. C++ has been my favorite programming language and I find GSoC 2013 a wonderful opportunity to create something valuable with it, while getting some 'value' out of it for myself. I like learning new things and trying to find out better ways of doing existing things. I like coding and listening to music (sometimes simultaneously too). Greetings to the entire Boost community. And Thank you! I really appreciate the great work Boost is doing for the rest of us, and I want to be on the other side now, and do something for the rest of them. That's all from my side. I wish to get through to Christopher Kormanyo, the mentor for the project I am interested in, to discuss more specifically about the further steps. Thanking you all once again, Best regards, Saurav

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Re: [boost] What Should we do About Boost.Test?
by legalize+jeeves＠mail.xmission.com 16 Apr '13

16 Apr '13

[Please do not mail me a copy of your followup] Sorry to come late to this party, I usually do not read the developers group on gmane because.... well.... I'm not a boost developer. However, I am a heavy proponent of Boost.Test and a heavy user of it. boost(a)lists.boost.org spake the secret code <m24nmai27z.fsf(a)pluto.luannocracy.com> thusly: >Look, I teach classes on Boost. If Boost.Test is not learnable and >teachable, I have to tell my students to stay away from it. That's >embarrassing for me, and bad for Boost. I wrote the 5-part tutorial on using Boost.Test for TDD: <http://legalizeadulthood.wordpress.com/2009/07/04/c-unit-tests-with-boost-t…> <http://legalizeadulthood.wordpress.com/2009/07/05/c-unit-tests-with-boost-t…> <http://legalizeadulthood.wordpress.com/2009/07/05/c-unit-tests-with-boost-t…> <http://legalizeadulthood.wordpress.com/2009/07/05/c-unit-tests-with-boost-t…> <http://legalizeadulthood.wordpress.com/2009/07/05/c-unit-tests-with-boost-t…> >From the URLs you can see that I wrote those tutorials in the summer of 2009 and it's been one of the most popular articles on my blog. I routinely share them in the C++ newsgroup and in the boost user's gmane newsgroup/list. I wrote them because I thought the documentation made it very difficult to get what you needed from it. At some point after posting this on newsgroups, Gennadiy said he was going to include links to it in the Boost.Test documentation. As far as I know, that never happened. I would be happy to start working on improving the documentation; I always found it to be the weakest part of the library. It works for Gennadiy, but IMO he's too close to the library to see how the documentation doesn't work for newcomers. I've written large technical documents myself (500+ pages on Microsoft's Direct3D which you can read from the link in my signature) and it is difficult to step away from your own expertise and present material in a manner that makes sense to newcomers. I generally recommend people use google mock or some other mocking library in conjunction with Boost.Test. While browsing around in the code I did come across source files mentioning "mocks", but it was so unlike every other approach to mock objects I've seen that I concluded it was only for some sort of internal use to Boost.Test itself. Now I see that it was intended for general use, but even from reading the example source file, I can't say I'd recommend it over google mock or turtle mock from what I understand at this point. Reading this thread, I get the impression that Gennadiy is a little defensive of the library. I guess who wouldn't be, if the thread opened up with a statement to the effect of "let's dump this stuff because it's junk". It is very much the product of one person and maybe that's why it is suffering with so much impedence mismatch with other people's brains. Even though I like Boost.Test, I have gotten mixed signals about contirbutions towards improving it. I asked in the user's group if Gennadiy would accept a patch that would allow me to write my own assertions that supplied file/line information at the point the assertion was invoked instead of at the point the assertion was implemented. I asked on 23 Oct 2012 and didn't get an answer. I asked again a week later and didn't get an answer then, either. This left me without the feeling of "patches are welcome" that boost usually gives me. -- "The Direct3D Graphics Pipeline" free book <http://tinyurl.com/d3d-pipeline> The Computer Graphics Museum <http://computergraphicsmuseum.org> The Terminals Wiki <http://terminals.classiccmp.org> Legalize Adulthood! (my blog) <http://legalizeadulthood.wordpress.com>

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[any] last commit breaks program_options
by Jürgen Hunold 15 Apr '13

15 Apr '13

Hi! It seems that introducing move semantics to Boot.Any in r 83901 breaks compilation of program_options. /home/hunold/src/devel/boost/boost/program_options/variables_map.hpp:58:38: note: no known conversion for argument 1 from ‘boost::program_options::variable_value’ to ‘boost::program_options::variable_value&’ Full build log attached. Any Ideas? Yours, Jürgen -- * Dipl.-Math. Jürgen Hunold ! * voice: ++49 4257 300 ! Fährstraße 1 * fax : ++49 4257 300 ! 31609 Balge/Sebbenhausen * jhunold(a)gmx.eu ! Germany

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GSOC 2013 Parallelized Backend
by Muhammad Junaid Muzammil 15 Apr '13

15 Apr '13

Hello, This is Junaid form National University of Sciences and Technology. I have gone through the GSOC 2013 idea listing. I am pretty much interested in extension of odeint. I am more interested for the parallelization over the GPUs preferably NVIDIA. From the details listed there, it seems that Boost community is more interested in parallelization over the CPUs i.e. much preference is given to OpenMP and MPI. Is that the case here? Regards, Junaid.

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GSOC 2013: Boost.Math Bernoulli Numbers and Applications to Special Functions
by Shubham Gupta 15 Apr '13

15 Apr '13

I am a fourth year Dual Degree (B.Tech+M.Tech) student of Computer Science and Engineering at IIT, Delhi, and would like to express my interest in the project concerned with extending the Boost.Math library to include implementation for Bernoulli numbers. I have read the Wikipedia page for Bernoulli numbers and also some of their applications and definitions. As suggested in the Projects page, I have implemented the Akiyama–Tanigawa algorithm for second Bernoulli numbers and also tested my implementation for the first 10 second Bernoulli numbers using Boost.Test library. Even though I have been using C++ in algorithmic coding competitions for over 2 years, I am still comparatively new to the Boost libraries. I am currently browsing through the capabilities provided by Boost.Math, and also their implementations I would request the concerned mentors and the community to advise me on how to proceed from here, and point out additional things which I can do. -- Shubham Gupta Undergraduate Student Computer Science and Engineering Indian Institute of Technology, Delhi

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[gsoc 2013] What about projects without a mentor?
by Hardy Huang 15 Apr '13

15 Apr '13

Hi! In the boost home page for GSOC 2013, there are some ideas without details and mentors on the bottom of the page, such as some project about algorithms and data structure. Since I am good at algorithm and data structure, knowing that there are some idea projects relative with algorithm and data structure, like radix sort, trie, I want to know something detail about the plan to develop algorithm and data structure. Are these projects involved in gsoc 2013? Can anyone tell me about it, if they were, how can I get more information about them? Thanks very much, I am expecting to receive some useful replies. Best Regards Huang Zhe

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library for uBLabs.. GSOC 2013
by Niranjan Singh 15 Apr '13

15 Apr '13

Hello david, First of all thank you for your kind concern to my proposal. For uBLabs, As I go through the ideas and page, then i see that many challenges are quite interesting projects, and can be done. I would like to work in matrix and vector handling Regarding this here is what I understand and my thought. As its true linear algebra so we have to go as in maths so if we have to multiply two vectors then as it can be represented in matrix (row matrix or column matrix ) form so first of all we have to convert into one form then we have to multiply both the matrix and then convert back to vector form. Simmilarly * can be done with two matrices or one matrix and one vector. For implementing this in c++ we would be needing classes for defining various properties and methods for matrix and vectors. I can be more specific if I know what developments in this have been done, so that we can start with that. with many thanks and regards, Niranjan Singh

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Re: [boost] JSON Parser GSoC 2013
by Stephan Bourgeois 15 Apr '13

15 Apr '13

Michael Marcin wrote: I find the most useful interface is to just provide a datatype you're > expecting and let the json parser try its best to do the right thing. > For example: > string raw_json = R"({ > data:{ > a:"hello", > b:"world", > c:3, > widget:3.5 > } > })"; > [...] > struct my_type5 > { > struct my_data > { > string a; > string b; > int c; > float widget; > } data; > }; > // these should all just work, with maybe a little bit of > // metaprogramming to describe the types to the json library > json::deserialize<my_type5>( json ); I agree. This is, by far, the most intuitive interface. I understand how this can be implemented for data types like map or even Boost.Fusion vector in case of JSON multiple type arrays. However, I have no idea how to implement this in the example above with a struct! Unless of course there is no field name check nor type checking, and the JSON values are just copied sequentially into the struct regardless of field names. Btw I don't even know how to do this without using C++0x extended initializer lists. Otherwise we require some form of reflection in C++. I imagine I should look into Boost.Serialization...? I looked at Boost.Fusion adapt_struct, but that looks quite complicated. Am I missing something? Please let me know what you think. Kind regards, Stephan.

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gsoc project
by Shamsher Siddiqui 14 Apr '13

14 Apr '13

i know c++ well and i like algorithm very much .So I have chosen 1)Algorithms 2)Boost.Chrono/Date I would like to work on this project this summer . I have read https://svn.boost.org/svn/boost/sandbox/chrono_date/libs/date/doc/date.html this plz give me how to start developing. I have completed the Algorithm course in my major and pretty good at it .help me in this project so that i can on this project

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[gsoc 2013] Boost.odeint project
by Artemy Margaritov 14 Apr '13

14 Apr '13

Hello. My name is Artemy Margaritov. I am a third year student of Moscow Institute of Physics and Technology and I'd like to participate in Gsoc this year. I have some questions to start with. 1. Are the parts "Implicit Routines" and "Parallelized Backends" of Boost.odeint project separate tasks? 2. Is it possible for two students to be enrolled in Boost.odeint (one student to "Implicit Routines", another to "Parallelized Backends")? -- Best regards, Artemy Margaritov

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Re: [boost] GSOC 2013
by Antony Polukhin 14 Apr '13

14 Apr '13

2013/4/14 Niranjan Singh <niranjan32331(a)gmail.com>: > Hello sir, > > Sorry for not being clear in my previous message , here I want to propose > you two ideas..which we can work on > > 1. Implementing a graphical interface for problems so that all outputs can > be viewed by user in a good way. Algorithms will be the same like Dijkstra's > , Bellman ford , Kruskul e.t.c as they are already present in BGL. BGL can output to DOT format (the one that is used by graphviz to visualize graphs). Are you going to improve that output or proposing something absolutely different? > 2. Implementing algorithms for Travelling Salesman problem or Chinese > postman problem, Job scheduling or Edge colouring. This sounds interesting. Can you write code using same approaches as in Boost.Graph? See some sources of BGL, get the idea of how it works. > P.S: Actually Sir I have many ideas in my mind, that's why I tell them > whichever be the best or worth full. :)) > > with many thanks > Niranjan Singh See this link https://svn.boost.org/trac/boost/wiki/SoCSubmissionTemplate and fill a proposal. This link may also help https://svn.boost.org/trac/boost/wiki/SoCHints -- Best regards, Antony Polukhin

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[preprocessor] BOOST_PP_OVERLOAD not defined if variadic macros not supported.
by Mostafa 14 Apr '13

14 Apr '13

I just found out the hard way that BOOST_PP_OVERLOAD is "silently" not defined if variadic macros are not supported , ie in c++03. This led to quite a frustrating session of debugging on the premise that there's something wrong with my include paths/environment variables. It would be very nice if BOOST_PP_OVERLOAD errored explicitly if variadic macros were not supported by the compiler, or at lease have a gentle reminder to the reader in BOOST_PP_OVERLOAD documentation (and, where appropriate, in other places) that variadic macros are only standard in c++11 and may not be supported on all compilers, hence one might get a BOOST_PP_OVERLOAD undeclared error. Mostafa

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GSOC 2013 . BOOST GLB
by Niranjan Singh 14 Apr '13

14 Apr '13

@antoshk Hello sir, As I go through the graph library of boost, everything seems to be done like all major algorithms for graphs. That's pretty good however we can use it to implement a structure of methods which deals with problems like Chinese postman problem, Decision making poblem , Project management.,Graph partitioning and clustering , Distribution of Eigen values and compression e.t.c With graph we can solve friend-of-friend problems and also implement a simple command line social network based on c++ with the help of graphs. This would be really interesting. However shortest path algorithms can be implemented from one cutting plane algorithm , and Ant algorithm. It would be better if we can change the input and output display by using graphics so that user gets an interactive output of graph. With these graph techniques and algorithms can be use for calculating polynomials time verification via hamiltonian cycles and NP problems. May be useful in Boost uBLabs. with many thanks and regards Niranjan Singh

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GSOC 2013
by Niranjan Singh 14 Apr '13

14 Apr '13

@antoshk Hello sir, As I go through the graph library of boost, everything seems to be done like all major algorithms for graphs. That's pretty good however we can use it to implement a structure of methods which deals with problems like Chinese postman problem, Decision making poblem , Project management.,Graph partitioning and clustering , Distribution of Eigen values and compression e.t.c With graph we can solve friend-of-friend problems and also implement a simple command line social network based on c++ with the help of graphs. This would be really interesting. However shortest path algorithms can be implemented from one cutting plane algorithm , and Ant algorithm. It would be better if we can change the input and output display by using graphics so that user gets an interactive output of graph. With these graph techniques and algorithms can be use for calculating polynomials time verification via hamiltonian cycles and NP problems. May be useful in Boost uBLabs.

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GSOC 2013
by Niranjan Singh 13 Apr '13

13 Apr '13

Hello, My name is Niranjan , It was really a pleasure seeing a poject like this, and the ideas were also very good. I like to contribute to the vector ,making new matrix class. I would like to propose you my idea as below As *Graph theory* as a subject also and is becoming increasingly significant as it is applied to other areas of mathematics, science and technology. It is being actively used in fields as varied as *biochemistry (genomics), electrical engineering (communication networks and coding theory), computer science (algorithms and computation) and operations research (scheduling).* The powerful *combinatorial methods* found in graph theory have also been used to prove fundamental results in other areas of pure mathematics. And so is becoming an important subject in mathematics and algorithms also. So I was thinking to make a library to implement all the graph functions and its various properties and applications in it so that it can be used by student to understand the concept and it can also be used to solve problems like *Travelling Salesman problem, finding chromatic number, edge colouring. * Finding *shortest path , face colouring* e.t.c. With the help of small functions user can create a program which tackles the big problem. Lots of data-structures can also be implemented. Thanks. P.S. Sir, As my end semester are exams are on .. so its possible that i couldn't reply you fast but I do want to do this project. Exams will over on 30 april.. Thanks for you concern.

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Niranjan Singh has invited you to open a Google mail account
by Niranjan Singh 13 Apr '13

13 Apr '13

I've been using Gmail and thought you might like to try it out. Here's an invitation to create an account. You're Invited to Google Mail! Niranjan Singh has invited you to open a Google Mail account. Google Mail is Google's free email service, built on the idea that email can be intuitive, efficient and fun. Google Mail has: *Less spam* Keep unwanted messages out of your inbox with Google's innovative technology. *Lots of space* Enough storage so that you'll never have to delete another message. *Built-in chat* Text or video chat with Niranjan Singh and other friends in real time. *Mobile access* Get your email anywhere with Google Mail on your mobile phone. You can even import your contacts and email from Yahoo!, Hotmail, AOL or any other web mail or POP accounts. Once you create your account, Niranjan Singh will be notified of your new Google Mail address so you can stay in touch. Learn more<http://mail.google.com/mail/help/intl/en/about.html>or get started<http://mail.google.com/mail/a-b2df9a7699-186fc6feff-CUGUbjU3pJUkhZ0HbL1w6xE…> ! Sign up<http://mail.google.com/mail/a-b2df9a7699-186fc6feff-CUGUbjU3pJUkhZ0HbL1w6xE…> Google Inc. | 1600 Amphitheatre Parkway | Mountain View, California 94043

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JSON Parser GSoC 2013
by Stephan Bourgeois 13 Apr '13

13 Apr '13

Hi everybody, I am studying for an MSc in Computer Science at Oxford Brookes University. I have taken a compiler construction course this year and I am therefore interested in the JSON Parser idea for the Boost library. Open Source JSON parsers have already been implemented in C++ and in Java. Examples of Java libraries are: Gson, quick-json. Even if other libraries already exist, developers who are using Boost for their project will appreciate having a JSON parser within Boost. >From a compiler construction background, writing a JSON parser is not difficult. The JSON grammar is simple and the specification is easy to find. Potential difficulties can exist with robustness of error handling and recovery. The question is what data structure we should use to represent JSON objects, and how the user can access key/value pairs in those objects. (examples: Boost.PropertyTree, pre-existing C++ object, ...) Ideally we should offer validating and non-validating implementations. We should also offer JSON generation as well as parsing. Let me know what you think. Kind regards, Stephan.

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Regarding proposal for GSOC
by Niranjan Singh 12 Apr '13

12 Apr '13

If I have to send my proposal for the poject in GSOC then whom should I mail. This link only or is there some other email. Thanks

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JSON Parser GSoC 2013 (part 2)
by Stephan Bourgeois 12 Apr '13

12 Apr '13

Hi everybody, thank you for all your replies. I will try to summarize my impressions so far: 1. Although there is a solution in Boost.PropertyTree, a majority of users consider it to be incomplete, and quite a few developers are using external libraries at present. 2. As Bjorn Reese pointed out, a solution should offer several different interfaces. Some being already implemented in the protoc library. Michael Marcin suggested that something similar to JsonFX in C# be added to Bjorn's list. 3. There is already a Lexer implementation as part of the tokenizer API in protoc. This is how I imagine I could contribute to the project: 1. Collect requirements for functionality and interfaces. 2. review existing Java, C++, C#, Android library solutions. 3. Write a Parser with error recovery using the Lexer from the protoc library. Or adapt an existing parser if there is a good reason for doing so. 4. review JSON specific issues like type casting and how to deserialize arrays with multiple types. (see posts by Arindam Mukherjee and Michael Marcin on deserialization) 5. With the help of my mentor, implement the different interfaces, preferably in a modular way. (I know an example of this in compiler design using the visitor pattern for code generation) Please don't be offended as I only had the time to have a quick look at a single library. I understand that I need to look at a wider code base from other libraries and familiarize myself with general issues related to JSON and serialization. Bjorn Reese offered to mentor this project, please let us know if someone more "officially involved" with Boost needs to approve this. Please let me know what you think. Stephan

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[gsoc-2013] Physics Library Abstraction Layer
by Preston Hamlin 12 Apr '13

12 Apr '13

Hello, my name is Preston Hamlin and I am a current CS undergraduate at the Florida State University. I was reading over the list of ideas provided and then referenced the source code libraries to get a feel for what was being asked for. I found the prospect of writing an abstraction layer for PhysX or related libraries to be interesting. I am somewhat familiar with THREE.js which is an abstraction of WebGL. In THREE.js there is a heavy amount of abstraction to the degree of providing geometric primitives, particles effect presets, simple materials and basic data structures (matrices, vectors, etc...). Given the platform that THREE.js operates on, such a degree is understandable. How much of the physics library is to be abstracted away in generic structures and functions? I would think that having a few simple primitives (cube, low-poly sphere, etc...) would be required since they are commonly used. However more advanced meshes like a torus might be better produced through using modifiers on said primitives rather than a built-in preset. I think the degree of abstraction is most important for modifiers, and I desire to get a feel for what is being looked for. I assume the end goal is to be able to produce Blender/Unity/3dsMax usable code as well as standalone utilities. Many thanks, -Preston

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Re: [boost] JSON Parser GSoC 2013
by John Venarchick 12 Apr '13

12 Apr '13

> 2013/4/12 Michael Marcin <mike.marcin(a)gmail.com> > >> Arindam Mukherjee wrote: >> >>> In JSON we typically deal with maps and arrays. The arrays themselves >>> could >>> have arbitrary types (string, object, array, numeric, boolean, null) as >>> elements. The key types in the maps are always strings and the value types >>> in the maps could be anything that can appear in an array, including >>> another map or array. >>> >>> Due to this, I'd imagine being able to use Boost.Variant or Boost.Any in a >>> list and as a value_type in a map would help. >>> >>> I have been doing some work with JSON and boost by modifying the current 1.53 ptree. I created a type for use as the data_type of the ptree that represents the various options for JSON data (no value, null value, bool, integer, float, string). It uses boost::variant and visitors. I have it working for my purposes, but would want to make it a little nicer before submitting a patch. I also implemented property_tree::translator_ between to make it work with the spirit classic parser in json_parser_read and json_parser_write. I can post more if anyone is interested. I'm also working a generic way to load arbitrary structures from the created ptree. -John V

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Re: [boost] [gsoc-2013] Physics Library Abstraction Layer
by Preston Hamlin 12 Apr '13

12 Apr '13

Considering that I have received positive feedback on this project, I shall likely make a proposal for it when the time comes. Before then, I would like to pin down the scope and breadth of this library. I am in possession of the PhysX SDK and have been reading it over to come up with some questions to ask so that (should my proposal be accepted) I would not have to be overly concerned later. On the first page of the SDK documentation, it is denoted that several distributable (PhysX) DLLs are required for applications on the Windows platform. Since Boost is a library project, I am unsure what to do with DLL files other than unceremoniously stick them in a Resources folder until the time comes, or have a script built into one of the library files. Perhaps contact Nvidia? I have worked a little with WinAPI, but not in the case of using an SDK. Since this would be a beginning point for the library, might I assume that complex mesh deformations and simulations (e.g. fluid dynamics) are beyond the scope of what should be done over the summer? Certainly one could implement certain models with effort, but I mean that the library will lack explicit methods for something of the following degree: http://www.youtube.com/watch?v=7Who8EpbvCY The same question goes for Multithreading. I will continue to tinker with and read over the SDK(s) and brush up on my matrix arithmetic. For the proposal, should I have a couple concrete classes? Or would pseudocode/feature descriptors suffice? More questions on the way, -Preston

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Fwd: How to start contributing for Boost
by Hasit Bhatt 12 Apr '13

12 Apr '13

I'm 3rd year B.Tech student in Computer Science with quite good proficiency in c,c++ and python. I'm applying for Google Summer Of Code. How should I start?

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Can C++11 INVOKE be defined with C++98 compilers?
by Vicente J. Botet Escriba 12 Apr '13

12 Apr '13

Hi, I would like to implement C++11 INVOKE on C++98 compilers. I have a C++11 implementation on boost/thread/detail/invoke.hpp based on the one of libc++. Could this be done or there is something that can not be done inherently? Best, Vicente

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GSoC 2013: ODE or B-trees?
by Артём Серов 11 Apr '13

11 Apr '13

Hello! My name is Artem Serov. I would like to participate GSoC in Boost and I have a dilemma. I don't have enough information to choose one of two projects in boost: B-trees and Ordinary Differential Equations and want to find out which project matches me better. Before composing a formal application (with all formal requirements) for a project and deeper investigating of the environment i hope to get a piece of advice about my doubts. A few facts: - the 3rd year student of Moscow Institute of Physics and Technology (State University), Russia. - ~1 year exprerience of C/C++ industrial programming in Intel as intern. - no experience in open souce project contribution. Both projects are very challenging and interesting for me. ODE: I had cources of Theory of ODE, Computional Mathematics and Parallel programming (OpenMPI) at the university, so i am familiar with the topic. B-trees: The topic "B-trees" is located in the additional list of ideas for GSoC, so there is no concrete information except the title. Could someone (maybe who have put this in the ideas list) will tell anything: maybe requirements, any thoughts, why is it mentioned in GSoC ideas list, why isn't this idea in a main list or any information like in projects in the main ideas list, please? What would you advise me: to apply for the concrete project from the main list or to develop the project from additional list? What is preferable for the community? Could you give a kind of very brief estimation and comparisson of difficulty of both projects? -- Thanks, Artem Serov

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[Graph] Efficiently finding cycles in a (multi)graph
by Louis Dionne 11 Apr '13

11 Apr '13

Dear Boost, I have implemented the `hawick_circuits` algorithm described in [1] for finding all the elementary circuits of a directed (multi)graph. I implemented it in a generic fashion, planning to propose it for inclusion in Boost. Boost.Graph currently contains the `tiernan_all_cycles` algorithm for finding all the cycles in a graph. However, it is undocumented and it has a time bound (for which no precise analysis is provided) that makes it unsuitable even for moderately sized graphs. In fact, I implemented `hawick_circuits` because `tiernan_all_cycles` did not cut it for my application. My implementation is available at [2]. It is licensed under the Boost license and was tested using the test suite at [3]. I am posting this message for two reasons: 1. To know whether there is interest for such an algorithm in Boost.Graph. 2. To spread the word that this implementation exists for C++, to save people the hassle of reinventing the wheel before Boost.Graph officially provides it. I will create a Trac ticket if there is interest, but note that I won't submit a patch immediately because I am in deep juice with school right now. Regards, Louis Dionne P.S.: More information on the test suite can be found at [4]. [1] http://bit.ly/12LMwIr [2] http://bit.ly/10MSAhW [3] http://bit.ly/YdLHVn [4] http://bit.ly/16SvlW6

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GSoC 2013
by İslam Yaşar 11 Apr '13

11 Apr '13

Hi, I'm a graduate student and work since 2 years as a C++ developer on Unix-like systems (FreeBSD and Linux), i want to implement a library for Boost. It is a thread-safe queue that is implemented on disk. You can use it as a IPC. Is anyone interested to mentor this project ? Thanks Islam Yasar

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Boost.uBLAS for GSoC 2013
by Sathyam Vellal 11 Apr '13

11 Apr '13

Hello. I'm Sathyam Vellal, a 3rd year undergraduate student pursuing Computer Science. I'm interested in contributing to Boost.uBLAS in unifying the vector and matrix representations. I've looked at the docs ( http://www.boost.org/doc/libs/1_53_0/libs/numeric/ublas/doc/index.htm) to get an idea of the library. Does anyone have any suggestions on how I could proceed more and connected to this project? Thank you -- Sathyam M Vellal Computer Science and Engineering, P.E.S. Institute of Technology, Bangalore, India.

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GSoC 2013 : Boost.uBLAS
by Jignesh Jain 11 Apr '13

11 Apr '13

I am interested in this project for Gsoc, which involves unification of vector and matrix libraries. I have been browsing boost ublas code, but have no idea about how should I begin as I am totally new to Boost. Can Someone please guide me some approach for getting started in this project. Thank you.

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Boost.Multiprecision GSoC 2013
by Nikhar Agrawal 10 Apr '13

10 Apr '13

Hi, My name is Nikhar Agrawal. I'm a 2nd year Computer Science student. I'm interested to work for Boost in GSoC and I found the project Boost.Multiprecision really really interesting. Any pointers on how should I go about it? Meanwhile, I'll go through this book:- http://www.loria.fr/~zimmerma/mca/mca-cup-0.5.1.pdf Thanks

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[thread] using Boost.Thread with move-only arguments
by Fernando Pelliccioni 10 Apr '13

10 Apr '13

Hi Vicente, I have an issue with Boost.Thread contructor using move-only type arguments. The "Thread Constructor with arguments" section of the documentation says ... template <class F,class A1,class A2,...> thread(F f,A1 a1,A2 a2,...); Preconditions: F and each An must by copyable or movable. http://www.boost.org/doc/libs/1_53_0/doc/html/thread/thread_management.html… "An" could be copyable or movable, but the following example fails to compile... error: use of deleted function 'A::A(const A&)' //Begin code ------------------------------------ #include <boost/thread.hpp> struct A { A() = default; A( const A& other) = delete; A& operator=( const A& other) = delete; A( A&& other) = default; A& operator=( A&& other) = default; void run() {} }; void f( A a ) { a.run(); } void exec_boost() { A a; boost::thread t( f, std::move(a) ); t.join(); } //End code -------------------------------------- I think we should modify ... template <class F,class A1> thread(F f,A1 a1,typename disable_if<boost::thread_detail::is_convertible<F&,thread_attributes >, dummy* >::type=0): thread_info(make_thread_info(boost::bind(boost::type<void>(),f,a1))) { start_thread(); } ... by ... template <class F,class A1> thread(F&& f,A1&& a1,typename disable_if<boost::thread_detail::is_convertible<F&,thread_attributes >, dummy* >::type=0): thread_info(make_thread_info(boost::bind(boost::type<void>(),f,boost::forward<A1>(a1)))) { start_thread(); } ( In the all family of related ctors in "boost/thread/detail/thread.hpp" ) But, I don't know if boost::bind is forwarding its arguments I think we should modify Boost.Bind to be similar to std::bind. Is there any reason why Bind has not changed so far? Have you found any limitations? If Bind can not be changed, I think Boost.Thread should use some other tool similar to Bind to make forwarding parameters. GCC Libstdc++ use a Bind-lite tool for std::thread. I can work on this if you want. What do you think? Environment: Windows 7 64bits MinGW - GCC 4.7.2 MSVC 2010 MSVC 2012 Boost 1.53.0 Non-Variadic template code branch Regards, Fernando Pelliccioni

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Re: [boost] GSoC 2013 : Implementing Dynamic Programming Algorithms
by Aman Gupta 09 Apr '13

09 Apr '13

Hi, Thanks for the reply. The first thing I want to implement is a Integer-Knapsack problem which takes in a precision error(i.e. an epsilon which is a indicator of the allowed error in the input) The input parameters are Weights, Values and the error. The first thing to do is massage the values according to the error (e.g. if the value is ~10^4 divide it down to ~10^3 according to the error) then run the a dynamic programming algorithm, which has a running time of O(n^3/e) (n : number of items, e :error) Hence, an arbitrarily close approximation is possible with a running time trade-off. Also, a vanilla variety of the knapsack problems(with small instances) which gives the optimal solution can also be implemented. I also want to implement the assignment problem, which also arises in a lot of situations in real life ( http://en.wikipedia.org/wiki/Assignment_problem) using the Hungarian Algorithm. I realize this requires effort but I'm really interested in adding a feature to the boost library. Regards, Aman Gupta

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GSoC 2013 - Boost registration?
by Paul A. Bristow 09 Apr '13

09 Apr '13

http://www.google-melange.com/gsoc/events/google/gsoc2013 March 18: 19:00 UTC Mentoring organizations can begin submitting applications to Google. March 29: 19:00 UTC Mentoring organization application deadline. Just checking that Boost has/is registering? Paul --- Paul A. Bristow, Prizet Farmhouse, Kendal LA8 8AB UK +44 1539 561830 07714330204 pbristow(a)hetp.u-net.com

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GSoC 2013 : Implementing Dynamic Programming Algorithms
by Aman Gupta 09 Apr '13

09 Apr '13

Hi, I am Aman Gupta from BITS-Pilani India, I am a 4th year Undergraduate Student majoring in Computer Science. I've noticed that boost does not contain dynamic programming algorithms like Integer-Knapsack, Longest Common Sub-sequence. I was thinking that implementing this would be a good project. I realize most of these problems are non-polynomial in complexity but I was thinking implementing them to a certain size will not be problem. Also, since some of the dynamic programming algorithms have alternate greedy algorithms which compromise on correctness but are faster, implementing those can be useful. The knapsack problem(which comes in a lot of situations) for which there exists an algorithm which gives an arbitrarily close approximation to the optimal value can be implemented. ( e.g. f(weights,values,error) could be the function, the user has a trade-off between error and computation time). I think it could be useful in situations where the user just decides the error he wants or perhaps how fast he wants his computation. Please let me know if this seems like a valid project idea to you! Thanks, Aman Gupta

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[move] move's is_convertible does not compile with aligned data
by Tobias Loew 09 Apr '13

09 Apr '13

The implementation of move's is_convertible-type has the same problems on MSVC with aligned types as reported for type_trait's is_convertibale in Ticket #5271 https://svn.boost.org/trac/boost/ticket/5271 As type_trait's implementation has been fixed, a simple solution would be letting the user (and not the code in move.hpp:41) [not] define BOOST_MOVE_AVOID_BOOST_DEPENDENCIES regards Tobias -- View this message in context: http://boost.2283326.n4.nabble.com/move-move-s-is-convertible-does-not-comp… Sent from the Boost - Dev mailing list archive at Nabble.com.

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boost/thread.hpp UBICOM processor
by Aswin Paranji 09 Apr '13

09 Apr '13

Hi, I'm trying to compile boost library 1.53 using the ubicom toolchain provided by our embedded partner. During compilation of the boost library there was a linker error (_sync_fetch_add). This was overcome by adding define statement BOOST_SP_USE_PTHREADS, along with FENCED in user-config.hpp. The application was linked properly. Running the application within the embedded box exits with a segmentation fault happening before printing the first line of the main function. This was narrowed down to boost/thread.hpp header. Removing the header allows the application to print the first line and return. The problem I have is, I do not have GDB/GDBServer to assist me. Also, i could not use back_trace as the toolchain does not have the necessary header files. Can anyone tell me what might be causing the problem. I'm sure there is some sort of conflict between the processor architecture with thread or the toolchain which was used to compile boost. The GCC version is 4.4.1 Appreciate if someone can help me on this. Thanks, Aswin Paranji

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[phoenix] doesn't compile with gcc 4.9 snapshot
by Nathan Ridge 08 Apr '13

08 Apr '13

Hi, I'm trying to compile some code that uses Boost with a GCC 4.9 snapshot, but something seems to be going badly wrong. Something as simple as a file containing the include: #include <boost/phoenix/core.hpp> fails to compile, with the following errors: In file included from boost/proto/matches.hpp:42:0, from boost/phoenix/core/domain.hpp:12, from boost/phoenix/core/actor.hpp:17, from boost/phoenix/core.hpp:15, from test.cpp:1: boost/proto/traits.hpp: In instantiation of 'struct boost::proto::tag_of<boost::proto::_>': boost/phoenix/core/domain.hpp:25:18: required from here boost/proto/traits.hpp:241:42: error: no type named 'proto_tag' in 'struct boost::proto::_' typedef typename Expr::proto_tag type; ^ In file included from boost/phoenix/core/argument.hpp:15:0, from boost/phoenix/core.hpp:17, from test.cpp:1: boost/phoenix/core/terminal.hpp: In instantiation of 'struct boost::phoenix::detail::placeholder_idx<boost::proto::make<boost::is_placeholder<boost::proto::_value>()> >': boost/phoenix/core/terminal.hpp:122:18: required from here boost/phoenix/core/terminal.hpp:115:16: error: 'value' is not a member of 'boost::proto::make<boost::is_placeholder<boost::proto::_value>()>' struct placeholder_idx ^ The exact same code compiles fine with GCC 4.8 and earlier. Any ideas as to what might be going wrong? Thanks, Nate

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Boost.Graph for GSoC
by Daniel Mitchell 08 Apr '13

08 Apr '13

Hi all, I'm a researcher and graduate student at the University of Texas at Austin and I'm interested in doing a Boost.Graph project for GSoC. I was thinking of doing one or more planar graph algorithms, in particular the multiple source shortest paths algorithm for planar graphs described at http://courses.csail.mit.edu/6.889/fall11/lectures/L11.html The algorithm assumes that the sources are located on a single face. It proceeds by calculating the shortest paths tree from one source and then minimally modifying the tree to efficiently get the shortest paths from the other sources. The algorithm uses a dynamic tree data structure, so developing that data structure would be part of the project too. I've made prior contributions to BGL. I worked with Doug Gregor to implement color maps for the breadth first and Dijkstra's algorithms. One of my current areas of research is movement ecology, where planar graphs can be used to study movement. Let me know what you think. Daniel Mitchell

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[container] stable_vector::back() is broken in Boost 1.53
by Klaim - Joël Lamotte 08 Apr '13

08 Apr '13

Tested on both VS2010 and VS2012, boost 1.53, with default boost no option set: ############ #include <boost/container/stable_vector.hpp> #include <iostream> int main() { boost::container::stable_vector< int > values; values.emplace_back( 42 ); int& bad_value = values.back(); // bad address int& good_value = values.front(); int& also_good_value = values.at(0); // imply values[0] std::cout<< " ADDRESS OF BAD VALUE : " << &bad_value << std::endl; std::cout<< " ADDRESS OF GOOD VALUE : " << &good_value << std::endl; std::cout<< " ADDRESS OF ALSO GOOD VALUE : " << &also_good_value << std::endl; } ############ This code displays addresses of the bad_value object very low on Debug and very high on Release. I believe that .back() is broken. However, when I test there : http://liveworkspace.org/code/3F11CK$2 it seems to work with any available compiler. So either it's LiveWorkspace which use an older boost version, or this issue arise only on VC. I made a ticket: https://svn.boost.org/trac/boost/ticket/8412 Joel Lamotte

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GSoC 2013: Boost is a mentoring organization
by Boris Schaeling 08 Apr '13

08 Apr '13

Boost is a mentoring organization in this year's GSoC program. Thanks to everyone who added proposals to <https://svn.boost.org/trac/boost/wiki/SoC2013> and to Google for inviting us! According to the GSoC calendar at <https://google-melange.appspot.com/gsoc/events/google/gsoc2013> we have now two weeks where would-be student participants discuss application ideas. If you are interested in participating in the program - either as a student or as a mentor - get active now! :) 1) Have a look at our ideas list at <https://svn.boost.org/trac/boost/wiki/SoC2013>. Find something which interests you or think of a brand new project. 2) Send a mail to the mailing list at <mailto:boost@lists.boost.org> to let people know what you are interested in and what you have to offer. 3) Discuss your idea with others and try to turn it into an actual GSoC project. You need at least a project description, a goal, a mentor and a student. :) Boris

1 0

Adding some image libs to boost build
by Christian Henning 08 Apr '13

08 Apr '13

I have added jpeg, png, and tiff jam files to boost trunk. These files will be needed by gil::io tests. There are still some remaining issues which I like to discuss in this thread: 1. building these libs sometimes requires renaming header and/or source files to the correct architecture. Should we leave that up to the user or should bjam take care of it. And if so, how will we configure that. One example is jpeg: see jconfig.vc -> jconfig.h 2. Tiff has a file nmake.opt which is included in the makefile. How will we include all those options? Regards, Christian

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Release milestone.
by Vicente J. Botet Escriba 08 Apr '13

08 Apr '13

Hi, I would like to merge some fixes in Boost.Thread, but I suspect that the release branche should be blocked as for https://svn.boost.org/trac/boost/wiki/ReleaseSchedule. On which stage (milestone) is the release process? Best, Vicente

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[gil] numeric extension, arithmetic operators
by Harg Tholan 08 Apr '13

08 Apr '13

Hey, Do we plan to overload arithmetic operators for Pixel as wrappers of the numeric extension? or should users derive a class from Pixel adding such functionality? ATM, for diving two pixels (rgb_8 for example), I have to call the division this way: pix_r = pixel_divide_t<rgb_8_pixel_t, rgb_8_pixel_t, rgb_8_pixel_t>().operator()(pix2, pix1); The thing is that I have a template class that makes use of operator/ at some point on one of the template parameters, and I would like to be able to use it with 'Pixel' type. Thank you!

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Re: [boost] future<>::then() Error returning future<void> (on trunk)
by Vicente J. Botet Escriba 07 Apr '13

07 Apr '13

Le 22/01/13 22:56, Vicente Botet a écrit : > Fernando Pelliccioni wrote >> Hi Vicente, hi all, >> >> I noticed that in the trunk there is a implementation of >> future<>::then(). >> Thank you very much for your efforts to implement it! > Hi Fernando, > > I have started with a restricted implementation. While trying to cover with > the whole requirements I didn't reach to get correct implementation. This is > way this new feature is not delivered yet. For the time been I don't think > the current implementation is ready for production code. > > >> The following example, compiles OK >> >> boost::future >> <int> >> f1 = boost::async([]() { return 123; }); >> f1.then([](boost::future >> <int> >> const& f) { >> return std::string(""); >> }); >> >> >> But this one fails to compile: >> boost::future >> <int> >> f1 = boost::async([]() { return 123; }); >> f1.then([](boost::future >> <int> >> const& f) { >> }); >> >> Here future<>::then() have to returns future >> <void> >> like ... >> >> boost::async([]() { }); >> >> Am I right? > Yes, it should. I have no access to my development environment for this > week. Could you post the compiler error? > > >> On the other hand, have you taken into account the following paper? >> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3451.pdf > I read it and the mail exchanges related to this paper. > Currently I didn't reached to make it working at all when the future > destructor blocks, but I'm not sure this is the hidden problem as I have > also other issues when the future destructor doesn't blocks. > > I'm really sorry that the current state is not really usable :( > Hi Fernando, I have reworked the future::then function, and even if it is not yet complete (e.g. deferred is not implemented for c++98 compilers) it start to be usable for c++11 compilers, even if BOOST_THREAD_DONT_PROVIDE_FUTURE_INVALID_AFTER_GET is not defined. BTW, joining on the async future destructor works also. Please could you give it a try and let me know whatever you can find that doesn't works as you expect, Best, Vicente

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C++11 and compilers not supported by vendors any more
by Antony Polukhin 06 Apr '13

06 Apr '13

Hi, I've got an almost ready patch for Boost.Any, that adds rvalues support to it via Boost.Move. But the trouble is following: Current version of patch may (and would) break compilation on ancient compilers, like MSVC6, BCC 5.5 and g++ 2.95. It can be tuned, to work even on those platforms, but: * I have no access to those antiquities, so it is impossible to run tests * It will take huge amount of time, to make it work What is the current policy in such situations (may ancient compilers support be dropped)? -- Best regards, Antony Polukhin

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Re: [boost] Review managers wanted for augmented data structures
by James Hirschorn 06 Apr '13

06 Apr '13

Vadim Stadnik wrote > Hi all, > > > At present, neither Boost library nor STL provides containers using > augmented data structures. I suggest that the Boost community consider > solving the challenging problem – how to extend STL by integrating > advanced > data structures. > > ... > > Augmented trees are non-standard due to different performance guarantees. > At the same these data structures are beneficial for complex algorithms, > since they offer a wider set of more efficient operations compared to > standard containers. The typical performance improvement for one operation > is O(log N) against O(N). For less efficient operations these trees > normally provide running time O(log N) against O(1), which is good enough > for many applications. This is very similar to a project I have been working on, with the intention of submitting to boost. The new data structure I have implemented is called a skip list. They can be used in place of balanced trees, and according to the inventor, insertion and deletion are significantly faster than for balanced trees (I have not tested this yet). See, e.g. William Pugh. 1990. Skip lists: a probabilistic alternative to balanced trees. Commun. ACM 33, 6 (June 1990), 668-676. DOI=10.1145/78973.78977 http://doi.acm.org/10.1145/78973.78977 The difference in performance guarantees are much more subtle than you describe above. For example, skip lists have expected O(log n) insert, delete and search, versus O(log n). In practice, the expected O(log n) time is just as good as true O(log n), unless a performance bound is required with certainty, because the probability of the skip list having height much larger than log n is extremely low. I also implemented what I called augmented skip lists, which allow for expected O(log n) rank lookup (i.e. random access). I wasn't aware of the counter tree library, or else I would probably have just used it instead of implementing skip lists. I used skip lists to provide "drop in" STL replacements. Now I have skip_list::set and skip_list::multiset, and I could similarly make skip_list::map and skip_list::multimap. There is also augmented_skip_list::set and augmented_skip_list::multiset. For now the augmented versions have an additional member function nth_element providing E[O(log n)] random access. Hopefully, this will be helpful towards the goals you have described. > There are two libraries in the Boost review schedule: > > http://www.boost.org/community/review_schedule.html > > "STL Extensions" and "Countertree". None of them has as yet a review > manager. The order of the reviews may not be significant. It is more > important that at least one library pass the review. This would help > integrating other advanced data structures. > > > Are there Boost experts who could volunteer to take responsibility of > review manager for any of these two libraries? Data structures are very interesting to me, and I am in between jobs, so I have time to review one of these. If I take the time to review, I hope someone will be willing to review my skip list library, if I complete it and submit it to boost. -- View this message in context: http://boost.2283326.n4.nabble.com/Review-managers-wanted-for-augmented-dat… Sent from the Boost - Dev mailing list archive at Nabble.com.

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[any] C++11 support
by Antony Polukhin 06 Apr '13

06 Apr '13

Hi, There is a patch for Boost.Any, that adds rvalue references support (via Boost.Move) and noexcepts (see ticket #6999 any.patch). It also includes a set of tests, and they pass well. Previous maintainers of the library are away for a long time, so if there will be no objections till the end of next weekend, I'll apply the patch. -- Best regards, Antony Polukhin

1 0

Scope Tracer or General Scope Function with parameter or variable values
by Anlin Zhang 06 Apr '13

06 Apr '13

Hi, I'm wondering if a "Scope Tracer" or a "General Scope Function" can be easily implemented with existing boost libraries now. One example use case is to log variable or parameter values or any program state when entering or leaving a scope, but it can do more than just logging, it can, for example, lock/unlock mutex, or prepare/teardown test cases, etc. For logging requirement, to give you an idea, the expected log message looks like this: >04/10/09 05:29:12:210257 entering func foo with parameter a=10, b=1.5, d.x=10, d.y=[string], global d=2, filename:test.cpp>04/10/09 05:29:12:210257 entering while() a=10, b=1.5, d.x=10>04/10/09 05:29:12:210257 leaving while() a=9, b=1.5, d.x=9>04/10/09 05:29:12:210257 entering while() a=9, b=1.5, d.x=9>04/10/09 05:29:12:210257 leaving while() a=8, b=1.5, d.x=8>...>04/10/09 05:29:12:210257 entering while() a=2, b=1.5, d.x=2>04/10/09 05:29:12:210257 leaving while() a=1, b=1.5, d.x=1>04/10/09 05:29:12:210257 entering while() a=1, b=1.5, d.x=1>04/10/09 05:29:12:210257 leaving while() a=0, b=1.5, d.x=0>04/10/09 05:29:12:210257 leaving function foo with parameter a=0, b=1.5, d.x=0, d.y=[string], global d=2, filename:test.cpp It does not have to be logging, it can do any general processing when entering/leaving a scope. I implemented a small library to do so in 2008 mainly for tracing, it worked fine for me and I never revisited it again until recently. Wondering if boost has libraries to support such a requirment. My implementation has a template class logger_class which can manage the log-level at runtime and send the log message to standard-output or other places. Application code use a macro to invoke the library, the macro can be disabled at compile time, or weakened to only log scope without variables. Example of the macro definition: #ifdef ENABLE_ONLY_SCOPE_TRACER #define SCOPE_TRACER(logger_class, logger, args, level, scope) \ scope_tracer<logger_class> tracer_obj(logger, __FUNCTION__, __FILE__, __LINE__); \ if (logger.get_level() >= level){ \ tracer_obj.init(level, scope).noMore(); \ } #else #ifdef DISABLE_SCOPE_VAR_TRACER #define SCOPE_TRACER(logger_class, logger, args, level, scope) #else #define SCOPE_TRACER(logger_class, logger, args, level, scope) \ scope_tracer<loggerClass> tracer_obj(logger, __FUNCTION__, __FILE__, __LINE__); \ if (logger.get_level() >= level){ \ tracer_obj.init(level, scope) << args; \ tracer_obj.noMore(); \ } #endif#endif Application code example: int globalVar; void MyClass::func1( A a, B&b, C* c, int d, std::string & s){ SCOPE_TRACER(MyLogger, test_logger, a<<b<<c<<d<<s<<globalVar, LOG_LEVEL_TRACE, "func1"); ... int localVar; while(x){ SCOPE_TRACER(MyLogger, test_logger, x<<a<<b<<c<<d<<s<<globalVar<<localVar, LOG_LEVEL_TRACE, "while(x)"); ... } ... } As you see, "<<" operator is being used. But it does not have to be only "<<" operator. Basically any C++ operator can be supported between the logger class and logged type. And the logger_class is not limited to just do tracing, it can virtuall do anything. I can attach the code if needed. The code was compiled with GCC on linux and VisualStudio on Windows. If the above functionality can be easily achieved using existing boot library, please advise how. Otherwise is it worth to request such a feature in boost? Thanks,Anlin

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Regression tests crashing
by Tom Kent 03 Apr '13

03 Apr '13

Sometime yesterday most of the regression tests that I run (not the incremental ones?) started crashing and not sending any results. The screen output is the general error: "No such file or directory: '/home/tomkent/teeks99-02/a/results/boost/bin.v2/libs/any/test/any_test.test'" Looking at the tail of the results/bjam.log file shows this: error: at /home/tomkent/teeks99-02/a/tools_bb/kernel/modules.jam:107 error: Unable to find file or target named error: 'has_float128.cpp' error: referred to from project at error: '../libs/multiprecision/config' That was on Ubuntu 12.04, running the gcc-4.6 tests, but the others (including windows) have the same error. I don't believe anything else changed on the machines that were running the regression tests. You can still see the previous results on the regression results page. Tom Kent

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[utility]result_of - erroneous result type from a C++11 lambda
by Vicente J. Botet Escriba 03 Apr '13

03 Apr '13

Hi, I've started to use C++11 lambda functions with Boost.Thread. The following works with clang-3.2 boost::future<int> f1 = boost::async( []() -> int {return 123;} ); But it fails with gcc-4.6.2, 4.7.2 and 4.8.0 ../example/lambda_future.cpp:25:91: erreur: conversion from ‘boost::future<void>’ to non-scalar type ‘boost::future<int>’ requested boost::future<int> f1 = boost::async( []() -> int {return 123;} ); The current implementation of boost::async uses boost::result_of to get the result type of the callable parameter. Is this a know bug on boost::result_of or gcc compiler? Best, Vicente

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generate algorithm
by Fabian Bösch 02 Apr '13

02 Apr '13

Dear Boost community I am developing a library which extends the STL generate algorithm. It's aim is to improve performance for highly optimized (e.g. vectorized) generation mechanisms while it retains the same interface. This is especially useful when dealing with random number generation as there are several libraries (e.g. Intel MKL or AMD ACML) which provide means to generate a block of random values at once. However, the current STL generate algorithm is not able to cope with such "range generation". Is there any interest in a such a library for Boost? Cheers, Fabian Bösch

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[boost.lockfree] Lockfree on Windows?
by Philip Bennefall 02 Apr '13

02 Apr '13

Hello, I am in need of a lock free fifo for my current project so I looked into lockfree. However, in the documentation I see: boost.lockfree has been tested on the following platforms: a.. g++ 4.4, 4.5 and 4.6, linux, x86 & x86_64 b.. clang++ 3.0, linux, x86 & x86_64 My question is what the status is on Windows? The documentation for boost.atomic says that Windows has been tested, so is there a reason why lockfree might have platform specific issues? When I run the example provided for the single producer/single consumer queue, I get the expected results so it does seem to work. It also states that the queue is lock free. Is it safe to use on Windows at present? Thanks in advance for any information. Kind regards, Philip Bennefall

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[extension] library under construction status
by Lorenzo Caminiti 02 Apr '13

02 Apr '13

Hello all, What's the status of Jeremy Pack's library under construction Boost.Extension? P.S. I read the docs and I have a couple of comments: 1. shared_library as RAII Why isn't shared_library an RAII object? If there's a good reason for that, a RAII object should also be provided scoped_library that will open at construction and automatically close at destruction. 2. get should use function type syntax get<result_type, arg1_type, arg2_type, ...> should be changed to get<result_type (arg1_type, arg2_type, ...)> 3. type_map purpose/name The introduction of type_map seems arbitrary... some rationale needs to be provided as soon as it's introduced in Tutorial 2. Is there a better name than type_map? That name tells me little about what it is.. maybe, factory_map given that it's a map strings to factories? 4. call(type_map) lib.call(type_map) the name call is too generic, it should be changed to set or even better get_factories: type_map types; if(!lib.call(types)) ... Changed to: factory_map factories; if(!lib.get_factories(factories)) ... 5. type_map doesn't allow for multiple constructors type_map doesn't allow for derived classes to have constructors with different signatures than the base class. It also doesn't allow for classes (derived or base) to have multiple constructors. In any case, the syntax should use member function types, changing the current syntax: std::map<std::string, factory<animal, int> >... to: std::map<std::string, factory<void (*::animal)(int)> 6. I didn't understand parameter_map purpose, usage, etc :( Thanks. --Lorenzo

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Building ThreadPool with boost::function in boost::lockfree::queue
by Ryan Fogarty 01 Apr '13

01 Apr '13

I am having trouble typedef-ing a lockfree::queue with boost::function as the element for a ThreadPool class I am writing. TestJobQueue1 below compiles fine while TestJobQueue2 compile fails. I am using gcc 4.7.2 and boost_1_53_0. void doSomething() { std::cout << "Called doSomething\n"; } typedef boost::function<void ()> FunctionType; class TestJobQueue1 { public: typedef std::vector<FunctionType> FunctionArray; TestJobQueue1() { std::cout << sizeof(FunctionType) << std::endl; FunctionType f(&doSomething); FunctionArray funcArray; funcArray.push_back(f); std::cout << funcArray.size() << std::endl; } }; class TestJobQueue2 { public: typedef boost::lockfree::queue<FunctionType> QueueType; TestJobQueue2() { std::cout << sizeof(FunctionType) << std::endl; FunctionType f(&doSomething); QueueType funcQueue; funcQueue.push(f); } }; >> g++ -c -I/usr/local/boost_1_53_0/include TestFunctionCompleteness.cpp produces: In file included from TestFunctionCompleteness.cpp:11:0: /usr/local/boost_1_53_0/include/boost/lockfree/queue.hpp: In instantiation of ‘class boost::lockfree::queue<boost::function<void()> >’: TestFunctionCompleteness.cpp:42:17: required from here /usr/local/boost_1_53_0/include/boost/lockfree/queue.hpp:79:1: error: invalid application of ‘sizeof’ to incomplete type ‘boost::STATIC_ASSERTION_FAILURE<false>’ /usr/local/boost_1_53_0/include/boost/lockfree/queue.hpp:83:1: error: invalid application of ‘sizeof’ to incomplete type ‘boost::STATIC_ASSERTION_FAILURE<false>’ >> g++ -c --std=c++0x -I/usr/local/boost_1_53_0/include TestFunctionCompleteness.cpp produces: In file included from TestFunctionCompleteness.cpp:11:0: /usr/local/boost_1_53_0/include/boost/lockfree/queue.hpp: In instantiation of ‘class boost::lockfree::queue<boost::function<void()> >’: TestFunctionCompleteness.cpp:42:17: required from here /usr/local/boost_1_53_0/include/boost/lockfree/queue.hpp:79:5: error: static assertion failed: (boost::has_trivial_destructor<T>::value) /usr/local/boost_1_53_0/include/boost/lockfree/queue.hpp:83:5: error: static assertion failed: (boost::has_trivial_assign<T>::value) Is boost::function somehow an incomplete type and not expected to work in boost::lockfree::queue or is this a bug in the queue implementation? Can anyone suggest a simple workaround? Thank you, Ryan Fogarty

2 3

traits classes vs. metafunctions
by Stefan Strasser 01 Apr '13

01 Apr '13

Hi everyone, are there any guidelines for boost libraries on when to use traits classes and when to use a metafunction for each member of a would-be traits class? I've seen both in boost libraries. c++11 uses traits classes (iterator_traits, pointer traits, ...), but Abrahams and Gurtovoy [1] argue that traits classes ("traits blobs") should be avoided "at all costs" because they are an unnecessary concatenation of multiple metafunctions into one metafunction with multiple return values. in practice, this means that if a single 'traits class member' aka 'metafunction result' ought to differ from the defaults, the entire traits class has to be reimplemented by the user, not only the metafunction whose result ought to differ from the default. on the other hand, asking a user to implement 5 or more metafunctions is much more tedious than implementing a traits class. possibility 1) template<...> struct property1 : mpl::bool_<...>{}; template<...> struct property2 : mpl::bool_<...>{}; template<...> struct property3 : mpl::bool_<...>{}; 2) template<...> struct ..._traits{ typedef mpl::bool_<...> property1; typedef mpl::bool_<...> property2; typedef mpl::bool_<...> property3; }; you could provide both, but in which "direction"? does a traits class refer to metafunctions, or do metafunctions refer to a traits class? a) template<...> struct ..._traits{ typedef typename property1<...>::type property1; typedef typename property2<...>::type property2; typedef typename property3<...>::type property3; }; b) template<...> struct property1 : ..._traits<...>::property1{} template<...> struct property2 : ..._traits<...>::property2{} template<...> struct property3 : ..._traits<...>::property3{} which is accessed when "calling" the metafunction? it seems to me that metafunctions are better for the "caller" and traits classes are better for the implementor of the traits/metafunctions. in my case, the caller is a library and the implementor is the user, so you might choose a traits class over metafunctions. but what if a new member is added that wasn't there before (like "property4"). the implementor of an (old) traits class could not have known about the new member, so accessing the new member (by the library) will result in an error, while a new metafunction "property4" could simply return a default. should new properties of traits classes only be accessed after making sure they exist, using SFINAE? there isn't a precedent for this in c++11. only new traits classes were introduced, but no new members of already existing traits classes. should metafunctions always be preferred? why did c++11 choose traits classes over metafunctions, even though the concept of a metafunction was introduced in c++11 (<type_traits>). Thanks [1] Abrahams; Gurtovoy: C++ Template Metaprogramming, 2.2 Metafunctions

7 14

[config] gcc-4.8 and __GXX_EXPERIMENTAL_CXX0X__
by Vicente J. Botet Escriba 01 Apr '13

01 Apr '13

Hi, it seems that gcc-4.8 doesn't defines any more __GXX_EXPERIMENTAL_CXX0X__ when the flag -std=c++11 is given. This means that all the BOOST_NO_CXX11_ are defined. Could something be done to make usable gcc-4.8 in c++11 mode? Best, Vicente

2 4

[mpi] Boost.MPI and MPI 3!
by Renato Forti 01 Apr '13

01 Apr '13

Hi All, Boost.MPI project will support MPI version 3 with that provide some support to fault tolerance! Have any work in this area? Thanks

2 2

[build & test] clang-3.2 for Win32
by Jim Bell 01 Apr '13

01 Apr '13

I took the liberty to run regressions with clang-3.2 on Win32. It's pretty unhappy, and most failures have to do with it not building shared libraries (DLLs) correctly. Not finding symbols. I found a (non-boost) thread that talks about that being a problem with it. Even so, I had a couple questions: 1. It gets labeled clang-linux-3.2, though it's under the Windows umbrella in the regression matrix. How do we fix that? user-config.jam 'using clang ;' does seem to work fine. 2. I get these warnings. They seem like clang's problem, not ours. Am I right? ..\boost/test/execution_monitor.hpp:59:7: warning: 'dllexport' attribute only applies to variables and functions [-Wignored-attributes] class BOOST_TEST_DECL translate_exception_base { ..\boost/test/detail/config.hpp:88:29: note: expanded from macro 'BOOST_TEST_DECL' # define BOOST_TEST_DECL BOOST_SYMBOL_EXPORT ..\boost/config/platform/win32.hpp:30:42: note: expanded from macro 'BOOST_SYMBOL_EXPORT' # define BOOST_SYMBOL_EXPORT __declspec(dllexport) <built-in>:154:38: note: expanded from macro '__declspec' #define __declspec(a) __attribute__((a)) 3. I tried to coerce the regression to use only static libraries (since clang does build boost static pretty well)... --bjam-options='link=static runtime-link=static' but this made some part of the regression tests very unhappy: error: link=shared together with runtime-link=static is not allowed error: such property combination is either impossible error: or too dangerious to be of any use That's understandable, as it goes against the grain. But is there a way to inform the tests somehow? It's easy to imagine wanting to explicitly test what a shared library does, but what about cases where it doesn't matter if it's shard or static? (Are they distinguishable?) If anyone's interested, please peruse the mess I made of the regression matrix. And purge them from the matrix, too, eventually.

1 0

Associative container using a vector
by Stefan Strasser 01 Apr '13

01 Apr '13

Hi everyone, I often find myself using a specific data structure and I'm wondering whether: - it has a wellknown name - there is a generic equivalent in a boost library - or there is interest to add one. The basic idea is that you have a bunch of values stored in one object of type A: struct A{ vector<Value> values; }; and then you have multiple objects of type B that each have to associate data with each value stored in A. you could use: struct B{ map<Value,Data> data; }; but since A::values already provides a contiguous index for the values you can just as well store the data in B in a vector with matching indexes, and make sure that the indexes used in A::values don't change: struct A{ vector<Value> values; vector<std::size_t> freelist; map<Value,std::size_t> index; void erase(...){ push index of unused value to freelist; } void push_back(Value){ reuse a freelist entry or values.push_back; } }; struct B{ vector<optional<Data> > data; }; keep in mind that there is one object A for many objects B. you can now access the associated data of many objects B by looking up the index once in object A, and by wasting some space in B::data for unused entries: b.data[a.index[value]] If Data is a pointer or any other type that knows an empty() state, you can also get rid of optional<> and generalize it as two template like: template<class Value> class index; template<class Mapped,class OptionalTraits=boost_optional_traits> class vector_map; Is there anything like that?

3 4

[config] BOOST_NOEXCEPT on MSVC
by Michael Marcin 01 Apr '13

01 Apr '13

Why isn't BOOST_NOEXCEPT defined to be throw() for msvc? Microsoft Visual Studio 11.0\VC\include\yvals.h defines: #define _NOEXCEPT throw () and the rest of the standard library implementation uses it ex. void swap(thread& _Other) _NOEXCEPT { // swap with _Other _STD swap(_Thr, _Other._Thr); } http://msdn.microsoft.com/en-us/library/wfa0edys.aspx states: throw() The function does not throw an exception. However, if an exception is thrown out of a function marked throw(), the Visual C++ compiler will not call unexpected (see unexpected (CRT) and unexpected (<exception>) for more information). If a function is marked with throw(), the Visual C++ compiler will assume that the function does not throw C++ exceptions and generate code accordingly. Due to code optimizations that might be performed by the C++ compiler (based on the assumption that the function does not throw any C++ exceptions) if a function does throw an exception, the program may not execute correctly. It seems a better choice here than expanding BOOST_NOEXCEPT to nothing.

2 1

Re: [boost] [fusion] What do we do with nil ?
by Enrique Nieloud 31 Mar '13

31 Mar '13

Hi!, Sorry to bother, but is is patch officially included in version 1.53.0? I'm having trouble to compile under XCode 4 and it seems related to the "nil" word. thanks, - Enrique

1 0

Re: [boost] Review managers wanted for augmented data structures
by Dave Abrahams 31 Mar '13

31 Mar '13

on Mon Mar 04 2013, Vadim Stadnik <vadimstdk-AT-gmail.com> wrote: > On Mon, Mar 4, 2013 at 7:35 PM, Stefan Strasser <strasser(a)uni-bremen.de>wrote: > >> Am 04.03.2013 08:48, schrieb Martin Knoblauch Revuelta: >> >> Do you mean that you would declare them RandomAccess iterators? >>> >>> We can expect to have containers with millions of elements. For that >>> size, O(log N) is about 20 times faster than O(log N log N). That >>> makes a big difference. >>> >> >> isn't that a reason for providing optimized specializations of some STL >> algorithms, instead of introducing another iterator category? >> >> how would a new iterator category even help? >> as long as your iterator is a forward iterator, the user is allowed to >> call std::binary_search on your iterator, which uses the same algorithm on >> any iterator category. (only functions used by binary_search like >> std::advance are specialized on the category) >> where in all this would your tree-optimized binary_search code be called? >> >> the standard doesn't require random access iterator ops to be constant >> time. >> >> > Unfortunately, there is a problem of iterator categories with augmented > trees. The C++ standard specifies computational complexity for iterator > operations, although they are not shown in tables, since all of them are > required to be constant time. In both C++03 and C++11 this is formulated in > the section 24.1.8. Are you sure these iterators don't fall under the *amortized* constant time requirements, just like those of the ordered associative containers? -- Dave Abrahams

2 3

[gil] undocumented/unintended concept requirements in color_convert
by Michael Marcin 31 Mar '13

31 Mar '13

I was trying to add other color spaces support and noticed that the rgb to cmyk converter contains: typedef typename channel_type<P2>::type T2; T2 x = channel_traits<T2>::max_value()-get_color(dst,black_t()); if (x>0.0001f) { float x1 = channel_traits<T2>::max_value()/float(x); T2 should model: http://www.boost.org/doc/libs/1_53_0/libs/gil/doc/html/g_i_l_0264.html but this code additionally requires T2 to be greater-than comparable to float and convertible to float.

3 4

Re: [boost] [exception] uncaught_exception_count, scope(failure), scope(success)
by Evgeny Panasyuk 31 Mar '13

31 Mar '13

>06.02.2013 2:57, Emil Dotchevski: >>> While scope(exit) is some kind of ad-hoc replacement for RAII wrappers, >>> scope(failure) and scope(success) are not. >>> Nowadays scope(failure) and scope(success) are emulated in C++ via >>> ScopeGuard idiom. >> >> Could you clarify what does uncaught_exceptions_count() use look like? >> How is it different scope guard? > > [skipped] There is proposal by Herb Sutter for add similar functionality to ISO - std::unwinding_exception http://isocpp.org/blog/2013/03/n3614-unwinding-exception , http://isocpp.org/files/papers/N3614.pdf which is aimed on providing basis for implementation of scope(failure)/scope(success). Emil, could you please clarify what is your position on adding uncaught_exception_count into Boost.Exception? ( https://github.com/panaseleus/stack_unwinding/blob/master/boost/exception/u… ) -- Evgeny Panasyuk

1 0

Experimenting with modular Boost
by Jonathan Wakely 30 Mar '13

30 Mar '13

The instructions at https://svn.boost.org/trac/boost/wiki/TryModBoost seem to be bogus, apparently because the cloned repo contains no .gitmodules file so the 'git submodule update --init' command does nothing, and I then get an error for the last step: $ cmake -P forward_headers.cmake CMake Error: Error processing file:forward_headers.cmake I'm "only" using Git 1.7.12 but I don't think that's the problem. The older instructions at https://svn.boost.org/trac/boost/wiki/CMakeModularizationStatus refer to a non-existent http://github.com/boost-lib/boost URL, so they don't work either. I've looked at several other wiki pages, but they're also inconsistent or don't help. Is there any accurate documentation for modular Boost? How does someone try modular boost?

2 1

[Filesystem] v3 path separator changes
by Alexander Lamaison 30 Mar '13

30 Mar '13

I'm finally getting round to moving to Filesystem v3 and now my code is breaking all over the place. The cause is the output of string() on Windows which has changed behaviour. I'm manipulating Unix paths for use over SFTP, but doing so on Windows. For instance I might want to append "c" to the Unix path "/a/b". path p("/a/b"); p /= "c"; cout << p.string(); In version 2 this would output "/a/b/c" but now it produces "/a/b\c". Why the breaking change? I'm trying to understand the rationale behind many of the v3 changes which [1] and [2] don't even begin to cover. [1] http://www.boost.org/doc/libs/1_53_0/libs/filesystem/doc/v3.html [2] http://www.boost.org/doc/libs/1_53_0/libs/filesystem/doc/deprecated.html Alex -- Swish - Easy SFTP for Windows Explorer (http://www.swish-sftp.org)

8 33

[switch generator] status
by Jeff Flinn 29 Mar '13

29 Mar '13

Does anyone know the current status of Steven's switch generator library, I see it was reviewed/accepted in 2008, but I don't see it in trunk or any release. Thanks, Jeff

2 1

[config] gcc implemented N3276 decltype
by Michel Morin 29 Mar '13

29 Mar '13

gcc 4.8.1 and 4.9.0 will support N3276 decltype. ( http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52748 ) May I commit an attached patch? Regards, Michel

3 4

Helping With Boost?
by Thales 29 Mar '13

29 Mar '13

Hello! I'm a C++ programmer (Windows 7 platform, Visual Studio) and I'm interested in helping with this project. I've downloaded the latest from the repository and have built the Win32 libraries. Is there anything I can try my hand at to get started? :-) Thanks for any feedback, ...John

4 5

GSoC: Getting ready for the application
by Boris Schaeling 27 Mar '13

27 Mar '13

Can those who planned to add a proposal but didn't do yet update https://svn.boost.org/trac/boost/wiki/SoC2013 as soon as possible? And can those who added a proposal check it one last time? Andrew reminded me that Boost wasn't accepted last year because we had a superficial list of ideas without realistic goals and expectations. We should be able to increase our chances if we document actual requirements and possibly design approaches. According to Google they look extensively at every org's ideas page. So this is really important. Thanks, Boris

5 4

Serialise on Mac OSX 10.8, XCode and GCC
by Tim Burgess 27 Mar '13

27 Mar '13

Hi, I have an XCode c++ project that uses the static serialisation library (as well as FileSystem, IOStream and System). The project started out on XCode 3.6 on Mac OSX 10.6, where it successfully built and ran using Boost 1_49_0, built against Apple's 10.6 SDK. However, I needed to use the XCode debugger to track down some run-time issues and found I couldn't access the debugger on this version of XCode (I'm blind and have to use the VoiceOver utility to gain access to my Mac). Having taken advice, I upgraded to Mac OSX 10.8, SDK 10.8 and XCode 4.6, which solves my debugging issue. Unfortunately, my project no longer links correctly. The linker complains that it can't find symbols for my architecture (x86_64) - the messages are in the the form: "boost::archive::basic_xml_iarchive<boost::archive::xml_wiarchive>::load_sta rt(char const*)", referenced from: "boost::archive::basic_xml_iarchive<boost::archive::xml_wiarchive>::load_ove rride(boost::archive::version_type&, int)", referenced from: "boost::archive::basic_xml_iarchive<boost::archive::xml_wiarchive>::load_ove rride(boost::archive::class_id_type&, int)", referenced from: (I've truncated the output here for brevity). I get no linker errors for any of the other Boost binaries - it's only the serialisation library that creates a problem. The project is configured to compile with the llvmgcc42 compiler, as it also uses the wxWidgets libraries, which don't support compilation using clang. Boost versions tried: 1_50_0, 1_52_0 and 1_53_0. Boost build options tried: 1 - Default (no options specified) - this worked on Mac OSX 10.6, Snow Leopard. 2 - As follows: macosx-version=10.3 macosx-version-min=10.6 architecture=combined threading=multi link=static address-model=32_64 3 - As follows: architecture=combined address-model=32_64 I'm a novice using Boost and the Mac, so would appreciate any suggestions as to how I can resolve this issue. Best wishes. Tim Burgess Raised Bar Ltd. Tel: +44 (0)1827 719822 Web: http://www.raisedbar.net We can supply Roland and Avid products with specialist pre and post-sales support for visually-impaired users - just drop us a line for a quote. Don't forget to sign our on-line petition to lobby for improved access to music education and music technology at: http://www.raisedbar.net/petition.htm

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Re: [boost] [Boost-commit] svn:boost r83608 - trunk/status
by Steven Watanabe 27 Mar '13

27 Mar '13

AMDG On 03/27/2013 12:13 PM, chhenning(a)gmail.com wrote: > > Modified: trunk/status/Jamfile.v2 > ============================================================================== > --- trunk/status/Jamfile.v2 (original) > +++ trunk/status/Jamfile.v2 2013-03-27 15:13:44 EDT (Wed, 27 Mar 2013) > @@ -86,6 +86,7 @@ > fusion/test # test-suite fusion > geometry/test # test-suite geometry > gil/test # test-suite gil > + gil/io/test # test-suite gil::io This just broke the regression tests: ERROR: rule "jpeg.init" unknown in module "toolset". /run/media/steven/regression/tools_bb/build/project.jam:995: in using ../libs/gil/io/test/Jamfile.v2:12: in modules.load In Christ, Steven Watanabe

2 1

Adding gil extensions to boost_release
by Christian Henning 27 Mar '13

27 Mar '13

Hi all, quick question: Is the release branch open? Thanks, Christian

4 8

[gil] YCbCr color space added
by Christian Henning 27 Mar '13

27 Mar '13

Hi all, there has been some interest in adding the ycbcr color space to gil. For that I just added the color space with color conversions and a new image type for subsampled images. Thanks for Juan Puertos for the color conversion routines! I believe, so far, the ycbcr is very rudimentary and there is a lot of more work to do but it's a beginning. Please let me know what you think. Sources: http://svn.boost.org/svn/boost/trunk/boost/gil/extension/toolbox/color_spac… http://svn.boost.org/svn/boost/trunk/boost/gil/extension/toolbox/image_type… Regards, Christian

1 0

Re: [boost] [multi-array] compiler errors with visual studio 2012 (nfarnsworth@web.de)
by Dan Searles 27 Mar '13

27 Mar '13

>Date: Sat, 23 Mar 2013 14:12:24 +0100 (CET) >From: nfarnsworth(a)web.de >To: boost(a)lists.boost.org >Subject: [boost] [multi-array] compiler errors with visual studio 2012 >Message-ID: > <trinity-07de36eb-bb16-4dc9-b97b-68516d068e24-1364044344811@3capp-webde-bs37> > >Content-Type: text/plain; charset="UTF-8" > > > Hello, > have this c++ example which compiles with Visual Studio 2010 but with Visual > Studio 2012 I got this compiler errors: > 1>------ Build started: Project: MultiArrayDemo, Configuration: Debug Win32 > ------ > 1> MultiArrayDemo.cpp > 1>d:\sandbox\multiarraydemo\multiarraydemo\multiarraydemo.cpp(11):error > C2059: syntax error : '<' > 1> d:\sandbox\multiarraydemo\multiarraydemo\multiarraydemo.cpp(25) > : see reference to class template instantiation 'Data<T>' being compiled > 1>d:\sandbox\multiarraydemo\multiarraydemo\multiarraydemo.cpp(11):error > C2238: unexpected token(s) preceding ';' > ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== > The example uses the boost 1.53 version. Here is the example code: > #include "stdafx.h" > #include <boost/multi_array.hpp> > const int rows = 3; > const int cols = 5; > template<class T> struct Data > { > typedef boost::multi_array<T,2> data_type; > typedef typename data_type::array_view<1>::type view_type; //here is the > first error > typedef typename data_type::index_range range; > Data() > :A(boost::extents[rows][cols]) > { > double tmp[] = > {1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0,9.0,10.0,11.0,12.0,13.0,14.0,15.0}; > A.assign(tmp,tmp+ (rows * cols)); > } > data_type A; > }; > int _tmain(int argc, _TCHAR* argv[]) > { > > Data<double>* data = new Data<double>(); > Data<double>::view_type myView = > data->A[boost::indices[0][Data<double>::range()]]; > delete data; > return 0; > } > Does anybody know how to solve this problem? > Best regards and thank you in advance > Niklas According to Microsoft, the code is non-conformant. Visual Studio 2010 allowed the code to be compiled, but 2012 tightened the requirement. See: http://msdn.microsoft.com/en-us/library/bb531344.aspx (Second point, "Use the template keyword...", but note that they highlighted the wrong keyword). The simple fix is to add the keyword 'template': typedef typename data_type::template array_view<1>::type view_type; //here is the first error Dan Searles

1 0

[fusion] sequence io manipulators
by Jeff Flinn 27 Mar '13

27 Mar '13

When streaming unrelated fusion sets to unrelated ostringstreams from different threads, I get an invalid iterator error. This appears to be due to using a boost::fusion::detail::stream_data::attach's local static arena instance. static void attach(Stream& stream, T const& data) { static arena ar; // our arena ar.data.push_back(new T(data)); stream.pword(get_xalloc_index<Tag>()) = ar.data.back(); } I assume there are issues with using the unguarded stream_data::data std::vector<T*> from multiple threads. This implementation looks problematic in that the arena data does not get cleaned up until program exit as well. Jeff

5 7

[atomic] Could you merge to trunk?
by Vicente J. Botet Escriba 26 Mar '13

26 Mar '13

Hi, there are some modification on trunk that need to be merged to release branch because there are some incompatibilities. Could this be done soon? Thanks, Vicente

3 2

GSoC: Backup admin wanted
by Boris Schaeling 26 Mar '13

26 Mar '13

Anyone who wants to be the backup admin for the GSoC program (in case Boost is accepted)? Drop me a mail if you are interested. We need one for the application. :) Thanks, Boris

1 0

[persistent] BerkeleyDB, SQLite, more
by Stefan Strasser 26 Mar '13

26 Mar '13

Hello everyone, if this is the first time you're hearing about this library proposal, please start by reading the "Motivation" and "Approach" sections here: http://tinyurl.com/ct2vfp5 I've had some time to kill lately, so there are now working storage backends for BerkeleyDB and SQLite. Here's a simple example storing and modifying some objects in a BerkeleyDB: http://pastebin.com/yXJbTdz7 There is also a virtual interface that lets you decide which database to use at runtime, or dynamically link different DBMSs. You'll also be able to use multiple databases at once and have global transactions among them, if the DBMS supports two-phase commits. Are there any suggestions for other storage engines to support? If you are familiar with one you are also very welcome to contribute. The interface is very simple and no knowledge of library internals is needed. At this point storage engines to support should be: - transactional. There is code for a MVCC transaction layer from my own storage engine, but it's not generic enough yet to just put it on top of a non-transactional engine like google's LevelDB. - good at handling BLOBs to store serialized objects. Object/Relational mapping is a whole other project. - preferrably have a very free license. The BerkeleyDB code is seperated from the rest so I don't think there are problems with the GPL-like license "infecting" the entire library if you don't use it. But if you do, it's GPL or commercial. I've looked at Tokyo Cabinet in some detail, but it seems more like a collection of functions to me, that one could use to build a DB with, than a robust product. I would like to be proven wrong on this, as it's often compared to BerkeleyDB and is LGPL-licensed. Suggestions for other embedded databases that could be supported are also welcome. Best regards, Stefan

1 0

New regression test reporting system
by Steven Watanabe 26 Mar '13

26 Mar '13

AMDG I just replaced the XSL scripts used to generate the regression test reports with a C++ implementation. If you encounter any broken links, bad markup, etc., please let me know. I rushed this a bit because xsltproc was misbehaving, and the old reports were coming out empty, so I haven't checked the output as thoroughly as I would have liked, yet. It should become more stable in the next day or two. In Christ, Steven Watanabe

2 2

[gil] Pixel Hasher
by Harg Tholan 26 Mar '13

26 Mar '13

Hey, I've been looking for a hashing function for PixelBased types... with no succes, so I created one. Does this have any value for users? Regards,

2 5

[gil] numeric extensions pixel division.
by Harg Tholan 26 Mar '13

26 Mar '13

Hey, It seems that in the numeric extensions it is implemented the division of channels, but not the division of pixels. Are you planning to include it at some point? thanks.

2 4

Boost.Graph for GSoC 2013 - Yes/No/Maybe?
by Darius L. 25 Mar '13

25 Mar '13

Hi all, I'd like to gauge the interest in proposing a project in Boost.Graph for GSoC (and beyond). Would anyone be interested in additions to Boost.Graph? (to-do list here hasn't changed in a while: http://www.boost.org/doc/libs/1_53_0/libs/graph/doc/challenge.html) If so, what exactly would you be interested in? Also, would anyone be open to mentoring for this project?

4 3