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[range] Proposal: addition of front(), back(), at(), operator[]
by Adam Wulkiewicz 26 Mar '14

26 Mar '14

Hi, I propose to add the functions described below to the Boost.Range. I found the use of those very convenient WRT the corresponding use of begin() and end(), and a lot more readable. 1. front() returning the reference to the first element precondition (assert): !empty(rng) return *begin(rng); 2. back() returning the reference to the last element precondition (assert): !empty(rng) For BidirectionalRange return *(--end(rng)); For SinglePassRange it could iterate over the range and return the reference to the last element 3. at() returning the reference to the i-th element of the range precondition (throw std::out_of_range or assert): index < size(rng) For RandomAccessRange return *(begin(rng) + index); For SinglePassRange it could iterate over the range and return the required element For me, non-throwing at() would be more useful however this behavior won't be intuitive. So the following should also be provided: 4. sub(), subscript(), el(), element(), at_index(), at_(), index(), indexed(), access(), operator[], ...? the implementation of indexing operator[] same as 3 but instead of throwing an assert would be used The use of operator[] could be similar to this: { using boost::range::subscript_operator; rng[index]; } So not very convenient. But maybe you have a better idea? Regards, Adam

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Re: [boost] [Parallel Algorithms] Queries regarding the Boost.Thread / Parallel algorithms
by Naveen 26 Mar '14

26 Mar '14

Hi, In my previous mail, I was speaking about the compiler optimization dependencies while creating a parallel version of the following code: DO J = 1, 100 DO I = 1, 100 DO K = 1, 100 C(I,J) = C(I,J) + A(I,K) * B(K,J) END DO END DO END DO As you know, the above code is the 2D-Matrix multiplication logic. I tested the above logic using various compiler optimization levels from -o0, -o1, -o2 and -o3. There were no problems due to the compiler optimizations. I have used pthreads to convert the serial code to its parallel version. Initially, the serial version took 72sec to execute and the parallel version with 4 threads took around 16sec. Please have a look at the attachment for the complete working source code. The question now is, I have used the threads as shown in the pseudo code below: int main() { create_pthreads(assign_thread_ID, call the function); join_threads(thread_ID); destroy_threads(); } function_called_by_each_thread(thread_ID) { all_computations; } All thread documentation reaches to some sort of options like this. Is this the correct way to approach the problem for creating parallel algorithms for boost threads. Please clarify, whether there are any alternative approaches available to achieve parallelism using threads. PS: Please have a look at the code for further details Regards, *NAVEEN* | Mobile: 832-720-2393 | about.me <http://about.me/naveen.namashivayam> |

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Re: [boost] [Parallel Algorithms] Queries regarding the Boost.Thread / Parallel algorithms
by Naveen 26 Mar '14

26 Mar '14

Hi, Based on understanding the proposal, I'm just curious to know how we are gonna use the compiler optimizations when creating the parallel_xxx functions. Say any normal loop would be optimized by the compiler using any of the loop transformations like loop interchange, loop unrolling, loop fusion etc., let us consider a sample FORTRAN code to : DO J = 1, 100 DO I = 1, 100 DO K = 1, 100 C(I,J) = C(I,J) + A(I,K) * B(K,J) END DO END DO END DO which may or may not be optimized by the compiler into something like this DO K = 1, 100 DO I = 1, 100 DO J = 1, 100 C(I,J) = C(I,J) + A(I,K) * B(K,J) END DO END DO END DO so, when we try to introduce our parallel algorithm in to the loop containing J, it may be interchanged depending upon the compiler properties. So, should we plan for such scenarios. When we try to introduce our parallel functions the only way possible is to make the compiler optimizations temporarily inactive on those tasks. But, by doing so the performance of the application will be affected. Should we really tackle this scenario or am i looking into a completely irrelevant picture? Regards, *NAVEEN* | Mobile: 832-720-2393 | about.me <http://about.me/naveen.namashivayam> |

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[bind] BOOST_BIND_NO_PLACEHOLDERS and unspecified-placeholder-type's
by Joaquín Mª López Muñoz 25 Mar '14

25 Mar '14

Hello, The non-documented BOOST_BIND_NO_PLACEHOLDERS macro suppresses the definition of (anonymous namespace)::_1, (anonymous namespace)::_2, etc., presumably to cope with potential clashes with other libs' placeholders such as Boost.Lambda's when in the presence of using directives. The problem with this is that using Boost.Bind without placeholder names requires writing code such as bind(f,boost::arg<1>(),boost::arg<2>()); but boost::arg<> is not documented!! (in fact, Boost.Bind synopsis explicitly defines _1, _2 etc. as having undocumented types unspecified-placeholder-type-1, unspecified-placeholder-type-2 and so on). Maybe Boost.Bind documentation can be changed so that BOOST_BIND_NO_PLACEHOLDERS and boost::arg<> are documented? Thank you, Joaquín M López Muñoz Telefónica Digital ________________________________ Este mensaje se dirige exclusivamente a su destinatario. Puede consultar nuestra política de envío y recepción de correo electrónico en el enlace situado más abajo. This message is intended exclusively for its addressee. We only send and receive email on the basis of the terms set out at: http://www.tid.es/ES/PAGINAS/disclaimer.aspx

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[ANN] CppCon 2014 Call for Submissions
by Boris Kolpackov 25 Mar '14

25 Mar '14

Hi, CppCon is the annual, week-long face-to-face gathering for the entire C++ community. The conference is organized by the C++ community for the community and so we invite you to present. Have you learned something interesting about C++, maybe a new technique possible in C++11? Or perhaps you have implemented something cool related to C++, maybe a new C++ library? If so, consider sharing it with other C++ enthusiasts by giving a talk at CppCon 2014. Submissions deadline is May 15 with decisions sent by June 13. For topic ideas, possible formats, and submission instructions, see the Submissions page: http://cppcon.org/submissions/ Hope to hear you speak! Boris

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[Fusion] Can repetitive_view support "at" function?
by TONGARI J 25 Mar '14

25 Mar '14

I know it's a bit weird for asking repetitive_view which cannot model BidirectionalSequence to support the functionality of RandomAccessSequence, but it seems quite reasonable to support "at" when the underlying sequence models RandomAccessSequence even though repetitive_view cannot model RandomAccessSequence itself. Thoughts?

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[algorithm] Test failure in C++14
by Ben Pope 25 Mar '14

25 Mar '14

"clang++-3.4" -c -x c++ -std=c++1y -stdlib=libc++ -O0 -g -fno-inline -Wall -g -fPIC -DBOOST_ALL_NO_LIB=1 -DBOOST_TEST_DYN_LINK=1 -DBOOST_TEST_NO_AUTO_LINK=1 -I".." -o "/home/ben/development/boost/test/build/results/boost/bin.v2/libs/algorithm/test/is_permutation_test1.test/clang-linux-3.4~c14_libc++/debug/is_permutation_test1.o" "../libs/algorithm/test/is_permutation_test1.cpp" In file included from ../libs/algorithm/test/is_permutation_test1.cpp:13: ../boost/algorithm/cxx11/is_permutation.hpp:178:6: error: declaration conflicts with target of using declaration already in scope bool is_permutation ( ForwardIterator1 first1, ForwardIterator1 last1, ^ /usr/include/c++/v1/algorithm:1374:1: note: target of using declaration is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, ^ ../boost/algorithm/cxx11/is_permutation.hpp:104:12: note: using declaration using std::is_permutation; // Section 25.2.12 ^ ../boost/algorithm/cxx11/is_permutation.hpp:205:6: error: declaration conflicts with target of using declaration already in scope bool is_permutation ( ForwardIterator1 first1, ForwardIterator1 last1, ^ /usr/include/c++/v1/algorithm:1361:1: note: target of using declaration is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, ^ ../boost/algorithm/cxx11/is_permutation.hpp:104:12: note: using declaration using std::is_permutation; // Section 25.2.12 ^ 2 errors generated. I haven't looked in detail, but it looks like those two overloads were added in C++14 and need guarding with a suitable #if __cplusplus >= C++1Y_version_here Ben

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[GSoC 14] Request community to rank proposals
by Niall Douglas 24 Mar '14

24 Mar '14

Dear Boost Community, The Google Summer of Code 2014 proposals for Boost are in, and we would deeply appreciate the community's help in ranking the proposals according to merit before the 1st of April. To vote, the process is easy: 1. Go to this page https://www.google-melange.com/gsoc/homepage/google/gsoc2014 and click the "Log in" button under Mentors and Administrators. 2. Now click "Create Profile" on the same page. Note that even if you registered last year, you must register again in 2014. Fill in the form. Note that after submitting it drops you at "Edit Profile", which is confusing. 3. Click "My Dashboard", then "Connect with organisations". 4. Choose "Boost C++ Libraries". 5. In the message box, write this: "I am a member of the Boost community and the email(s) I normally post to boost mailing lists with is <email>" filling in the email address(es) you normally use to post to boost mailing lists. This lets us verify that you are indeed a long standing member of the Boost community. 6. Once we approve your request, you will get an email with the subject "Welcome as organisation member". You can now return to the Dashboard on the GSoC website where there will be a new item "Proposals". 7. Work your way through as many of the 42 proposals as you can. You can score them using the stars at the bottom of each proposal page, taking care to read any comments by the mentors and students if present. PLEASE try to rank some of the lowest scored proposals, every year we get a lot of people who only rank the top five and don't bother with the rest. Try to score on the basis of (i) proposal quality and your best estimate of the student's capability (ii) if the student came early to the mailing lists to ask for help writing the proposal (the mentors who helped them with their proposals have usually indicated this in the private comments) (iii) usefulness/appropriateness of the feature or work being proposed. Remember a good GSoC is more about getting promising new engineers into Boost and C++ than necessarily getting code to pass Boost peer review in a single summer. 8. Optional: If a proposal looks especially great to you and you feel able to mentor a student this year, please slide the "wish to mentor" button. Just because a proposal already has willing mentors does NOT mean you should not add yourself - we have at least two mentors with many attached very highly ranked proposals and we really don't want to have to reject an outstanding proposal just because we can't find the mentors for it as no mentor can realistically mentor more than two projects simultaneously. As you know, Google Summer of Code is usually worth $35,000 - $50,000 to Boost each year, and a successful GSoC raises our visibility and reputation in the wider open source community. Our thanks to you in advance for taking the time to vote. Niall Douglas Boris Schäling --- Boost C++ Libraries Google Summer of Code 2014 admin https://svn.boost.org/trac/boost/wiki/SoC2014

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[build][testing] Auto-generated tests not present in reports
by Andrey Semashev 24 Mar '14

24 Mar '14

Hi, Recently I added auto-generation of compile tests which basically check that every Boost.Log public header is self-contained (i.e. can be included on its own, does not have any missing includes etc.) This is done in the test/Jamfile.v2 as follows: rule test_all { local all_rules = ; local file ; local headers_path = [ path.make $(BOOST_ROOT)/libs/log/include/boost/log ] ; for file in [ path.glob-tree $(headers_path) : *.hpp ] { local rel_file = [ path.relative-to $(headers_path) $(file) ] ; if ! [ MATCH "detail/(.*)" : $(rel_file) ] { #ECHO $(rel_file) ; all_rules += [ compile compile/self_contained_header.cpp : <define>"BOOST_LOG_TEST_HEADER=$(rel_file)" : self_contained_header/$(rel_file) ] ; } } ... other test targets are also generated here return $(all_rules) ; } This rule also generates targets for other tests, including compile tests. It works locally, I can see the generated tests for all headers being compiled. However, I made this change quite some time ago but still I don't see these tests in the test reports table. I can see other tests which are generated by the same test_all rule, so it works. What could be the problem? Any ideas? Thanks.

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[Boost][Range] Non-mutating algorithm on non const qualified range
by Albert Yiamakis 24 Mar '14

24 Mar '14

Hello, In the users mailing list I have remarked that this piece of code: https://gist.github.com/Kojirion/9714131 will fail to compile, without providing 'mutable' iterators. I have since found out it will also compile by simply const qualifying the dummy object. (ie const Dummy dummy;) The reason is that without it this: is_const<Dummy> gets evaluated to false, resulting in boost::mpl::eval_if_c<false, boost::range_const_iterator<Dummy>, boost::range_mutable_iterator<Dummy> > Surely this is not intended behavior and it should be possible to use a range that has only const iterators in a non-mutating algorithm without const qualifying it? Albert

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