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[containers] Vector-like container, which takes O(log(N)) > for insert/erase, question to Adam Wulkiewicz about iterators
by Alexander Kuprijanov 06 Apr '14

06 Apr '14

Hi, again, Adam! > > Date: Sat, 05 Apr 2014 16:59:18 +0200 > From: Adam Wulkiewicz <adam.wulkiewicz(a)gmail.com> > And I strongly dissagree with the statement that your container should > be the first choice. std::vector<> will outperform it in most of the > real-life use-cases. Vector outperforms it only (roughly) 2 times on small arrays (when it contains only one leaf) on all operations, only (roughly) 3 times on iterating access on all sizes and only log(N) times on random access. But it severely (N/log(N)) outperforms vector in all insert/erase cases. See my explained test results. I still believe it's close to first choise. > Also, IMHO the most important feature of std::list<> is insert() and > erase() not invalidating other iterators. AFAIU in your container > iterators may be invalid after insert()? That is very interesting question. Currently such sort of persistent iterators (I call them bookmarks) are not implemented. PLEASE PLEASE PLEASE, EVERYBODY, give me an example of the task when such iterators are necessary. Will this feature add feature to my container, if implemented? Best regards, A.K.

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[container] Vector-like container, which takes O(log(N)) for insert/erase, response to Adam Wulkiewicz about performance
by Alexander Kuprijanov 06 Apr '14

06 Apr '14

Hi, Adam! > Date: Sat, 05 Apr 2014 16:59:18 +0200 > From: Adam Wulkiewicz <adam.wulkiewicz(a)gmail.com> > Again, the times you measure are too small to reasonably tell which one > is faster. You could perform each test 10k more times to keep the > results around 1s. I believe my calculations are reliable. I'm sorry I did not explained it earlier and did not provide clarification on github. Firstly, the output is time per one operations in milliseconds. E.g., if it says 1.00e-4, it means 1e-7 seconds or 0. 000 000 1 seconds per one operation. The operation performed many times and result is divided. Secondly, in each operation there are many calculations, by both repeating and array growing. If the line before array says "averaged on 500 measurements" and in array size is 1024, it meant that it was 500 arrays and each of them growed from 512 elements to 1024 elements, giving 256000 atomic additions. Each of them took 1.17e-04 ms in average, they all took about 30 ms. Granularity of Linux timer (which is used in test) is 1 ms, so tolerance in the case is 3%. > Instead of comparing it with a different implementation I guess it would > be sufficient to contain only 2 children in the internal nodes. > Well, I in fact found that numbers 14/28 are near optimum. (There are several optimums for different operations.) Theory agrees with practice, the best performance is when leaf/branch fits one cache line. (In fact, my container allows minimum L=4 M=4, each branch and leaf may have from 2 to 4 items. It behaves worse generally.) I tried to compare it with rope because I was asked to do so. I'll compare it with other similar containers as well. Rope has other problems such as balancing when critical and so on. Best regards, A.K.

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Proposal: Vector-like container, which takes O(log(N)) for insert/erase, response to Bjorn Reese about copy-on-write
by Alexander Kuprijanov 06 Apr '14

06 Apr '14

> Date: Fri, 04 Apr 2014 19:24:53 +0200 > From: Bjorn Reese <breese(a)mail1.stofanet.dk> > To: boost(a)lists.boost.org > Subject: Re: [boost] Proposal: Vector-like container, which takes > O(log(N)) for insert/erase (Glen Fernandes) > Message-ID: <533EEAE5.2040304(a)mail1.stofanet.dk> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > On 04/04/2014 02:10 PM, Lars Viklund wrote: > >> As for the Copy-on-Write semantics, isn't the general consensus that CoW >> is a horrible horrible thing and is very hard to get right+fast in the >> modern world with concurrency? > > Yes: > > http://www.gotw.ca/publications/optimizations.htm > Hi, Bjorn, 1) Proposed Copy-on-Write (CoW) optimization will be only option. Developer will chose, which container he or she wants: a) without CoW, b) with CoW with internal locks, c) with CoW without internal locks (very dangerous). Option "a" will be the first choise. Option "c" is used either in single-threaded apps or if he/she knows that all shallow copies are maintained in the single thtread or behind single semaphore which protects all shallow copies. 2) The article states mostly that there are ineffective optimizations of CoW. CoW by itself is not that bad. Citation: Plain 1726ms Plain_FastAlloc 642ms COW_Unsafe 1629ms COW_AtomicInt 1949ms COW_CritSec 10660ms COW_Mutex 33298ms e.g., the AtomicInt is 10-15% slower than plain, while Mutex 33 times. 3) There are situations where it's worth. Firstly, mobile/embedded devices are memory greedy. Secondly, small changes in very large arrays, such as text editors. Thirdly, no need to implement "undo" command in text editors, that reduces development time. But I see that community does not appreciate this feature so I do it in the end of my priority list. Best regards, A.K.

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[git] Near future.. How do we deal with git-native libraries?
by Rene Rivera 05 Apr '14

05 Apr '14

As the owner of the Predef library which exists originally in github and not svn.. I'm wondering about some things for the near future (as in this coming week): 1. Where will the git repo live for a library? Will the repo need to stay in the boostorg organization? Or is it possible/desirable to use the existing repo that's part of my user account? 2. I notice that there's a ".gitattributes" file in the svn imported version of the Predef repo. Will I need to add that file to my actual Predef git repo? And if so, is there a single canonical version of that file I should use? And a followup.. In the future if that file changes, does it need to change for all repos consistently? Rene. -- -- -- Grafik - Don't Assume Anything -- Redshift Software, Inc. - http://redshift-software.com -- rrivera/acm.org - grafik/redshift-software.com -- 102708583/icq - grafikrobot/aim - grafikrobot/yahoo

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[asio] Bug: Handlers execute on the wrong strand.
by Greg Barron 04 Apr '14

04 Apr '14

Hi All, I would like to refer you to this bug report: https://svn.boost.org/trac/boost/ticket/9203 I won't paste the full contents of the bug report into this message. The executive summary is that the allocation algorithm for the implementation of asio::strand can and does allocate the implementation of an existing strand to strands that are subsequently allocated. This can have the effect that handlers wrapped in strand (b) will actually be executed on strand (a). I consider this to be a bug but if there is something that I'm misunderstanding about the operation of strands it would be great if you could help me clear it up. If the consensus is that this is a bug, what are the chances for it to be included in the 1.56 release? It is probably too late to be included in the 1.55 release. I've implemented a work around which could only be described as a hack and would be embarrassed to show it to anybody. But it gets me over my hump :). Thanks! -- Greg

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Re: [boost] Proposal: Vector-like container, which takes O(log(N)) for insert/erase (Glen Fernandes)
by Alexander Kuprijanov 04 Apr '14

04 Apr '14

Hi, again, I've implemented a container which should replace vector and have O(log(N)) for insert/delete. Please review. https://github.com/alexkupri/array/blob/master/description/description.txt The code is small, the description is verbose. Best regards, A.K.

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Boost.asio avoid the use of pipe
by Thomas Heller 03 Apr '14

03 Apr '14

Hi list, I'm currently trying to get a asio based software to run on CNK (a very lightweight kernel) which only implements a subset of the POSIX functions. One of the functions which is not implement is pipe. However, asio uses this in the epoll and select reactor. Is there any possibility to avoid that pipe is used? What options do I have? Cheers, Thomas

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[typeof] failed to compile under dependent context
by feverzsj 03 Apr '14

03 Apr '14

hi, list here is some code failed to compile with msvc9. Not sure if it is wrong use case or bug. template<class T> struct A { static T apply() { return T(); } }; template<class T> struct B { typedef BOOST_TYPEOF_TPL(A<T>::apply()) type; // error C2064: term does not evaluate to a function taking 0 arguments }; template<class T> BOOST_TYPEOF_TPL(A<T>::apply()) foo2() // error C2064: term does not evaluate to a function taking 0 arguments { } template<class T> void foo1() { BOOST_TYPEOF_TPL(A<T>::apply()) t; // ok } Regards, zsj -- View this message in context: http://boost.2283326.n4.nabble.com/boost-typeof-failed-to-compile-under-dep… Sent from the Boost - Dev mailing list archive at Nabble.com.

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Boost.Geometry selected for MySQL
by Barend Gehrels 03 Apr '14

03 Apr '14

Hi, Recent news which is published this week (actually today): Boost.Geometry will be used for MySQL 's spatial database features. http://mysqlserverteam.com/building-mysql-with-boost/ This also means MySQL (server) will now use Boost libraries from now on. Regards, Barend

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[BGL] Visual Studio 12 finish_edge() failure, general BOOST_TTI_HAS_MEMBER_FUNCTION failure?
by Michael Behrns-Miller 01 Apr '14

01 Apr '14

Hello boost! In the BGL, finish_edge() is a visitor function of DFS, but it is optional. It is made optional via BOOST_TTI_HAS_MEMBER_FUNCTION. Here's how BGL defines it: ------------- BOOST_TTI_HAS_MEMBER_FUNCTION(finish_edge) template <bool IsCallable> struct do_call_finish_edge { template <typename E, typename G, typename Vis> static void call_finish_edge(Vis& vis, const E& e, const G& g) { vis.finish_edge(e, g); } }; template <> struct do_call_finish_edge<false> { template <typename E, typename G, typename Vis> static void call_finish_edge(Vis&, const E&, const G&) {} }; template <typename E, typename G, typename Vis> void call_finish_edge(Vis& vis, const E& e, const G& g) { // Only call if method exists do_call_finish_edge<has_member_function_finish_edge<Vis, void>::value>::call_finish_edge(vis, e, g); } ------------- In all my efforts, the Visual Studio 12 compiler fails to call finish_edge(). I've tried templated versions, direct versions, virtual versions, with and without const params, inline and not inline. In every case, VS says "code will not be hit, no executable code is associated with this line. possible causes: preprocessor directives or compiler/linker optimizations". I'm in debug mode with minimal optimizations, and there's no preprocessor wrapper. It's possible there's a problem with the way I'm calling it, but it happens when I use a simple example from another user. This ticket includes very simple sample code that should fire the finish_edge() function. It does not work for me using VS 12: https://svn.boost.org/trac/boost/ticket/9770 https://svn.boost.org/trac/boost/attachment/ticket/9770/test.cc I have a large project depending on the BGL, which has been great otherwise. I've coded a workaround by using the other non-optional visitor functions. But there are edge cases (sorry, no pun intended! ha) that fail with my workaround. The only possible solution is to get finish_edge() to fire. I'd like to do it the intended way, rather than rewrite BGL code to make finish_edge() non-optional. I'll go try this with a recent version of gcc now... Thanks for any input at all! Michael Behrns-Miller

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[git] Creating merge bases.
by Daniel James 01 Apr '14

01 Apr '14

Hi, After creating a merge base for iostreams last night, I thought I might do it for some other modules where I can find a good merge base. I won't do it for any modules with post-subversion commits on master, and I won't change any content without a pull request, so this shouldn't be disruptive. Does this sound okay? It should help anyone wishing to work on a module, as they can get a better idea of what hasn't been merged to master, and it should make it easier to merge changes. Daniel

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Proposal: Vector-like container, which takes O(log(N)) for insert/erase
by Alexander Kuprijanov 01 Apr '14

01 Apr '14

Hi, everybody! I've implemented a container, which has interface similar to vector and takes O(log(N)) for inserting/erasing. Shortly speaking, it has BTrees inside and intrusive leaves, and exploits idea of so-called "rope". I would like to name it alex_kupriianov_array (after myself) and add it to boost. Please tell me who is the coordinator of containers and what is the procedure of adding something to boost. If the community finds it useful, I'll add more features. Among them: 1) non-intrusive version of the container; 2) shallow/partial/lazy copying; if you copy an array and then modify small part of it (for example, beginning), it will keep different beginnings and common end; 3) bookmarks - sort of sticky iterators, which are sticky to a certain element, no matter if there are insertions/deletions before them. Contact me: alexkupri at gmail dot com

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[align] [review] Pre-review comments
by Steven Watanabe 31 Mar '14

31 Mar '14

AMDG I saw the announcement of the review and decided to take a look at the library today. All the following is based on: commit 0d361143c18254efddacfd48775a2776ca7d5e11 Author: Glen Fernandes <glenfe(a)live.com> Date: Thu Mar 27 17:45:12 2014 -0700 Documentation: align: "alignment shall be a fundamental alignment value or an extended alignment value and a power of two." Please define these terms. Also warning: suggest parentheses around ‘and’ within ‘or’ [-Wparentheses] aligned_alloc: I notice that alignment is only required to be a power of two. Is there a reason this is different from align? aligned_allocator: template<class T, size_t Alignment = 1> class aligned_allocator; I'd really like to see the requirements on Alignment written out somewhere, even if we can deduce it from the fact that it calls aligned_alloc. Also, does the standard guarantee that all alignments are powers of 2? Otherwise lcm(2^k, alignof(T)) is not guaranteed to be a power of 2. If it is guaranteed, then lcm(2^k, alignof(T)) == max(2^k, alignof(T)) This is probably worth noting. aligned_allocator notes: "Specifying minimum alignment is generally only suitable for containers such as vector and undesirable with other, node-based, containers." I had to think about this for a few seconds. If you're going to say this, you should probably explain why. aligned_allocator_adaptor: template<class A> aligned_allocator_adaptor(A&& alloc); Not explicit? Should aligned_allocator_adaptor really be convertible from anything? template<class U> aligned_allocator_adaptor(const aligned_allocator_adaptor<U, Alignment>& other); Requires: Allocator shall be constructible from A. Copy/paste error. There is no A here. pointer allocate(size_type n, const_void_pointer hint = 0); Requires: hint is a value obtained by calling allocate(), or else nullptr. Calling allocate on what? Not just this object, but any equivalent aligned_allocator_adaptor, should work. aligned_allocator_adaptor notes "This adaptor class can be used with any C++11 or C++03 allocator including those allocators whose pointer type is a smart pointer." I don't see how this could possibly work with a smart pointer when aligned_allocator_adaptor explicitly uses raw pointers. Your tests pass for we with msvc 9.0-12.0, gcc-mingw-4.6.2, and clang-3.4 on Windows and with gcc 4.7.2 on Linux. aligned_allocator.hpp:100 aligned_free(memory); This is vulnerable to ADL if std::aligned_free is ever created (or my_ns::aligned_free for that matter). (Note that the corresponding aligned_alloc is safe becase std::size_t has no associated namespaces) aligned_allocator.hpp:104 enum { Size = static_cast<std::size_t>(-1) / sizeof(T) }; There's absolutely no reason to use an enum as far as I can see. You can just return this value. aligned_allocator.hpp:139 memory->~U(); I seem to recall msvc warning that memory is unused in cases like this. You may need to supress the warning. detail/align.hpp:28 if (n1 <= space && size <= space - n1) You might add a comment about avoiding overflow, so that no one is tempted to refactor it into an simpler "equivalent" test. test/Jamfile.v2: This is a lot more verbose than it needs to be. Try just: import testing ; run align_test.cpp ; run aligned_alloc_test.cpp ; ... test-suite is obsolete (it just groups all the targets under a single name, which is completely pointless when that's all you have in the Jamfile) and the braces just create a compound statement (like in C++) test/align_test.cpp: You need to test the following: - There is not enough space in the buffer. - In particular, you need to validate the exact boundaries where align starts to return 0. test/aligned_alloc_test.cpp: You need tests for the following conditions: - size == 0 - size < alignment - size > alignment && gcd(size, alignment) != alignment - the allocation fails because size is too large. - Also write to the allocated memory to (hopefully) verify that the data structure used by aligned_alloc is safely outside this region. test/aligned_allocator_adaptor_test.cpp: You're only testing allocate/deallocate. You also need tests for the other members. - rebind - copy constructor/copy assignment operator - construct/destroy - allocate with a hint - allocate with 0 size test/aligned_allocator_test.cpp: same as aligned_allocator_adaptor_test.cpp. test/is_aligned_test.cpp You need tests for: - is_aligned returns false. Your entire test suite would pass with bool is_aligned(...) { return true; } In Christ, Steven Watanabe

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symbolic link missing in modular-boost/boost/numeric
by David Bellot 31 Mar '14

31 Mar '14

Hi, it seems the symbolic link to ublas is missing in "modular-boost"/boost/numeric. I would be very grateful if someone with more admin rights than me could add it and commit it please ? Many thanks. Best regards, David

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[git][iostreams] Forking without an established merge point
by Bjorn Reese 31 Mar '14

31 Mar '14

If I look at the develop branch of Boost.Iostreams then GitHub says that "This branch is 253 commits ahead and 91 commits behind master". It appears that Boost.Iostreams has not established a merge point between master and develop as described in: https://svn.boost.org/trac/boost/wiki/PostCvtMergePoint I am trying to fork Boost.Iostreams to create some patches for it. Normally I would need to work off the develop branch (or a branch originating from develop), but if I do so my pull-requests will include the entire commit history of the component. If I look at the network graph of Iostreams, it appears that everybody else branches off the master branch. How do I proceed?

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[GSOC 2014] Boost.Thread / Work-Stealing-Thread-Pool
by Shuxiong Ye 30 Mar '14

30 Mar '14

Hi boost community, My name is Shuxiong Ye, and I am applying GSOC2014. My proposal is here[1]. There are very few comments on it. Any suggestions or questions will be welcome to improve it. Thanks. [1] https://google-melange.appspot.com/gsoc/proposal/review/student/google/gsoc… Shuxiong Ye

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New numeric data type proposal
by Damian Alberto Vicino 30 Mar '14

30 Mar '14

Hi, I work in a simulation tools' research group and we developed a basic data type for handling time representation that we want to share. The data type is kind of a mix between MultiPresicionFloatingPoint and Rational. We are using this kind of data type in concrete simulator implementations because of a theoretic problem with the formalisms we implement, in which the floating point error can not be bounded. We published a paper in Simutools14 a few days ago explaining how this unbound errors are reached under a specific formalism (DEVS) and why they are not easy to detect. I can share the paper if someone interested in the details, or provide some toy examples to discuss. And we are working in showing same kind of errors in other formalisms. A simplified version of the proposed data type is: Number<N, D, M, E> where in the common case the four are some integer-like type. The number can be interpreted as N/D * M * 2^E where N and D are never modified unless required for operation of compatibility. Compatibility operation is called when an operation between 2 numbers having different N/D happens. It can also be thought as a variable radix MPFP. We choose this implementation because when used as replacement of integer or float, it doesn’t decrease significantly the performance. It only decrease significantly when operating with values that were not representable in any of those (if we simplify N/D). I will love to discuss implementation details, alternative ideas to handle the problem (this one worked for us, but sure there is other options too that may be more generic or performant in generic scenarios). Also, I’m up to code the whole thing, and to share the naive implementation we got in our simulator so far to start the discussion. Best regards, Damian Vicino

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[spirit] How to detect Spirit.Qi expressions?
by Andrey Semashev 30 Mar '14

30 Mar '14

Hi, Is there a way to detect at compile time that a certain type is a Boost.Spirit.Qi parser? That includes template expressions and grammars. Basically, I want to detect if qi::parse(b, e, expr) would be a sensible thing to do. I tried this: boost::is_same< typename proto::domain_of< ExpressionT >::type, spirit::qi::domain > But domain_of returns default_domain for Boost.Spirit.Qi template expressions.

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Getting fully uptodate
by Paul A. Bristow 29 Mar '14

29 Mar '14

Sync SHA-1: 44d48257a7eb39837880afb81ceb2153e86e5a8c * Changed Boost.Log to Boost.Sync in the supported compilers section. Fixes #9388. Current HEAD detached, you are working on (no branch). Do you want to create branch now? Chose "no" [detached HEAD 3a9d142] deletions 37 files changed, 4971 deletions(-) delete mode 100644 include/boost/sync/condition_variables/condition_variable.hpp delete mode 100644 include/boost/sync/condition_variables/cv_status.hpp delete mode 100644 include/boost/sync/condition_variables/notify_all_at_thread_exit.hpp delete mode 100644 include/boost/sync/detail/condition_variables/basic_condition_variable_windows.h pp delete mode 100644 include/boost/sync/detail/condition_variables/condition_variable_posix.hpp delete mode 100644 include/boost/sync/detail/condition_variables/condition_variable_windows.hpp delete mode 100644 include/boost/sync/detail/config.hpp delete mode 100644 include/boost/sync/detail/footer.hpp delete mode 100644 include/boost/sync/detail/header.hpp delete mode 100644 include/boost/sync/detail/interlocked.hpp delete mode 100644 include/boost/sync/detail/link_config.hpp delete mode 100644 include/boost/sync/detail/mutexes/basic_mutex_windows.hpp delete mode 100644 include/boost/sync/detail/mutexes/mutex_posix.hpp delete mode 100644 include/boost/sync/detail/mutexes/mutex_windows.hpp delete mode 100644 include/boost/sync/detail/pthread.hpp delete mode 100644 include/boost/sync/detail/system_error.hpp delete mode 100644 include/boost/sync/detail/throw_exception.hpp delete mode 100644 include/boost/sync/detail/time_traits.hpp delete mode 100644 include/boost/sync/detail/time_units.hpp delete mode 100644 include/boost/sync/detail/tss.hpp delete mode 100644 include/boost/sync/detail/waitable_timer.hpp delete mode 100644 include/boost/sync/detail/weak_linkage.hpp delete mode 100644 include/boost/sync/exceptions/lock_error.hpp delete mode 100644 include/boost/sync/exceptions/resource_error.hpp delete mode 100644 include/boost/sync/exceptions/runtime_exception.hpp delete mode 100644 include/boost/sync/exceptions/wait_error.hpp delete mode 100644 include/boost/sync/locks/lock_guard.hpp delete mode 100644 include/boost/sync/locks/lock_guard_fwd.hpp delete mode 100644 include/boost/sync/locks/lock_options.hpp delete mode 100644 include/boost/sync/locks/shared_lock.hpp delete mode 100644 include/boost/sync/locks/shared_lock_fwd.hpp delete mode 100644 include/boost/sync/locks/unique_lock.hpp delete mode 100644 include/boost/sync/locks/unique_lock_fwd.hpp delete mode 100644 include/boost/sync/locks/upgrade_lock.hpp delete mode 100644 include/boost/sync/locks/upgrade_lock_fwd.hpp delete mode 100644 include/boost/sync/mutexes/mutex.hpp delete mode 100644 include/boost/sync/traits/is_condition_variable_compatible.hpp Success (78 ms @ 29-Mar-14 15:49:53) All appears OK, I:\modular-boost\libs\sync>git status HEAD detached from 44d4825 nothing to commit, working directory clean but the Tortoise GIT folder icon for /libs/sync is still red (Red ! icon means "modified"?) so I have committed to develop and it is still red :-( Fumbling, I have tried a git.exe submodule update --init -- "libs/sync" No submodule mapping found in .gitmodules for path 'libs/sync' git did not exit cleanly (exit code 1) (875 ms @ 29-Mar-14 17:09:10) Suggestions as to what I am misunderstanding/doing wrong to get develop branch to a fully uptodate state? Paul PS I have a similar problem with /tools/regression/build where there appear to be no modifications and nothing to revert, but the build folder icon is red, leaving me uneasy that a red face will follow ;-) I've added the build vcide folder items and committed and finally the icon is green. This doesn't feel something that I should have to do in order to get uptodate... so I must be missing something. It would be quicker to clone from scratch! Paul A. Bristow Prizet Farmhouse Kendal UK LA8 8AB +44 01539 561830 07714330204

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Post-git forking process
by Sohail Somani 29 Mar '14

29 Mar '14

Hey all, Often, I find bugs in Boost that I need to patch manually before the next release. What I used to do before was keep a copy of Boost in my source tree which made this easier: just patch it directly. This made it easy to modify, but annoying to post patches and honestly, they just got lost most of the time. With Git, it should become easier to contribute said patches as well as pull in whichever particular changes I need. However when I attempted such a fork recently, I was a bit lost. As I understood it, the process should have been: 1. Create a fork of https://github.com/boostorg/boost and use this fork in my project 2. Create a fork of the library/libraries I wanted to patch 3. Update the submodules in my boostorg/boost fork to point to my forked libraries 4. Post a pull request for the respective libraries. Once the changes have been accepted, point back to the official boostorg repo I failed terribly, no doubt due to PEBKAC. Is there a chance that someone could write a tutorial or a how-to guide for the recommended process of forking Boost with Git? The main thing I need is the ability to have a patched version of Boost that I can use while the patches are being reviewed/accepted/rejected. Thanks, Sohail

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[variant] assign and access the assigned value simultaneously
by feverzsj 28 Mar '14

28 Mar '14

hi list, for common case: boost::variant<Val,...> var; var = val; Val& v = boost::get<Val>(var); why not supply a interface like: Val& v = var.assign(val); for simplity, and the unnecessary "get" is also elimited. regards -- View this message in context: http://boost.2283326.n4.nabble.com/variant-assign-and-access-the-assigned-v… Sent from the Boost - Dev mailing list archive at Nabble.com.

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1.56 release
by Barend Gehrels 27 Mar '14

27 Mar '14

Hi, The last message about the release schedule was (if I see it correctly) at January 15, and the calendar is empty. Is there more news about the release planning? I'm especially interested in the planning for the 1.56 release. Thanks, Barend Gehrels

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[Parallel Algorithms] Queries regarding the Boost. Thread / Parallel Algorithms
by Naveen 27 Mar '14

27 Mar '14

Hi, I am look into various available reduction algorithms available to make a performance comparison for boost threads. I made a decent search on all the documents available for various reduction algorithms. If there are any specific implementations, please share the details. Regards, *NAVEEN* | Mobile: 832-720-2393 | about.me <http://about.me/naveen.namashivayam> |

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Creating a new(-ish) library in modular boost ?
by Paul A. Bristow 26 Mar '14

26 Mar '14

I have fumbled (and stumbled) trying to create a revised-possibly-to-be-proposed for Boost library in the new modular boost format. So far I have created a folder /modular-boost/svg_plot And copied all the files into it in the new modular format and got the library working OK (compiling, tests, examples, docs etc). Then I created my repository by doing I:\modular-boost\libs>git init svg_plot Initialized empty Git repository in I:/modular-boost/libs/svg_plot/.git/ Then I GIT Added various files, and committed these to my repository. (Should I have pushed?) I tried to tell git to ignore some files like log files, etc (but I don't get a .gitignore file when I think I should - the Tortoise GIT window has various options like .gitignore in the repos root, but no 'OK' button, just a close??? I have a .gitignore at /modular-boot/ but it does not contain the files to ignore (and I would not expect it to). I've set the GITHub default storage directory to \modular-boost\libs but a scan for repos only find modular-boost I went to my GITHUB page and followed the invitation to drag the svg_plot repository onto the page. Some files are listed (but ones I want to ignore) and then all options are unresponsive or greyed out and eventually GITHUB hangs and then crashes :-( So both GIT and I are confused ! Can anyone suggest what sequence of actions I should take to set this up? Thanks Paul Paul A. Bristow Prizet Farmhouse Kendal UK LA8 8AB +44 01539 561830 07714330204

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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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