February 2014 - Boost - lists.boost.org

Call for Review: Boost.Test documentation rewrite
by legalize+jeeves＠mail.xmission.com 19 May '14

19 May '14

[Please do not mail me a copy of your followup] Boost.Test documentation rewrite: <http://user.xmission.com/~legalize/tmp/boost.test/libs/test/doc/html/> Please post all comments to this list. I've been working on this as time permits for a number of months and I think now things are "finished" enough to warrant wider review. It is a true rewrite using quickbook; I generally used the implementation source code as the answer to my questions about things while writing the documentation. Early snapshots were reviewed by Tom Kent, Alexander Lamaison, Paul A. Bristow and Julian Gonggrijp. A special thanks to them for providing me with useful feedback and suggestions. The main thing that still remains to be added is a detailed explanation of the floating-point comparison algorithms used by BOOST_REQUIRE_CLOSE, BOOST_REQUIRE_CLOSE_FRACTION and BOOST_REQUIRE_SMALL. The corresponding examples also need to be updated. The existing online documentation has had all the math symbols stripped out of it, so it is pretty useless. I'm probably just going to typeset the formulas with LaTeX and then capture them as images that are included in the documentation. (See <https://svn.boost.org/trac/boost/ticket/9539>) I'm guessing that modular boost should allow me to clone libs/test, make all my changes there and then issue a pull request, but I'm not sure how far along things are with the git transition? -- "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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required toolsets
by Steven Watanabe 14 May '14

14 May '14

AMDG The list of required toolsets in explicit-failures-markup.xml is out-dated. Therefore, if no one objects, I propose setting it to the following: msvc-10.0, msvc-11.0, gcc-4.6, gcc-4.7, clang-darwin-11, clang-darwin-4.2.1, clang-linux-3.1, clang-linux-3.2, gcc-mingw-4.7, gcc-mingw-4.6 (two releases of each major compiler that appears in both the trunk and release regression tests) The sole effect of this is to determine which toolsets appear in the issues list: http://www.boost.org/development/tests/trunk/developer/issues.html In Christ, Steven Watanabe

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[atomic] Support for specialized instructions
by Andrey Semashev 14 May '14

14 May '14

Hi, I've been contemplating the idea of adding support for some specialized atomic instructions to Boost.Atomic. Since I'm only familiar with x86 architecture, my current candidates are: * Increment/decrement with a check for zero result (lock inc/dec). The decrement is the most essential of the two because it would be useful for reference counters of various kinds. The increment is mostly beneficial in terms of code size, and it probably doesn't need the check for zero in most cases. * In-place logical operations (lock and/or/xor). These are useful in cases when the code needs to operate on flags or bit sets but doesn't need the result of the operation. Optional variants can be provided with a test for zero result. * Bit set/reset operations (lock bts/btr). The use cases are similar to the logical operations but the advantage is that the previous value of the altered bit can be returned. BTW, these operations are needed in Boost.Sync to implement mutexes on Windows. All these operations can be implemented through the standard atomic<> interface, and that's what would be done on platforms without support for the specialized instructions. For now the idea is to add special member functions to atomic<>, when used with arithmetic types. I was thinking about providing free functions as well, although I think that the complete set of the standard atomic functions would be required for that. Comments? Opinions?

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Why no non-null smart pointers?
by Ross MacGregor 29 Apr '14

29 Apr '14

I just created a very small smart pointer libary for our project. It will contain two types of shared pointers: SharedHandle and NullableSharedHandle. SharedHandle will be a shared pointer that cannot be null by ensuring a non-null construction while NullableSharedHandle will basically be a typedef for boost::shared_ptr. I firmly believe that code can be made more reliable by minimizing the use of nullable pointers. To this end, I think it is important that we start using non-null pointer types. Ideally the compiler would be able to understand a non-null pointer and catch bugs at compile time, but I think we can still improve things with a few runtime checks. If we make sure that a shared pointer is constructed with a non-null pointer and ban any reset() type methods, we guarentee that it points to something. This can be beneficial for the following reasons: 1. Any function that uses this type will no longer be burdened with precondition checks to make sure variables of this type are not null. 2. It's type is simply more explicit and better explains its function. 3. Moving the non-null check to the creation phase will reduce the possibility of encountering null pointer exceptions at runtime (assuming there are many more pointer references than constructor calls). So my little pointer library seems to make a lot of sense, but if so why hasn't this simple smart pointer variation made it into boost yet? Has this been discussed somewhere already? My search on non-null smart pointers is not revealing much discussion on the topic. Regards, Ross

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[algorithm] Review Request: edit_distance
by Erik Erlandson 14 Apr '14

14 Apr '14

I would like to request a formal review for inclusion of the edit_distance() function. Description: The edit distance is the length of the shortest (or least-cost) edit script from one sequence to another, where an edit script is defined as a sequence of insertion, deletion and (optionally) substitution operations. The function implementing the edit distance is named edit_distance. This function will return the edit distance between two sequences, where sequences may be any valid range object supporting forward iteration. The edit_distance function will also, if requested, return the edit script. http://en.wikipedia.org/wiki/Edit_distance Documentation: http://erikerlandson.github.io/algorithm/libs/algorithm/doc/html/algorithm/… Code resides on a branch of my fork of Boost.Algorithm: https://github.com/erikerlandson/algorithm/tree/edit_distance The feature branch above includes the doc, unit tests and examples that are integrated via Jamfiles. The new dev resides specifically in this subdir: https://github.com/erikerlandson/algorithm/tree/edit_distance/sequence I have built the tests and examples on gcc and clang, with and without c++11 mode. I don't have access to a windows/MSVC build env, so I am definitely curious if it compiles properly in that env. My concept is that boost::algorithm::sequence can eventually serve as a home to additional related algorithms, for example other sequence comparison algorithms or perhaps other categories of sequence-related algorithms.

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boost::optional -- updates for C++11 move semantics
by Diggory Hardy 10 Apr '14

10 Apr '14

Dear list, I wanted something like boost::optional, but with support for move- construction/assignment, so I went ahead and had a go at patching it. Attached is based on boost 1.49 (Ubuntu package). Could someone please review? I've not contributed to boost before. The changes at least aren't too complicated, but: 1) I'm not entirely sure if the move constructor (line 636) and swap function (line 1046) are implemented in the best way (also see line 279), 2) and I have no idea how is_[not_]reference_tag (line 486) works. 3) There should maybe also be a unit test. Of course, I am happy for my contributions to be published under the boost licence. Regards, Diggory

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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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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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[algorithm] Test failure in C++14
by Ben Pope 24 Mar '14

24 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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