November 2017 - Boost - lists.preview.boost.org

MSVC toolset versions on VS2017
by Tom Kent 20 Nov '17

20 Nov '17

I just came across this article on feature updates for their compiler during the VS2017 lifetime, I thought the section talking about version numbers might be of interest to the boost build maintainers and boost config maintainers. The blog post can be found here: https://blogs.msdn.microsoft.com/vcblog/2017/11/15/msvc-conformance-improve… The interesting part about version numbers is three-quarters of the way down the post, under the "MSVC toolset version number increases to 14.12". The … [View More]

2 1

[multiprecision]: 15% slowdown using -std=c++11 compiler flag
by Kim Walisch 20 Nov '17

20 Nov '17

I have been investigating a 15% performance regression in my C++ primesum program (https://github.com/kimwalisch/primesum/tree/256-bit) over the last 2 days. By lots of benchmarking I was able to identify the boost multiprecision library together with -std=c++11 (or -std=gnu++11) as the culprit for the performance regression because I have also a version of the primesum program which does not use the boost multiprecision library and in this version there is no performance regression when … [View More]

2 2

[contract] _NOEXCEPT errors in <ostream> for Clang 5.0 C++1z on Teeks Linux
by Lorenzo Caminiti 20 Nov '17

20 Nov '17

Hello all, Most of Boost.Contract regression test fail for toolset clang-gnu-linux-5.0~c++1z~lc on platform teeks99-02-dc5-1z-lc-Docker-64on64 because of the following error on #include <ostream> done by Boost.Range (and sometimes by Boost.IOStreams): "clang++-5.0" -c -x c++ -Wno-c99-extensions -std=c++1z -stdlib=libc++ -isystem/usr/include/libcxxabi -O0 -g -fno-inline -Wall -g -fPIC -m64 -DBOOST_ALL_NO_LIB=1 -DBOOST_CONTRACT_DISABLE_THREADS -DBOOST_CONTRACT_DYN_LINK -… [View More]

5 9

[operators] A modern SFINAE-based version of boost::operators?
by Beman Dawes 19 Nov '17

19 Nov '17

Peter Sommerlad, committee member and C++Now presenter who often proposes additions to fill in holes in the standard library, asked me: Are you aware of anybody who tried to provide a boost::operators style of automatically providing additional operators with a single base class that through SFINAE injects all possible operators based on the ones defined in the template parameter? This won't give you the control of the current boost::operators, but would be much easier to teach. For example … [View More]

14 31

[python] Incorrect link
by Christian Henning 19 Nov '17

19 Nov '17

Hi all, on page http://boostorg.github.io/python/doc/html/tutorial/tutorial/embedding.html the link to http://www.python.org/doc/api/exceptionHandling.html is dead. Perhaps, it should be this link: https://docs.python.org/3/tutorial/errors.html Regards, Christian

1 0

[release] Boost 1.66.0 Beta 1 Release Candidate 2
by Daniel James 19 Nov '17

19 Nov '17

The release candidates for the 1.66.0 beta release are now available at: <https://dl.bintray.com/boostorg/beta/1.66.0.beta.1/source/> You need to scroll past the first release candidates to find the downloads. The SHA256 checksums are as follows: e7b23e638e8c3a9da1512439385b04850829cea7bd56d8398677c096857d830b boost_1_66_0_b1_rc2.7z 5d0405eb73bd609ebcd54bbc96d4f1e2d97c51b96c4703706695ddd94f942d6b boost_1_66_0_b1_rc2.tar.bz2 … [View More]

3 2

Re: [boost] Adding polymorphic_value to boost
by Tom 19 Nov '17

19 Nov '17

> Message: 10 > Date: Thu, 16 Nov 2017 02:14:30 -0700 > From: Jonathan Coe <jonathanbcoe(a)gmail.com> > To: boost(a)lists.boost.org > Cc: Matt Calabrese <calabrese(a)google.com> > Subject: [boost] Adding polymorphic_value to boost > Message-ID: > <CAAbBDD9Ck+LhQ4iUraBtBkxexVKDt167qxyfTpDQqYM9bcMqLQ(a)mail.gmail.com> > Content-Type: text/plain; charset="UTF-8" > > I'd like to propose adding the class-template `polymorphic_value` to boost. > … [View More]> `polymorphic_value` is designed to allow the compiler to correctly generate > special member functions for classes with polymorphic components (It's > `any` with an interface). > > `polymorphic_value` has been proposed for standardisation in P0201 and has > advanced through the Library Evolution group in Albuquerque (Nov 5-10). > https://wg21.link/p0201 > > A working draft of the proposal and implementation can be found at > https://github.com/jbcoe/polymorphic_value > > I gave a presentation about polymorphic_value at C++::London here: > https://skillsmatter.com/skillscasts/9539-a-polymorphic-value-type-for-c-pl… > > Matt Calabrese has kindly offered to be review manager. > > Kind regards, > > Jon Hi, I'd be interested in such a utility. Mathias Gaunard proposed something similar on the mailing list a long while ago, I implemented a simple version myself based on that. I have a small number of questions. Given that this is a value type, does the current approach over-expose pointer (ownership) in the interface (in essence it still appears to be a glorified smart pointer) and understate its more fundamental purpose as a regular value with dynamic type? There might be other things which can usefully be added for such a value type, for example permitting direct construction of an object of specific (derived) type, by passing the type as well as the arguments for the constructor of that type (or wrapping the arguments in some kind of in-place factory with explicit type). Something like: // Simple wrapper to enable a static type to be passed through a forwarding constructor. template <typename T> struct Type {}; // Forwarding constructor - actual type is deduced from type wrapped in (unnamed) first argument's type template <typename D, typename... Args> explicit poly_obj(Type<D>, Args&&... args); // Also could have an emplace member function template <typename D, typename... Args> void emplace(Type<D>, Args&&... args); In theory you wouldn't need to expose pointers in the interface at all? In fact, should a type-erasure library be preferred (e.g., Boost.TypeErasure or Adobe.Poly) as it provides a more general solution for manipulating polymorphic value types (though typically harder to use)? Would you be considering supporting C++98 via using the boost::move library? Regards, Tom [View Less]

1 0

[gil][test] HOWTO set up the Boost testing process for projects with extra prerequisites ?
by Stefan Seefeld 17 Nov '17

17 Nov '17

Hi, I just merged some work to GIL's `develop` branch. This notably involves improvements to the testing infrastructure. Testing GIL is a bit involved, as it requires various backend libraries (PNG, JPEG, TIFF, etc.) to be installed. While the stand-alone testing works fine (https://github.com/boostorg/gil/blob/develop/.travis.yml#L304-L306) the integrated testing will thus fail, until the testing logic is augmented by the necessary instructions to a) install the prerequisites and b) invoke … [View More]

3 8

[density] paged memory and concurrency
by Giuseppe Campana 17 Nov '17

17 Nov '17

Hi, in the last year I’ve been experimenting concurrent data structures on density, a C++11 library focused on: - Page-based memory management. - Heterogeneous and function queues. Single-threaded, mutex-ed, lock-free and spin-locking versions are available. Lock-free and spin-locking queues support any combination of single/multiple producers/consumers. - Lifo memory management, mainly to provide a safe alternative to alloca with almost the same performances. - Parametric control of the … [View More]

1 0

Re: [boost] [Boost-users] Could guys help me on a boost MPI link error
by degski 16 Nov '17

16 Nov '17

On 16 November 2017 at 07:33, Renfan Luo <Renfan.Luo(a)perpetuum.com> wrote: > Thanks a lot! After changing X64 to X86 on the top of drop-down window > of IDE, the problem has been fixed. > You're welcome, degski

1 0