March 2016 - Boost - lists.preview.boost.org

Re: [boost] Boost CRC maintainer (Daryle Walker) missing in action?
by Olaf van der Spek 19 Jun '17

19 Jun '17

Hi Daryle, Any luck on your new setup? Gr, Olaf On Mon, Nov 28, 2011 at 1:11 AM, Daryle Walker <darylew(a)gmail.com> wrote: > I can look at it once I've finished my new setup. > > I had to reset my computer after a partial crash years ago. I never > got around to recreating my programming setup. My computer had been > at its maximum Operating System level back then, which is now 3 > versions behind. For the past few months, I've had my sister's old > laptop, with Windows Vista, and am trying to add a programming setup > to it now. > > > On Tue, Nov 22, 2011 at 7:18 AM, Beman Dawes <bdawes(a)acm.org> wrote: >> Hi Daryle, >> >> This guy has volunteered to take over maintenance of Boost CRC. Should >> we take him up on his offer? > >> ---------- Forwarded message ---------- >> From: >> Date: Wed, Nov 2, 2011 at 7:51 AM >> Subject: [boost] Boost CRC maintainer (Daryle Walker) missing in action? >> To: boost(a)lists.boost.org >> >> >> Hi, >> >> It looks like the Boost CRC maintainer (Daryle Walker) is missing in action? >> >> No response to tickets from the past 3 years. What's the procedure in this case? >> >> https://svn.boost.org/trac/boost/ticket/2492 >> https://svn.boost.org/trac/boost/query?component=crc&col=id&col=summary&col… > > -- > Daryle Walker > Mac, Internet, and Video Game Junkie > darylew AT gmail DOT com -- Olaf

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[msm] [statechart] unmerged PRs
by András Kucsma 23 May '17

23 May '17

Hi Everyone, There are a couple of PRs for msm and statechart by me and others, which didn't get any attention for many months now. Can the maintainers please take a look at them? https://github.com/boostorg/msm/pulls https://github.com/boostorg/statechart/pulls Thank you, Andras

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[container] moving a pre-built vector into a flat_set
by Sam Kellett 12 Mar '17

12 Mar '17

a common problem i encounter is that i have two stage's w/r/t to a large collection of data: building and querying. vector is obviously the king of building. flat_set is the king of querying. so what i often tend to do is build up a very large vector, sort it then create a flat_set using the flat_set(ordered_unique_t) constructor. however this still copies the entire vector into the flat_set, right? what i would like to be able to do is move the vector straight into the flat_set, something like: std::vector<T> data; flat_set data_set1(std::move(data)) // move vector in and sort it // or: std::sort(data.begin(), data.end()); // sort vector flat_set data_set2(ordered_unique_t, std::move(data)) // and move it in is this doable (am i just being blind?) or is there plans/interest for this?

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[nowide] Library Updates
by Artyom Beilis 04 Mar '17

04 Mar '17

Hello, Disclaimer: --------------- I recently discovered that virtually all e-mails sent from Yahoo account to any mailing lists go to user's spam due to recent Yahoo's DMARC policy. So I'm sending some important stuff from GMail account that almost certainly was missed: What is Boost.Nowide: -------------------------------- Boost.Nowide is a library that make cross platform Unicode aware programming easier. The library provides an implementation of standard C and C++ library functions, such that their inputs are UTF-8 aware on Windows without requiring to use Wide API. It was inspiration and inspired by http://utf8everywhere.org/ development ideas and policy. Some updates regarding Boost.Nowide ------------------------------- 1. Library moved to github and its format is converted to modular boost layout: https://github.com/artyom-beilis/nowide 2. Fixed unsupported std::ios::ate flag by boost::nowide::fstream 3. Added some C++11 interfaces to boost::nowide::fstream 4. Added integration functionality with boost::filesystem: https://github.com/artyom-beilis/nowide/blob/master/include/boost/nowide/in… Note: that the links to the source code on review schedule aren't relevant, it should be: - Code: https://github.com/artyom-beilis/nowide - Documentation: http://cppcms.com/files/nowide/html/ Also the library is still looking for review manager. Artyom Beilis P.S.: I'm sorry if you are getting this as "duplicate"

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[MPL] A Proposal
by Bruno Dutra 16 Nov '16

16 Nov '16

Dear Community, About a year ago today, there was a proliferation of threads [1][2][3] in this mailing list concerning the future of Boost.MPL, or even whether it had a future at all, and opinions diverged widely on the matter. Many have expressed concerns about the fact Boost.MPL was long outdated and proposed major changes to open path for modernization, while some others argued against it, fearing unexpected and disastrous side-effects could propagate throughout the rest of Boost. A few questioned if it was worth it at all to spend any further resources on Boost.MPL given the fact new alternatives were coming up, such as Boost.Hana, which departed entirely from template metaprogramming, yet some argued TMP remained a competitive alternative for type computations in C++14 as it has been demonstrated by Peter Dimov in his impressive articles [4] on modern TMP. Amidst all this, a proposal by Robert Ramey [5] caught my attention and inspired me to develop what I call Metal [6], a template metaprogramming library designed on the same core principles as Boost.MPL, but written from the very beginning to take full advantage of C++11. Metal was not designed to be a strict drop in replacement for Boost.MPL though, it was rather meant to be regarded as a modern version of Boost.MPL's original API, diverging only where it could really benefit from modern C++ and that essentially means gains of several orders of magnitude in performance** and lower memory consumption. At this point Metal is very close to where I originally intended to bring it and I think it's time I gauge interest from the community on a modest proposal I've been maturing along the past year. As a modern approach to the same task that Boost.MPL was meant to address, I don't believe Boost would benefit at all from yet another TMP library that would essentially compete with Boost.MPL and even Boost.Hana in some cases, specially as maintainers of older code that depends on Boost.MPL would have to go through major refactoring efforts in order to benefit from such an addition to Boost. I would like to propose something different instead. My proposal is to make Metal officially into a new revision of Boost.MPL's API, essentially MPL2 as the original proposal by Robert Ramey put it, merging both into one single TMP library. The idea would be to provide a thin proxy for the current Boost.MPL API which would have two backends configurable by preprocessor switches: the original implementation and a another one based on Metal. This way older code using Boost.MPL could see immediate gains on performance by selecting the newer backend on supported compilers, while at the same time legacy code maintained on older compilers could still rely on Boost.MPL's impressive ability to run virtually anywhere. On the other hand, newer projects interested on pure type computations would have the newer API entirely available to them. This proposal also overcomes the problem of dealing with the maintainability of Boost.MPL, since it provides a way for smooth transition from legacy hacks required by ancient compilers into a cleaner and easier to maintain C++11 codebase, besides avoiding any breaking changes within existing code in the process. Furthermore, should this proposal make it into Boost, I would be naturally willing to take responsibility for the maintenance of Boost.MPL, which AFAIK has been maintained by the CMT for quite some time now, often with limited resources. Comparing Metal and Boost.MPL there are a few noteworthy differences. Metafunction Classes have proven themselves entirely unnecessary and have thus been removed altogether in favour of pure Lambdas (in the Boost.MPL sense). Moreover, iterators make little sense in a functional world, so these too have been removed despite the fact they may easily be emulated in the new design. Moreover Metal develops the concept of optionals, that is, its metafunctions only have a nested ::type defined when they may be successfully computed, what may be safely tested using metal::is_just and may also be used to SFINAE out of miscomputations. Finally I'd like to point out that Metal was designed to be portable across as many compilers as possible and three of the most popular ones are continuously tested using Travis and Appveyor: Clang 3.5+, GCC 4.8+ and MSVC 14 (2015). I hope this is a reasonable proposal and I look forward into your opinions about it. ** Even though I haven't published any benchmarks yet, an example follows just to back my claims regarding performance (just tested on my personal laptop running linux): //Generate a list containing 10 thousand instances of std::integral_constant, from 0 to 9999 using l = metal::enumerate_t<metal::integer<10000>>; // GCC 5.3 ~0.4 s // Clang 3.7 ~0.5 s //Transform a list containing 5 thousand numbers by squaring each element using l1 = metal::enumerate_t<metal::number<long long, 5000>>; using l2 = metal::transform_t<metal::pow<metal::_1, metal::integer<2>>, l1>; // GCC 5.3 ~5.6 s // Clang 3.7 ~3.0 s [1]: http://thread.gmane.org/gmane.comp.lib.boost.devel/257680 [2]: http://thread.gmane.org/gmane.comp.lib.boost.devel/257983 [3]: http://thread.gmane.org/gmane.comp.lib.boost.devel/258843 [4]: http://pdimov.com/cpp2/simple_cxx11_metaprogramming.html [5]: http://rrsd.com/blincubator.com/bi_suggestion/mpl-lite-or-mpl2/ [6]: http://brunocodutra.github.io/metal/ Regards, Bruno Dutra

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[config] RFC PR 82
by Domagoj Saric 01 Aug '16

01 Aug '16

Hi everyone, I am finally getting back to (trying to) contributing some of my personal projects to Boost. For two of those, Err (https://github.com/psiha/err) and especially Functonoid (a C++11 generalization and rewrite of my previous Boost.Function related work) I need some lower level codegen and/or optimiser control functionality (i.e. portable macros wrapping toolset specific attributes and pragmas) that I've added to my personal fork of Boost.Config and which I've now submitted in the subject PR (https://github.com/boostorg/config/pull/82) I don't expect this PR to be accepted as is/'just like that' so I'm opening this thread where we can discuss which of those changes/macros are welcome, which need more work and which, for some reason, should not be part of Boost.Config (and which, in turn then, I have to move to some 'internal implementation headers' in libraries that will need them). To avoid 'spamming' (and save time;) I'll skip the explanation of the individual macros as I expect them to mostly be self-explanatory (if not from their name then from the minimal Boost.Config documentation additions that are part of th PR). ps. I'll be on the (off) road for the next three weeks so I don't know when I'll be able to respond until I get back... -- "What Huxley teaches is that in the age of advanced technology, spiritual devastation is more likely to come from an enemy with a smiling face than from one whose countenance exudes suspicion and hate." Neil Postman

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[clang][preprocessor] Testing of clang emualting the VC++ preprocessor on Windows
by Edward Diener 07 Apr '16

07 Apr '16

I have made local changes in the Boost preprocessor config.hpp on the 'develop' branch to have clang's emulation of the non-standard VC++ preprocessor act like the VC++ preprocessor as far as Boost PP is concerned. Boost PP has a large number of workarounds for VC++ without which Boost PP preprocessor code would not work when compiling using any version of VC++. I have tested the usual compilers extensively to make sure they are unaffected by these changes as well as the normal clang-linux implementation. Everything remains the same for these compilers with my changes so I am assured the changes will not affect any other compiler implementation. I was able to test both clang-3.8 and the latest build of clang, which is clang-3.9, by invoking clang-cl. My user-config.jam file for these entries looks like: using clang-win : 3.8 : SomePath/clang-cl : <compatibility>vc12 using clang-win : 3.9 : SomePath/clang-cl : <compatibility>vc14 By passing toolset=clang-win-3.8 or toolset=clang-win-3.9 I was able to successfully test these implementations against the Boost PP test code. There are quite a few failures in this clang emulation of the VC++ preprocessor when tested against the preprocessor test code. In fact testing clang emulation of VC++ preprocessor when I don't treat clang as VC++ in Boost PP, but as its normal C++ standard conforming preprocessor, still fails a few cases but far less than when clang is treated as VC++ in Boost PP. Needless to say when invoking clang-linux, which tests the normal clang implementation whether on Windows or Linux, there are no failures in the Boost PP tests. I am perfectly willing to push my changes to 'develop' for the preprocessor. The changes are essentially just in the Boost PP config.hpp file, which sets macros which control the compiler workarounds in Boost PP. As I have previously stated I am not personally willing to try to figure out or report to clang why their VC++ preprocessor emulation in Boost PP is failing, but others who are interested can do so if they wish. My personal reasons for this is that I think it is a very bad thing to attempt to replicate an already flawed C++ preprocessor in another compiler in general code. I also have spent enough time working with the VC++ preprocessor trying to find workarounds for its non-standard behavior that I do not want to do so for another preprocessor which attempts to be non-standard. I posted this to alert others to my plans to update Boost PP on 'develop' with this change, in case anybody is greatly opposed to it or wants to discuss it further. The change will not affect any other compiler but clang in VC++ preprocessor emulation mode. Unless I hear objections etc. I plan to push my update within the next day although I will wait awhile for any replies to this post.

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Nasty compile time reflection and iteration for POD types using C++14 without macro
by Antony Polukhin 07 Apr '16

07 Apr '16

Hello, I've come up with a trick that may be useful in Boost.Hana, Boost.Serialization or some other libraries. Here's a small motivating example: #include <cstdio> #include <boost/type_index.hpp> #include "magic.hpp" struct foo { unsigned char i0; unsigned int i1; unsigned short i2; unsigned long long i3; unsigned char ar[2]; int q; std::size_t w; int* p1; const void* p2; int const**const**** p_crazy; const double d; }; template <std::size_t I, class T> void print(T& f) { printf( "%lu\t\t%s\n", (std::size_t)get(f), boost::typeindex::type_id<decltype(get(f))>().pretty_name().c_str() ); } int main() { foo f {10, 11, 12, 13, {14, 15}, 16, 17, 0, 0, 0, 30.0}; print<0>(f); print<1>(f); print<2>(f); print<3>(f); print<4>(f); print<5>(f); print<6>(f); print<7>(f); print<8>(f); print<9>(f); print<10>(f); print<11>(f); static_assert(tuple_size<foo>() == 12, "failed tuple size check"); } That example will output: 10 unsigned char 11 unsigned int 12 unsigned short 13 unsigned long long 14 unsigned char 15 unsigned char 16 int 17 unsigned long 0 int* 0 void const* 0 int const** const**** 30 double Core ideas: 1) We may detect the POD structure fields by the POD's constructor: template <std::size_t I> struct ubiq { std::size_t* ref_; template <class Type> constexpr operator Type() const noexcept { ref_[I] = type_to_id(identity<Type>{}); return Type{}; } }; template <class T, std::size_t... I> constexpr auto type_to_array_of_type_ids(std::size_t* types) noexcept -> decltype(T{ ubiq{types}... }) { return T{ ubiq{types}... }; } Here type_to_array_of_type_ids will return array with types via `types`, each element of array encodes some basic type. 2) Then we convert that array into an std::index_sequence<I...> and create a type with same layout as our POD type: template <std::size_t... I> constexpr auto as_tuple_impl(std::index_sequence<I...>) noexcept { return std::tuple< decltype( id_to_type(std::integral_constant<std::size_t, I>{}) )... >{}; } 3) Now we have a type with same layout, and we cast the structure to that type: template <std::size_t I, class T> decltype(auto) get(const T& val) noexcept { auto t = reinterpret_cast<const decltype(detail::as_tuple<T>())*>( std::addressof(val) ); return get(*t); } Drawbacks: * works for POD types only (could be possibly extended to trivial constructible type) * structures with non-default alignment are not supported * step 3) contains an UB, but even without that step we're still able to get field types of the POD type and fields count * current draft implementation does no support nested PODs (could be fixed easily) * current draft implementation works only on libc++ (could be fixed easily, requires reimplementing std::tuple) * there's no known to me way to make get<>() method constexpr * does not detect constness (because of that get<>() always returns const reference) Is there any interest in this feature? Sources https://github.com/apolukhin/magic_get/blob/master/magic2.cpp Online experiments can be done here: http://coliru.stacked-crooked.com/a/c33857e566e76ce2 -- Best regards, Antony Polukhin

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Boost 1.61.0 Beta 1
by Vladimir Prus 06 Apr '16

06 Apr '16

The first beta packages for 1.61.0 beta 1 are now available: http://boost.cowic.de/rc/boost_1_61_0_b1.zip http://boost.cowic.de/rc/boost_1_61_0_b1.7z http://boost.cowic.de/rc/boost_1_61_0_b1.tar.bz2 http://boost.cowic.de/rc/boost_1_61_0_b1.tar.gz There are no changes compared to RC2, expect for different names of the archives and different name of the top-level directory in the archives. The SHA256 checksums are as follows: 3f8888099ee6f62b412a13be916dead2bacbdd6d69e5afd5b6fea4bb738e5df4 boost_1_61_0_b1.7z 866941f0038b27fcc69ced1490b2dc5fa8d20f505d66b939a92a68ef194d1a6c boost_1_61_0_b1.tar.bz2 0b92c5fb5b91641409b9675b2fd11d3b3fa5f71dd986d3b5fb03da201bf55474 boost_1_61_0_b1.tar.gz 9dffe5ee7f5f7bf7695f5738c686e44bd266933e3ca68732b0de5520c3c82615 boost_1_61_0_b1.zip Signed list of checksums should be posted within 24 hours. As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. It was discovered that the .zip and .7z archives actually have LF line endings, at least in some places. Fixing this is not quite trivial, as Travis uses ancient version of Ubuntu and Git, and is not deemed critical, as most Windows editors handle LF just fine. We might do something for the final release, or might not. Thanks! -- The release managers

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[build] How to use with clang on windows?
by John Maddock 03 Apr '16

03 Apr '16

What's the correct way to configure clang on windows with current Boost.Build? If I use: using clang-win : 3.7 : "C:/Progra~2/MICROS~4.0/VC/Clang 3.7/bin/x86/clang.exe" : <cxxflags>-std=c++11 <compatibility>vc14 ; to configure the clang that ships with VC14 I see: compile-c-c++ ..\..\..\bin.v2\libs\smart_ptr\test\shared_ptr_basic_test.test\clang-vc14-win-3.7\debug\shared_ptr_basic_test.obj clang.exe: error: no such file or directory: '/Od' clang.exe: error: no such file or directory: '/Ob0' clang.exe: error: no such file or directory: '/W3' clang.exe: error: no such file or directory: '/GR' clang.exe: error: no such file or directory: '/MDd' clang.exe: error: no such file or directory: '/Zc:forScope' clang.exe: error: no such file or directory: '/Zc:wchar_t' clang.exe: error: no such file or directory: '/wd4675' clang.exe: error: no such file or directory: '/EHs' Same errors with the llvm clang-3.9. On the other hand if I initialize with: using clang : : "C:/Progra~2/LLVM/bin/clang.exe" : <cxxflags>-std=c++14 <compatibility>vc14 <cxxflags>-fms-compatibility-version=19.00.22609 ; Then this sort of works for llvm clang, but not the msvc one (can't find c2.exe), but the compiler is identified as "clang-linux" and I see: LINK : warning LNK4044: unrecognized option '/-start-group'; ignored LINK : warning LNK4044: unrecognized option '/Bstatic'; ignored LINK : warning LNK4044: unrecognized option '/Bdynamic'; ignored LINK : warning LNK4044: unrecognized option '/-end-group'; ignored Plus some linker errors such as: yield_k_test.obj : error LNK2019: unresolved external symbol __mm_pause referenced in function "void __cdecl boost::detail::yield(unsigned int)" (?yield@detail@boost@@YAXI@Z) Ideas? Thanks, John.

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