February 2015 - Boost - lists.preview.boost.org

boost interval arithmetic
by Павел Кудан 05 Feb '15

05 Feb '15

The difference in behaviour of comparison operators and basic arithmetic operators looks as probable misconception. Default and changeable behaviour of comparison operators consists in throwing exception in intermediate situation (intersecting intervals, ! (a>b) == (a <= b) is not applicable). Great decision for correct migration from float numeric code. The only and unchangeable behaviour of arithmetic operators consists in silent returning only one of possible intervals in intermediate situation (possible return is not single, multiple interval result). The source of mistakes and undesired behaviour at migration from float numeric. At least, throwing exception by arithmetic operators at intermediate situation would provide behaviour unity of comparison and arithmetic operators and functions. Best regards, Pavel Coodan

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[release-mgt] Name of release manager's repository?
by Beman Dawes 05 Feb '15

05 Feb '15

We used to have a directory <boost-root>tools/release that contained scripts used by release managers. As part of the modularization effort, it was separated into its own GitHub repository, boostorg/release. It is not a submodule of the boost super-module as it is primarily of interest only to release managers. That seems to me to be a "good thing". But I'm wondering if the "release" name might be confusing, since it doesn't contain releases or release tags themselves. Would renaming it "release-mgt" or similar be clearer? --Beman

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BOOST_HAS_PRAGMA_ONCE
by Stephen Kelly 05 Feb '15

05 Feb '15

Hello, As of commit 5b20f4910d8b6b48b0b6ad2df693d36edf54cf21 in the interprocess repo, the affected files seem to expect prior include of config by the the includer. Apparently this is not obvious to everyone, so it seems worth pointing out. Thanks, Steve.

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Regression tests stopped on Saturday?
by Neil Groves 05 Feb '15

05 Feb '15

Hi, I know there has been a lot go good work going on updating regression testing, and I might have missed an email. I'm currently waiting for some tests to cycle, but there appear to have been no updates since Saturday. Is this expected? Thanks, Neil Groves

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Boost regression testing on Android
by Dmitry Moskalchuk 04 Feb '15

04 Feb '15

Hi all, We've just published CrystaX NDK 10.1 (https://www.crystax.net/android/ndk) which is a drop-in replacement for the Google's Android NDK, and we've included prebuilt Boost 1.57.0 libraries there, to make life easier for those developers who want to use Boost on Android. The reason I write here is that in CrystaX NDK we were able to build Boost for Android without any changes in Boost sources, just because CrystaX NDK makes Android much more POSIX-conformant than original Android is, and Boost just works on top of it. If you're interested how we did it, please read description of CrystaX NDK release on https://www.crystax.net/android/ndk. Another important point is that we were able to run Boost regression tests on Android devices - again, without any changes in Boost sources, just providing own 'adbrunner' script as tests launcher. The only thing needed is to plug one or more Android devices to USB ports and/or run one or more Android emulators and then run script for Boost testing provided by CrystaX NDK. As long as those devices/emulators are available by ADB, Boost regressions tests will run on all of them. As far as I know, Boost is not yet officially supported on Android platform, mainly because of lack of regular regression testing procedure. I wonder if someone would be interested in our results and, if yes, would he/she like to participate in further Boost-on-Android improvements? -- Dmitry Moskalchuk

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[mixin] Library name
by Borislav Stanimirov 04 Feb '15

04 Feb '15

To those unfamiliar with the Boost.Mixin - it is a new library submitted for review. The docs are here: http://ibob.github.io/boost.mixin/index.html The code is here: https://github.com/iboB/boost.mixin It has been suggested multiple times that perhaps the name "mixin" isn't appropriate, so I was wondering if I can find a better one. The current name, mixin, is, as the library itself, inspired by the mixins in the Ruby programming language. However, it doesn't do exactly what Ruby's mixins do (as mentioned here: http://ibob.github.io/boost.mixin/boost_mixin/introduction.html#boost_mixin… ) My current alternative ideas are: * EntityComponent - not great since it doesn't exactly follow the entity-component-system pattern, although it can be said that it allows the construction of entities from components. * DynamicMixin - to emphasize that it's not to be confused with the CRTP mixins. It still has "mixin" in it's name though. * Trait - since it resembles the traits in Self, Scala, PHP, etc. However, a trait is more a "compile time" feature (even when talking about PHP) * TypeComposition or TyCo - a very vague description * Polymorph - since it allows the composition of polymorphic types at run time, but that's pobably even more vague Other ideas are welcome. Thanks -- Borislav

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A general qurey
by Mudit Sharma 04 Feb '15

04 Feb '15

What can be done to run boost on Dev-C++? What else can be used for boost?

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[chrono][multiprecision][gsoc] Project proposal, looking for feedback and mentor.
by Damian Vicino 03 Feb '15

03 Feb '15

Hi, I’m collaborating with other students working in “Simulation Driven Development” (SimDD), mostly for embed systems. The main idea in SimDD is modelling complete systems (not necessarily software) and make simulations of them. Once the simulation has the expected results start replacing some sub-models (software pieces) by real application code. The pieces that are not replaced are used to provide testing facilities. The main fields where this SimDD is used are robotics and embed systems. Where you can clearly separate models in three groups: the software, the interaction (i.e. sensors) and the environment. The software is what you are developing, the environment is the things the software will interact with and the sensors are what info the software gets from the environment and how. When the software is ready, it interacts with the sensors and the simulated environment for testing. Once tested in simulated environments it can be implemented in real world. In this context, I work in time representation problems for discrete event simulation and I will like to propose some additions to the Boost library as GSOC project. — Adding a clock to chrono for virtual simulation time, so models and real code can both work using same library for time representation. — Adding multi base support for multi-precision library. — Adding the option for an accurate mode to multi-precision (meaning a failure should happen when the result requires to be rounded and, if possible, detected at compile time). — Supporting multi base multi-precision in chrono. — For sure, documentation and tests included for everything. Is anybody interested in these additions? Can you provide some feedback about them? Is anybody interested in be my mentor for GSOC in this project? In the last year, I had being working in a general-purpose Discrete Event Simulation library as a side-project that I hope to contribute to boost. The library was submit for registration to blincubator today and in the following days I will be uploading it. Best regards, Damian Vicino

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[config] Visual Studio 2015 Preview CTP 5 FWIW
by Beman Dawes 03 Feb '15

03 Feb '15

VC++ in the 2015 CTP 5 is reporting version 19.00.22512, so needs to be bumped in compiler/visualc.hpp. C++14 digit separators and C++11 universal character names in literals are supposed to be implemented, but I haven't tested them. It would also be interesting if some of bugs in recently added C++11/14 features have been fixed. --Beman

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Hi everyone
by PUNEET KOHLI 03 Feb '15

03 Feb '15

Hello guys. I came to know about your organization from the melange page.Your projects really got me interested. I am a very proficient in c & c++. I have been doing a lot of competitive programming for more than a year so , i can certainly code.I wish to apply to GSOC this year and would love the opportunity if it comes from your organization. Thus, i am looking for a way to contribute and work for you.

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[preprocessor] integration of 'vctuple' branch breaks [accumulator] on msvc
by Jürgen Hunold 02 Feb '15

02 Feb '15

Hi! It seems that commit 01848af60d7639fd441b5d03462e848175cf1692 Merge: fd135a0 dc54fee Author: Edward Diener <...@...> Date: Fri Jan 30 23:16:08 2015 -0500 Merge branch 'vctuple' into develop completely breaks Boost.Accumulator on all msvc versions. I've some code breaking with msvc-12.0 and the msvc-10.0 tests in the regression matrix are all red. For example: http://www.boost.org/development/tests/develop/developer/output/teeks99-08c… fails with: .../accumulators/reference_accumulator.hpp(72) : error C2061: syntax error : identifier 'BOOST_PP_CAT' .../accumulators/reference_accumulator.hpp(72) : error C2947: expecting '>' to terminate template-parameter-list, found '>' .../accumulators/reference_accumulator.hpp(72) : fatal error C1903: unable to recover from previous error(s); stopping compilation Yours, Jürgen -- * Dipl.-Math. Jürgen Hunold ! * voice: ++49 4257 300 ! Fährstraße 1 * fax : ++49 4257 300 ! 31609 Balge/Sebbenhausen * jhunold(a)gmx.eu ! Germany

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GSOC 2015 : Project on Concurrent Hash Tables
by Anmol Sood 02 Feb '15

02 Feb '15

Hi, I am Anmol Sood,a second year undergraduate student, pursuing Mathematics and Computing at Indian Institute of Technology,Delhi. I have been following the Boost mailing list for the last couple of months and I have been trying to understand some Boost libraries and enhancing my skills in generic programming at the same time. I saw the GSOC 2015 Boost page ( https://svn.boost.org/trac/boost/wiki/SoC2015) and the project on concurrent hash tables looks really interesting to me. I would like to know on the kind of pre-requisite skills required for the project and if I could share the progress I am making on writing code for the programming competency test here. Any tips/advice on helping me to get started on working for this project will be really helpful. Thanks.

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Re: [boost] [type_traits] Rewrite and dependency free version
by Emil Dotchevski 02 Feb '15

02 Feb '15

On Mon, Feb 2, 2015 at 11:57 AM, Robert Ramey <ramey(a)rrsd.com> wrote: > this is the result of naming issues. the word array has been used for > boost::array, std::array and the built-in C/C++ array. They all ended > up in the same header so that one could find them when they were needed. > Ideally they should be separated, and boost::array's serialization should go into a boost::array header. As for serialization core dependencies, isn't it possible to define serialization function template overloads for user-defined types without including serialization library headers? E.g. aren't all function calls one makes in operator<< overloads dependent on the archive template argument? -- Emil Dotchevski Reverge Studios, Inc. http://www.revergestudios.com/reblog/index.php?n=ReCode

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[sync] [thread] Faster mutex
by Antony Polukhin 02 Feb '15

02 Feb '15

Hi, One of the Mesa developers implemented a faster mutex: http://lists.freedesktop.org/archives/mesa-dev/2015-January/075260.html According to the sources of glibc, Mesa's mutex has a much smaller size (only 1 uint32_t vs 6 ints + 2 pointers), performs less actions before and after the actual syscall (no getting and setting of the mutex->__data.__owner, no type field checks) This gives an ~10% speedup. Just curious, maybe ideas from Mesa's mutex could be useful for some of the Boost libraries. -- Best regards, Antony Polukhin

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[predef][check] linux clang triggers BOOST_MAC_OS
by Jürgen Hunold 01 Feb '15

01 Feb '15

Hi! I'm using clang + libc++ on Linux and the Predef "check" magic activates "BOOST_MAC_OS". That means I get: Performing configuration checks - symlinks supported : yes warn: Unable to construct ./info_as_objcpp warn: Unable to construct ./info_as_objc - BOOST_OS_MACOS : yes when running the predef test suite. Command chain: cd libs/predef/test rm -rf ../../../bin.v2/libs/predef/ ../../../bin.v2/check/ ../../../bin.v2/project-cache.jam b2 -a --verbose-test 2>&1 -d+2 --debug-configuration | tee verbose.log verbose.log is attached as zip file. And in fact the macos test are run: clang-linux.compile.c.without-pth BOOST_ROOT/src/devel/boost/bin.v2/libs/predef/test/macos_endian.test/clang- linux-3.7.0/debug/macos_endian.o which is only supposed to be run on macos. The test even passes because it internally checks for "__APPLE__" being defined, which should probably be removed, as the check should be done by the build system. Compiler: clang++ -v clang version 3.7.0 (trunk 227683) Target: x86_64-unknown-linux-gnu Thread model: posix That is current clang trunk. Though I'm already running with -d+2 --debug-configuration I get no output from the configuration test itself. Any ideas on how to debug this further? Yours, Jürgen -- * Dipl.-Math. Jürgen Hunold ! * voice: ++49 4257 300 ! Fährstraße 1 * fax : ++49 4257 300 ! 31609 Balge/Sebbenhausen * jhunold(a)gmx.eu ! Germany

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Change in range requirements
by Ganssauge, Gottfried 01 Feb '15

01 Feb '15

Please consider the following program: bool predicate(char c) { return c != '0'; } int main (int, char **) { using namespace boost::adaptors; boost::copy( boost::make_iterator_range( std::istream_iterator<char>(std::cin >> std::noskipws), std::istream_iterator<char>()) | filtered(predicate), std::ostream_iterator<char>(std::cout)); return 0; } It works brilliantly with boost-1.54 although std::istream_iterator is only an input iterator. Recently I tried switching to boost-1.57, but suddenly this program stopped working - it won't compile any longer, because istream_iterator is not a forward_iterator: g++ -I ~/source/aurora-python/test-build/parts/boost range_filter.cpp -o range_filter ... # lots of gobbledygook skipped range_filter.cpp:18:64: required from here /home/gotti/source/aurora-python/test-build/parts/boost/boost/concept_check.hpp:210:13: error: conversion from 'boost::iterators::single_pass_traversal_tag' to non-scalar type 'boost::iterators::forward_traversal_tag' requested Y y = x; ^ When I build an equivalent program using boost::filter_iterator it keeps compiling and working fine. Why is it, that the requirements for certain range adaptors (e.g. filtered, transformed) suddenly exclude input ranges? The corresponding iterator adaptors keep working... Gottfried Ganßauge Entwickler Content Engineering & Development ------------------------------------------------------------------ Haufe-Lexware GmbH & Co. KG Ein Unternehmen der Haufe Gruppe Munzinger Str. 9, 79111 Freiburg Tel. +49 761 898-0 Internet: http://www.haufe-lexware.com ------------------------------------------------------------------ Kommanditgesellschaft, Sitz und Registergericht Freiburg, HRA 4408 Komplementäre: Haufe-Lexware Verwaltungs GmbH, Sitz und Registergericht Freiburg, HRB 5557; Martin Laqua Beiratsvorsitzende: Andrea Haufe Geschäftsführung: Isabel Blank, Markus Dränert, Jörg Frey, Birte Hackenjos, Randolf Jessl, Markus Reithwiesner, Joachim Rotzinger, Dr. Carsten Thies ------------------------------------------------------------------

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Regression testing - is procedure changed?
by Dmitry Moskalchuk 01 Feb '15

01 Feb '15

I just found that there was commit into master where whole $BOOST/tools/regression folder was removed - https://github.com/boostorg/boost/commit/50ca965a872e5d454dbdc36c2764e6e3ba…. That means instructions at http://beta.boost.org/development/running_regression_tests.html are not actual anymore. Could any one advice how to do regression testing now? I'm bit confused since I already spent significant time setting up regular regression testing of Boost on Android, and now it become completely broken. -- Dmitry Moskalchuk

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Re: [boost] [Boost-testing] master and develop regressions shunt on "error: Could not find a Jamfile..."
by Jürgen Hunold 01 Feb '15

01 Feb '15

Hi Jim, Am Sonntag, 1. Februar 2015, 05:17:40 schrieb Jim Bell: > Note that I'm using a preinstalled bjam.exe. > > Both master and develop regressions shunt with this in results/bjam.log: Rene has removed tools/regression without removing the reference to it. My PR at https://github.com/boostorg/boost/pull/57 fixes this. I'm not sure if the new regression repository should be re-added as a submodule instead. Yours, Jürgen -- * Dipl.-Math. Jürgen Hunold ! * voice: ++49 4257 300 ! Fährstraße 1 * fax : ++49 4257 300 ! 31609 Balge/Sebbenhausen * jhunold(a)gmx.eu ! Germany

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Automatically updating libs/maintainers.txt
by Daniel James 01 Feb '15

01 Feb '15

Hi, I've just written a little script to update libs/maintainers.txt from the library metadata. You can see the main changes here: https://github.com/boostorg/boost/commit/94897806350320ac87d629bb933d5aea4d… I've only done this on develop so far, so nothing's final. I will do the library list as well soon, but that might be a bit more disruptive. Daniel

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[type_traits] Rewrite and dependency free version
by John Maddock 01 Feb '15

01 Feb '15

I'm going to throw this out there to see what folks think: In a branch called "Version2", see https://github.com/boostorg/type_traits/tree/Version2 is a partially rewritten type_traits lib: it doesn't yet contain all the traits of the old one, but there's a pretty good selection to test. The main pros for this version are: 1) Zero dependencies other than Boost.Config. 2) No horrible macro-obfuscation - all "real code", making it easier to read and maintain. 3) Substantially reduced template instantiations where practical - often half as many as before. 4) Substantially reduced #includes - the aim is that all files should include only what they need and no more - with what's needed determined by the actual implementation variant when appropriate. There were also a lot of spurious #includes left over from old workarounds no longer used. The main cons: 1) I don't know what I've broken, but surely something, you can help by testing but I would guess we would never be 100% sure it's all right until it's out in the field. This is the main reason for avoiding this until now. 2) MPL interoperability should still work, but files which expect type_traits headers to have included mpl ones will be broken unless they explicitly include what they need. 3) Current MPL inter-operability is fragile see https://github.com/boostorg/type_traits/blob/Version2/include/boost/type_tr… 4) Function dispatching to an mpl::bool_ involves an (inline) function call where as the old inheritance scheme did not. This should mostly disappear once optimizations are turned on, but is still a potential issue for some folks I suspect. 5) I haven't got to the "difficult" headers like common_type.hpp yet. 6) Whatever I've forgotten ;) Of course (2), (3) and (4) could be solved by making mpl's bool.hpp some kind of "core" header. So... what I need from you kind folks is: * Is this the right way forward? * Can you test with your favourite compilers and compare with results for develop - So far I've tested with msvc-10,11,12,14 Intel 14,15, GCC-4.5.4...4.9.1, plus a reasonably recent clang. * If anyone would like to help converting further traits all help would be much appreciated.... Oh and the compiler requirements in the docs are all wildly out of date too... Regards, John.

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A possible solution to the SFINAE/decltype puzzler
by pfultz2 01 Feb '15

01 Feb '15

A couple years ago Eric Niebler posted a question on here about improving error messages with SFINAE and trailing decltype: http://boost.2283326.n4.nabble.com/C-11-decltype-SFINAE-puzzler-td4632622.h… The problem was getting a useful error message when writing something like this: struct h_f { template<class T> auto operator()(T x) const -> decltype(*x) { return *x; } }; constexpr static h_f h = {}; struct g_f { template<class T> auto operator()(T x) const -> decltype(h(x)) { return h(x); } }; constexpr static g_f g = {}; struct f_f { template<class T> auto operator()(T x) const -> decltype(g(x)) { return g(x); }; }; constexpr static f_f f = {}; int main() { f(0); } His solution at the time was to turn the substitution failures into errors. Of course, this has some problems as well. First, it removes the template constraints from the functions. Secondly, it can produce more errors(rather than one error with multiple "notes"). Ideally, it would be better to transport to the top the substitution failures. Well, using template aliases this can be done: https://gist.github.com/pfultz2/3d66795ef18361699fbb When I compile this code I get an error like this: reveal1.cpp:104:5: error: no matching function for call to object of type 'const reveal_failure<f_f>' f(0); ^ reveal1.cpp:56:10: note: candidate template ignored: substitution failure [with Ts = <int>, Id = identity]: indirection requires pointer operand ('int' invalid) auto operator()(Ts&&... xs) const -> decltype(F()(std::forward<Ts>(xs)...)) ^ Now, when there is multiple overloads(or multiple notes), this can be extended to handle this situation, as well. An overload for each note, can be added. Plus, the backtrace can be "flattened" so that only the "leafs" are shown. I do this here: https://gist.github.com/pfultz2/ac74129e73393f798e41 So for the 'advance' function it shows an error like this: reveal2.cpp:288:5: error: no matching function for call to object of type 'reveal<conditional<advance_advanceable, advance_decrementable, advance_incrementable> >' advance(f, 1); ^~~~~~~ reveal2.cpp:215:13: note: candidate template ignored: disabled by 'enable_if' [with Ts = <foo &, int>, Id = identity] REQUIRE_OF(models<Advanceable(Iterator, int)>()); ^ reveal2.cpp:7:82: note: expanded from macro 'REQUIRE_OF' #define REQUIRE_OF(...) template<class Id> using apply = typename std::enable_if<(Id()(__VA_ARGS__)), int>::type ^ reveal2.cpp:234:13: note: candidate template ignored: disabled by 'enable_if' [with Ts = <foo &, int>, Id = identity] REQUIRE_OF(models<Decrementable(Iterator)>()); ^ reveal2.cpp:7:82: note: expanded from macro 'REQUIRE_OF' #define REQUIRE_OF(...) template<class Id> using apply = typename std::enable_if<(Id()(__VA_ARGS__)), int>::type ^ reveal2.cpp:258:13: note: candidate template ignored: disabled by 'enable_if' [with Ts = <foo &, int>, Id = identity] REQUIRE_OF(models<Incrementable(Iterator)>()); ^ reveal2.cpp:7:82: note: expanded from macro 'REQUIRE_OF' #define REQUIRE_OF(...) template<class Id> using apply = typename std::enable_if<(Id()(__VA_ARGS__)), int>::type ^ reveal2.cpp:168:10: note: candidate template ignored: substitution failure [with Ts = <foo &, int>]: no matching function for call to object of type 'advance_advanceable' auto operator()(Ts&&... xs) -> decltype(F1()(std::forward<Ts>(xs)...)) ^ ~~ reveal2.cpp:174:10: note: candidate template ignored: substitution failure [with Ts = <foo &, int>, $1 = 0]: no matching function for call to object of type 'conditional<advance_decrementable, advance_incrementable>' auto operator()(Ts&&... xs) -> decltype(F2()(std::forward<Ts>(xs)...)) ^ So there is one note for each overload of `Advanceable`, `Decrementable`, and `Incrementable`. There is two additional notes at the bottom, this comes from the original function(ideally it would need to be normalized). I go into more detail about how this works here: http://pfultz2.com/blog/2015/01/31/improving-error-messages/ However, this is isn't quite perfect yet. First, it requires putting the type requirements into a nested failure struct. Secondly, not all the types are reported back to clang. It doesn't show the user what type `Iterator` is. Ideally, it would be nice if there was a way to push clang to report the substitution failure at least one level deeper for an expression. This is about as close as I've gotten. Is there any feedback? Questions? Perhaps some improvements? Thanks, Paul Fultz II -- View this message in context: http://boost.2283326.n4.nabble.com/A-possible-solution-to-the-SFINAE-declty… Sent from the Boost - Dev mailing list archive at Nabble.com.

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