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[fixed_point] First presentation from GSoC 2015 and more
by Christopher Kormanyos 25 Oct '16

25 Oct '16

Hello Boost developers, A partial implementation of fixed-point in a Boost-like style based on proposal N3352 is now available.This work is the result of developments from 2013-2016, including efforts from GSoC 2015. The source code is available at: fixed_point-masterPreliminary docs are available at: fixed_point-docWe are potentially interested in submitting this work for inclusion in Boost. We are now requesting comments and suggestions for improvements, corrections and any further test results if these become available.Some key library features include:* proper C++ header-only implementation * full numeric_limits and <cmath> functions * flexible template choice of split between resolution and range * automatic selection of underlying integral representation * portability and high efficiency for bare metal microcontrollers * interoperation with Boost.Math * seamless extension to high-precision using Boost.Multiprecision * extensive test suite Thank you for your consideration. Best regards,Christopher Kormanyos

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[serialization] 2 blocking bugs
by alainm 25 Oct '16

25 Oct '16

Hi, My Boost.MPI builds are currently failing because of two blocking bugs in serialization (merge request 47 and 46). Could someone have a look please ? Thanks Alain

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boost @ Meeting C++ 2016
by Jens Weller 24 Oct '16

24 Oct '16

Hello boost community, a short and final reminder, that the Meeting C++ conference is just a few weeks away! A few tickets are still available, here is the schedule: https://meetingcpp.com/index.php/schedule16.html The schedule also has the link to the student program and diversity tickets! Also there is still a few places available in the boost workshop with Boris Schäling and Michael Caisse. I plan to have a meetup for boost users in one of the breaks in the upper lounge, so that the boost communtiy is able to actually meet at Meeting C++! thanks, Jens Weller

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Interest in chained relational operations
by Rahman Salim Zengin 24 Oct '16

24 Oct '16

Hi, The code in question is a simple chained comparison implementation. It works with any type If relational operators for that type is defined. https://github.com/rszengin/chain May some people find it useful?

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predef: BOOST_COMP_MSVC defined for Gcc/Linux?
by Oliver Kowalke 24 Oct '16

24 Oct '16

Hi, test '#if defined(BOOST_COMP_MSVC)' evaluates to true with GCC on Linux. what I'm missing? Oliver

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[interprocess] interprocess_condition blocks on notify_all if other process crashes
by Remi Chateauneu 22 Oct '16

22 Oct '16

When two processes share memory, and if one of them dies leaving a mutex in locked state, then the other process blocks on a notify using a interprocess_condition, stored in shared memory. This is described here: http://stackoverflow.com/questions/18240263/boost-interprocess-condition-bl… The reason is that this condition uses in general, a ipcdetail::spin_condition. Here is what it does in boost/interprocess/sync/interprocess_condition.hpp and boost/interprocess/sync/spin/condition.hpp : inline void spin_condition::notify(boost::uint32_t command) { //This mutex guarantees that no other thread can enter to the //do_timed_wait method logic, so that thread count will be //constant until the function writes a NOTIFY_ALL command. //It also guarantees that no other notification can be signaled //on this spin_condition before this one ends m_enter_mut.lock(); It locks an internal mutex, and if it is already locked and not unlocked by the crashed process, we are blocked. A fix is to replace lock() by: if( ! m_enter_mut.timed_lock(delay) ) throw an_exception(); A cleaner fix would be to derive a subclass from spin_condition to implement something like: bool derived_spin_condition::timed_notify(boost::uint32_t, ptime delay) What do you think ? Thanks.

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[config] Changes to reflect Visual C++ "15" preview 5
by Beman Dawes 21 Oct '16

21 Oct '16

Boost.Config is current reporting these macros for msvc 14.0 update 3 and later: BOOST_NO_COMPLETE_VALUE_INITIALIZATION Xiang Fan of the VC++ compiler team kindly tested "15" preview 5 against boost without this macro is still getting errors. So this one is still needed. BOOST_NO_CXX11_HDR_CODECVT That's wrong. <codecvt> has been supplied at least since msvc 10.0. I'll submit a P/R. BOOST_NO_CXX14_AGGREGATE_NSDMI Here is a test program, based on the config docs: #include <cassert> struct Foo { int x, y = 42; }; int main() { Foo foo = { 1234 }; assert(foo.y == 42); assert(foo.x == 1234); } That now passed on "15" preview 5, so I'll summit a P/R. BOOST_NO_CXX14_CONSTEXPR The "15" preview 5 release notes say "The most notable compiler changes include complete support for generalized constexpr" I know from conversations with msft folks that they put a lot of effort into constexpr fixes, and that they would like bug reports if anyone is finds constexpr bugs with "15" preview 5. I'll submit a P/R. BOOST_NO_TWO_PHASE_NAME_LOOKUP This one still applies. The backstory has changed a lot, however. Enough progress has been made on the new parser that two phase name lookup should ship next year, and maybe even early next year. But don't hold your breath quite yet. Thanks to Andrew Pardoe for fact checking a draft of this post. --Beman

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Review Manager needed for the C++14 Reflections Library that works Without Macro nor Markup (ex magic_get)
by Antony Polukhin 20 Oct '16

20 Oct '16

Hello, PFR is a C++14 library that represents POD structures as tuples and provides tuple-like methods for PODs. Library has a set of predefined operators for PODs and useful functions for everyday use. Works with user-defined types without any macro nor boilerplate code. Has additional (theoretical) features for C++17. Library: https://github.com/apolukhin/magic_get Docs: http://apolukhin.github.io/magic_get/ Boost Library Incubator: http://blincubator.com/bi_library/pfr-pod-flat-reflection/?gform_post_id=16… Anyone wishing to become the Review Manager for the library? -- Best regards, Antony Polukhin

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[spirit][qi] How to write a boost::spirit::qi parser to do what '?' does in regex?
by Han Wang 19 Oct '16

19 Oct '16

Let's say we have a regex "start:(?: ([0-9]{1,2}))? ([0-9].*)". It will match std::string string1 = "start: 01 0ab"; and std::string string2 = "start: 0ab"; We can also get the 2 matched string respectively. I try to use boost::spirit::qi parser to parse string2 but it couldn't match. qi::rule<std::string::const_iterator, std::string()> rule1 = qi::repeat(1,2)[qi::digit]; qi::rule<std::string::const_iterator, std::string()> rule2 = qi::digit >> *qi::char_; std::vector<std::string> attr; auto it_begin = string2.begin(); auto it_end = string2.end(); if (qi::parse( it_begin, it_end, qi::lit("start:") >> -(qi::lit(" ") >> rule1) >> qi::lit(" ") >> rule2 >> qi::eoi, attr)) std::cout<<"match"<<std::endl; else std::cout<<"not match"<<std::endl; We can of course use a look-ahead operator to check what's behind rule1, but is there a more generic approach to implement regex operator '?' ? Thanks!

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[container] small_flat_set and small_flat_map
by Sam Kellett 19 Oct '16

19 Oct '16

Given that Boost.Container has a small_vector now, would a piece of work that changed flat_set and flat_map to use small_vector<0> internally be feasible? I ask because I feel like if this was the case it would be almost trivial to expose flat_tree<N> through small_flat_set<N> and small_flat_map<N> types to provide the small size optimisation for these two containers.

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