- Boost - lists.boost.org

[review] Review of PolyCollection will start in a few days
by Ion Gaztañaga 30 Apr '17

30 Apr '17

Dear Boost community, The formal review of Joaquín M López Muñoz's PolyCollection library will start on Wednesday, May 3rd and ends on May 12th. This library implements fast containers of polymorphic objects. Typically, polymorphic objects cannot be stored directly in regular containers and need be accessed through an indirection pointer, which introduces performance problems related to CPU caching and branch prediction. Boost.PolyCollection implements a novel data structure that is able to contiguously store polymorphic objects without such indirection, thus providing a value-semantics user interface and better performance. Three polymorphic collections are provided: * boost::base_collection * boost::function_collection * boost::any_collection dealing respectively with classic base/derived or OOP polymorphism, function wrapping in the spirit of std::function and so-called duck typing as implemented by Boost.TypeErasure. If you are interested, you can start preparing your review with the following information: Repositories: Incubator: http://blincubator.com/bi_library/polycollection/?gform_post_id=1643 Github: https://github.com/joaquintides/poly_collection and the documentation here: http://rawgit.com/joaquintides/poly_collection/website/doc/html/index.html See you on Wednesday! Ion

1 0

[integer][math]Heads up on revised gcd/lcm code
by John Maddock 30 Apr '17

30 Apr '17

First some history.... Some time ago, the old gcd/lcm code was moved from Boost.Math to Boost.Integer as a means of reducing inter-library dependencies. Unfortunately a number of tasks were never completed: the docs weren't added to Boost.Integer, and the Boost.Math code never got updated to redirect to the moved headers. Fast forward a couple of years and when Jeremy Murphy contributed a new version of the gcd/lcm code as part of supporting polynomial gcd, and since I'd completely forgotten about the move, this got integrated into Boost.Math leaving us with two divergent versions. As part of sorting this mess out, I've now pushed to Boost.Integer a "best of both" version of this code, so far as I can tell, all dependent libraries are unaffected by the change, though I do need to do some more work on supporting obsolete compilers I no longer have access to. The main enhancements are: * New mixed binary/Euclid algorithm added, this seems to be the best performing algorithm in most cases, and is now the default for most integer types (performance is deeply dependent on the input though, so your mileage may vary). * In addition to integer and rational support, polynomial gcd is now supported via boost::math::polynomial. * There are new range based gcd-lcm algorithms for calculating the gcd/lcm of all the values in an iterator range, this is primarily for polynomial gcd support. * There are new variadic overloads of gcd/lcm for calculating gcd/lcm over more than 2 values. * The gcd/lcm functions are now constexpr in C++14 land, this means that the old compile time calculation traits classes are rendered obsolete for current compilers. * The gcd/lcm functions are now noexcept where appropriate. * Compiler intrinsics are now used speed up binary-gcd steps where possible, sadly this is incompatible with constexpr support since the intrinsics aren't yet constexpr :( Please do let me know if you find any snags, best, John. --- This email has been checked for viruses by AVG. http://www.avg.com

3 17

Boost MultiIndex slow mass insertion
by miticodonati＠libero.it 29 Apr '17

29 Apr '17

I have the following structure: typedef boost::multi_index_container< MyClass, boost::multi_index::indexed_by< boost::multi_index::hashed_unique<boost::multi_index::member<MyClass, int, &MyClass::label>>, boost::multi_index::ordered_non_unique<boost::multi_index::member<MyClass, double, &MyClass::dist>> > > MyClassSet; If i populate it in a loop: MyClassSet all: for (int y = 0; y < input.rows; ++y) { MyClass c; // .... all.insert(c); } the insertion time is quite slow. It probably need to continuously re-order the underlying implementation. Anyway i would expect that populating it with a single call it would be faster (e.g. sorting the whole set only at the end). Example: std::vector<MyClass> vec; // ... MyClassSet all(vec.begin(), vec.end()); BUT... the times are almost equal. My question is: is this intended behaviour? Is there a faster way to mass populate the container (e.g. not enforcing the invariants/orderings at each 'insert')?

3 2

[clang] clang-cl expansion of macros
by Edward Diener 29 Apr '17

29 Apr '17

You can get clang-cl ( clang-win ) to show its VC++ emulated expansion of macros somewhat by passing the c++ option '-fmacro-backtrace-limit=0' to the compiler. It is still blessedly difficult to see the what and the why of clang's error messages when expanding macro using clang-cl, but at least it gives you a better chance of understanding where clang's emulation of VC++ has gone wrong. I have posted bug 27380 to the llvm/clang bug tracker at https://llvm.org/bugs/show_bug.cgi?id=27380 showing the main failure in VC++ emulation which I see when testing Boost PP with clang-cl.

3 8

[quickbook] diagnosing a missing [endsect]?
by Peter Dimov 28 Apr '17

28 Apr '17

I just noticed a missing [endsect] in the middle of one of the .qbk files in the Core documentation. The main .qbk file contains [include addressof.qbk] [include checked_delete.qbk] [include demangle.qbk] [include enable_if.qbk] [include explicit_operator_bool.qbk] [include ignore_unused.qbk] [include is_same.qbk] [include lightweight_test.qbk] [include no_exceptions_support.qbk] [include noncopyable.qbk] [include null_deleter.qbk] [include ref.qbk] [include scoped_enum.qbk] [include swap.qbk] [include typeinfo.qbk] and in the middle of lightweight_test.qbk an [endsect] was missing. The end result of it was that the following includes went into the [section] opened in lightweight_test.qbk, as subsections. This wasn't noticeable from a cursory look so it went unnoticed for a while. Is it worth diagnosing this problem in some way? We probably can't disallow unbalanced sections in an [include], but this could be a warning? (If someone pays it any attention, of course.) Presumably, at the end of the file there'll be a [section] left open? This could be made an error so it'd be harder to miss.

4 23

[core] [noncopyable] Add nonmoveable?
by Viktor Sehr 27 Apr '17

27 Apr '17

In addition to noncopyable, I sometimes want to force classes to be nonmoveable as well (mainly node-type classes in tree structures which other classes point to). Therefore I'd suggest adding a cousin to noncopyable; boost::nonmoveable which simply prevents an instance to be nonmoveable (as well as noncopyable). Note; even due the delete modifier were added in C++11 I still think inheriting boost:noncopyable\nonmoveable syntactically nicer than manually marking the copy\move constructors\assignment operators delete. /Viktor Sehr

4 8

[1.64][python] not building for Visual x64
by Raffi Enficiaud 27 Apr '17

27 Apr '17

Hi, I have some trouble building boost.python for the freshly released boost 1.64: there is no boost.python binary generated, and "bin.v2/libs" does not contain any folder named "python". Maybe related: the machine has python2.7 and 3.4 installed. The command for building: b2 toolset=msvc-14.0 --layout=versioned --build-type=complete --without-log -j 4 address-model=64 threading=multi runtime-link=shared The same command was used for 1.63 with no issue. What am I missing? Let me know if this is a chair-to-keyboard problem. Best, Raffi PS: logs of the second run attached (the number of messages for the first run is flooding the console).

2 2

[stacktrace] Two days remaining before review ends
by Niall Douglas 27 Apr '17

27 Apr '17

Current summary of votes cast so far: * Peter Dimov: Unconditional acceptance * Vladimir Batov: Unconditional acceptance Am I missing any? If you are going to make a review and a recommendation, please do so soon. Niall -- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/

6 9

[release] Epic fail: Numeric cast in 1.64 does not match trunk
by Antony Polukhin 26 Apr '17

26 Apr '17

Hello, File https://github.com/boostorg/numeric_conversion/blob/master/include/boost/nu… does not match the one in release 1.64 That file was fixed and merged to master a long time ago, however boost_1_64_0.7z archive still has on outdated version (one with std::unary_function). This looks like an issue within some release scripts. Issue was noted here: https://svn.boost.org/trac/boost/ticket/12972 -- Best regards, Antony Polukhin

4 4

How to contribute??
by Saurabh Singh 25 Apr '17

25 Apr '17

Hey, This is Saurabh from New Delhi, India. I want to contribute to Boost and help you guys in fixing bugs. Can you please help me to get started in doing so. Thanks

3 2