November 2012 - Boost - lists.preview.boost.org

[#pragma once]
by Sid Sacek 18 Nov '12

18 Nov '12

I've worked with the MSVC, Sun and GCC compilers. Each one of them supports #pragma once. Is there any reason to wrap this pragma within #ifdefs? Are there any compilers out there today that don't support this #pragma? #if defined( _MSC_VER ) && ( _MSC_VER >= 1020 ) # pragma once #endif Could we change this coding pattern so that it no longer looks like MSVC is being selfish? -Sid Sacek

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Re: [boost] Countertree
by Leo Goodstadt 18 Nov '12

18 Nov '12

> Subject: Re: [boost] Review Wizard Report for November 2012 > Hi all, > I would like to request a formal review of the library ?Countertree + > Suballocator? [countertree] > > Project location ( zip file with code and documentation) : > https://dl.dropbox.com/u/8437476/works/countertree_code_doc.zip > > Quick view of documentation with code download : > https://dl.dropbox.com/u/8437476/works/countertree/index.html > > For the people who don't know this project, this is a description : > > *COUNTERTREE* > > This library is an implementation of a binary red-black counter tree. This > tree have an additional counter in each leaf. This permit the access to the > elements by the position, like in a vector. It is a random access container > with random access iterators Among other things, countertree would allow the boost Statistical Accumulators Library to support rolling median and rolling quantiles efficiently. This would be very useful. I had previously had to hack the tree class in the Policy-Based Data Structures part of the gnu c++ library. (see http://gcc.gnu.org/onlinedocs/libstdc++/ext/pb_ds/tree_order_statistics_nod…) Leo Goodstadt

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Review Wizard Report for November 2012
by Ronald Garcia 17 Nov '12

17 Nov '12

============================================== Review Wizard Status Report for November 2012 ============================================== News ==== 1. ODEInt Reviewed 2. Boost 1.52.0 Released. No New Libraries. Open Issues =========== The following libraries have review managers, but have not yet been scheduled for review: * Range Extensions - added May 2012; review manager: Neil Groves. The following libraries have been reviewed and await reports from their review managers: * Predef - reviewed February 2012; review manager: Joel Falcou. * Coroutine - reviewed September 2012; review manager: Hartmut Kaiser. The following libraries have been accepted to Boost, but have not yet been submitted to SVN: * Constrained Value - accepted September 2010; author: Robert Kawulak. * GIL.IO - accepted January 2011; author: Christian Henning. * Contract - accepted September 2012; author: Lorenzo Caminiti. The following libraries have been accepted and submitted to SVN, but have not yet appeared in a release: * Atomic - accepted July 2011; author Helge Bahmann. * Type Traits Introspection - accepted August 2011; author: Edward Diener. * Lockfree - accepted August 2011; author: Tim Blechmann. The following libraries have been accepted provisionally to Boost, but have not been submitted for mini-review and full acceptance: * Endian - accepted provisionally November 2011; author: Beman Dawes. * Log - accepted provisionally March 2010; author: Andrey Semashev. General Announcements ===================== As always, we need experienced review managers. Please take a look at the list of libraries in need of managers and check out their descriptions. In general review managers are active boost participants, including library contributors, infrastructure contributors, and other mailing list participants with a substantial track record of constructive participation. If you can serve as review manager for any of them, email Ron Garcia or John Phillips, "rxg at cs dot cmu dot edu" and "phillips at pacific dot mps dot ohio-state dot edu" respectively. We are also suffering from a lack of reviewers. While we all understand time pressures and the need to complete paying work, the strength of Boost is based on the detailed and informed reviews submitted by you. If you are interested in reviewing a library but won't have time during the review period, you can always prepare your review ahead of time. No rule says you can only work on a review during the review period. A link to this report will be posted to www.boost.org. If you would like us to make any modifications or additions to this report, please email Ron or John. The review schedule is an unordered list of the libraries awaiting review. As such, any library on the schedule can be reviewed once the developer is ready, a review manager has been secured, and the manager, developer, and wizards agree on a date to schedule the review. Review Schedule =============== * Join (M) * Pimpl (M) * Sorting (M) * Quaternions, Vectors, Matrices (M) * Variadic Macro Data (M) * Block Pointer (M) * Singularity (M) * Extended Complex Numbers (M) * Metaparse (M) * Polygon: Voronoi Extensions * Coroutine * Range Extensions * Nowide (M) * Array (M) * TypeIndex (M) * STL Extensions (M) ``(M)`` marks libraries that need review managers. -------------------- Join ---- :Author: Yigong Liu :Review Manager: Needed :Download: http://channel.sourceforge.net/ :Description: Join is an asynchronous, message based C++ concurrency library based on join calculus. It is applicable both to multi-threaded applications and to the orchestration of asynchronous, event-based applications. It follows Comega's design and implementation and builds with Boost facilities. It provides a high level concurrency API with asynchronous methods, synchronous methods, and chords which are "join-patterns" defining the synchronization, asynchrony, and concurrency. Pimpl ----- :Author: Vladimir Batov :Review Manager: Needed :Download: https://github.com/boost-vault/Miscellaneous/blob/master/Pimpl.zip :Description: The Pimpl idiom is a simple yet robust technique to minimize coupling via the separation of interface and implementation and then implementation hiding. This library provides a convenient yet flexible and generic deployment technique for the Pimpl idiom. It's seemingly complete and broadly applicable, yet minimal, simple and pleasant to use. Sorting ------- :Author: Steven Ross :Review Manager: Needed :Download: https://github.com/boost-vault/Sorting :Description: A grouping of 3 templated hybrid radix/comparison-based sorting algorithms that provide superior worst-case and average-case performance to std::sort: integer_sort, which sorts fixed-size data types that support a rightshift (default of >>) and a comparison (default of <) operator. float_sort, which sorts standard floating-point numbers by safely casting them to integers. string_sort, which sorts variable-length data types, and is optimized for 8-bit character strings. All 3 algorithms have O(n(k/s + s)) runtime where k is the number of bits in the data type and s is a constant, and limited memory overhead (in the kB for realistic inputs). In testing, integer_sort varies from 35% faster to 2X as fast as std::sort, depending on processor, compiler optimizations, and data distribution. float_sort is roughly 70% faster than std::sort. string_sort is roughly 2X as fast as std::sort. Quaternions, Vectors, Matrices ------------------------------ :Author: Emil Dotchevski :Review Manager: Needed :Download: http://www.revergestudios.com/boost-qvm/ :Description: QVM defines a set of generic functions and operator overloads for working with quaternions, vectors and matrices of static size. The library also defines vector and matrix data types, however it allows users to introduce their own types by specializing the q_traits, v_traits and m_traits templates. Variadic Macro Data ------------------- :Author: Edward Diener :Review Manager: Needed :Download: `Boost Sandbox <http://svn.boost.org/svn/boost/sandbox/variadic_macro_data/>`__ :Description: This library adds support and functionality for variadic macros to Boost as well as integrating variadic macros with the Boost PP library without changing the latter library in any way. Block Pointer ------------- :Author: Phil Bouchard :Review Manager: Needed :Download: https://svn.boost.org/svn/boost/sandbox/block_ptr/ :Description: Deterministic memory manager of constant complexity capable of handling cyclic collections. Singularity ----------- :Author: Ben Robinson :Review Manager: Needed :Download: https://github.com/cppmaven/Singularity :Description: The Singularity Design Pattern allows you to restrict any class to a single instance. Unlike the infamous Singleton, Singularity gives you direct control over the lifetime of the object, does not require you to grant global access to the object, nor does it limit you to the default constructor for that object. Extended Complex Numbers ------------------------ :Author: Matthieu Schaller :Review Manager: Needed :Download: http://code.google.com/p/cpp-imaginary-numbers/ :Description: The library is an extension of the std::complex class addressing two issues: 1. The standard does not guaranty the behaviour of the complex class if instantiated with types other than float/double/long double. 2. Some calculation where pure imaginary numbers (i.e. multiples of sqrt(-1)) appear are unnecessarily slowed down due to the lack of support for these numbers. The code I submit contains two interleaved classes boost::complex and boost::imaginary which can be instantiated with any type T provided T overloads the usual arithmetic operators and some basic (real) mathematical functions depending on which complex function will be used. It is thus an extended version of Thorsten Ottosen's n1869 proposal (http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2005/n1869.html) Metaparse --------- :Author: Abel Sinkovics :Review Manager: Needed :Download: http://abel.web.elte.hu/metaparse/metaparse.zip :Description: Metaparse is a library for constructing parsers parsing at compile-time based on template metaprogramming. The parsers built with the library take boost::mpl::strings as input and can produce - types - objects (types with public static members) - callable C++ functions (types with public static method) - template metafunction classes as output (based on the input being parsed). On compilers supporting constexpr the library provides the following syntactic sugar for writing the input of the parsers: BOOST_STRING("this is a string") The library can be used for implementing DSLs in C++, including DSLs making C++ template metaprogramming easier (see examples). Polygon: Voronoi Extensions --------------------------- :Author: Andril Sydorchuk :Review Manager: Lucanus Simonson :Download: http://svn.boost.org/svn/boost/sandbox/gtl/ :Description: This library extends Boost.Polygon with the following features: - Robust and efficient implementation of the sweepline algorithm that allows to construct Voronoi diagram, Delaunay triangulation and medial axis of a set of points and line segments. - Coordinates of the output geometries are computed within the 64 machine epsilon relative error (6 mantissa bits). - Voronoi diagram data structure that allows efficient traversal and data association with the output Voronoi graph. - No 3rd party dependencies (e.g. GMP, MPFR), all the required multiple precision types are implemented as part of the library. - The input and output coordinate type domains are configurable via coordinate type traits, thus allowing to compute coordinates of the Voronoi vertices within any required precision. - The full construction of the Voronoi diagram of 100 000 points takes only 0.27 seconds (see benchmarks). Coroutine --------- :Author: Oliver Kowalke :Review Manager: Hartmut Kaiser :Download: http://gitorious.org/boost-dev/boost-dev/archive-tarball/coroutine :Description: This library is an implementation of coroutines and generators using Boost.Context. Range Extensions ---------------- :Author: Akira Takahashi :Review Manager: Neil Groves :Download: https://github.com/faithandbrave/OvenToBoost :Description: This project adds some features of the Oven Range Library to Boost.Range. Features: - Additional Range Adaptors (taken, taken_while, dropped, dropped_while, elements, elements_key, memoized, outdirected) - Extensions for using Lambda (regular function, regular operator) - Infinite Range (iteration function) - and additional range utilities. Nowide ------ :Author: Artyom Beilis :Review Manager: Needed :Download: http://cppcms.com/files/nowide/ :Description: This library makes cross platform Unicode aware programming easier. It 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. Array ----- :Author: Brian Smith :Review Manager: Needed :Download: https://github.com/BrianJSmith/Array :Description: The array class is a C++11 compatible implementation of static multidimensional arrays. TypeIndex --------- :Author: Antony Polukhin :Review Manager: Needed :Download: https://github.com/apolukhin/type_index :Description: TypeIndex is an extended C++11 type_index library, that * works with disabled RTTI * can store const-volatile-reference info about types (if user requested it) * has all the functionality of std::type_index * has portable across compilers and platforms functionality for getting demangled type names * works across modules/shared libraries * does not require C++11 to work STL Extensions -------------- :Author: Vadim Stadnik :Review Manager: Needed :Download: https://github.com/vstadnik/stl_ext_adv_review :Description: The proposed library [stl_ext_adv] offers augmented array based B+ trees and STL containers that support the interfaces of the C++03 sequences and associative containers. The library offers a number of extensions and performance improvements that are not available in C++03 and C++11 standard containers. Libraries under development =========================== See http://svn.boost.org/trac/boost/wiki/LibrariesUnderConstruction for a current listing of libraries under development.

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[1.53] request to merge lockfree (c++11 only)
by Tim Blechmann 17 Nov '12

17 Nov '12

hi all, i'm not sure about the state of atomic, as the original author hardly reacts on emails and atm, i don't have the time to adopt it ... i'd therefore request permission to merge boost.lockfree into release, depending on std::atomic<>. this means, that it will require gcc-4.8 or msvc 2012 in c++11 mode to compile it (not sure about clang++, as their c++11 support under linux is pretty broken). the architecture of boost.lockfree is modular, so once boost.atomic is merged, it is trivial to use it again and allow use of the library with pre-c++11 compilers ... this is far from ideal, but boost.atomic has been blocking the release of boost.lockfree for a long time and it doesn't look like that it will be available before std::atomic<> is widely supported ... thoughts? tim

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1.53 schedule change
by Daniel James 17 Nov '12

17 Nov '12

Hello everyone, I just noticed that I forgot to account for Christmas when setting the schedule for 1.53. I've adjusted it so that the deadlines for new libraries and major changes are a week earlier (as specified on the release schedule page). Sorry about that. There's still 3 weeks before the new library deadline, but please let us know soon if you have a new library for 1.53. thanks, Daniel

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Boost.Process 0.5: Another update/potential candidate for an official library
by Boris Schaeling 17 Nov '12

17 Nov '12

I've uploaded a new version of Boost.Process 0.5 to <http://www.highscore.de/boost/process0.5/>: - Made child movable and non-copyable on Windows (destructor closes handles) - Added cross-platform helpers in a new header file boost/process/mitigate.hpp - Updated and improved documentation (eg. FAQ is new) - Added the POSIX initializer notify_io_service (Boost.Asio helper) - Minor bug fixes and improvements (eg. in search_path() on Windows) At this point there is nothing left on my todo list. I got quite a lot of feedback so far and would appreciate if people can look at this new version again. If there are no major shortcomings found, I'll ask for a formal review. Boris

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[container] container_detail::pair piecewise constructor
by László Szécsi 17 Nov '12

17 Nov '12

Hi everyone, boost::container::container_detail::pair's piecewise constructor is missing, as acknowledged in a comment. This makes container::flat_map::emplace less useful (perhaps useless) as the following will not work: boost::container::flat_multimap<TestKey, TestValue> testMap; testMap.emplace(boost::container::container_detail::piecewise_construct, boost::make_tuple(30), boost::make_tuple(50)); where both TestKey and TestValue are non-copyable, moveable classes with a constructor taking an int. The compilation error message will correctly say that boost::container::container_detail::pair does not have a constructor with three arguments. I tried to implement the missing piecewise constructor based on std::pair's in the g++ standard libraries. I failed at it, so I would like to request some assistance and education. This is where I got: // from the standard lib template<std::size_t _Num> struct _Build_index_tuple { typedef typename _Build_index_tuple<_Num-1>::__type::__next __type; }; // from the standard lib template<> struct _Build_index_tuple<0> { typedef _Index_tuple<> __type; }; template <class... Args1, class... Args2> pair(piecewise_construct_t, ::boost::tuple<Args1...> first_args, ::boost::tuple<Args2...> second_args) : pair(::boost::move(first_args), ::boost::move(second_args), typename _Build_index_tuple<sizeof...(Args1)>::__type(), typename _Build_index_tuple<sizeof...(Args2)>::__type()) {} template<typename... Args1, std::size_t... Indices1, typename... Args2, std::size_t... Indices2> explicit pair(tuple<Args1...> tuple1, tuple<Args2...> tuple2, _Index_tuple<Indices1...>, _Index_tuple<Indices2...>) : first(::boost::forward<Args1>(std::get<Indices1>(tuple1))...), second(::boost::forward<Args2>(std::get<Indices2>(tuple2))...) { } This gets me a recursive error message far too long to quote, starting with: error C2664: 'boost::container::container_detail::pair<Key,T>::pair(std::pair<Key,T> &&)' : cannot convert parameter 3 from 'boost::tuples::tuple<int,boost::tuples::null_type // lot of null_types omitted to 'boost::tuples::tuple<boost::tuples::null_type, // lot of null_types omitted I used the VS2012 Nov CTP compiler. I understand that variadic templates have not been very portable and boost::unordered, which has a piecewise constructor implementation, does it completely differently and much more painfully. But is there a reason for the approach I tried not to work with boost at all? Could you please help me fix this code? Thank you very much, Laszlo Szecsi

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Updated serialization performance tests
by Brian Wood 16 Nov '12

16 Nov '12

Shalom I've updated this page -- http://webEbenezer.net/comparison.html with results from Boost 1.52. A few notes about the testing: I decided to use -O2 on the Linux/g++ tests. In previous tests I used -O3. I hadn't updated the Windows test results since the Boost 1.48 time-frame. Around Boost 1.51 I had to start building the serialization library in Boost with runtime-link=static in order to get the Windows tests to build. I haven't understood why that became necessary, but the results for the serialization library in Boost seem to have been adversely affected by this. On Windows, I now report that tests built with the serialization library in Boost are over 1.8 times slower than parallel Ebenezer tests. Previously I reported the tests built with the serialization library in Boost were between 1.7 and 1.8 times slower than the Ebenezer tests. -- Brian Ebenezer Enterprises -- making programming fun again. http://webEbenezer.net

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Boost.Test and Xcode 4.5 in C++11 Mode
by Dean Michael Berris 16 Nov '12

16 Nov '12

Hi Everyone, I'm trying to build Boost.Test in trunk in C++11 mode with Apple's released Clang compiler with Xcode 4.5. Is this supported by Boost.Test? I keep getting this error somewhere deep in some preprocessor parts which is far outside my understanding. Here's my user-config.jam: using clang : : : <cxxflags>-Wall <cxxflags>-Wself-assign <cxxflags>-std=c++11 <cxxflags>-stdlib=libc++ <linkflags>-stdlib=libc++ ; I ask because I'm using Boost.Test as my current unit testing framework for cpp-netlib. I'm going to need to make a decision on whether I can continue using Boost.Test in C++11 mode as cpp-netlib is moving to C++11-only in its next version. Thanks in advance. -- Dean Michael Berris www.deanberris.com

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[test] A new ERROR in trunk including C++11 features on C++98 mode
by Vicente J. Botet Escriba 16 Nov '12

16 Nov '12

Hi, there is yet an error including C++11 features. Please could you take care of it? Thanks, Vicente darwin.compile.c++ ../../../bin.v2/libs/test/build/darwin-4.2.1/debug/link-static/threading-multi/framework.o In file included from ../../../boost/test/tools/assertion.hpp:19, from ../../../boost/test/tools/impl.hpp:25, from ../../../boost/test/test_tools.hpp:373, from ../../../boost/test/impl/framework.ipp:27, from ../../../libs/test/src/framework.cpp:16: ../../../boost/test/utils/is_forward_iterable.hpp:58: error: ‘>>’ should be ‘> >’ within a nested template argument list ../../../boost/test/utils/is_forward_iterable.hpp:61: error: ‘>>’ should be ‘> >’ within a nested template argument list "g++" -ftemplate-depth-128 -O0 -fno-inline -Wall -pedantic -g -gdwarf-2 -fexceptions -DBOOST_ALL_NO_LIB=1 -I"../../.." -c -o "../../../bin.v2/libs/test/build/darwin-4.2.1/debug/link-static/threading-multi/framework.o" "../../../libs/test/src/framework.cpp" ...failed darwin.compile.c++ ../../../bin.v2/libs/test/build/darwin-4.2.1/debug/link-static/threading-multi/framework.o...

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BOOST_FUSION_ADAPT_STRUCT - Printing Array Elements
by forums_mp 16 Nov '12

16 Nov '12

Given the snippet below. How do I print the contents within the array ? I'd expect to see a counting pattern when the array is encountered but that's not the case. Thanks in advance. [code] #include <boost/mpl/eval_if.hpp> #include <boost/mpl/identity.hpp> #include <boost/mpl/next_prior.hpp> #include <boost/fusion/mpl.hpp> #include <boost/fusion/adapted.hpp> // BOOST_FUSION_ADAPT_STRUCT // boost::fusion::result_of::value_at #include <boost/fusion/sequence/intrinsic/value_at.hpp> #include <boost/fusion/include/value_at.hpp> // boost::fusion::result_of::size #include <boost/fusion/sequence/intrinsic/size.hpp> #include <boost/fusion/include/size.hpp> // boost::fusion::at #include <boost/fusion/sequence/intrinsic/at.hpp> #include <boost/fusion/include/at.hpp> # include <iostream> # include <vector> typedef std::vector < int > INT_VEC ; // Your existing struct struct my_struct { int i; bool j; int arr1 [ 100 ]; // INT_VEC vv ; // my_struct() // : vv ( 100 ) // {} }; // Generate an adapter allowing to view "Foo" as a Boost.Fusion sequence BOOST_FUSION_ADAPT_STRUCT( my_struct, (int, i) (bool, j) (int, arr1[ 100 ] ) // (int, vv[100]) ) template <typename T2> struct parse_foo { static void parse(T2 & f); }; struct display { template <typename T> void operator()(T& t) const { std::printf(" --%s--%s-- \n", typeid(t).name(), boost::lexical_cast<std::string>(t).c_str()); if (typeid(t).name()[0] == 'c') std::printf(" --%s--%s-- \n", typeid(t).name(), t); parse_foo<T>::parse(t); } }; template <> void parse_foo<int >::parse(int & f) { std::cout << f << std::endl; } template <> void parse_foo<char>::parse(char & f) {}; template <> void parse_foo<bool>::parse(bool & f) { std::cout << f << std::endl; }; #include <boost/fusion/include/sequence.hpp> #include <boost/fusion/include/algorithm.hpp> #include <boost/fusion/include/vector.hpp> #include <boost/fusion/include/adapt_struct.hpp> #include <boost/lexical_cast.hpp> int main() { my_struct f; f.i = 33 ; f.j = false ;; for ( int odx ( 0 ); odx < 100; ++odx ) { f.arr1 [ odx ] = odx ; } boost::fusion::for_each(f, display()); } [/code] -- View this message in context: http://boost.2283326.n4.nabble.com/BOOST-FUSION-ADAPT-STRUCT-Printing-Array… Sent from the Boost - Dev mailing list archive at Nabble.com.

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Re: [boost] [Boost-commit] svn:boost r81360 - in trunk: boost/algorithm libs/algorithm/test
by Steven Watanabe 15 Nov '12

15 Nov '12

AMDG On 11/15/2012 11:45 AM, marshall(a)idio.com wrote: > <snip> > + // construct/copy > + BOOST_CONSTEXPR basic_string_ref () > +#ifdef BOOST_NO_CXX11_NULLPTR > + : ptr_(NULL), len_(0) {} > +#else > + : ptr_(nullptr), len_(0) {} > +#endif Really? The two branches have exactly the same effect. The only reason to prefer nullptr is aesthetic and this is more than offset by the #ifdef. > + > + basic_string_ref(const charT* str) > + : ptr_(str), len_(std::strlen(str)) {} > + strlen only works for char. You need to use traits::length > +#ifndef BOOST_NO_CXX11_HDR_INITIALIZER_LIST > +// !! How do I do this? Look how initializer_lists work! > + basic_string_ref(std::initializer_list<charT> il); // TODO > +#endif > + Although this can be implemented, it's incredibly dangerous, because the string_ref will be left dangling when the initializer_list goes out of scope. > + > + // iterators > + BOOST_CONSTEXPR const_iterator begin() const { return ptr_; } > + BOOST_CONSTEXPR const_iterator cbegin() const { return ptr_; } > + BOOST_CONSTEXPR const_iterator end() const { return ptr_ + len_; } > + BOOST_CONSTEXPR const_iterator cend() const { return ptr_ + len_; } > + const_reverse_iterator rbegin() const { return const_reverse_iterator (end()); } > + const_reverse_iterator crbegin() const { return const_reverse_iterator (end()); } > + const_reverse_iterator rend() const { return const_reverse_iterator (begin()); } > + const_reverse_iterator crend() const { return const_reverse_iterator (begin()); } > + Check for tabs? > + // capacity > + BOOST_CONSTEXPR size_type max_size() const { return len_; } I'm not convinced that this definition is correct. Returns: the size of the largest possible string. Note that this does not say that it returns the maximum size that this particular string_ref object can hold without reassignment. > + > + int compare(basic_string_ref x) const { > + int cmp = std::memcmp ( ptr_, x.ptr_, std::min(len_, x.len_)); > + return cmp != 0 ? cmp : ( len_ == x.len_ ? 0 : len_ < x.len_ ? -1 : 1 ); > + } > + > + bool starts_with(charT c) const { return !empty() && front() == c; } > + bool starts_with(basic_string_ref x) const { > + return len_ >= x.len_ && std::memcmp ( ptr_, x.ptr_, x.len_ ) == 0; > + } > + > + bool ends_with(charT c) const { return !empty() && back() == c; } > + bool ends_with(basic_string_ref x) const { > + return len_ >= x.len_ && std::memcmp ( ptr_ + len_ - x.len_, x.ptr_, x.len_ ) == 0; > + } > + You can only use memcmp for char. You have to use traits::compare here. > + > +// Have to use traits here > + size_type find(basic_string_ref s) const { > + const_iterator iter = std::find_if ( this->cbegin (), this->cend (), > + s.cbegin (), s.cend (), traits::eq ); > + return iter = this->cend () ? npos : std::distance ( this->cbegin (), iter ); > + } > + I think you mean std::search, not std::find_if. > + size_type find(charT c) const { > +#ifdef BOOST_NO_CXX11_LAMBDAS > + const_iterator iter = std::find_if ( this->cbegin (), this->cend (), > + detail::string_ref_traits_eq<charT, traits> ( c )); > +#else > + const_iterator iter = std::find_if ( this->cbegin (), this->cend (), > + [c] ( charT val ) { return traits::eq ( c, val ); } ); > +#endif > + return iter == this->cend () ? npos : std::distance ( this->cbegin (), iter ); > + } > + As with NULL/nulptr, I don't see the point of using C++11 lambdas if you have to #ifdef it with a C++03 implementation. In Christ, Steven Watanabe

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[multiprecision] OK to merge to Trunk?
by John Maddock 15 Nov '12

15 Nov '12

Folks, Unless there are any objections, I'd like to merge the multiprecision library to SVN Trunk pretty soon. Here are the main changes since the review, which have mostly concentrated on the interface changes: * Non-expression template operators further optimized with rvalue reference support. * Many functions made `constexp`. * Differentiate between explicit and implicit conversions in the number constructor. * Removed "mp_" prefix from types. * Allowed mixed precision arithmetic. * Changed ExpressionTemplates parameter to class `number` to use enumerated values rather than true/false. * Changed ExpressionTemplate parameter default value to use a traits class so that the default value depends on the backend used. * Added support for fused-multiply-add/subtract with GMP support. * Tweaked expression template unpacking to use fewer temporaries when the LHS also appears in the RHS. * Refactored `cpp_int_backend` based on review comments with new template parameter structure. * Added additional template parameter to `mpfr_float_backend` to allow stack-based allocation. * Added section on mixed precision arithmetic, and added support for operations yielding a higher precision result than either of the arguments. * Added overloads of integer-specific functions for built in integer types. Things requested in review, but not yet done: * We can reuse temporaries in multiple subtrees (temporary caching). Low priority for now. * cpp_dec_float should round to nearest. Chris currently has no time for this, and it's really hard to do *right*. * A 2's complement fixed precision int that uses exactly N bits and no more. Refactoring of cpp_int should make this easier to add as an option in future. There are also documentation updates pending (mostly relating to the new improved performance results), and more tests I want to add/run, bit basically I need to get things widely tested to move forward now. Release schedule wise, I think it'll be hard to get things ready for the next release, but the release after that really should be on the cards. So basically now is the last chance for folks to complain before the interface gets ossified ;-) As ever current code is in the sandbox under /big_number/ and docs can be viewed online here: http://svn.boost.org/svn/boost/sandbox/big_number/libs/multiprecision/doc/h… Regards, John.

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boost filesystem path as utf-8 revisited
by Rush Manbert 15 Nov '12

15 Nov '12

In the original thread, I found this reply by Beman: ----------------- > > > How exactly do I imbue UTF-8 codecvt in a path? I Googled around and > couldn't find anything. There are two approaches: * If you always want all class path arguments and returned values with a value type of char to be treated as being UTF-8 encoded, and aren't worried about changing a potentially dangerous global, then do this: #include <boost/filesystem/detail/utf8_codecvt_facet.hpp> ... std::locale global_loc = std::locale(); std::locale loc(global_loc, new boost::filesystem::detail::utf8_codecvt_facet); boost::filesystem::path::imbue(loc); ----------------- I do want what is described and would like to use this approach, but we use boost::filesystem all over the place and in our code we never do any sort of "global initialization", so I'm trying to figure out how to get the code snippet executed. I can see two ways to approach this: 1) Add this code snippet to the boost::filesystem::path constructor. But is it too late then? 2) Define a class whose only purpose is to execute this code when it is constructed and arrange to have a static singleton instance of the class defined. In one of our libraries we need to be very careful about static class construction order, so this may be difficult. I haven't dealt with this sort of issue in quite a while and I may be a little rusty. Any suggestions? Are there new goodies in C++ that might help me? Thanks, Rush

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program_options::store() interface extension
by ST 15 Nov '12

15 Nov '12

Hi, I need to supply to my app a config file with following entries: item1 = 123 item2 = 435 item3 = 345 ... itemN = 562 where N is not known in advance, so there is no way to register such options. The only way to deal with them is to pass them as unregistered options and then use collect_unrecognized(). But then dealing with a vector<string> is not quit convenient. My suggestion is to add an a storeUnregistered flag to the store() function which will be false by default, but if set to true, will store all unregistered options with their values as strings. It will be possible then to check whether an item was provided like this: vm.count("item1") and cast its value like this: vm["item1"].as<int>() . Or is there already a good way to do what I need? Thank you in advance, ST

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Re: [boost] [container] container_detail::pair piecewise constructor
by László Szécsi 15 Nov '12

15 Nov '12

I did some more research and it turns out std-style piecewise construction fails with VS2012 Nov CTP compiler, just like my attempt at adding piecewise construction to boost::container_detail::pair. In particular, the following dummy code compiles under g++ 4.7.1 but not under VS2012 Nov CTP. class Foo { public: template <class... Args1, class... Args2> Foo( const ::std::piecewise_construct_t, ::std::tuple<Args1...> first_args, ::std::tuple<Args2...> second_args) { } }; int main(){ Foo s( std::piecewise_construct, std::move( std::make_tuple(30) ), std::move( std::make_tuple(50) )); } I guess the time is not ripe for the container implementation to use true variadic templates yet. Is there ongoing effort to implement container_detail::pair's piecewise constructor in the same way as it was implemented in boost::unordered? Best regards, Laszlo Szecsi

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[optional] Support for moving values
by Adam Badura 14 Nov '12

14 Nov '12

Are there any plans to add support for move constructors and assignment operators? I noticed that many Boost libraries miss that support. And it is especially "visible" in case of such utilities like boost::optional or boost::variant. Adam Badura

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Boost 1.52.0 released!
by Marshall Clow 14 Nov '12

14 Nov '12

Release 1.52.0 of the Boost C++ Libraries is now available. These open-source libraries work well with the C++ Standard Library, and are usable across a broad spectrum of applications. The Boost license encourages both commercial and non-commercial use. This release contains numerous enhancements and bug fixes for existing libraries. For details, including download links, see http://www.boost.org/users/news/version_1_52_0 You can also download directly from SourceForge: http://sourceforge.net/projects/boost/files/boost/1.52.0/ To install this release on your system, see http://www.boost.org/doc/libs/release/more/getting_started/index.html Thanks, --The Boost release team Beman Dawes Daniel James Eric Niebler Marshall Clow Rene Rivera Vladimir Prus

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[optional] Types without assignment operator
by Adam Badura 14 Nov '12

14 Nov '12

I use boost::optional for deferred construction. Something similar to the idea described in "Bypassing expensive unnecessary default construction" in Boost.Optional documentation. Only in my case I do this because the mentioned construction requires virtual function calls and this cannot be done in owning object constructor and has to be postponed. So instead of accessing the object directly I always access it by a function. That function first checks if the object is already constructed (boost::optional is initialized) and if so just returns it. Otherwise it first constructs it. That approach requires only copy construction (or even move construction if boost::optional would support moving in the first place). Yet due to implementation details the embedded type has to be assignable as well. Even thou assignment operator will never be called (in this scenario). Is there a way to avoid this issue? If not then how about adding a function like "assign" (possibly named otherwise or with additional defaulting argument) which could assign by first destroying old object (if any) and then copy/move constructing a new one. This would obviously be bad from exception safety (guarantees) point of view, but well... don't call the function if you don't like that. And in scenarios like mine it would not be an issue since there would be no object to destroy anyway. (Also the function could assert/throw on that condition...) Now the Synopsis part of the Boost.Optional documentation does mention (Typed)InPlaceFactory assign operators which do look promising for solving this issue. But firstly they are not documented in following Detailed Semantics part. There is even no link in the Synopsis. (Is this docs bug? In which part? Missing docs or extra functions?) And secondly (Typed)InPlaceFactory support is "intrusive". I cannot add it to a class without changing the class itself. And in my case I cannot change the class (boost::program_options::options_description - why cannot it be copy assigned, that I don't know...). Maybe adding some extra wrapper would help but I don't think it would be a solution. Rather a somewhat ugly workaround. Adam Badura

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Possible submission: Expanded std::bind compatible with std::move
by スマートアシュリー 14 Nov '12

14 Nov '12

I noticed that std::bind inst compatible with std::move.. I created a workaround for it in c++11 here. I would like to see it added to boost if thats ok. Please review my code... and let me know if its a viable candidate to be added to boost and what code changes are need before that. http://code-slim-jim.blogspot.jp/2012/11/perfect-forwarding-bind-compatable…

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[type_erasure] issue when taking any<> by const ref
by Thomas Petit 13 Nov '12

13 Nov '12

Hi, I'm playing with the boost type erasure library (from the sandbox) and hit some issues. Imagine that I have an any accepting some concept : > typedef any<concept1<>, concept2<>> some_any_t; and a std::vector to put a few any in it : > std::vector<some_any_t> v; Then If I iterate over the vector by taking each element by reference >for(some_any_t& : v) >{ >} everything is fine and consistent with why I expect. However if I iterate by taking element by const ref >for(const some_any_t& : v) >{ >} then some issue appears. Here is an example showing the problems (with one any using a concept defined by BOOST_TYPE_ERASURE_FREE and one any using a concept defined by BOOST_TYPE_ERASURE_MEMBER) ................................................... #include <boost/type_erasure/any.hpp> #include <boost/type_erasure/operators.hpp> #include <boost/type_erasure/free.hpp> #include <boost/type_erasure/member.hpp> namespace mpl = boost::mpl; namespace te = boost::type_erasure; template <typename T> void free(const T& t) { std::cout << typeid(t).name() << std::endl; std::cout << "default free\n"; } void free(const int& i) { std::cout << typeid(i).name() << std::endl; std::cout << "int\n"; } BOOST_TYPE_ERASURE_FREE((has_free), free, 1); template<class T = te::_self> struct free_concept : mpl::vector<has_free<void(const T&)> > {}; typedef te::any<mpl::vector<te::copy_constructible<>, free_concept<>>> any_free_t; struct Base { virtual void member() const { std::cout << "Base member\n"; } }; struct Derived : public Base { virtual void member() const { std::cout << "Derived member\n"; } }; BOOST_TYPE_ERASURE_MEMBER((has_member), member, 0) struct member_concept : mpl::vector<has_member<void()> > {}; typedef te::any<mpl::vector<te::copy_constructible<>, member_concept>> any_member_t; int main() { any_free_t af1(5); any_free_t af2(5.0); std::vector<any_free_t> v; v.push_back(af1); v.push_back(af2); for(any_free_t& af : v) { free(af); } Base b; Derived d; std::vector<any_member_t> v2; v2.push_back(b); v2.push_back(d); for(any_member_t& am : v2) { am .member(); } } ....................................................... In the previous code, if add a const here : for(const any_free_t& af : v) { free(af); } then instead of calling the int overload of the free function and the template overload with a double type, the templated free function is called both time but, unfortunately the type of T is always the same as the any. Another point, if I add a const here : for(const any_member_t& am : v2) { am .member(); } then I get a compile error. (with visual 2012 and gcc 4.7) I'm a bit puzzled by this behavior. Are any<> types never supposed to be taken by const ref ? How can we iterate over anys while preserving constness ? Thanks. Thomas.

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boost threads and linking boost statically into a DLL
by Carlos Empujon 13 Nov '12

13 Nov '12

Recently I had some trouble to linking boost statically into a DLL. After searching around I found that there has been a discussion on http://boost.2283326.n4.nabble.com/Fwd-Thread-Solution-to-conflict-with-MFC… However it seems that the patch proposed there (see below) did not make it into the trunk. Has there been a special reason why this has not been included into the normal distribution? Cheers, Carlos /** * tss.cpp * * This file is intended to correctly build a dll using boost::thread * It is taken from * * http://boost.2283326.n4.nabble.com/Fwd-Thread-Solution-to-conflict-with-MFC… * * $Id$ */ #include <windows.h> #include <boost/thread/detail/tss_hooks.hpp> extern "C" BOOL WINAPI RawDllMain(HINSTANCE hInstance, DWORD dwReason, LPVOID); namespace { BOOL WINAPI dll_callback(HANDLE h, DWORD dwReason, LPVOID p) { #ifdef _DLL if(!RawDllMain(static_cast<HINSTANCE>(h),dwReason,p)) return false; #endif // _DLL switch (dwReason) { case DLL_THREAD_DETACH: boost::on_thread_exit(); break; case DLL_PROCESS_DETACH: boost::on_process_exit(); break; } return true; } } extern "C" { extern BOOL (WINAPI * const _pRawDllMain)(HANDLE, DWORD, LPVOID)=&dll_callback; } namespace boost { void tss_cleanup_implemented() {} }

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Release branch now open for merging
by Marshall Clow 12 Nov '12

12 Nov '12

The release branch (https://svn.boost.org/svn/boost/branches/release) is open for merging all stable changes from trunk, including bug fixes and major upgrades to existing libraries. Breaking changes should be coordinated via the mailing list with the developers of the other libraries affected. New libraries may be added, but require permission of a release manager. In other words, merging *does not* require permission from a release manager, except for new libraries. Boost Calendar with the release schedule: http://www.boost.org/development/index.html Release schedule explanation: http://svn.boost.org/trac/boost/wiki/ReleaseSchedule Release practices for developers: http://svn.boost.org/trac/boost/wiki/ImprovingPractices -- The Release Managers, Beman Dawes Daniel James Eric Niebler Marshall Clow Rene Rivera Vladimir Prus

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[iostream] Bug in indirect_streambuf::seek_impl
by Jorge Lodos Vigil 12 Nov '12

12 Nov '12

Hi Currently indirect_streambuf::seek_impl always modifies input and output pointers with code: setg(0, 0, 0); setp(0, 0); See detail/indirect_streambuf.hpp. However, this is incorrect for dual seekable streams buffers which only modifies one set of pointers on each seek (in or out). As a consequence, dual seekable devices cannot be correctly seek. Those 2 lines should be replaced by: if (is_convertible<category, dual_seekable>::value) { if (which == BOOST_IOS::in) { setg(0, 0, 0); } if (which == BOOST_IOS::out) { setp(0, 0); } } else { setg(0, 0, 0); setp(0, 0); } I have created ticket https://svn.boost.org/trac/boost/ticket/7681 Thanks, Jorge

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enable_if quirk? bug?
by Gennadiy Rozental 12 Nov '12

12 Nov '12

Hi, While working on some portability for Boost.Test I found this weird behavior. Abstracting out Boost.Test specific staff it goes like this: template<typename T> inline typename boost::enable_if_c<!boost::is_float<T>::value, int>::type foo( T&& v ); template<typename T> inline typename boost::enable_if_c<!boost::is_float<T>::value, int>::type foo( T&& v ) { return 1; } ... foo(1); MSVC 10 producing this error: error C2668: 'foo' : ambiguous call to overloaded function test.cpp(31): could be 'int foo<int>(T &&)' with [ T=int ] test.cpp(27): or 'int foo<int>(T &&)' with [ T=int ] while trying to match the argument list '(int)' Now change boost::enable_if_c with seemingly equivalent std::enable_if: template<typename T> inline typename std::enable_if<!boost::is_float<T>::value, int>::type foo( T&& v ); template<typename T> inline typename std::enable_if<!boost::is_float<T>::value, int>::type foo( T&& v ) { return 1; } and MSVC 10 is happy to accept this code. This is somewhat unfortunate since I hoped to use boost::enable_if across compilers. Gennadiy

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