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allocate_shared and allocation size
by Olivier Tristan 18 Dec '12

18 Dec '12

Hi Guys, What would be the best way to get the size required by the allocation of a shared_ptr used when using allocate_shared ? So far, it looks like to be something related to the sizeof sp_counted_impl_pda< P, D, A >, but I would like to know the cleaner way of getting this info. The goal is to preallocate my pool with the right number of planned shared_ptr in order to avoid allocation.(real time thread) Thanks ! -- Olivier Tristan uvi.net

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[Boost.MultiArray]: size question
by gast128 18 Dec '12

18 Dec '12

Dear all, we use here the multi_array as a 2 dimensional matrix. Often we want to resize the row or column dependent on some GUI event. Code could be: void Bla::ResizeRows(size_t nRows) { m_matrix.resize(boost::extents[nRows][m_matrix[0].size()]); } However this uses the 0-index of row count (i.e. 'm_matrix[0].size()') to determine the size of the columns. Will this not crash if you have 0 rows? And if so is there a better alternative? wkr.

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Boost MPI on homogeneous machines
by Kyle Joseph Berger 17 Dec '12

17 Dec '12

Hello, Has anyone successfully used the homogeneous options in boost MPI before? I build boost mpi after uncommenting the appropriate line in the boost mpi config.cpp file and enabled BOOST_IS_BITWISE_SERIALIZABLE([classname]) for several of my classes that I pass, but I saw no change in performance, so I am not sure if it is enabled. The documentation says the following: More optimizations are possible on homogeneous machines, by avoiding MPI_Pack/MPI_Unpack calls but using direct bitwise copy. This feature can be enabled by defining the macro BOOST_MPI_HOMOGENEOUS when building Boost.MPI and when building the application. In addition all classes need to be marked both as is_mpi_datatype and as is_bitwise_serializable, by using the helper macro of Boost.Serialization: I defined the macro when building boost and marked the classes, but I could find no information anywhere on what to do when building the application, so I am thinking maybe this is what I am missing. Any help would be much appreciated. Thanks, Kyle

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error while installing boost 1.36 and 1.52
by naveen kumar 17 Dec '12

17 Dec '12

Dear Boost user, while installing boost, i am getting many error messages as below, how to overcome these errors, please help me thanking you in advance Naveen Building the Boost C++ Libraries. Performing configuration checks - 32-bit : no - 64-bit : yes - x86 : yes - has_icu builds : no warning: Graph library does not contain MPI-based parallel components. note: to enable them, add "using mpi ;" to your user-config.jam - iconv (libc) : yes - icu : no - icu (lib64) : no - gcc visibility : yes - long double support : yes warning: skipping optional Message Passing Interface (MPI) library. note: to enable MPI support, add "using mpi ;" to user-config.jam. note: to suppress this message, pass "--without-mpi" to bjam. note: otherwise, you can safely ignore this message. Component configuration: - chrono : building - context : building - date_time : building - exception : building - filesystem : building - graph : building - graph_parallel : building - iostreams : building - locale : building - math : building - mpi : building - program_options : building - python : building - random : building - regex : building - serialization : building - signals : building - system : building - test : building - thread : building - timer : building - wave : building ...patience... ...patience... ...patience... ...patience... ...found 8697 targets... ...updating 824 targets... gcc.compile.c++ bin.v2/libs/iostreams/build/gcc-4.4.6/release/threading-multi/bzip2.o libs/iostreams/src/bzip2.cpp:20:56: error: bzlib.h: No such file or directory libs/iostreams/src/bzip2.cpp:31: error: ‘BZ_OK’ was not declared in this scope libs/iostreams/src/bzip2.cpp:32: error: ‘BZ_RUN_OK’ was not declared in this scope libs/iostreams/src/bzip2.cpp:33: error: ‘BZ_FLUSH_OK’ was not declared in this scope libs/iostreams/src/bzip2.cpp:34: error: ‘BZ_FINISH_OK’ was not declared in this scope libs/iostreams/src/bzip2.cpp:35: error: ‘BZ_STREAM_END’ was not declared in this scope libs/iostreams/src/bzip2.cpp:36: error: ‘BZ_SEQUENCE_ERROR’ was not declared in this scope libs/iostreams/src/bzip2.cpp:37: error: ‘BZ_PARAM_ERROR’ was not declared in this scope libs/iostreams/src/bzip2.cpp:38: error: ‘BZ_MEM_ERROR’ was not declared in this scope libs/iostreams/src/bzip2.cpp:39: error: ‘BZ_DATA_ERROR’ was not declared in this scope libs/iostreams/src/bzip2.cpp:40: error: ‘BZ_DATA_ERROR_MAGIC’ was not declared in this scope libs/iostreams/src/bzip2.cpp:41: error: ‘BZ_IO_ERROR’ was not declared in this scope libs/iostreams/src/bzip2.cpp:42: error: ‘BZ_UNEXPECTED_EOF’ was not declared in this scope libs/iostreams/src/bzip2.cpp:43: error: ‘BZ_OUTBUFF_FULL’ was not declared in this scope libs/iostreams/src/bzip2.cpp:44: error: ‘BZ_CONFIG_ERROR’ was not declared in this scope libs/iostreams/src/bzip2.cpp:48: error: ‘BZ_FINISH’ was not declared in this scope libs/iostreams/src/bzip2.cpp:49: error: ‘BZ_RUN’ was not declared in this scope libs/iostreams/src/bzip2.cpp: In static member function ‘static void boost::iostreams::bzip2_error::check(int)’: libs/iostreams/src/bzip2.cpp:62: error: ‘BZ_OK’ was not declared in this scope libs/iostreams/src/bzip2.cpp:63: error: ‘BZ_RUN_OK’ was not declared in this scope libs/iostreams/src/bzip2.cpp:64: error: ‘BZ_FLUSH_OK’ was not declared in this scope libs/iostreams/src/bzip2.cpp:65: error: ‘BZ_FINISH_OK’ was not declared in this scope libs/iostreams/src/bzip2.cpp:66: error: ‘BZ_STREAM_END’ was not declared in this scope libs/iostreams/src/bzip2.cpp:68: error: ‘BZ_MEM_ERROR’ was not declared in this scope libs/iostreams/src/bzip2.cpp: In constructor ‘boost::iostreams::detail::bzip2_base::bzip2_base(const boost::iostreams::bzip2_params&)’: libs/iostreams/src/bzip2.cpp:80: error: expected type-specifier before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:80: error: expected ‘)’ before ‘bz_stream’ libs/iostreams/src/bzip2.cpp: In destructor ‘boost::iostreams::detail::bzip2_base::~bzip2_base()’: libs/iostreams/src/bzip2.cpp:83: error: expected type-specifier before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:83: error: expected ‘>’ before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:83: error: expected ‘(’ before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:83: error: ‘bz_stream’ was not declared in this scope libs/iostreams/src/bzip2.cpp:83: error: expected primary-expression before ‘>’ token libs/iostreams/src/bzip2.cpp:83: error: expected ‘)’ before ‘;’ token libs/iostreams/src/bzip2.cpp: In member function ‘void boost::iostreams::detail::bzip2_base::before(const char*&, const char*, char*&, char*)’: libs/iostreams/src/bzip2.cpp:88: error: ‘bz_stream’ was not declared in this scope libs/iostreams/src/bzip2.cpp:88: error: ‘s’ was not declared in this scope libs/iostreams/src/bzip2.cpp:88: error: expected type-specifier before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:88: error: expected ‘>’ before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:88: error: expected ‘(’ before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:88: error: expected primary-expression before ‘>’ token libs/iostreams/src/bzip2.cpp:88: error: expected ‘)’ before ‘;’ token libs/iostreams/src/bzip2.cpp: In member function ‘void boost::iostreams::detail::bzip2_base::after(const char*&, char*&)’: libs/iostreams/src/bzip2.cpp:97: error: ‘bz_stream’ was not declared in this scope libs/iostreams/src/bzip2.cpp:97: error: ‘s’ was not declared in this scope libs/iostreams/src/bzip2.cpp:97: error: expected type-specifier before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:97: error: expected ‘>’ before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:97: error: expected ‘(’ before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:97: error: expected primary-expression before ‘>’ token libs/iostreams/src/bzip2.cpp:97: error: expected ‘)’ before ‘;’ token libs/iostreams/src/bzip2.cpp: In member function ‘int boost::iostreams::detail::bzip2_base::check_end(const char*, const char*)’: libs/iostreams/src/bzip2.cpp:104: error: ‘bz_stream’ was not declared in this scope libs/iostreams/src/bzip2.cpp:104: error: ‘s’ was not declared in this scope libs/iostreams/src/bzip2.cpp:104: error: expected type-specifier before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:104: error: expected ‘>’ before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:104: error: expected ‘(’ before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:104: error: expected primary-expression before ‘>’ token libs/iostreams/src/bzip2.cpp:104: error: expected ‘)’ before ‘;’ token libs/iostreams/src/bzip2.cpp: In member function ‘void boost::iostreams::detail::bzip2_base::end(bool)’: libs/iostreams/src/bzip2.cpp:118: error: ‘bz_stream’ was not declared in this scope libs/iostreams/src/bzip2.cpp:118: error: ‘s’ was not declared in this scope libs/iostreams/src/bzip2.cpp:118: error: expected type-specifier before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:118: error: expected ‘>’ before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:118: error: expected ‘(’ before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:118: error: expected primary-expression before ‘>’ token libs/iostreams/src/bzip2.cpp:118: error: expected ‘)’ before ‘;’ token libs/iostreams/src/bzip2.cpp:121: error: ‘BZ2_bzCompressEnd’ was not declared in this scope libs/iostreams/src/bzip2.cpp:122: error: ‘BZ2_bzDecompressEnd’ was not declared in this scope libs/iostreams/src/bzip2.cpp: In member function ‘int boost::iostreams::detail::bzip2_base::compress(int)’: libs/iostreams/src/bzip2.cpp:128: error: expected type-specifier before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:128: error: expected ‘>’ before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:128: error: expected ‘(’ before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:128: error: ‘bz_stream’ was not declared in this scope libs/iostreams/src/bzip2.cpp:128: error: expected primary-expression before ‘>’ token libs/iostreams/src/bzip2.cpp: In member function ‘int boost::iostreams::detail::bzip2_base::decompress()’: libs/iostreams/src/bzip2.cpp:133: error: expected type-specifier before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:133: error: expected ‘>’ before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:133: error: expected ‘(’ before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:133: error: ‘bz_stream’ was not declared in this scope libs/iostreams/src/bzip2.cpp:133: error: expected primary-expression before ‘>’ token libs/iostreams/src/bzip2.cpp: In member function ‘void boost::iostreams::detail::bzip2_base::do_init(bool, void* (*)(void*, int, int), void (*)(void*, void*), void*)’: libs/iostreams/src/bzip2.cpp:144: error: ‘bz_stream’ was not declared in this scope libs/iostreams/src/bzip2.cpp:144: error: ‘s’ was not declared in this scope libs/iostreams/src/bzip2.cpp:144: error: expected type-specifier before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:144: error: expected ‘>’ before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:144: error: expected ‘(’ before ‘bz_stream’ libs/iostreams/src/bzip2.cpp:144: error: expected primary-expression before ‘>’ token libs/iostreams/src/bzip2.cpp:144: error: expected ‘)’ before ‘;’ token libs/iostreams/src/bzip2.cpp:161: error: ‘BZ2_bzCompressInit’ was not declared in this scope libs/iostreams/src/bzip2.cpp:164: error: ‘BZ2_bzDecompressInit’ was not declared in this scope "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -pthread -fPIC -DBOOST_ALL_NO_LIB=1 -DBOOST_IOSTREAMS_DYN_LINK=1 -DBOOST_IOSTREAMS_USE_DEPRECATED -DNDEBUG -I"." -c -o "bin.v2/libs/iostreams/build/gcc-4.4.6/release/threading-multi/bzip2.o" "libs/iostreams/src/bzip2.cpp" ...failed gcc.compile.c++ bin.v2/libs/iostreams/build/gcc-4.4.6/release/threading-multi/bzip2.o... ...skipped <pbin.v2/libs/iostreams/build/gcc-4.4.6/release/threading-multi>libboost_iostreams.so.1.52.0 for lack of <pbin.v2/libs/iostreams/build/gcc-4.4.6/release/threading-multi>bzip2.o... ...skipped <pstage/lib>libboost_iostreams.so.1.52.0 for lack of <pbin.v2/libs/iostreams/build/gcc-4.4.6/release/threading-multi>libboost_iostreams.so.1.52.0... ...skipped <pstage/lib>libboost_iostreams.so for lack of <pstage/lib>libboost_iostreams.so.1.52.0... gcc.compile.c++ bin.v2/libs/locale/build/gcc-4.4.6/release/threading-multi/posix/posix_backend.o common.mkdir bin.v2/libs/locale/build/gcc-4.4.6/release/threading-multi/std gcc.compile.c++ bin.v2/libs/locale/build/gcc-4.4.6/release/threading-multi/std/codecvt.o gcc.compile.c++ bin.v2/libs/locale/build/gcc-4.4.6/release/threading-multi/std/collate.o gcc.compile.c++ bin.v2/libs/locale/build/gcc-4.4.6/release/threading-multi/std/converter.o gcc.compile.c++ bin.v2/libs/locale/build/gcc-4.4.6/release/threading-multi/std/numeric.o gcc.compile.c++ bin.v2/libs/locale/build/gcc-4.4.6/release/threading-multi/std/std_backend.o gcc.compile.c++ bin.v2/libs/locale/build/gcc-4.4.6/release/threading-multi/util/gregorian.o gcc.link.dll bin.v2/libs/locale/build/gcc-4.4.6/release/threading-multi/libboost_locale.so.1.52.0 common.copy stage/lib/libboost_locale.so.1.52.0 ln-UNIX stage/lib/libboost_locale.so common.mkdir bin.v2/libs/math/build common.mkdir bin.v2/libs/math/build/gcc-4.4.6 common.mkdir bin.v2/libs/math/build/gcc-4.4.6/release common.mkdir bin.v2/libs/math/build/gcc-4.4.6/release/threading-multi common.mkdir bin.v2/libs/math/build/gcc-4.4.6/release/threading-multi/.. common.mkdir bin.v2/libs/math/build/gcc-4.4.6/release/threading-multi/../src common.mkdir bin.v2/libs/math/build/gcc-4.4.6/release/threading-multi/../src/tr1 . . . . . . . gcc.link.dll bin.v2/libs/program_options/build/gcc-4.4.6/release/threading-multi/libboost_program_options.so.1.52.0 common.copy stage/lib/libboost_program_options.so.1.52.0 ln-UNIX stage/lib/libboost_program_options.so common.mkdir bin.v2/libs/python common.mkdir bin.v2/libs/python/build common.mkdir bin.v2/libs/python/build/gcc-4.4.6 common.mkdir bin.v2/libs/python/build/gcc-4.4.6/release common.mkdir bin.v2/libs/python/build/gcc-4.4.6/release/threading-multi gcc.compile.c++ bin.v2/libs/python/build/gcc-4.4.6/release/threading-multi/numeric.o In file included from ./boost/python/detail/prefix.hpp:13, from ./boost/python/numeric.hpp:8, from libs/python/src/numeric.cpp:6: ./boost/python/detail/wrap_python.hpp:50:23: error: pyconfig.h: No such file or directory ./boost/python/detail/wrap_python.hpp:75:24: error: patchlevel.h: No such file or directory ./boost/python/detail/wrap_python.hpp:78:2: error: #error Python 2.2 or higher is required for this version of Boost.Python. ./boost/python/detail/wrap_python.hpp:142:21: error: Python.h: No such file or directory In file included from ./boost/python/object/pointer_holder.hpp:14, from ./boost/python/to_python_indirect.hpp:10, from ./boost/python/converter/arg_to_python.hpp:10, from ./boost/python/call.hpp:15, from ./boost/python/object_core.hpp:14, from ./boost/python/object.hpp:9, from ./boost/python/tuple.hpp:10, from ./boost/python/numeric.hpp:10, from libs/python/src/numeric.cpp:6: ./boost/python/instance_holder.hpp:34: error: ‘PyObject’ has not been declared ./boost/python/instance_holder.hpp:41: error: expected ‘;’ before ‘(’ token ./boost/python/instance_holder.hpp:45: error: ‘PyObject’ has not been declared In file included from ./boost/python/object/pointer_holder.hpp:21, . . . . .

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Deadline extension: C++ Now 2013, Call for Submissions
by Hartmut Kaiser 15 Dec '12

15 Dec '12

Please see below for the extended deadline. ---------------------------------------------------------------------------- C++ NOW CONFERENCE 2013 - Aspen CO, USA, May 13-17, 2013, www.cppnow.org ---------------------------------------------------------------------------- CALL FOR SUBMISSIONS -------------------- We invite you to submit session proposals to the 2nd annual C++ Now Conference (Aspen CO, USA, May 13-17, 2013). Building upon the resounding success of C++ Now 2012 and five years of BoostCon, C++ Now 2013 will present leading speakers from the whole C++ community. The C++ Now Conference is dedicated to discussion and education about C++, an open and free language and standard. Our Conference will focus on discussion and education about open source software usage and developments in the C++ developer and user community. To reflect the breadth of the C++ and Boost communities, the conference includes sessions aimed at three constituencies: C++ and Boost end-users, hard-core Boost library and tool developers, and researchers pushing the boundaries of computation. The program fosters interaction and engagement within and across those groups, with an emphasis on hands-on, participatory sessions. As a multi-paradigm language, C++ is a melting pot where the most compelling ideas from other programming communities are blended in powerful ways. Historically, some of the most popular sessions at C++ Now have highlighted these concepts, from DSLs to functional programming to transactional memory and more. Bring your C#, Python, Ruby or Haskell influences to bear in an environment that will broaden their exposure. At C++ Now 2013 we would like to focus on parallel and distributed computing with C++. However, by no means this is intended to restrict the topics of proposals we hope to see. Any other topic related to C++ as outlined below is perfectly fine for submission. IMPORTANT DATES --------------- New proposal submissions due: January 5th, 2013. Proposals decisions sent (tentative program available): January 30th, 2013. Fully scheduled program available: February 24th, 2013. BEST PRESENTATION AWARDS ------------------------ We know how much effort it takes to prepare talks for our conference. For this reason we will award the best presentations in the following categories: Best Presentation, Best Short Presentation, Best Tutorial, and Best Workshop. The awards will be given based on the audience's voting. Each award will include the author's name listed on the cover of the C++ Now website for that year and a plaque containing all the C++ Now conference information. SESSION TOPICS -------------- Topics of interest include, but are not restricted to, the following: * Parallelism in the new C++11 standard * Parallel, distributed and GPGPU topics relating to C++ * C++11 and how it changes life for users and library writers * General tutorial sessions on C++11, the C++11 Standards library, and one or more Boost libraries * In-depth sessions on using specific Boost libraries * Case studies on using Boost * Experts panels * Advanced sessions on implementation techniques used within Boost libraries * Development workshops to extend or enhance existing Boost libraries * Workshops on design process * Infrastructure workshops such as Build tools, Website, Testing * Concepts and Generic Programming * Hardware and infrastructure presentations focused on how libraries can make better use of the technology * Software development tools and their application to C++ and or Boost * Other topics likely to be of great interest to C++ users and developers Interactive and collaborative sessions are encouraged, as this is the style of learning and participation that has proven most successful at such events. Sessions can be tutorial based, with an emphasis on interaction and participant involvement, or workshop based, whether hands-on programming or paper-based, discussion-driven collaborative work. SESSION FORMATS --------------- Presentations Presentations focus on a practitioner's ideas and experience with anything relevant to C++11, Boost and users. Panels Panels feature three or four people presenting their ideas and experiences relating to C++11 and Boost's relevant, controversial, emerging, or unresolved issues. Panels may be conducted in several ways, such as comparative, analytic, or historic. Tutorials Tutorials are sessions at which instructors teach conference participants specific skills relevant to C++11 and Boost. Workshops Workshops provide an active arena for advancements in Boost-relevant topics. Workshops provide the opportunity for experienced practitioners to develop new ideas about a topic of common interest and experience. Author's Corner Presentations These were introduced at BoostCon 2008, and were a great success. They are short (30 minute) sessions, focusing on tips on usage and design. In addition, we're looking to uncover the hidden design gems in Boost libraries. Tool Vendors Presentations We actively encourage tool vendors and ISP's to submit proposals for a special Tool Vendors Session Track aimed at products related to Boost and C++ (compilers, libraries, tools, etc.). Other formats may also be of interest. Don't hold back a proposal just because it doesn't fit into a pigeonhole. SUBMITTING A PROPOSAL --------------------- Standard Sessions are 90 minutes. You may submit a proposal for fractions Or multiples of 90-minutes. Fractional proposals will be grouped into 90 Minute sessions covering related topics. Longer sessions, such as tutorials and classes, will be assigned three hour (i.e. half day), or six hour (i.e. full day) time slots. Please include: * The working title. * Type of session: presentation, panel, tutorial, workshop, authors corner, vendor track, other. * A paragraph or two describing the topic covered, suitable for the conference web site. * Proposed length: 10-20 minute short talks, 45 minutes, 90 minutes, half day, full day. * Alternate lengths, if you are willing to make adjustments: 10-20 minute short-talks, 45 minutes, 90 minutes, half-day, full day. * Audience: users, developers, both. * Level: basic, intermediate, advanced. * A biography, suitable for the conference web site. * Your contact information (will not be made public). SUBMISSION DETAILS ------------------ All submissions should be made through the EasyChair conference management system: http://www.easychair.org/conferences/?conf=cppnow2013. If you have not already registered at EasyChair, you will need to do so in order to submit your proposal. All submissions will go through a peer review process. Authors are invited (but are not required) to submit PDF versions of full papers of up to 10 pages in ACM conference proceedings format (see http://www.acm.org/sigs/publications/proceedings-templates) The full papers are not required unless you want them published in the proceedings. All accepted proposals will be made available in the Association for Computing Machinery (ACM) Digital Library (approval pending). Best papers, after further reviews, will be considered to be book chapters or journal articles in a renowned journal. The session materials go on the C++ Now website and will be available to attendees. For general information on the C++ Now 2013 paper submission or the scope of technical papers solicited; please refer to the conference website at www.cppnow.org. For any other questions about the submission process or paper format, please contact the Program Committee at cppnow2013(a)easychair.com. If you have any technical problems with EasyChair, please contact EasyChair for help. Note: Presenters must agree to grant a non-exclusive perpetual license to publish submitted materials, either electronically or in print, in any media related to C++ Now. Hartmut Kaiser, email: hartmut.kaiser(a)gmail.com (Program Committee Chair) Dave Abrahams, email: dave(a)boostpro.com (Conference Chair) On behalf of the conference organizers

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[regex] match_results: signatures of position(sub) and length(sub) are different, why?
by Frédéric Bron 14 Dec '12

14 Dec '12

Hi, On the following link, we can see that length and position member functions have different signatures: http://www.boost.org/doc/libs/1_52_0/libs/regex/doc/html/boost_regex/ref/ma… difference_type length(int sub = 0) const; difference_type position(unsigned int sub = 0) const; Why int for length(sub) and unsigned int for position(sub)? Frédéric

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[boost-python] some general questions
by Ovanes Markarian 14 Dec '12

14 Dec '12

Hello *, we are now considering to use some Python/C++ bindings and here came Boost Python to my mind. I would like to ask what is the state of the library? Is it still maintained? As far as I can see the library's doc is dated back to 2003 (some of the doc's parts are from 2005) and the latest python version to be known to work is Python 2.2.2. Is Python 2.7.2 going to work or supported at all? I also searched for some docs on how Boost Python bindings are going to work with PyPy. Found some really old post describing the problems to support Boost Python binding and some messages from the mailing list, which describe, which functions must be implemented to support Boost Python in PyPy. Any info would be great! Thanks, Ovanes

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[preprocessor] BOOST_PP_VARIADIC_SIZE() and g++ in 1.52
by Nat Linden 13 Dec '12

13 Dec '12

I'm trying to use a variadic macro to solve a problem. We use a third-party function I can't modify -- actually a family of functions of arbitrary arity. Before each call to that function, I want to examine and possibly modify its first argument. (So not completely arbitrary arity: there's always at least one argument.) What I'd really like is a variadic function. Unfortunately the compilers we use don't yet support those. We do have cross-platform support for variadic macros, albeit with idiosyncratic syntax. My problem is that I need: intercept(first, second, third) to expand to: targetfunc(transform(first), second, third) but I need: intercept(first) to expand to: targetfunc(transform(first)) // <= no trailing comma This is the role of BOOST_PP_COMMA_IF(). In Visual Studio 2010 I can write BOOST_PP_COMMA_IF(BOOST_PP_VARIADIC_SIZE(__VA_ARGS__)), and the code behaves as expected. In g++ 4.1, 4.2 and 4.4, however, my first problem is that BOOST_PP_VARIADICS is not set by default. When I set it explicitly, as permitted by the documentation[0], a call such as intercept("first", "second") (comma required) succeeds, but a call such as intercept("first") (comma forbidden) fails. Using -E and examining the preprocessed output from intercept("first") makes clear that BOOST_PP_COMMA_IF() is expanding to a comma, hence BOOST_PP_VARIADIC_SIZE() is expanding to nonzero. In fact, when I change the definition of the intercept() macro below to: #define intercept(FIRST, ARGS...) \ targetfunc(transform(FIRST) \ , boost::lexical_cast<std::string>(BOOST_PP_VARIADIC_SIZE(ARGS))) I see that BOOST_PP_VARIADIC_SIZE() expands to 1 for intercept("first") as well as for intercept("first", "second"). Is it possible to achieve what I want with my present suite of compilers? Is there some workaround we could use until (at some point in the indefinite future) we've upgraded all our compilers so that even the oldest of them supports variadic functions? [0] http://www.boost.org/doc/libs/1_52_0/libs/preprocessor/doc/topics.html ================ source code follows ================ #include <iostream> #include <string> #include <boost/preprocessor/variadic/size.hpp> #include <boost/preprocessor/punctuation/comma_if.hpp> // no targetfunc(void) void targetfunc(const std::string& first) { std::cout << "targetfunc('" << first << "')\n"; } void targetfunc(const std::string& first, const std::string& second) { std::cout << "targetfunc('" << first << "', '" << second << "')\n"; } // ... assume a family of targetfunc() arities ... // want to implicitly "do something" to targetfunc()'s first arg std::string transform(const std::string& arg) { return "transformed " + arg; } #if defined(_MSC_VER) // anonymous variadic arguments and __VA_ARGS__ keyword #define intercept(FIRST, ...) \ targetfunc(transform(FIRST) \ BOOST_PP_COMMA_IF(BOOST_PP_VARIADIC_SIZE(__VA_ARGS__)) \ __VA_ARGS__) #else // collectively-named variadic arguments #define intercept(FIRST, ARGS...) \ targetfunc(transform(FIRST) \ BOOST_PP_COMMA_IF(BOOST_PP_VARIADIC_SIZE(ARGS)) \ ARGS) #endif int main(int argc, char *argv[]) { std::cout << "BOOST_PP_VARIADICS = " << BOOST_PP_VARIADICS << "\n"; intercept("first", "second"); intercept("first"); // <= this line has trouble with g++ 4.1, 4.2, 4.4 return 0; }

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(no subject)
by Rydinare 13 Dec '12

13 Dec '12

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[Exception] Expected<T> C++03
by Szymon Gatner 12 Dec '12

12 Dec '12

Hi, I trying to implement Andrei's Expected<T> from his "Systematic Error Handling in C++" talk ( http://channel9.msdn.com/Shows/Going+Deep/C-and-Beyond-2012-Andrei-Alexandr…) in C++03 / BOOST In short: Expected<T> holds either T or exception_ptr holding exception that prevented T's creation. Think of single threaded future<T>. One of main purposes of this type is efficiency - code that computes T would normally throw in case of errors but instead it returns exception by value which causes Expected<T> to be initiated with exception type instead of actual value of T. Important part is that no throwing happens in library code (making it fast). As with future<T> throwing of stored exception only happens upon client's request - a call to get() in case of invalid computation (Expected<T>::valid() may be called beforehand to check if computation succeeded). To the point: Andrei's code uses std::make_exception_ptr() which I assume is std version of boost::copy_exception(). Now problem with copy_exception() is that it actually throws! So the whole idea of not throwing is gone by the fact that I don't know how to transform (const Exception&) into boost::exception_ptr (without throwing via copy_exception()). How does std::make_exception_ptr() work (as I assume it does not throw & return current_exception() as boost::copy_exception does)? Any suggestions welcome. Cheers. Szymon Gatner

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