August 2014 - Boost-users - lists.boost.org

[interprocess] Determine size of managed_shared_memory
by Kai Benndorf 12 Oct '19

12 Oct '19

Hi all, I want to create a managed_shared_memory in exactly the size I needed. Therefore I do something like this: size = sizeof( common_managed_shared_memory ); size += sizeof( MyClassInSharedMem ); managed_shared_memory segment(create_only, "name", size ); MyClassInSharedMem allocates itself some memory by segment->allocate(). I added this also to the size, but get a boost::interprocess::bad_alloc exception on allocating this additional memory. Are there some magic bytes I forgot to add? Many thanks in advance Kai

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[Range, Phoenix] What am I missing...
by Robert Jones 25 Apr '17

25 Apr '17

Hi Folks Can anyone explain the output of this program... #include <iostream> #include <boost/range/algorithm/copy.hpp> #include <boost/range/counting_range.hpp> #include <boost/range/adaptor/reversed.hpp> #include <boost/range/adaptor/transformed.hpp> #include <boost/phoenix/bind/bind_function.hpp> #include <boost/phoenix/core/argument.hpp> int f( int i ) { return i * 2; } int main( ) { using boost::adaptors::reversed; using boost::adaptors::transformed; using boost::counting_range; using boost::copy; using boost::phoenix::arg_names::_1; copy( counting_range( 1, 5 ) | reversed | transformed( f ), std::ostream_iterator<int>( std::cout, " " ) ); std::cout << std::endl; copy( counting_range( 1, 5 ) | reversed | transformed( bind( f, _1 ) ), std::ostream_iterator<int>( std::cout, " " ) ); std::cout << std::endl; } Which is... 8 6 4 2 1768406272 1768406272 1768406272 1768406272 I'm using Gcc 4.6.2 & Boost 1.53 Thx All.

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[statechart] Passing parameters from event to State Local Storage
by Christophe Bourez 16 Nov '16

16 Nov '16

I need to maintain a parameter into the state local storage. This parameter is initially contained in the event that causes the transition to the target state. I give hereafter a small illustrative example. typename sc = boost::statechart; class EvTest : public sc::event<EvTest> { public: EvTest(std::size_t val) : value(val) {} std::size_t getValue() const { return this->value; } private: std::size_t value; }; class MyStateMachine; class StSource; class StTarget; class StSource : public sc::simple_state<StSource, MyStateMachine> { public: typedef sc::custom_reaction<EvTest> reactions; sc::result react(const EvTest &event) { // How to pass event.getValue() to the target state ? transit<StTarget>(); } }; class StTarget : public sc::simple_state<StTarget, MyStateMachine> { public: StTarget(std::size_t val) : val(value) {} private: std::size_t value; }; Thanks, Christophe

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Re: [Boost-users] lexical_cast between double and string slow in Visual Studio 2013
by David Roberts 07 May '15

07 May '15

> That issue is unknown. I'd really appreciate the investigation. I have done some more investigation, and there are two factors that only cause the slowness when they both occur together. > Try excluding the lexical_cast from test, I have a feeling that this is only MSVC related issue: > > #include <sstream> > #include <string> > > int main (int, char **) > { > for (double count = 0.0; count < 1000000.0; count += 1.41) > { > std::stringstream ss; > ss << count; > std::string result = std::move(ss.str()); > ss.str(std::string()); > > ss << result; > ss >> count; > } > > return 0; > } > Running your test program does not exhibit the problem. It runs in around 3 seconds on my machine when built with either Visual Studio 2010 or Visual Studio 2013. However, changing it very slightly to match more closely what lexical_cast does internally does recreate the problem: #include <sstream> #include <string> int main (int, char **) { for (double count = 0.0; count < 1000000.0; count += 1.41) { std::stringstream ss; ss.unsetf(std::ios::skipws); ss.precision(17); ss << count; std::string result = std::move(ss.str()); ss.str(std::string()); ss << result; ss >> count; } return 0; } The effect of setting the precision to 17 is that lots of 9s appear in the string representations. (The number 17 is what boost::detail::lcast_get_precision(double*) chooses.) Without the precision call the contents of the string called result start off like this: 0 1.41 2.82 4.23 5.64 7.05 8.46 9.87 11.28 12.69 With precision set to 17 they start off like this: 0 1.4099999999999999 2.8199999999999998 4.2299999999999995 5.6399999999999997 7.0499999999999998 8.4599999999999991 9.8699999999999992 11.279999999999999 12.69 This happens for both Visual Studio 2010 and Visual Studio 2013. Then the next difference is that Visual Studio 2013 spends a lot longer handling all the extra 9s. Changing the program so that the double is converted to a string using std::stringstream without a precision call and then back to double using lexical_cast takes about 3 seconds for both Visual Studio 2010 and Visual Studio 2013. It is the combination of having all the extra 9s to parse and using Visual Studio 2013 that makes the test using lexical_cast to go both ways slow. Both Visual Studio 2010 and Visual Studio 2013 do the conversion by calling std::num_get<char,std::istreambuf_iterator<char,std::char_traits<char> > >::do_get() which then calls a function called _Stodx() which is implemented in xstod.c. This function is very different for the two versions. In Visual Studio 2010 it's a relatively thin wrapper around the C function strtod(). In Visual Studio 2013 _Stodx() has got a completely new implementation that's generated by #including xxstod.h with some macros defined. The original C function strtod() is much faster than the new _Stodx() when there are lots of 9s at the end of the strings being parsed. This modification to the program: #include <sstream> #include <string> #include <stdlib.h> int main (int, char **) { for (double count = 0.0; count < 1000000.0; count += 1.41) { std::stringstream ss; ss.unsetf(std::ios::skipws); ss.precision(17); ss << count; std::string result = std::move(ss.str()); ss.str(std::string()); ss << result; char *endptr; count = strtod(ss.str().c_str(), &endptr); } return 0; } has a runtime of about 3 seconds even though it's got to cope with all the 9s. I guess only someone from Microsoft or Dinkumware could comment on why _Stodx() was reimplemented. But the other thing is that by setting precision to 17 lexical_cast is bloating the string representations of the doubles with lots of 9s in both Visual Studio 2010 and Visual Studio 2013. Setting precision to 15 instead prevents this, and makes the original test run faster even with Visual Studio 2013 (about 4 seconds rather than 10). Regards, David

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Statechart serialization
by mbrodeur65 04 Mar '15

04 Mar '15

Hi, I'm looking for a solution to serialize boost::statechart objects. I'm aware that this feature is on the statechart library todo list but was wondering if there are any workaround to achieve this with the latest boost release (1.34) ? thanks for your help ! mbrodeur65 -- View this message in context: http://www.nabble.com/Statechart-serialization-tf4131326.html#a11749139 Sent from the Boost - Users mailing list archive at Nabble.com.

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[endian] Boost.Endian library added for 1.57.0
by Beman Dawes 14 Dec '14

14 Dec '14

The library provides integer and floating point types and conversion functions for portable byte ordering regardless of processor endianness. Although the primary uses are for file or network I/O, it is also useful for unaligned integers or floats, or for 3, 5, 6, and 7 byte integers. The library's predecessors have been in use for thirty years and developed independently multiple times. The repository is https://github.com/boostorg/endian The documentation is online at https://boostorg.github.io/endian/ See https://boostorg.github.io/endian/index.html#Release-history for changes since the Formal Review. No need to report "Inspection Report" problems; those will be cleaned up before 1.57.0 ships. Please do report any other problems or concerns, since the time between now and when the 1.57.0 beta ships in effect acts a mini-review period. If anyone has access to a big-endian platform with a modern C++ compiler, please, please run the endian test suite and report the results. All testing and use in recent years has been on little-endian platforms, so big-endian platform testing is a worry. Thanks for you patience, --Beman

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Fusion Move Semantics
by Ovanes Markarian 04 Dec '14

04 Dec '14

Hi! I would like to ask does fusion supports move semantics, or are all the values going to get copied. I use C++11 (clang with libstdcxx) and boost 1.54 (but can upgrade). In my use case I have boost::fusion::map and was wondering, that in case of moving of that map, is it going to forward the move call to contained values or not. Many thanks for help, Ovanes

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NT² 3.0 and Boost.SIMD - Stable release
by Joel Falcou 21 Nov '14

21 Nov '14

The first stable release of the 3.x series of MetaScale’s open-source software is available: NT² 3.0. It also includes its spin-off project, Boost.SIMD (not yet a Boost library). Many Issues have been closed since last beta. The main focus of this release cycle was to fix performances issues and to stabilize some parts of the API. Next step will be to separate NT2 and Boost.SIMD into separate repositories, thus making one more step toward Boost.SIMD submission into review. [ http://www.metascale.org/nt%C2%B2-3-0-and-boost-simd ] *Changes & Bug Fixes:* - Major performance improvements in both libraries - Added experimental support for the HPX runtime for parallelization on shared memory systems - Optimizations of many elemental functions, in particuler log/ex, frexp/ldexp and cbrt - More advanced shuffle pattern recognition for SIMD - Fixed issues with Visual Studio 2013 - More functions are force-inlined to ensure good performance - New functions for conversion between types and mixing of vectors of different sizes - Demo applications usable as benchmarks - Better handling of errors when an unsupported function is called - New API for custom memory allocators Full changelog is available at https://github.com/MetaScale/nt2/releases/tag/3.0.0. *How to get it ?* - Source and binary packages can be downloaded here: http://nt2.metascale.org/downloads - The release is also available on Github : https://github.com/MetaScale/nt2/releases - The main master branch is still under development : https://github.com/MetaScale/nt2

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[property_tree] Failure with Boost 1.56
by beet 10 Oct '14

10 Oct '14

Dear all, with the release of Boost 1.56, on Ubuntu 14.04 (g++ 4.8.2, 64 bit), code like the following suddenly fails to compile: pt::xml_writer_settings<char> settings('\t', 1); pt::write_xml(someFileName, ptr_out, std::locale(), settings); "pt" is obviously an alias for boost::property_tree. The error message I'm getting is /opt/boost156/include/boost/property_tree/detail/xml_parser_writer_settings.hpp:38:35: error: 'char' is not a class, struct, or union type typedef typename Str::value_type Ch; I can see the following possibly relevant change in property_tree: In Boost 1.55, from xml_parser.hpp: ----------------------------------- template<typename Ptree> void write_xml( const std::string & , const Ptree & , const std::locale & = std::locale() , const xml_writer_settings<typename Ptree::key_type::value_type >& = xml_writer_settings<typename Ptree::key_type::value_type >() ); In Boost 1.56, same header: --------------------------- template<typename Ptree> void write_xml( const std::string & , const Ptree & , const std::locale & = std::locale() , const xml_writer_settings<typename Ptree::key_type > & = xml_writer_settings<typename Ptree::key_type >() ); So xml_writer_settings is now given a Ptree::key_type instead of a Ptree::key_type::value_type which I assume is the reason for the above error. Is there a portable way to specify the type of indention character in write_xml ? Best Regards, Beet

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[thread] memory synchronization multiple mutexes
by firespot 19 Sep '14

19 Sep '14

Hi, How does memory synchronization and visibility behave when multiple mutexes are involved? I have two groups of threads (boost::thread_group) and two mutexes (boost::mutex m1, boost::mutex m2) + associated condition variables, with each thread group being responsible to write to some variables (here Ptr, run) and consistently using "its" mutex for locking. However there is a piece of code that looks - much simplified - like this: void f() { { boost::unique_lock<boost::mutex> Lock(m1); Ptr = someAddress; // set the Ptr from 0 to some memory address } { boost::unique_lock<boost::mutex> Lock(m2); run = 1; // was 0, inform that execution can proceed condVar2.notify_all(); } ... // wait until Ptr has been reset to 0 { boost::unique_lock<boost::mutex> Lock(m1); while (Ptr != 0) condVar1.wait(Lock); } } and another function: void g() { { boost::unique_lock<boost::mutex> Lock(m2); while (run == 0) condVar2.wait(Lock); } // run the execution, e.g. std::copy(Ptr, Ptr + 100, Target); // finally all finished, signal back that Ptr is not needed any more { boost::unique_lock<boost::mutex> Lock(m1); Ptr = 0; condVar1.notify_all(); } } f() is only invoked from a thread of the first group, and g() only from a thread of the second group. Whenever Ptr might get changes the first mutex (m1) and its associated condition-variable is used, and whenver run might get changed the second mutex and its associated conditional variable is used. The control flow guarantees that run is not set to 1 prior to Ptr being set, and thus in g() the "running" itself (here the std::copy) cannot commence earlier. However, what puzzles me now: I used a different mutex for setting Ptr and setting/checking run. Does this have any impact whatsoever on memory visibility across the threads in the two thread-groups? Specifically, is it always guaranteed that when g() continues its execution (because run == 1) that it must see the correct value of Ptr (a non-NULL value)? Or is it possible that it still sees 0 and I'd have to make a separate locking involving m1 to guarantee a proper read for Ptr as anything written under a lock of m1 is also only guaranteed to be later properly read if the locking also used m1? thanks!

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[Thread] Read-write locks
by lfrfly＠icqmail.com 18 Sep '14

18 Sep '14

I'm trying to create a standard read/write lock using Boost Threads, and I'm having a bit of difficulty mapping the Boost concepts onto the usual ones. A read/write lock should have several states: Locked for reading (multiple threads may lock at once), locked for writing (only one thread may lock, and no threads may be locked for reading at the same time), and unlocked. Ideally it would be nice if an RWL which is locked for reading may temporarily upgrade to locked for writing, then return to the locked for reading state. Boost supports several relevant notions of locking: shared locking, upgrade locking, and exclusive locking. This to me is a confusing distinction. In particular, a shared_mutex seems appropriate as the basis for a RWL, but is lock_upgrade() the equivalent of a write lock and lock_shared the equivalent of a read lock? This is unclear. If "upgrade locking" is not the same as "exclusive locking", then is an upgrade lock actually exclusive? Could someone please clarify this.

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[fusion] BOOST_FUSION_DEFINE_STRUCT with user defined methods
by Tobias Loew 15 Sep '14

15 Sep '14

Hi, I often use BOOST_FUSION_DEFINE_STRUCT not to generate a fusion-sequence per se, but to get a struct with - default initialisation for all members - a reasonable set of constructors - equality-check - all above without additional code But sometimes I would like to have additional methods in those structs, but deriving from those or fusion-adapting them loses at least one of the nice properties above. After looking at the BOOST_FUSION_DEFINE_STRUCT implementation I though about splitting the makro BOOST_FUSION_DEFINE_STRUCT_IMPL an inject my code in-between. Now my questions are: - Is there anything I've overseen and might detroy some fusion-mechanism? - Is there any chance to get macros like BOOST_FUSION_DEFINE_STRUCT_[BEGIN|END] (and also for the other BOOST_FUSION_DEFINE_... macros? Tobias -- View this message in context: http://boost.2283326.n4.nabble.com/fusion-BOOST-FUSION-DEFINE-STRUCT-with-u… Sent from the Boost - Users mailing list archive at Nabble.com.

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[Range] Strange!
by Robert Jones 10 Sep '14

10 Sep '14

Can anyone explain why my last output line is garbage? #include <iostream> #include <boost/range/algorithm/copy.hpp> #include <boost/range/counting_range.hpp> #include <boost/range/adaptor/reversed.hpp> #include <boost/range/adaptor/transformed.hpp> #include <boost/phoenix/bind/bind_function.hpp> #include <boost/phoenix/core/argument.hpp> int doubled( int i ) { return i * 2; } template <typename Range> void print_it( const Range & range ) { boost::copy( range, std::ostream_iterator<int>( std::cout, " " ) ); std::cout << std::endl; } int main( ) { using boost::adaptors::reversed; using boost::adaptors::transformed; using boost::counting_range; using boost::phoenix::arg_names::_1; print_it( counting_range( 1, 5 ) ); print_it( counting_range( 1, 5 ) | reversed ); print_it( counting_range( 1, 5 ) | transformed( doubled ) ); print_it( counting_range( 1, 5 ) | reversed | transformed( doubled ) ); print_it( counting_range( 1, 5 ) | transformed( bind( doubled, _1 ) ) ); print_it( counting_range( 1, 5 ) | reversed | transformed( bind( doubled, _1 ) ) ); } Output is 1 2 3 4 4 3 2 1 2 4 6 8 8 6 4 2 2 4 6 8 -711713824 -711713824 -711713824 -711713824 Compiling with gcc-4.9.1, Boost 1.56 on Fedora 20 64-bit. Thx, Rob.

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problem with asio signal_set and consecutive signals
by Lutz Schneider 02 Sep '14

02 Sep '14

Hi, I have a program and would like to stop it by sending SIGINT for writing some data to a file instead of exiting immediately. However, if the user of the program sends SIGINT again then the program should quit immediately and forget about writing data to a file. For portability reason I would like to use boost::asio for this purpose. My initial (simplified) approach (see below) did not work. Is this not possible or am I missing something? handler seems to be called only once (printing out the message) and the program always stops when the loop has reached the max iteration number. void handler( const boost::system::error_code& error, int signal_number) { if (!error) { static bool first = true; if(first){ std::cout << " A signal(SIGINT) occurred." << std::endl; // do something like writing data to a file first = false; }else{ std::cout << " A signal(SIGINT) occurred, exiting...." << std::endl; exit(0); } } } int main(){ // Construct a signal set registered for process termination. boost::asio::io_service io; boost::asio::signal_set signals(io, SIGINT); // Start an asynchronous wait for one of the signals to occur. signals.async_wait(handler); io.run(); size_t i; for(i=0;i<std::numeric_limits<size_t>::max();++i){ // time stepping loop, do some computations } std::cout << i << std::endl; return 0; } Cheers, LS

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Boost MPI Collective
by Nolen, Steven Douglas 02 Sep '14

02 Sep '14

In boost/mpi/collectives/reduce.hpp The template function specialization for reduce-ing a std::vector, should probably be modified. Ffrom template<typename T, typename Op> void reduce(const communicator & comm, std::vector<T> const & in_values, std::vector<T> & out_values, Op op, int root) { out_values.resize(in_values.size()); reduce(comm, &in_values.front(), in_values.size(), &out_values.front(), op, root); } To template<typename T, typename Op> void reduce(const communicator & comm, std::vector<T> const & in_values, std::vector<T> & out_values, Op op, int root) { if( comm.rank() == root ) out_values.resize(in_values.size()); reduce(comm, &in_values.front(), in_values.size(), &out_values.front(), op, root); } This will save an extraneous allocation on the non-root nodes. -steve

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[MSM] eUML compilation fails with gcc and -std=c++11
by caligano 01 Sep '14

01 Sep '14

Hi, I tried to compile some of the eUML MSM samples (e.g. http://www.boost.org/doc/libs/1_56_0/libs/msm/doc/HTML/examples/SimpleTimer…) using gcc 4.8 and with C+11 support enabled. However, I always get errors like the following one: error: ‘BOOST_PP_REPEAT_FROM_TO_M_1’ has not been declared I did not find anything about C++11 being not supported by Boost MSM, so I would like to know if I am doing anything wrong? Bye Manuel

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[Boost.Log] translate 3rd party log entries
by Olaf Peter 01 Sep '14

01 Sep '14

Hello, from 3rd party lib I have to integrate the logging message - incorporating into boost.log. But I run into the problem with scopes: main.cpp: In function 'int main(int, char**)': main.cpp:55:5: error: no matching function for call to 'boost::log::v2s_mt_posix::attributes::named_scope_entry::named_scope_entry(const char [6], const char*&, int&)' main.cpp:55:5: note: candidates are: /opt/boost/boost_1_55_0/boost/log/attributes/named_scope.hpp:88:5: note: boost::log::v2s_mt_posix::attributes::named_scope_entry::named_scope_entry(const string_literal&, const string_literal&, unsigned int) /opt/boost/boost_1_55_0/boost/log/attributes/named_scope.hpp:88:5: note: no known conversion for argument 2 from 'const char*' to 'const string_literal& {aka const boost::log::v2s_mt_posix::basic_string_literal<char>&}' /opt/boost/boost_1_55_0/boost/log/attributes/named_scope.hpp:63:8: note: boost::log::v2s_mt_posix::attributes::named_scope_entry::named_scope_entry(const boost::log::v2s_mt_posix::attributes::named_scope_entry&) /opt/boost/boost_1_55_0/boost/log/attributes/named_scope.hpp:63:8: note: candidate expects 1 argument, 3 provided The problem rises on string_literal of __FILE__ entry. How can I get this working?? Thanks, Olaf

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Review Wizard Status Report for August 2014
by Ron Garcia 30 Aug '14

30 Aug '14

============================================== Review Wizard Status Report for August 2014 ============================================== News ==== 1. Fiber Accepted Provisionally. January 2014. 2. Align Accepted. April 2014. 3. TypeIndex Accepted. May 2014. 4. Convert Accepted. June 2014. 5. Boost 1.56 Released -- New Libraries: Align, TypeIndex 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 accepted to Boost, but have not yet been integrated into Boost Git: * Contract - accepted September 2012; author: Lorenzo Caminiti. The following libraries have been accepted and submitted to Boost Git, but have not yet appeared in a release: * Convert - accepted June 2014; author: Vladimir Batov. The following libraries have been accepted provisionally to Boost, but have not been submitted for mini-review and full acceptance: * Fiber - accepted provisionally January 2014; author Oliver Kowalke. 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 ubc dot ca" and "johnphillipsithica at gmail dot com" 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) * Sorting (M) * Quaternions, Vectors, Matrices (M) * Block Pointer (M) * Singularity (M) * Extended Complex Numbers (M) * Metaparse (M) * Boost.Range Extensions * Nowide (M) * Array (M) * STL Extensions (M) * Countertree (M) * Process (M) * Asynchronous File I/O (M) * Application (M) * Edit Distance (M) * Mixin (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. 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. 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). 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. 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. Countertree ----------- :Author: Francisco Jose Tapia :Review Manager: Needed :Download: https://dl.dropbox.com/u/8437476/works/countertree_code_doc.zip :Description: 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. COUNTERTREE This kind of trees 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. With unordered information we have a vector with the same speed inserting and deleting in any position (O(log N)). With ordered information, we have the classes set, multiset, map and multimap, with identical interface than the STL classes, with the plus of access to the elements by position, like in a vector. The iterators are random access , and you can subtract them. SUBALLOCATOR The suballocator is a layer between the allocator and the data structures, compatible with any allocator with the STL definition. The suballocator replace to the allocator in the allocation of equal size elements. It provides speed, return the unused memory and decrease the memory used by the program and improve the cache performance due to the data locality improvement ( 30% of improvement of speed respect the std::allocator with GCC 4.7) Process ------- :Author: Boris Schaeling :Review Manager: Needed :Download: http://www.highscore.de/boost/process0.5/process.zip :Description: Boost.Process is a library to manage system processes. It can be used to: * create child processes * setup streams for child processes * communicate with child processes through streams (synchronously or asynchronously) * wait for processes to exit (synchronously or asynchronously) * terminate processes Asynchronous File I/O --------------------- :Author: Niall Douglas and Paul Kirth :Review Manager: Needed :Download: https://github.com/BoostGSoC/boost.afio/archive/boost-peer-review.tar.gz :Description: Boost.AFIO is a linear scalable, batch, chainable, asynchronous closure execution engine with an almost wait free implementation extending Boost.ASIO and Boost.Thread specialised as a portable asynchronous file i/o implementation library. Implementation of this first version has been kept as simple as possible (~ 1000 active LOC) at the cost of some performance, though with a good compiler you can expect 25-50% of the performance of using raw Boost.ASIO. Application ----------- :Author: Renato Tegon Forti :Review Manager: Needed :Download: https://github.com/retf/Boost.Application :Documentation: http://www.dokfile.com/appbeta4/docs/libs/application/doc/html/index.html :Description: Application provides an application environment, or start point to any people that want a basic infrastructure to build an system application on Windows or Unix Variants (e.g. Linux, MacOS). Application uses behaviours modeled using 'aspects' concept proposed by 'Vicente J. Botet Escriba', that allow easy extension and customization of library components. The application modes uses these components internally to achieve the user desirable behaviours. Application provide many useful ready-to-use features, e.g: * Run application as Windows Service; * Run application as UNIX/POSIX Daemon; * Plugin extension system; * Process(executable) Single instance Instantiation support; * Application SIGNAL/Callbacks customization; * Windows Service Setup feature; * And many others. Edit Distance ------------- :Author: Erik Erlandson :Review Manager: Needed :Download: https://github.com/erikerlandson/algorithm/tree/edit_distance/sequence :Description: The edit distance is the length of the shortest (or least-cost) edit script from one sequence to another, where an edit script is defined as a sequence of insertion, deletion and (optionally) substitution operations. The function implementing the edit distance is named edit_distance. This function will return the edit distance between two sequences, where sequences may be any valid range object supporting forward iteration. The edit_distance function will also, if requested, return the edit script. Mixin ----- :Author: Borislav Stanimirov :Download: https://github.com/iboB/boost.mixin :Documentation: http://ibob.github.io/boost.mixin/ :Review Manager: Needed :Description: Boost.Mixin is a library that allows the composition and modifications of polymorphic types at run time. Types and objects are constructed out of building blocks called mixins. The library uses the type boost::mixin::object as a placeholder, whose instances can be extended with existing classes (mixins), thus providing a particular instance with the functionality of all those types. Accessing the newly formed type's interface is made through messages: stand-alone functions generated by the library, which can be thought of as methods. This is given while also having full abstraction between the interface and the definition of types. An existing feature in another language similar to Boost.Mixin and also an inspiration for the library are the mixins in Ruby. The library also has similarities with the pattern entity-component-system. Libraries under development =========================== See http://svn.boost.org/trac/boost/wiki/LibrariesUnderConstruction for a current listing of libraries under development.

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[msm] forward declaration of state machine with non-default constructor
by caligano 29 Aug '14

29 Aug '14

Hi, I want to forward declare a state machine which has a non-default constructor. I found this example here: http://stackoverflow.com/a/10922799/678093 But I can't call the non-default constructor of the state machine. I either get - "error: call of overloaded ‘fsm(int)’ is ambiguous" (if inheriting constructors using C++11) or - "error: no matching function for call to ‘wrapper::fsm::fsm(int)" What can I do about it? Thanks, Manuel Example: ------------------------ // wrapper.h #include <boost/msm/front/state_machine_def.hpp> #include <boost/msm/back/state_machine.hpp> #include <boost/shared_ptr.hpp> class wrapper { wrapper(); struct fsm; boost::shared_ptr<fsm> player_fsm; }; ------------------------ // wrapper.cpp #include "wrapper.h" struct player_ : public boost::msm::front::state_machine_def<player_> { player_(int some_value) {} }; struct wrapper::fsm : public boost::msm::back::state_machine<player_> { using boost::msm::back::state_machine<player_>::state_machine; }; wrapper::wrapper() : player_fsm(new fsm(100)) { } ------------------------

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Re: [Boost-users] [graph] Unique vertices using setS
by Jeremiah Willcock 29 Aug '14

29 Aug '14

On Wed, Aug 27, 2014 7:24 PM EDT Nicholas Dahm wrote: >Is there any place where I could enforce unique properties? (i.e. not add a new vertex if it's properties are the same as an existing vertex) Not that I know of. >My graph is actually an implicit search tree for an A* search so there's lots of nodes which will be revisited via different paths. My current thought is to create the new vertex (which is a search tree state), then simply iterate through all existing vertices to see if any are identical in properties. However if the vertices were sorted by their properties in a set (i.e. weakly ordered), this would be much faster. Do you need to store the explored part of the search tree explicitly? You could instead use a custom graph type with your choice of vertex descriptor, then use associative_property_map to check for multiple visits to the same state. -- Jeremiah Willcock

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Cannot use Boost.Croutines with range based for
by Mueller-Roemer, Johannes Sebastian 29 Aug '14

29 Aug '14

Hi, I am (again) having issues with the Boost.Coroutines library. Aside from yet another new API, the coroutines no longer work with range based for. Even though the examples include range based for! With the following code (taken directly from the documentation and added the includes and main): #include <boost/coroutine/asymmetric_coroutine.hpp> #include <iostream> int main() { boost::coroutines::asymmetric_coroutine<int>::pull_type source( [&](boost::coroutines::asymmetric_coroutine<int>::push_type& sink){ int first=1, second=1; sink(first); sink(second); for(int i=0;i<8;++i){ int third=first+second; first=second; second=third; sink(third); } } ); for(auto i : source) std::cout << i << " "; } I get this error: D:\projects\combinators\coro_test.cpp: In function 'int main()': D:\projects\combinators\coro_test.cpp:20:15: error: 'begin' was not declared in this scope for(auto i : source) ^ D:\projects\combinators\coro_test.cpp:20:15: note: suggested alternatives: In file included from D:\projects\combinators\coro_test.cpp:1:0: D:/libs/mingw-amd64/boost_1_56_0/include/boost-1_56/boost/coroutine/asymmetric_coroutine.hpp:2255:1: note: 'std::begin' begin( boost::coroutines::push_coroutine< R > & c) ^ In file included from D:/libs/mingw-amd64/boost_1_56_0/include/boost-1_56/boost/range/functions.hpp:18:0, from D:/libs/mingw-amd64/boost_1_56_0/include/boost-1_56/boost/range.hpp:18, from D:/libs/mingw-amd64/boost_1_56_0/include/boost-1_56/boost/coroutine/asymmetric_coroutine.hpp:17, from D:\projects\combinators\coro_test.cpp:1: D:/libs/mingw-amd64/boost_1_56_0/include/boost-1_56/boost/range/begin.hpp:106:61: note: 'boost::range_adl_barrier::begin' inline BOOST_DEDUCED_TYPENAME range_iterator<const T>::type begin( const T& r ) ^ D:/libs/mingw-amd64/boost_1_56_0/include/boost-1_56/boost/range/begin.hpp:106:61: note: 'boost::range_adl_barrier::begin' D:\projects\combinators\coro_test.cpp:20:15: error: 'end' was not declared in this scope for(auto i : source) ^ D:\projects\combinators\coro_test.cpp:20:15: note: suggested alternatives: In file included from D:\projects\combinators\coro_test.cpp:1:0: D:/libs/mingw-amd64/boost_1_56_0/include/boost-1_56/boost/coroutine/asymmetric_coroutine.hpp:2260:1: note: 'std::end' end( boost::coroutines::push_coroutine< R > & c) ^ In file included from D:/libs/mingw-amd64/boost_1_56_0/include/boost-1_56/boost/range/functions.hpp:19:0, from D:/libs/mingw-amd64/boost_1_56_0/include/boost-1_56/boost/range.hpp:18, from D:/libs/mingw-amd64/boost_1_56_0/include/boost-1_56/boost/coroutine/asymmetric_coroutine.hpp:17, from D:\projects\combinators\coro_test.cpp:1: D:/libs/mingw-amd64/boost_1_56_0/include/boost-1_56/boost/range/end.hpp:100:61: note: 'boost::range_adl_barrier::end' inline BOOST_DEDUCED_TYPENAME range_iterator<const T>::type end( const T& r ) ^ D:/libs/mingw-amd64/boost_1_56_0/include/boost-1_56/boost/range/end.hpp:100:61: note: 'boost::range_adl_barrier::end' mingw32-make[2]: *** [CMakeFiles/coro-test.dir/coro_test.cpp.obj] Error 1 mingw32-make[1]: *** [CMakeFiles/coro-test.dir/all] Error 2 mingw32-make: *** [all] Error 2 For completeness sake: I am using MinGW-w64 with GCC 4.9.1 and the -std=c++11 flag Regards, Johannes S. Mueller-Roemer -- Johannes S. Mueller-Roemer, MSc Wiss. Mitarbeiter - Interactive Engineering Technologies (IET) Fraunhofer-Institut für Graphische Datenverarbeitung IGD Fraunhoferstr. 5 | 64283 Darmstadt | Germany Tel +49 6151 155-606 | Fax +49 6151 155-139 johannes.mueller-roemer(a)igd.fraunhofer.de | www.igd.fraunhofer.de

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[filesystem] : How to get a parametrized basic_string from filesystem::path
by Vincent R. 28 Aug '14

28 Aug '14

Hi, I am trying to modify an existing code to keep the possibility to use string or wstring, so I have changed the definition to parametrize it as shown below (Path inherits from path): template <class TChar> bool GetFileList(const std::basic_string<TChar>& i_strBaseDir, std::vector<std::basic_string<TChar> >& o_FileList) { boost::system::error_code ec; Path thePath(i_strBaseDir); boost::filesystem::directory_iterator iter(thePath, ec); if (! ec) { boost::filesystem::directory_iterator iter_end; for (; iter != iter_end; ++ iter) { boost::system::error_code ec; // This is to avoid an exception in case of any error if(!boost::filesystem::is_directory(iter->path(), ec)) //find file and not directory { std::basic_string<TChar> strFile = iter->path().????); // HOW TO DO IT o_FileList.push_back(strFile); } } } return (o_FileList.size() != 0); } My problem is with the following line : std::basic_string<TChar> strFile = iter->path().??????; I have solved like that (without testing it) : template <typename CharT, typename T> std::basic_string<CharT> string_cast(const T& r) { std::basic_ostringstream<CharT> stream; stream.imbue(std::locale::classic()); stream << r; return stream.str(); } std::basic_string<TChar> strFile = string_cast<TChar>(iter->path()); but since it uses some stream we might loose some performance. I have found another string_cast here : http://codereview.stackexchange.com/questions/1205/c-string-cast-template-f… that might be better in terms of performance. Do you have some other suggestion ? Wouldn't be interesting to add a boost::string_cast that would allow to convert from templated methods from/to string/wstring ? Thanks

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[graph] Unique vertices using setS
by Nicholas Dahm 27 Aug '14

27 Aug '14

Hi All, I'm trying to create a graph with unique vertices using setS for vertices, but it doesn't seem to be working. To test it I've made a simple example simply using int's for the vertex properties: typedef boost::adjacency_list<boost::setS, boost::setS, boost::undirectedS, int, int> gtype; typedef boost::graph_traits<gtype>::vertex_descriptor gvd; gtype gr; int v1 = 4; gvd vd1 = add_vertex(v1, gr); gvd vd2 = add_vertex(v1, gr); printf("vd1: %ld, gr[vd1]: %d\n", vd1, gr[vd1]); printf("vd2: %ld, gr[vd2]: %d\n", vd2, gr[vd2]); printf("num_vertices: %d\n", num_vertices(gr)); Output: vd1: 17473168, gr[vd1]: 4 vd2: 17473248, gr[vd2]: 4 num_vertices: 2 So my graph has two vertices represented by the int 4, suggesting it's not a set! Any idea what I'm missing? Is the set for vertex descriptors, but the vertices themselves stored elsewhere? cheers Nick

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Re: [Boost-users] [graph] Unique vertices using setS
by Jeremiah Willcock 27 Aug '14

27 Aug '14

On Wed, Aug 27, 2014 2:47 AM EDT Nicholas Dahm wrote: >Hi All, > >I'm trying to create a graph with unique vertices using setS for vertices, but it doesn't seem to be working. > >To test it I've made a simple example simply using int's for the vertex properties: > > typedef boost::adjacency_list<boost::setS, boost::setS, boost::undirectedS, int, int> gtype; > typedef boost::graph_traits<gtype>::vertex_descriptor gvd; > > gtype gr; > int v1 = 4; > gvd vd1 = add_vertex(v1, gr); > gvd vd2 = add_vertex(v1, gr); > printf("vd1: %ld, gr[vd1]: %d\n", vd1, gr[vd1]); > printf("vd2: %ld, gr[vd2]: %d\n", vd2, gr[vd2]); > printf("num_vertices: %d\n", num_vertices(gr)); > >Output: > > vd1: 17473168, gr[vd1]: 4 > vd2: 17473248, gr[vd2]: 4 > num_vertices: 2 > >So my graph has two vertices represented by the int 4, suggesting it's not a set! Any idea what I'm missing? Is the set for vertex descriptors, but the vertices themselves stored elsewhere? There is a difference between vertex descriptors and properties. There are no requirements that property values are unique for any graph type; those are up to you to set however you want. If gr[vd1] and gr[vd2] had the same address, that would be a problem. However, you initialized both of those property slots with the same value 4, and the graph type has no issue with you doing that. One reason for this is that the same graph can have multiple vertex and edge properties, and so you might want some of them to be unique and some not, so the graph type would not know where to enforce uniqueness. -- Jeremiah Willcock > >cheers > >Nick >_______________________________________________ >Boost-users mailing list >Boost-users(a)lists.boost.org >http://lists.boost.org/mailman/listinfo.cgi/boost-users

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[geometry] Buffer (with strategy) to offset polygons
by Olivier Tournaire 27 Aug '14

27 Aug '14

Dear all, I have used successfully the buffering algorithm to offset a shapefile of 2D polygons. However, there are 4 polygons (amongst nearly 4000) in my SHP does are not successfully processed. They do not have topology or orientation errors. I use GDAL 1.9 to read the SHP, boost 1.56 precompiled binaries from sourceforge on a 64bit windows 7. If someone is willing to have a look at the problem, I can share the files and the code I use. Here is a quick overview: typedef double coordinate_type; typedef boost::geometry::model::d2::point_xy<coordinate_type> point_xy_type; typedef boost::geometry::model::polygon<point_xy_type> polygon_type; boost::geometry::strategy::buffer::end_flat end_strategy; boost::geometry::strategy::buffer::point_square point_strategy; boost::geometry::strategy::buffer::side_straight side_strategy; boost::geometry::strategy::buffer::distance_symmetric<coordinate_type> distance_strategy(buffer_distance); boost::geometry::strategy::buffer::join_miter join_strategy(buffer_distance); polygon_type p; boost::geometry::model::multi_polygon<polygon_type> result; // Build a polygon_type from OGRPolygon OGRLinearRing* exteriorRing = polygon->getExteriorRing(); for(int i=0;i<exteriorRing->getNumPoints();++i) { OGRPoint pt; exteriorRing->getPoint(i,&pt); p.outer().push_back( point_xy_type(pt.getX(), pt.getY()) ); } for(int i=0;i<polygon->getNumInteriorRings();++i) { OGRLinearRing* interiorRing = polygon->getInteriorRing(i); polygon_type::ring_type ring; for(int j=0;j<interiorRing->getNumPoints();++j) { OGRPoint pt; interiorRing->getPoint(j,&pt); ring.push_back( point_xy_type(pt.getX(), pt.getY()) ); } p.inners().push_back(ring); } boost::geometry::buffer(p, result, distance_strategy, side_strategy, join_strategy, end_strategy, point_strategy); if(result.size() == 0) { int indexID = feature->GetFieldIndex("ID"); cout << "No result build for polygon with ID " << feature->GetFieldAsString(indexID) << endl; } else { typedef boost::geometry::strategy::distance::pythagoras<coordinate_type> pythagoras_distance_strategy; typedef boost::geometry::strategy::distance::projected_point<coordinate_type, pythagoras_distance_strategy> projected_point_strategy; boost::geometry::strategy::simplify::douglas_peucker<point_xy_type, projected_point_strategy> dp; OGRPolygon poly; for(size_t i=0;i<result.size();++i) { polygon_type result_i = result[i]; polygon_type result_i_simplified; boost::geometry::simplify(result_i, result_i_simplified, 0.1, dp); { OGRLinearRing ring; for(size_t j=0;j<result_i_simplified.outer().size();++j) ring.addPoint( result_i_simplified.outer()[j].x(), result_i_simplified.outer()[j].y() ); poly.addRing(&ring); } { OGRLinearRing ring; for(size_t j=0;j<result_i_simplified.inners().size();++j) { for(size_t k=0;k<result_i_simplified.inners()[j].size();++k) { ring.addPoint( result_i_simplified.inners()[j][k].x(), result_i_simplified.inners()[j][k].y() ); } poly.addRing(&ring); } } } Note that I use a simplification algorithm after buffering to remove colinear points. Hope you could help. Best regards, Olivier

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