March 2011 - Boost-users - lists.preview.boost.org

boost::python::return_value_policy<bp::reference_existing_object>() is weakref in python?
by Thomas Rab 23 Mar '11

23 Mar '11

I've used boost::python in the past, but this problem has me stumped. Here's part of the class I'm having issues with: class Entity { public: Entity(); ~Entity(); //Call to check our collider against all entities that have "tag" Collider* Collide(const std::string &tag); }; and here is the boost::python code: bp::class_< Entity_wrapper >( "Entity", bp::init< >() ) .def( "Collide" , (::Monocle::Collider * ( ::Monocle::Entity::* )( ::std::string const & ) )( &::Monocle::Entity::Collide ) , ( bp::arg("tag") ), bp::return_value_policy<bp::reference_existing_object>() ) In python if I do something like this: collider = entity.Collision("Paddle") collider is a weakref to 'type' Not a Collider. My other functions that return pointers seem to be fine. Is it just the call policy I'm using? What Collide does is call a static function ("Collide") of the Collision class, which in turn returns a Collider* on success and NULL otherwise. Any help would be appreciated! If you need anymore information, let me know! -- Tom Rab

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[boost::thread] lib broken in trunk for Win32
by teajay 22 Mar '11

22 Mar '11

Hello, I just noticed that the thread lib build for win32 is broken due to a superfluous #if on line 14 in the file tss_pe.cpp. Regards, Thomas Bernard

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[context review] Review - alternative version available
by Oliver Kowalke 22 Mar '11

22 Mar '11

Hi, I've uploaded an alternative version to boost vault (boost.context-alternative_version.zip : http://tinyurl.com/6fpnkro) The documentation is available at http://ok73.ok.funpic.de/alternative/boost/libs/context/doc/html/. changes: - fixed bug for x86_64/sysv/elf assembler file: missing assembler directive .type added - as suggested by Artyom and Vicente: - assembler implementation and native implementation of context switching functions compiled and applied as template arg to context<> -> context<> == context< protected_stack, asm_impl > on UNIX, context< protected_stack, native_impl > on Windows - for Windows assembler implementation is disabled Oliver

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[StateChart] How to pass arguments to a state constructor when doing state transition?
by Zhu Bicen 22 Mar '11

22 Mar '11

Hi all, I have a state like this, which has two parameters in it's constructor except the ctx. I want to know how to pass these two arguments to the constructor, when do state transition? I have tried this: transit< RepeatedPlayingState , 1, 2>(); But it cause compiling error? How to do this? I want to pass something to a new entered state. Thanks! class RepeatedPlayingState: public state< RepeatedPlayingState, PlayingState > { public: RepeatedPlayingState( my_context ctx , long start_pos, long end_pos) : my_base( ctx ){ context< PlayerFsm >().player_.PlayFromTo(start_pos, end_pos); } }; Best Regards Hill

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Re: [Boost-users] compilation error, please help
by Steven Watanabe 22 Mar '11

22 Mar '11

AMDG On 03/22/2011 09:59 AM, kovari andris wrote: > I have version 4.4.5 > I think the latest That wasn't what I was asking. g++ -v gives all the information about how the compiler was configured. In Christ, Steven Watanabe

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Re: [Boost-users] compilation error, please help
by Steven Watanabe 22 Mar '11

22 Mar '11

AMDG On 03/22/2011 08:42 AM, kovari andris wrote: > to the greater glory of God... > I did try some variations of g++ -pthread... > > but did not work. > I got all sorts of suggestions on different forums, but it gives the same error. All right. What does g++ -v say? In Christ, Steven Watanabe

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compilation error, please help
by kovari andris 22 Mar '11

22 Mar '11

Hi folks, I have: installed eclipse on ubuntu 10.10 installed libbost 1.4 using sinaptic pkg manager started a simple new c++ project, #include <boost/thread.hpp> int main(int argc, char* arg[]){ } I tried to build it, and had the error: Invoking: GCC C++ Compiler g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"main.d" -MT"main.d" -o"main.o" "../main.cpp" In file included from /usr/include/boost/thread/detail/platform.hpp:17, from /usr/include/boost/thread/thread.hpp:12, from /usr/include/boost/thread.hpp:13, from ../main.cpp:8: /usr/include/boost/config/requires_threads.hpp:47: error: #error "Compiler threading support is not turned on. Please set the correct command line options for threading: -pthread (Linux), -pthreads (Solaris) or -mthreads (Mingw32)" In file included from /usr/include/boost/thread/thread.hpp:12, from /usr/include/boost/thread.hpp:13, from ../main.cpp:8: /usr/include/boost/thread/detail/platform.hpp:67: error: #error "Sorry, no boost threads are available for this platform." In file included from /usr/include/boost/thread.hpp:13, from ../main.cpp:8: /usr/include/boost/thread/thread.hpp:19: error: #error "Boost threads unavailable on this platform" blablabla...so on... a lot more errors. what am I missing here? I dont understand the error message, and tried to write -pthread wherever I could, but did not work. Any tips? detailed or stepbystep solution please, because I am a beginner, and dont understand chinese:) thank you guys

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newbie fail: Too many levels of symbolic link
by Gary Pajer 22 Mar '11

22 Mar '11

I have a c++ shared library, and I'd like to use the classes and functions in python. So I'm trying boost.python. I'm on Ubuntu 10.10, and I've downloaded the boost tarball. I think I've followed the instructions here<http://www.boost.org/doc/libs/1_46_1/libs/python/doc/building.html>and (more to the point) here<http://www.boost.org/doc/libs/1_46_1/more/getting_started/unix-variants.htm…>to the letter. But when I execute "sudo ./bjam" I get dozens upon dozens of failures. For example, "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -pthread -DBOOST_ALL_NO_LIB=1 -DBOOST_PYTHON_SOURCE -DBOOST_PYTHON_STATIC_LIB -DNDEBUG -I"." -I"/usr/include/python2.6" -c -o "bin.v2/libs/python/build/gcc-4.4.5/release/link-static/threading-multi/numeric.o" "libs/python/src/numeric.cpp" ...failed gcc.compile.c++ bin.v2/libs/python/build/gcc-4.4.5/release/link-static/threading-multi/numeric.o... gcc.compile.c++ bin.v2/libs/python/build/gcc-4.4.5/release/link-static/threading-multi/list.o In file included from ./boost/python/detail/config.hpp:15, from ./boost/python/detail/prefix.hpp:14, from ./boost/python/list.hpp:8, from libs/python/src/list.cpp:5: ./boost/config.hpp:35: fatal error: ./boost/boost/config/compiler/gcc.hpp: Too many levels of symbolic links compilation terminated. The file references are different, but the error is always the same. What have I done wrong? thanks, gary_p

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[asio] What have to be done to receive UDP broadcast packets?
by Michael Schulze 22 Mar '11

22 Mar '11

Hi list, I struggle with setting up an asio udp socket on Linux that is able to receive broadcasts. I managed the sending of broadcasts, but receiving seems to have a problem. I also managed sending and receiving of broadcasts with the native socket api of Linux. However, in the project we use asio to have portability across platforms and therewith we need to receive broadcast with asio too. The question is: How should an asio udp socket be setup in order to receive broadcasts? I did the following: udp::socket socket(io_service); socket.open(udp::v4()); boost::asio::socket_base::broadcast option(true); socket.set_option(option); socket.bind(udp::endpoint(address_v4::any(),8888)); and then I started receive_from. What is wrong with this? I did not receive the sent broadcast. Regards, Michael

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Cannot dlclose() module when including exception_ptr.hpp in GCC 4.5
by ichramm 22 Mar '11

22 Mar '11

Hi I'm having and issue with boost and gcc 4.5, I'm posting here before posting in the gcc mailing list 'cause it only happends if using boost. Thre following problem was tested with boost 1.44 and boost 1.46 (single and multi threaded) Situation: - Environment with GCC 4.5.2 (kernel 2-6-36 and 4.6.37, glibc 2.11 and 2.12 - C application that loads/unloads dynamic modules using dlopen/dlclose - C++ dynamic module compiled/linked agans boost::thread, and including <boost/exception_ptr> Problem: - dlclose() always returns zero, so the module is never unloaded Including <boost/thread/thread.hpp> or any other boost header works fine This only happends with GCC 4.5, so it could be a problem related to gcc, but I dnot know it yet. I'm attanching 3 small test files, so you can check if this happens on your machine, just execute 'make run' After reading the test application you say 'remove the while loop!', but the right behavior is that the second call to dlclose() should fail with 'shared object ot open'. Thanks in advance -- Saludos! :wq PS: Escuse my poor english :P

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[asio] recommended way of handling unix signals ?
by Avi Bahra 22 Mar '11

22 Mar '11

I have been looking at the boost asio 1.45 docs but there is no mention of signal handling ? Is this is a known deficiency of asio, or are there any any recommended ways of handling signals in a asio server ? Best regards, Ta, Avi

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boost::asio close TCP connection cleany
by Marco Piacentini 22 Mar '11

22 Mar '11

Hy..I've seen in the tutorial that client side disconnect is called simply by a break in the read loop. I would like to know which is the step-by-step instruction to close correctly a TCP connection (both server and client side) and where I have to put them. I've seen the close and shutdown functions, but I don't know where call them. Finally...what I can do when an EOF error happens?? thank you..

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RegEx - Exception on faulty RE, or other report of failure.
by Kerry, Richard 22 Mar '11

22 Mar '11

Using Boost Regex for the first time I note that if there is an error in the syntax of the RE given then an exception is raised. Is this the only way of checking the RE syntax ? Or is there a function that I can call which can validate it for me without an exception. I don't see anything in the documentation (I'm using Boost 1.4 as I need to use it with Visual C++ 6). Regards, Richard. Richard Kerry BNCS Engineer Siemens IT Solutions and Services Ltd The Business Technologists Room 457 Drama Building, BBC Television Centre, Wood Lane, London, W12 7RJ T: +44 (0)20 82259063 F: +44 (0)20 8576 8182 M: +44 (0)7921 244993 Email: richard.kerry(a)siemens.com<blocked::mailto:richard.kerry@siemens.com> Website: www.siemens.co.uk/it-solutions<blocked::outbind://47/www.siemens.co.uk/it-solutions> This e-mail contains confidential information and is for the exclusive use of the addressee/s. If you are not the addressee, then any distribution, copying or use of this e-mail is prohibited. If received in error, please advise the sender and delete it immediately. We accept no liability for any loss or damage suffered by any person arising from use of this e-mail. Siemens IT Solutions and Services Limited Registered No: 1203466 England Registered Office: Faraday House, Sir William Siemens Square, Frimley, Camberley, GU16 8QD

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Boost - How does VC know what to link ?
by Kerry, Richard 22 Mar '11

22 Mar '11

Can someone explain (*) how Visual Studio gets to know which lib file to link with ? I see an entry (Auto-Linking under point 6 on the Getting Started page) which says that it does this, but I'd like to know how. I want to be sure that once I've started using Boost in a project then any of my colleagues building the same project will get the libraries pice-up properly. (*) or point me to the code that does it. Is is some sort of compiler directive that controls it ? It's Visual Studio 6 that I'm using, but I expect it's the same for others. Richard Kerry BNCS Engineer Siemens IT Solutions and Services Ltd The Business Technologists Room 457 Drama Building, BBC Television Centre, Wood Lane, London, W12 7RJ T: +44 (0)20 82259063 F: +44 (0)20 8576 8182 M: +44 (0)7921 244993 Email: richard.kerry(a)siemens.com<blocked::mailto:richard.kerry@siemens.com> Website: www.siemens.co.uk/it-solutions<blocked::outbind://47/www.siemens.co.uk/it-solutions> This e-mail contains confidential information and is for the exclusive use of the addressee/s. If you are not the addressee, then any distribution, copying or use of this e-mail is prohibited. If received in error, please advise the sender and delete it immediately. We accept no liability for any loss or damage suffered by any person arising from use of this e-mail. Siemens IT Solutions and Services Limited Registered No: 1203466 England Registered Office: Faraday House, Sir William Siemens Square, Frimley, Camberley, GU16 8QD

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[autolink] for gcc?
by alfC 22 Mar '11

22 Mar '11

Hi, I recently discovered boost/auto_link.hpp which besides the comment in the source file doesn't seem to be documented. The question is, can it be used with gcc c++? if not, is there an alternative? Thank you, Alfredo

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[asio] deadline_timer not waiting properly?
by Dylan Klomparens 22 Mar '11

22 Mar '11

Hello, I tried using the boost deadline_timer in this simple test application, but had some trouble. The goal is for the timer to trigger every 45 milliseconds using the "expires_at()" member function of the deadline_timer. (I need an absolute time, so I'm not considering expires_from_now(). I am also not concerned about drift at the moment). When I run the program, wait() does not wait for 45 ms! Yet, no errors are reported. Am I using the library incorrectly somehow? -- Dylan Sample program: #include <boost/asio.hpp> #include <boost/thread.hpp> #include <boost/bind.hpp> #include <boost/date_time/posix_time/posix_time.hpp> #include <iostream> using namespace std; int main() { boost::asio::io_service Service; boost::shared_ptr<boost::thread> Thread; boost::asio::io_service::work RunForever(Service); Thread = boost::shared_ptr<boost::thread>(new boost::thread(boost::bind(&boost::asio::io_service::run, &Service))); boost::shared_ptr<boost::asio::deadline_timer> Timer(new boost::asio::deadline_timer(Service)); while(1) { boost::posix_time::time_duration Duration; Duration = boost::posix_time::microseconds(45000); boost::posix_time::ptime Start = boost::posix_time::microsec_clock::local_time(); boost::posix_time::ptime Deadline = Start + Duration; boost::system::error_code Error; size_t Result = Timer->expires_at(Deadline, Error); cout << Result << ' ' << Error << ' '; Timer->wait(Error); cout << Error << ' '; boost::posix_time::ptime End = boost::posix_time::microsec_clock::local_time(); (cout << "Duration = " << (End - Start).total_milliseconds() << " milliseconds" << endl).flush(); } return 0; }

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boost binary_iarchive compiler error converting from side_t to streamsize
by Liron Kopinsky 21 Mar '11

21 Mar '11

Hi all, I'm having a problem were, when I #include <boost/archive/binary_iarchive.hpp>, it says that there is an error converting from size_t to std::streamsize. This seems to come from basic_binary_iprimitive.hpp line 181 because std::memcpy takes a size_t but it's passing in a std::streamsize. This seems to just be a warning, but even though I added #pragma warning(disable : 4244) and my compiler still isn't happy and gives this output: http://boost.codepad.org/faSZmjNM We seem to only have this problem when we're building in VS2010, but it works fine in 2005. Any help would be appreciated. Thanks, Liron Kopinsky Image Metrics Software Developer liron.kopinsky(a)image-metrics.com

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Boost Concept Library - fusion and other libraries
by Robert Ramey 21 Mar '11

21 Mar '11

Lately I've been exploring boost/fusion for a project which I have been thinking about for 25 years. I believe that this might be the tool to do what I want. In the course of my experiments with this library and it's associated documentation, I've been interested in understanding the libraries "concepts" (e.g. AssociativeSequence, etc) and the relationship if any to the boost concept library. To try to be more clear, when I see something in the documentation like "AssociativeSequence", I'm sort of hoping/expecting to write into my code something like template<typename S> struct my_type { ... BOOST_CONCEPT_ASSERT(( <AssociativeSequence<S> > )); ... }; But it seems that I can't do this. Why is this? a) Can I indeed write something like this if I include some specific headers that I haven't found? b) Should I be using some other concept checker such as something in MPL c) Am I wrong about thinking that it would be useful to have this? That is, is there some reason why I shouldn't expect to find this? In poking around, I don't find a lot I'm expecting to find. For example, I'm sort of expecting to find: boost::std::concepts { ... concept checking classes for STL } and something similar for all or most of the libraries who make extensive usage of "concepts" in their documentation. When I so grep for files which contain BOOST_CONCEPT (to catch BOOST_CONCEPT_ASSERT, etc.. I get the following: bash-3.2$ pwd /cygdrive/c/BoostRelease/boost bash-3.2$ grep -l BOOST_CONCEPT * */*.hpp concept_archetype.hpp concept_check.hpp concept/assert.hpp concept/requires.hpp concept/usage.hpp concept_check/borland.hpp concept_check/general.hpp concept_check/has_constraints.hpp concept_check/msvc.hpp graph/bron_kerbosch_all_cliques.hpp graph/buffer_concepts.hpp graph/graph_concepts.hpp graph/graphviz.hpp graph/metric_tsp_approx.hpp graph/stoer_wagner_min_cut.hpp graph/tiernan_all_cycles.hpp graph/transitive_reduction.hpp icl/closed_interval.hpp icl/continuous_interval.hpp icl/discrete_interval.hpp icl/interval_base_map.hpp icl/left_open_interval.hpp icl/map.hpp icl/open_interval.hpp icl/right_open_interval.hpp iterator/iterator_concepts.hpp range/concepts.hpp bash-3.2$ which suggests to me that this idea is only implemented in graph, icl, iterator and range libraries. Is there a reason for this, or is that it just hasn't been done. If it's the latter, is there a reason I don't see anyone on the requesting that libraries include concept checking classes. Also, reviewers don't seem to mention the lack of these classes in the code - though they complain about it if it's missing from the documentation. After sort of struggling with the whole concept concept, I'm think I'm coming to appreciate it's utility and maybe it's necessity. But given that no one seems to miss it in the boost libraries, I'm concerned that I'm still not getting it. Robert Ramey

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Re: [Boost-users] [boost::thread] interrupt a future get boost::unknown_exception
by 乔志强 21 Mar '11

21 Mar '11

It is only boost::thread int foo() { this_thread::sleep(seconds(1000)); return 0; } int main(int argc, char** argv) { boost::packaged_task<int> pt(&foo); boost::unique_future<int> fi = pt.get_future(); .......................... > > ------------------------------ > > Message: 2 > Date: Fri, 18 Mar 2011 16:43:54 +0100 > From: Viatcheslav.Sysoltsev(a)h-d-gmbh.de > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] [boost::thread] interrupt a future get > boost::unknown_exception > Message-ID: <op.vsjpzgww5q4lf0@pc-sysolts-zdmf> > Content-Type: text/plain; charset=utf-8; format=flowed; delsp=yes > > On Fri, 18 Mar 2011 11:30:11 +0100, ??? <qiaozhiqiang(a)leadcoretech.com> > wrote: > > > [Windows XP, VC++ 10, boost 1.46] > > When interrupt a future, the future.get() throw boost::unknown_exception, > > Not boost::thread_interrupted. > > > > Class boost::thread_interrupted should have a base class for > > current_exception_impl() to catch it ? or use BOOST_THROW_EXCEPTION in > > interruptible_wait) ? > > > > > > /////////////// > > namespace boost > > { > > class thread_interrupted > > {}; > > } > > > > > > exception_ptr current_exception_impl() > > { > > try > > { > > throw; > > } > > catch( > > exception_detail::clone_base & e ) > > { > > return exception_ptr(e.clone()); > > } > > ................ > > catch( > > std::exception & e ) > > { > > return > > exception_detail::current_exception_unknown_std_exception(e); > > } > > catch( > > boost::exception & e ) > > { > > return > > exception_detail::current_exception_unknown_boost_exception(e); > > } > > catch( > > ... ) > > { > > return > > exception_detail::current_exception_unknown_exception(); > > } > > > > > > // unknown_exception////////////////// > > ERROR: Throw in function (unknown) > > Dynamic exception type: class boost::exception_detail::clone_impl<class > > boost::unknown_exception> > > std::exception::what: Unknown exception > > > > > > > > //code ///////////////////// > > #include <boost/thread.hpp> > > #include <boost/date_time/posix_time/posix_time_types.hpp> > > #include <boost/thread/future.hpp> > > using namespace boost::posix_time; > > using namespace boost; > > > > int main(int argc, char** argv) > > { > > boost::packaged_task<int> pt( > > [=]()->int > > { > > this_thread::sleep(seconds(1000)); > > return 0; > > } > > ); > > boost::unique_future<int> fi = pt.get_future(); > > boost::thread task(std::move(pt)); // launch task on a thread > > > > task.interrupt(); > > > > try > > { > > int v = fi.get(); > > } > > catch (boost::exception& exc) > > { > > std::cerr << "ERROR: " << boost::diagnostic_information(exc) << > > std::endl; > > } > > } > > Wow, boost-1.46 and lambdas, you're really working on the edge. Just to be > sure it is a boost problem - can you make a classical function instead > lambda and try with it? The test case seems nearly like one from the > futures example - I really doubt it is a boost problem. > I'd be glad to experiment with it yourself but my latest ubuntu has only > gcc 4.4.5 and the lambdas said to be supported first from 4.5, plus I'd > need to build 1.46 first, which takes quite a time on my nearly-netbook.. > > -- Slava > >

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mpl and set of maps
by Peter Foelsche 21 Mar '11

21 Mar '11

It looks like two maps with the same entries but different ordering are considered different. I'm trying to create a set of maps and I'm inserting two maps. Both maps are identical but the order in which the items were inserted into the map is different. I was thinking that an associative sequence like set is using is_same to compare two elements and I tried to overload is_same -- but this did not work. See code below or attached. #include <boost/mpl/set.hpp> #include <boost/mpl/map.hpp> #include <boost/mpl/bool.hpp> #include <boost/mpl/long.hpp> #include <boost/mpl/for_each.hpp> #include <boost/mpl/insert.hpp> #include <iostream> ? struct print { template<typename T> void operator()(const T &_r) const { //std::cout << typeid(T).name() << "\n"; (*this)(_r, typename boost::mpl::is_sequence<T>::type()); } template<typename T> void operator()(const T &, const boost::mpl::true_ &) const { std::cout << "(\n"; boost::mpl::for_each<T>(print()); std::cout << ")\n"; } template<typename T0, typename T1> void operator()(const boost::mpl::pair<T0, T1> &, const boost::mpl::false_ &) const { std::cout << "pair(" << typeid(T0).name() << ", " << typeid(T1).name() << ")" << "\n"; } template<typename T> void operator()(const T &, const boost::mpl::false_ &) const { std::cout << typeid(T).name() << "\n"; } }; namespace boost { //namespace type_traits //{ //template<typename T0, typename T1> //struct is_same; ? using boost::mpl::map; using boost::mpl::true_; using boost::mpl::insert; ? template<typename T0, typename T1> struct is_same<map<T0, T1>, map<T1, T0> > { typedef boost::mpl::true_ type; }; ? template<typename T0, typename T1, typename T2> struct is_same<map<T0, T1, T2>, map<T2, T1, T0> > { typedef boost::mpl::true_ type; }; ? template<typename T0, typename T1, typename T2> struct is_same<map<T0, T1, T2>, map<T1, T2, T0> > { typedef boost::mpl::true_ type; }; ? template<typename T0, typename T1, typename T2> struct is_same<map<T0, T1, T2>, map<T0, T2, T1> > { typedef boost::mpl::true_ type; }; ? template<typename T0, typename T1, typename T2> struct is_same<map<T0, T1, T2>, map<T1, T0, T2> > { typedef boost::mpl::true_ type; }; //} } int main(int argc, char **argv) { using boost::mpl::long_; using boost::mpl::for_each; using boost::mpl::set; using boost::mpl::map; using boost::mpl::pair; using boost::mpl::insert; typedef long_<0> zero; typedef long_<1> one; typedef long_<2> two; typedef pair< zero, one > zero_2_one; typedef pair< one, one > one_2_one; for_each< insert< insert< set<>, insert< insert< map<>, zero_2_one >::type, one_2_one >::type >::type, insert< insert< map<>, one_2_one >::type, zero_2_one >::type >::type >(print()); return 0; }

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issue with make_shared
by Sean Farrow 21 Mar '11

21 Mar '11

Hi: Ok, having got to grips with fusion, and thought it was working. I now have an issue whereby when using make_shared, it is working in one case, and not in the other. I've got the following definition:P typedef boost::fusion::vector<PmStream*, MIDIInputThread, boost::shared_ptr<boost::asio::io_service> , boost::shared_ptr<boost::thread> > InputType; and when I use: InputType NewInput =InputType(Port, cl, boost::make_shared<boost::asio::io_service> , boost::make_shared<boost::thread>(boost::bind(&boost::asio::io_service::run, io.get()))); Replacing the asio::io declaration with an actual variable of type boost::shared_ptr<boost::asio::io_service> seems to work fine. Is ther anything I'm doing wrong that's not allowing me to use boost::make_shared? Any help appreciated. Regards Sean.

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refering to objects when constructing a boost::fusion::vector
by Sean Farrow 21 Mar '11

21 Mar '11

Hi list: I'm in the process of using boost::fusion::vector, with the following definition: typedef boost::fusion::vector<PmStream*, MIDIInputThread, boost::shared_ptr<boost::asio::io_service>, boost::shared_ptr<boost::thread> > InputType; I'm then constructing this using the following code: PmStream* Port; MIDIInputThread cl; InputType NewInput =InputType(Port, cl, boost::make_shared<boost::asio::io_service>, boost::make_shared<boost::thread>(boost::bind(&boost::asio::io_service::run, io.get()))); What I'm wondering is is there a way to refer to a previously declared argument in this case, I'd like to refer to the shared pointer containing the boost::asio::io_service. Given that I've not actually named this argument, could I use anything from either boost.fusion or boost.mpl to do what I require. Any help appreciated. Regards Sean.

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storing a boost.thread in a boost shared ptr
by Sean Farrow 21 Mar '11

21 Mar '11

Hi: I'm trying to store a boost.thread in a boost::fusion::vector, and need to use a shared ptr, due to boost.thrad being non-copyable I'm using Microsoft visual c++ 2010. I get the following error: 1>d:\devexpress\mdrlite\mdrlite\mdrlite\midiwidget.cpp(21): error C2664: 'boost::shared_ptr<T>::shared_ptr(boost::shared_ptr<T> &&)' : cannot convert parameter 1 from 'boost::_bi::bind_t<R,F,L>' to 'boost::shared_ptr<T> &&' with [ T=boost::thread ] and [ R=size_t, F=boost::_mfi::mf0<size_t,boost::asio::io_service>, L=boost::_bi::list1<boost::_bi::value<boost::asio::io_service *>> ] and [ T=boost::thread ] Reason: cannot convert from 'boost::_bi::bind_t<R,F,L>' to 'boost::shared_ptr<T>' with [ R=size_t, F=boost::_mfi::mf0<size_t,boost::asio::io_service>, L=boost::_bi::list1<boost::_bi::value<boost::asio::io_service *>> ] and [ T=boost::thread ] No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called My boost thread is defined as: boost::thread t(boost::bind(&boost::asio::io_service::run, io.get())); and io is defined as: boost::shared_ptr<boost::asio::io_service> io; I'm obviously overlooking something, I just carn't work out what? Any help appreciated. Regards Sean.

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[context review] Review starts today, Mars 21st 2011
by Vicente BOTET 21 Mar '11

21 Mar '11

Hi all, The review of Oliver Kowalke Context library starts today Mars 21st 2011, and will end on Mars 30th. Boost.Context is a basic building block library that is used for more higher abstractions. It is used by Boost.Fiber, Boost.Tasklet and Boost.Task from the same author. I really hope to see your vote and your participation in the discussions on the Boost DEVELOPMENT mailing lists! WARNING !!!!!!!!!!!!! Only on the Boost DEVELOPMENT mailing lists Please use [context review] as prefix of your post to make easier the review follow up. You can download a frozen version for the review from the Vault, TinyURL: http://tinyurl.com/5r77rel or The documentation is available directly here: http://ok73.ok.funpic.de/boost/libs/context/doc/html/ --------------------------------------------------- About the library: Boost.Context provides a possibility to switch between different user-level context and is intended to be the basis for a higher abstraction like coroutine and fiber. A user-level context represents the current execution state, including all registers and CPU flags, the instruction pointer, the stack pointer. boost::context encapsulates such a user-level context and is able to store/restore its associated user-level context. This allows multiple execution paths running on a single thread using a sort of cooperative scheduling (in contrast a thread is preemptively scheduled) - the running boost::context decides explicitly when its yields to allow another boost::context to run (user-level context switching). A context can only run on a single thread at any point in time but may be migrated between thread. A context switch between threads costs usually thousands of CPU cycles on x86 compared to a user-level context switch with few hundreds of cycles. Boost.Context differes to setjmp()/longjmp() in the fact that the C99 standard does not require that longjmp() preserves the current stack frame, e. g. jumping into a function which was exited via a call to longjmp() is undefined. Boost.Context allows to select the mechanism provided by the operating system (ucontext on UNIX, Windows Fibers on Windows) or a faster implementation provided by this library (fcontext using assembler). --------------------------------------------------- Please always state in your review, whether you think the library should be accepted as a Boost library! Additionally please consider giving feedback on the following general topics: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? - Are you knowledgeable about the problem domain? Have a good review, Vicente Review Manager

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[Fusion] value_at_c and its relatives not applicable to Associative Sequence?
by TONGARI 21 Mar '11

21 Mar '11

Hi, the document says that 'value_at_c' accepts a Forward Sequence, and set/map, which is of Associative Sequence as well as Forward Sequence, why the following does not work? #include <boost/fusion/include/value_at.hpp> #include <boost/fusion/include/set.hpp> int main() { namespace fs = boost::fusion; typedef fs::result_of::value_at_c<fs::set<int>, 0> >::type type; return 0; }

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