April 2013 - Boost-users - lists.preview.boost.org

Re: [Boost-users] Bind/Function: use reference arguments in template variadic functions
by Yannick POTIN 12 Apr '13

12 Apr '13

> >> template<class ...classes> >> boost::function0<void> call_something(classes&... c) > > Thank you, It actually allows me to use references in these functions. > I just tried and g++ is waiting for only references but I need to use pointers and/or values too. > There is a way to use mixed types in template variadic functions ? > For perfect forwarding use: template<class... T> void call(T&&... t) { foo(std::forward<T>(t)...); } I tried this one too and it works fine thank you. However, I use these functions with boost::bind library and actually references are lost when I use it (and I need to). After some google searches, it seems that boost::bind officially does not support this use (due to internal references). So I tried with std::bind because I read somewhere the problem was fixed with its C++11 version. The problem is the same : with std::bind too, references are lost using std::forward. Does anyone made this duo bind/template variadic functions working together ? And if someone did, how did you do ? Regards, Yannick POTIN

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Document for static / dynamic library?
by young 12 Apr '13

12 Apr '13

How do I know which library have both dynamically linked library and static linked library? I heard of there may be some libraries that can only be statically linked (Boost.Test for example) and others which may only be dynamically linked (Boost.Threads for example), Does any document has the list for available library? Or I have to look at each library individually? -- View this message in context: http://boost.2283326.n4.nabble.com/Document-for-static-dynamic-library-tp46… Sent from the Boost - Users mailing list archive at Nabble.com.

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boost_thread-vc100-mt-1_53.lib vs libboost_thread-vc100-mt-1_53.lib
by young 12 Apr '13

12 Apr '13

I try to use boost library in VC++ application, I am wondering which library to use. For example, for boost thread, should I use boost_thread-vc100-mt-1_53.lib or libboost_thread-vc100-mt-1_53.lib? What is difference between them? or in more general, what is difference between boost_xxx_vc100-mt-1_53.lib and libboost_xxx_vc100-mt-1_53.lib? -- View this message in context: http://boost.2283326.n4.nabble.com/boost-thread-vc100-mt-1-53-lib-vs-libboo… Sent from the Boost - Users mailing list archive at Nabble.com.

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Re: [Boost-users] Bind/Function: use reference arguments in template variadic functions
by Yannick POTIN 12 Apr '13

12 Apr '13

AMDG On 04/11/2013 01:57 PM, Yannick POTIN wrote: > > <snip> > > // A template variadic function... > template<class ...classes> > boost::function0<void> call_something(classes... c) { > // ... here we are: > return boost::bind(call_a,boost::ref(c...)); > } > > <snip> > ---------------------------------------------- > After compilation, I get this output (watch the memory addresses): > 0xbfc8f994::operator()(): 1 > 0xbfc8f990::operator()(): 2 > 0xbfc8f984::operator()(): 1 > 0xbfc8f984::operator()(): 2 > I really don't know what happened (even if I can imagine). > But references are just lost and this is not good. > > So, here is my question: How can I make this working ? > The arguments of call_something are passed by value. Try: template<class ...classes> boost::function0<void> call_something(classes&... c) In Christ, Steven Watanabe Thank you, It actually allows me to use references in these functions. I just tried and g++ is waiting for only references but I need to use pointers and/or values too. There is a way to use mixed types in template variadic functions ? Regards, Yannick POTIN

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[preprocessor] How to transform sequence into sequence of tuples.
by Mostafa 12 Apr '13

12 Apr '13

How would I go about doing the following transformation: (a)(b)(c)(d) -> (a, b)(c, d) Thanks, Mostafa

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Asio Serial ports: enumerating all the devices
by Vincent Boucher 12 Apr '13

12 Apr '13

Hello, Are there cross-platform methods to discover all the devices currently connected through serial ports with Boost? The idea is to have a function returning a list of device objects, each containing a handle, the related vendor id, product id and the baud rate at which the device was able to communicate. My knowledge of serial communication is very limited, may be it is technically infeasible. Do you have any thoughts for Boost or other libs? Analog enumerate method for HID devices: http://www.signal11.us/oss/hidapi/ Thanks, Vincent

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Bind/Function: use reference arguments in template variadic functions
by Yannick POTIN 12 Apr '13

12 Apr '13

Hello, I'm working on a little project which use the template variadic technology. I use them with boost::bind and boost::function and found a very annoying bug. Because I have a lot of files very long and (sorry :-( ) uncommented. I made a simple but explicit example like this one : ---------------------------------------------- #include <boost/function.hpp> #include <boost/bind.hpp> #include <iostream> // A classic class... class A { public: // ... with a constructor A(int a) : a(a) { } // ... an operator void operator()() { std::cout << (void*)this << "::" << __func__ << "(): " << a << std::endl; } // ... and a member int a; }; // A stupid function... void call_a(A &a) { // ... which do something usefull // please not that this function NEEDs a reference a(); } // A template variadic function... template<class ...classes> boost::function0<void> call_something(classes... c) { // ... here we are: return boost::bind(call_a,boost::ref(c...)); } // Ok, this one, I think you know it more than I do int main(void) { // Let's create some objets A a1(1); A a2(2); // Call them to print the memory // position (see A::operator()()) a1(); a2(); // Create a boost::function0<void> and call it call_something<A>(boost::ref(a1))(); // Again call_something<A>(boost::ref(a2))(); return 0; } ---------------------------------------------- After compilation, I get this output (watch the memory addresses): 0xbfc8f994::operator()(): 1 0xbfc8f990::operator()(): 2 0xbfc8f984::operator()(): 1 0xbfc8f984::operator()(): 2 I really don't know what happened (even if I can imagine). But references are just lost and this is not good. So, here is my question: How can I make this working ? May I precise that this example only use one argument but my project actually use at most five so the boost::ref() call like in the call_something function is impossible (and does not work anyway). Before someone ask me if I can use pointer instead, I answer: Yes I can, but it will take a lot of time and if I can avoid this, I will. Thank you for reading, for your patience and for your answers ;-) Regards, Yannick POTIN

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Re: [Boost-users] [multiprecision] radix-2
by Lucas Sousa de Oliveira 12 Apr '13

12 Apr '13

Hey Paul, First of all, thanks for the tips, it did help a lot. But would you mind if I use you a little more to get up to speed with this project? Answering your first question, yes, I'm studying to the best of my capacities and time-constrains. I found the PDF a little too succint though. If you had some more recommended literature, I'd be very happy to read it. I took a brief look at the present library's code but I must confess I got a little confused. Probably because I was too unprepared. I'll do that again when I experiment a little more with the examples and know exactly what to look for. I did a couple of quick tests to see if my setup is working fine (it is). I tested it using some Boost.Math functions as suggested, but I reckon the test was not solid enough yet. I'll search for a few known big numbers and way to compute them tomorrow. I think it's more convenient (not to overuse the list) to put my files here (https://bitbucket.org/luk51000/multiprecision) It's currently empty since I my git broke today and I didn't have time to fix it, but I should be pushing code as soon as tomorrow. -- Lucas Oliveira On Wed, Apr 10, 2013 at 2:01 PM, <boost-users-request(a)lists.boost.org>wrote: > Send Boost-users mailing list submissions to > boost-users(a)lists.boost.org > > To subscribe or unsubscribe via the World Wide Web, visit > http://lists.boost.org/mailman/listinfo.cgi/boost-users > or, via email, send a message with subject or body 'help' to > boost-users-request(a)lists.boost.org > > You can reach the person managing the list at > boost-users-owner(a)lists.boost.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Boost-users digest..." > > > Today's Topics: > > 1. Re: Asio Serial ports: enumerating all the devices > (Kerry, Richard) > 2. Re: [BGL] Error using breadth_first_search with labeled_graph > (Jeremiah Willcock) > 3. Re: [multiprecision] radix-2 (Paul A. Bristow) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Wed, 10 Apr 2013 13:22:14 +0000 > From: "Kerry, Richard" <richard.kerry(a)atos.net> > To: "boost-users(a)lists.boost.org" <boost-users(a)lists.boost.org> > Subject: Re: [Boost-users] Asio Serial ports: enumerating all the > devices > Message-ID: > < > 61C67DC73308BD49B2D4B65072480DBA15397181(a)DEFTHW99EZ1MSX.ww931.my-it-solutions.net > > > > Content-Type: text/plain; charset="us-ascii" > > > "vendor id, product id " > What's that ? > I mean for a serial device. If they are present in the device protocol > then fine, but that depends on the individual devices and their protocols. > You can check whether there has been any traffic, which might be useful, > but serial connections are just streams of bytes. > > > Unhelpfully, > Richard. > > > PS > I do recognize "vendor id, product id " for SNMP and for other protocols > working at a higher level than "serial". > > > > > > ________________________________ > From: Boost-users [mailto:boost-users-bounces@lists.boost.org] On Behalf > Of Vincent Boucher > Sent: 10 April 2013 13:40 > To: boost-users(a)lists.boost.org > Subject: [Boost-users] Asio Serial ports: enumerating all the devices > > Hello, > > Are there cross-platform methods to discover all the devices currently > connected through serial ports with Boost? > > The idea is to have a function returning a list of device objects, each > containing a handle, the related vendor id, product id and the baud rate at > which the device was able to communicate. > > My knowledge of serial communication is very limited, may be it is > technically infeasible. Do you have any thoughts for Boost or other libs? > > > Analog enumerate method for HID devices: > http://www.signal11.us/oss/hidapi/ > > Thanks, > > Vincent >

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"Simple" graceful stop of boost thread
by Michael Powell 11 Apr '13

11 Apr '13

Hello, I know this is possible, just don't have all the templates at the ready. Graceful way of stopping a boost worker thread from running. I am familiar with C# .NET threading, I can fairly simply signal an AutoResetEvent, for instance, and wait a nominal period for it to be set. Afterwards, this tells the thread to stop what it's doing at an opportune moment. Meanwhile the parent thread is joining the worker thread(s) back up. Something like that. I just need a few tips what concept to link up: i.e. mutex? shared_mutex? lock? shared_lock? I'll have a start_work, stop_work, and working type motif going on. I call start_work to start the working thread going. Simple enough. I will call stop_work to signal the worker thread(s) to stop and join up with the worker threads. Somewhere in between the worker thread is polling the lock does it need to stop, do it's work, then back around again. And so on... Thank you... Regards, Michael Powell

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Confirm required libs for boost
by Michael Powell 11 Apr '13

11 Apr '13

Hello, I believe I've identified them, but wanted to make sure. We're targeting ArchLinux ARM. Thus far, I am using boost for chrono (date/time) and threading are the two major features needing special attention in my build settings. I've identified libraries to link against: rt, pthread (from my toolchain), boost_system, boost_date_time, and boost_thread. Build seems satisfied with those issues at the moment, 'course I haven't run anything on our target. That I know of, most everything is statically linked, except rt and the pthread issue, which probably need a package for deployment, or to manually copy to target. Sounds about right? Regards, Michael Powell

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Error messages during configuration checks
by Braden McDaniel 11 Apr '13

11 Apr '13

I'm seeing these error messages interspersed with the normal output of the Boost build's configuration checks: > Performing configuration checks > - x86 : yes > has_icu_test.cpp > libs\regex\build\has_icu_test.cpp(12) : fatal error C1083: Cannot open include file: 'unicode/uversion.h': No such file or directory > - 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 > has_iconv.cpp > libs\locale\src\..\build\has_iconv.cpp(8) : fatal error C1083: Cannot open include file: 'iconv.h': No such file or directory > - iconv (libc) : no > has_iconv.cpp > libs\locale\src\..\build\has_iconv.cpp(8) : fatal error C1083: Cannot open include file: 'iconv.h': No such file or directory > - iconv (separate) : no > has_icu_test.cpp > libs\locale\src\..\build\has_icu_test.cpp(12) : fatal error C1083: Cannot open include file: 'unicode/uversion.h': No such file or directory > - icu : no > has_icu_test.cpp > libs\locale\src\..\build\has_icu_test.cpp(12) : fatal error C1083: Cannot open include file: 'unicode/uversion.h': No such file or directory > - icu (lib64) : no > has_gcc_visibility.cpp > libs\math\config\has_gcc_visibility.cpp(7) : fatal error C1189: #error : "This is a GCC specific test case". > - gcc visibility : no > - long double support : yes I don't recall seeing these when building Boost previously (using the same compiler, Visual C++ 2008); though it's possible I'm misremembering and they're just sticking out more now. What I have started doing differently is that I'm now calling b2 from a CMake script (via execute_process); but if that's what's triggering this, I don't understand how. Has anyone here seen this before? How might these error messages be suppressed? -- Braden McDaniel braden(a)endoframe.com

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ASIO file monitoring help
by SRD 11 Apr '13

11 Apr '13

I'm using an ASIO extention that was suggested for file monitoring. I've added this to my project and though I see a change when I add a file to the directory being monitored, I see no futher changes thereafter. Can anyone offer some insight as to how this should work? Any help much appreciated. void create_file_handler(const boost::system:error_code &ec, const boost::asio::dir_monitor_event &ev) { cout << "file name: " << ev.filename << endl; cout << " type : " << ev.type << endl; // now edit file ... } // from within main() boost::thread t; { boost::asio::io_service io_service; boost::asio::dir_monitor dm(io_service); dm.add_directory("C:\\Users\\SRD\\DirA"); boost::asio::dir_monitor_event ev = dm.monitor(); dm.async_monitor(create_file_handler); t = boost::thread(boost::bind(&boost::asio::io_service::run, boost::refio_service))); boost::system_time time = boost::get_system_time(); time += boost::posix_time::time_duration(0, 0, 1); boost::thread::sleep(time); } t.join(); io_service.reset(); // now do app stuff ..

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How is the proactor pattern of boost.asio implemented in linux?
by Journeyer J. Joh 11 Apr '13

11 Apr '13

Hi list, I am wondering about boost.asio. Boost.asio must have a proactor implementation on Linux, I guess. How does the proactor of boost.asio work? Does it use epoll? Is it edge-triggered? What about real-time signal? Doesn't boost.asio use real-time signal on Linux? What is the recommended implementation of boost.asio for asynchronous and non-blocking overlapped IO on Linux? Thank you in advance! ---------------------------------------- Journeyer J. Joh o o s a p r o g r a m m e r a t g m a i l d o t c o m ----------------------------------------

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[BGL] Error using breadth_first_search with labeled_graph
by Julio Cezar Novais Raffaine 10 Apr '13

10 Apr '13

Hi, I'm having the above (end of email) error message when compiling my source using breadth_first_search in a labeled_graph, here are some of my definitions: I'm using boost 1.51.0. struct VertexProperty { string x; }; typedef boost::property<boost::edge_weight_t, double> IndexProperty; typedef boost::labeled_graph< boost::adjacency_list<boost::vecS, boost::setS, boost::bidirectionalS, VertexProperty, IndexProperty>, std::string> GraphT; I also created the following visitor: class recurrence_bfs_visitor : public boost::default_bfs_visitor { public: GraphT::vertex_descriptor check_node; recurrence_bfs_visitor(GraphT::vertex_descriptor node) : boost::default_bfs_visitor(), check_node(node) {} template < typename Vertex, typename Graph > void discover_vertex(Vertex u, const Graph & g) const { if( u == check_node ) throw std::runtime_error(""); } }; Then I call my functions in this way: auto v1 = g.vertex(e1); auto v2 = g.vertex(e2); recurrence_bfs_visitor vis(v2); boost::breadth_first_search(g.graph(), v1, boost::visitor(vis)); Where g is my GraphT and e1,e2 are strings that I receive as parameters. Here are the error message: 1>d:\projects\cprojects\boost_1_51_0\boost\graph\detail\adjacency_list.hpp(2499): error C2039: 'type' : is not a member of 'boost::property_value<PropertyList,Tag>' 1> with 1> [ 1> PropertyList=VertexProperty, 1> Tag=boost::vertex_index_t 1> ] 1> d:\projects\cprojects\boost_1_51_0\boost\graph\detail\adjacency_list.hpp(2576) : see reference to class template instantiation 'boost::adj_list_any_vertex_pa::bind_<Tag,Graph,Property>' being compiled 1> with 1> [ 1> Tag=boost::vertex_index_t, 1> Graph=boost::adjacency_list<boost::vecS,boost::setS,boost::bidirectionalS,VertexProperty,IndexProperty>, 1> Property=VertexProperty 1> ] 1> d:\projects\cprojects\boost_1_51_0\boost\graph\detail\adjacency_list.hpp(2709) : see reference to class template instantiation 'boost::detail::adj_list_choose_vertex_pa<Tag,Graph,Property>' being compiled 1> with 1> [ 1> Tag=boost::vertex_index_t, 1> Graph=boost::adjacency_list<boost::vecS,boost::setS,boost::bidirectionalS,VertexProperty,IndexProperty>, 1> Property=VertexProperty 1> ] 1> d:\projects\cprojects\boost_1_51_0\boost\graph\properties.hpp(224) : see reference to class template instantiation 'boost::adj_list_vertex_property_selector::bind_<Graph,Property,Tag>' being compiled 1> with 1> [ 1> Graph=boost::adjacency_list<boost::vecS,boost::setS,boost::bidirectionalS,VertexProperty,IndexProperty>, 1> Property=VertexProperty, 1> Tag=boost::vertex_index_t 1> ] 1> d:\projects\cprojects\boost_1_51_0\boost\graph\properties.hpp(233) : see reference to class template instantiation 'boost::detail::vertex_property_map<Graph,PropertyTag>' being compiled 1> with 1> [ 1> Graph=boost::adjacency_list<boost::vecS,boost::setS,boost::bidirectionalS,VertexProperty,IndexProperty>, 1> PropertyTag=boost::vertex_index_t 1> ] 1> d:\projects\cprojects\boost_1_51_0\boost\graph\named_function_params.hpp(259) : see reference to class template instantiation 'boost::property_map<Graph,Property>' being compiled 1> with 1> [ 1> Graph=boost::adjacency_list<boost::vecS,boost::setS,boost::bidirectionalS,VertexProperty,IndexProperty>, 1> Property=boost::vertex_index_t 1> ] 1> d:\projects\cprojects\boost_1_51_0\boost\mpl\eval_if.hpp(41) : see reference to class template instantiation 'boost::detail::const_type_as_type<T>' being compiled 1> with 1> [ 1> T=boost::property_map<boost::adjacency_list<boost::vecS,boost::setS,boost::bidirectionalS,VertexProperty,IndexProperty>,boost::vertex_index_t> 1> ] 1> d:\projects\cprojects\boost_1_51_0\boost\mpl\eval_if.hpp(41) : see reference to class template instantiation 'boost::mpl::eval_if<C,F1,F2>' being compiled 1> with 1> [ 1> C=boost::mpl::true_, 1> F1=boost::detail::const_type_as_type<boost::property_map<boost::adjacency_list<boost::vecS,boost::setS,boost::bidirectionalS,VertexProperty,IndexProperty>,boost::vertex_index_t>>, 1> F2=boost::property_map<boost::adjacency_list<boost::vecS,boost::setS,boost::bidirectionalS,VertexProperty,IndexProperty>,boost::vertex_index_t> 1> ] 1> d:\projects\cprojects\boost_1_51_0\boost\graph\named_function_params.hpp(274) : see reference to class template instantiation 'boost::mpl::eval_if<C,F1,F2>' being compiled 1> with 1> [ 1> C=boost::is_same<boost::param_not_found,boost::param_not_found>, 1> F1=boost::mpl::eval_if<boost::mpl::true_,boost::detail::const_type_as_type<boost::property_map<boost::adjacency_list<boost::vecS,boost::setS,boost::bidirectionalS,VertexProperty,IndexProperty>,boost::vertex_index_t>>,boost::property_map<boost::adjacency_list<boost::vecS,boost::setS,boost::bidirectionalS,VertexProperty,IndexProperty>,boost::vertex_index_t>>, 1> F2=boost::mpl::identity<boost::param_not_found> 1> ] 1> d:\projects\cprojects\boost_1_51_0\boost\graph\breadth_first_search.hpp(316) : see reference to class template instantiation 'boost::detail::choose_impl_result<GraphIsConst,Graph,Param,Tag>' being compiled 1> with 1> [ 1> GraphIsConst=boost::mpl::true_, 1> Graph=boost::adjacency_list<boost::vecS,boost::setS,boost::bidirectionalS,VertexProperty,IndexProperty>, 1> Param=boost::param_not_found, 1> Tag=boost::vertex_index_t 1> ] 1> d:\projects\cprojects\boost_1_51_0\boost\graph\breadth_first_search.hpp(340) : see reference to function template instantiation 'void boost::detail::bfs_dispatch<boost::param_not_found>::apply<VertexListGraph,recurrence_bfs_visitor,boost::graph_visitor_t,boost::no_property>(VertexListGraph &,void *,const boost::bgl_named_params<T,Tag,Base> &,boost::param_not_found)' being compiled 1> with 1> [ 1> VertexListGraph=boost::adjacency_list<boost::vecS,boost::setS,boost::bidirectionalS,VertexProperty,IndexProperty>, 1> T=recurrence_bfs_visitor, 1> Tag=boost::graph_visitor_t, 1> Base=boost::no_property 1> ] 1> d:\novosprojetos\experiments\orcgraph\graphlib\graph.cpp(124) : see reference to function template instantiation 'void boost::breadth_first_search<boost::adjacency_list<OutEdgeListS,VertexListS,DirectedS,VertexProperty,EdgeProperty>,recurrence_bfs_visitor,boost::graph_visitor_t,boost::no_property>(const VertexListGraph &,void *,const boost::bgl_named_params<T,Tag,Base> &)' being compiled 1> with 1> [ 1> OutEdgeListS=boost::vecS, 1> VertexListS=boost::setS, 1> DirectedS=boost::bidirectionalS, 1> VertexProperty=VertexProperty, 1> EdgeProperty=IndexProperty, 1> VertexListGraph=boost::adjacency_list<boost::vecS,boost::setS,boost::bidirectionalS,VertexProperty,IndexProperty>, 1> T=recurrence_bfs_visitor, 1> Tag=boost::graph_visitor_t, 1> Base=boost::no_property 1> ] 1>d:\projects\cprojects\boost_1_51_0\boost\graph\detail\adjacency_list.hpp(2504): error C3203: 'type' : unspecialized class template can't be used as a template argument for template parameter 'ValueType', expected a real type 1>d:\projects\cprojects\boost_1_51_0\boost\graph\detail\adjacency_list.hpp(2504): error C2955: 'boost::type' : use of class template requires template argument list 1> d:\projects\cprojects\boost_1_51_0\boost\type.hpp(14) : see declaration of 'boost::type' 1> d:\projects\cprojects\boost_1_51_0\boost\type.hpp(14) : see declaration of 'boost::type' 1>d:\projects\cprojects\boost_1_51_0\boost\graph\detail\adjacency_list.hpp(2506): error C3203: 'type' : unspecialized class template can't be used as a template argument for template parameter 'ValueType', expected a real type 1>d:\projects\cprojects\boost_1_51_0\boost\graph\detail\adjacency_list.hpp(2506): error C2955: 'boost::type' : use of class template requires template argument list 1> d:\projects\cprojects\boost_1_51_0\boost\type.hpp(14) : see declaration of 'boost::type' 1> d:\projects\cprojects\boost_1_51_0\boost\type.hpp(14) : see declaration of 'boost::type' 1>d:\projects\cprojects\boost_1_51_0\boost\graph\breadth_first_search.hpp(316): error C2893: Failed to specialize function template 'boost::two_bit_color_map<IndexMap> boost::make_two_bit_color_map(size_t,const IndexMap &)' 1> With the following template arguments: 1> 'boost::adj_list_vertex_property_map' -- Julio Cezar Novais Raffaine Sistemas de Engenharia, Odebrecht SA São Paulo, SP http://elloxas.blogspot.com/

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[multiprecision] radix-2
by Lucas Sousa de Oliveira 10 Apr '13

10 Apr '13

Hey guys, I'm considering participating in this year's GSoC 2013 with Boost. I think the multiprecision problem is very interesting and I'll give my best to implement it But first, what would you think is the challenge here? What would make this problem very complex? I'm studying the general radix algorithm and it doesn't seem to be that bad. Am I being misled? All the best, -- Lucas Oliveira

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Re: [Boost-users] ASIO with std::thread
by Marat Abrarov 10 Apr '13

10 Apr '13

> Are there any implications of using std::thread and std::future, etc. with > boost.asio (instead of boost.thread, etc.)? I'd be thankful if you could > provide me the answer in detail and give me helpful pointers to online > links and provide examples. Specifically, I'm very interested in using > std::future and promise with std::thread but I want future with ASIO based > sockets. > > In addition, it'd be just great if you could also provide me an example of > using boost's chrono based stead clock for setting up interval timers to, > for example, get an event after every 10 seconds. As short example: #if defined(WIN32) #include <tchar.h> #include <windows.h> #endif #include <cstdlib> #include <cstddef> #include <utility> #include <iostream> #include <exception> #include <thread> #include <future> #include <vector> #include <memory> #include <algorithm> #include <functional> #include <boost/asio.hpp> #include <boost/optional.hpp> #include <boost/utility/in_place_factory.hpp> namespace ma { namespace test { namespace asio_future { class connect_task { public: typedef boost::system::error_code result; typedef std::future<result> future; private: typedef connect_task this_type; typedef std::promise<result> promise; this_type& operator=(const this_type&); public: connect_task() : promise_(std::make_shared<promise>()) { } connect_task(const this_type& other) : promise_(other.promise_) { } connect_task(this_type&& other) : promise_(std::move(other.promise_)) { } void operator()(const boost::system::error_code& error) { promise_->set_value(error); } future get_future() { return promise_->get_future(); }; private: std::shared_ptr<promise> promise_; }; // connect_task class io_task { public: typedef std::pair<boost::system::error_code, std::size_t> result; typedef std::future<result> future; private: typedef io_task this_type; typedef std::promise<result> promise; this_type& operator=(const this_type&); public: io_task() : promise_(std::make_shared<promise>()) { } io_task(const this_type& other) : promise_(other.promise_) { } io_task(this_type&& other) : promise_(std::move(other.promise_)) { } void operator()(const boost::system::error_code& error, std::size_t bytes_transferred) { promise_->set_value(std::make_pair(error, bytes_transferred)); } future get_future() { return promise_->get_future(); }; private: std::shared_ptr<promise> promise_; }; // io_task class io_service_pool { private: typedef io_service_pool this_type; io_service_pool(const this_type&); this_type& operator=(const this_type&); public: io_service_pool(boost::asio::io_service& io_service, std::size_t size) : work_guard_(boost::in_place(std::ref(io_service))) { for (; size; --size) { threads_.emplace_back([&io_service]() { io_service.run(); }); } } ~io_service_pool() { work_guard_ = boost::none; std::for_each(threads_.begin(), threads_.end(), [](std::thread& thread) { thread.join(); }); } private: boost::optional<boost::asio::io_service::work> work_guard_; std::vector<std::thread> threads_; }; // io_service_pool void run_test() { const boost::asio::ip::tcp::endpoint endpoint( boost::asio::ip::address_v4::loopback(), 7); const std::size_t cpu_count = std::thread::hardware_concurrency(); const std::size_t io_threadpool_size = cpu_count < 2 ? 2 : cpu_count; boost::asio::io_service io_service(io_threadpool_size); io_service_pool io_threadpool(io_service, io_threadpool_size); boost::asio::ip::tcp::socket socket(io_service); { // Connect to localhost:7 connect_task handler; connect_task::future future = handler.get_future(); socket.async_connect(endpoint, std::move(handler)); if (connect_task::result result = future.get()) { std::cout << "Failed to connect: " << result << std::endl; return; } std::cout << "Connected" << std::endl; } { // Send some data const std::string data = "Hello from Boost.Asio!"; io_task handler; io_task::future future = handler.get_future(); boost::asio::async_write( socket, boost::asio::buffer(data), std::move(handler)); io_task::result result = future.get(); if (result.first) { std::cout << "Failed to send: " << result.first << std::endl; return; } std::cout << "Sent: " << data << std::endl; } } // run_test } // namespace asio_future } // namespace test } // namespace ma #if defined(WIN32) int _tmain(int /*argc*/, _TCHAR* /*argv*/[]) #else int main(int /*argc*/, char* /*argv*/[]) #endif { try { ma::test::asio_future::run_test(); return EXIT_SUCCESS; } catch (const std::exception& e) { std::cerr << "Unexpected exception: " << e.what() << std::endl; } catch (...) { std::cerr << "Unknown exception" << std::endl; } return EXIT_FAILURE; } Regards, Marat Abrarov.

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How is the proactor pattern of boost.asio implemented in linux?
by Journeyer J. Joh 10 Apr '13

10 Apr '13

Hello list, In ACE and on Linux the Proactor pattern is not recommended. Instead of this, ACE_Dev_Poll_Reactor seems to be recommended. It is one of Reactor implementation. ACE_Dev_Poll_Reactor uses epoll in a level-trigger method. But, I am not sure of this information.... I just found some blog essays on internet. Now I wonder about boost.asio. boost.asio must have a proactor implementation on Linux, I guess. How does the proactor of boost.asio work? Does it use epoll? Is it edge-triggered? What about real-time signal? Doesn't boost.asio use real-time signal on Linux? What is the recommended implementation of boost.asio for asynchronous and non-blocking overlapped IO on Linux? Thank you in advance! ---------------------------------------- Journeyer J. Joh o o s a p r o g r a m m e r a t g m a i l d o t c o m ----------------------------------------

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ASIO with std::thread
by asif saeed 10 Apr '13

10 Apr '13

Hi, I am a newbie to both boost.asio and std::thread and std::future and so on and am just learning and trying to develop a messaging library. Are there any implications of using std::thread and std::future, etc. with boost.asio (instead of boost.thread, etc.)? I'd be thankful if you could provide me the answer in detail and give me helpful pointers to online links and provide examples. Specifically, I'm very interested in using std::future and promise with std::thread but I want future with ASIO based sockets. In addition, it'd be just great if you could also provide me an example of using boost's chrono based stead clock for setting up interval timers to, for example, get an event after every 10 seconds. Best regards, -Asif

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Efficient "[][]" operator overloading (encapsulating a MultiArray)
by Jiří Vyskočil 09 Apr '13

09 Apr '13

Hello, I need to encapsulate a 3D MultiArray inside another class "GridArray". The reason is that GridArray will have another implementation not using MultiArray and it seems much easier to provide an abstration over MultiArray, than to reimplement its interface for the other implementation. I need to keep the [][][] operator access to the structure. I created a class like this, but it is slow: template<class T> class GridArray<T,3> { public: GridArray(int x, int y, int z): _array(boost::extents[x][y][z]) { } boost::multi_array<T, 3> _array; struct SliceRef { struct ColRef { SliceRef &_parent; int _x, _y; ColRef(SliceRef &p, const int x, const int y): _parent(p), _x(x), _y(y) {} T& operator[](const int z) { return _parent._parent._array[_x][_y][z]; } }; GridArray<T,3> &_parent; int _x; SliceRef(GridArray<T,3> &p, const int x): _parent(p), _x(x) {} ColRef operator[](const int y) { return ColRef(*this,_x,y); } }; SliceRef operator[](const int x){ return SliceRef(*this,x); } }; I am unable to write a minimal test case - if I compare using multi_array directly vs. using this GridArray class in a simple test program (compiled with -O2), the performance is the same. But the real code shows about 20% slowdown - it's a numerical simulaiton, I create several arrays at the beginning and then do computations with them. The rest of the code hasn't been touched - I only chanded the constructors for the arrays and replaced a header which contained some typedefs with a header containing this class. Do you have any idea what might be going on? Is there a better way to write an interface for successive [] operators? Thanks, Jiri

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message_queue memory leak in Boost::test
by John Davies 09 Apr '13

09 Apr '13

I have this simple test case: BOOST_AUTO_TEST_CASE(TestLogin) { message_queue inQueue(open_or_create, "InQueue", 100, 100); remove("InQueue"); } And Boost::test reports a memory leak: Running 1 test case... *** No errors detected Detected memory leaks! Dumping objects -> {668} normal block at 0x0039DE78, 57 bytes long. Data: <struct boost::in> 73 74 72 75 63 74 20 62 6F 6F 73 74 3A 3A 69 6E {667} normal block at 0x0039DE40, 8 bytes long. Data: <x 9 > 78 DE 39 00 00 00 00 00 Object dump complete. Press any key to continue . . . If I comment out the two lines of code there is no memory leak. Is this something I have to live with? In my real code the message_queue is alive the whole time the program is running.

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[Boost.Test + Turtle] Suggestion how to test async events.
by Daniele Barzotti 09 Apr '13

09 Apr '13

Hi, I'm trying to take a first touch with Boost.Test and Turtle. I have some objects for network communication with async notifications. class ServerHandler : public MessageEventHandler { public: ServerHandler() { // Register the messages I want to manage this->RegisterMsg(E_MSG_METHOD_CONNECT, Poco::delegate(this, &ServerHandler::OnMsgMethodConnect)); } // Messages Handlers virtual void OnMsgMethodConnect(const void* pSender, TArgs& args) { cout << "ServerHandler receive E_MSG_METHOD_CONNECT" << endl; MSG_METHOD_CONNECT& msg = RetrieveMessage<MSG_METHOD_CONNECT>(args.msg); }; }; This class is an observer which handle the notification through the OnMsgMethodConnect method. The test body I wrote is: // declare a 'mockServerHandler' class implementing 'ServerHandler' MOCK_BASE_CLASS( mockServerHandler, ServerHandler ) { MOCK_METHOD( OnMsgMethodConnect, 2 ); }; BOOST_AUTO_TEST_SUITE(NetMessageDispatcherTest) BOOST_AUTO_TEST_CASE(Test1) { mockServerHandler mockSvr; SessionFactory* sf = new SessionFactory( &mockSvr ); IMessageFactory* mf = new PBMessageFactory(); NetMessageDispatcher* server = new NetMessageDispatcher(sf, mf, NULL, E_DISP_SERVER); NetMessageDispatcher* client = new NetMessageDispatcher(sf, mf, NULL, E_DISP_CLIENT); BOOST_CHECK( server->Init("LOCALHOST", "TestServer") == 0 ); BOOST_CHECK( server->Connect(8000, "127.0.0.1") == 0 ); BOOST_CHECK( client->Init("LOCALHOST", "TestClient") == 0 ); BOOST_CHECK( client->Connect(8000, "127.0.0.1") == 0 ); MOCK_EXPECT( mockSvr.OnMsgMethodConnect ).once().with(????) } BOOST_AUTO_TEST_SUITE_END() Now, I have to test if into the ServerHandler::OnMsgMethodConnect() the argument args.msg (which is a message class) has the correct values. EG. if (msg.station_type() == EStationType::ST_CLIENT) => OK Which is the correct way to do it? Regards, Daniele.

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file monitoring
by SRD 08 Apr '13

08 Apr '13

I'm looking for a way to get notified as soon as a new file has been created. So I was wondering if boost has a way of monitoring files so I can send them off as soon as I receive them. This would have to work for Linux and windows. I saw a few posts which seem to indicate that its not there yet, but that was some time ago. Thanks,

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[boost::asio] how should I use accept and io_service?
by Shenyu Yao 08 Apr '13

08 Apr '13

Hi guys, this is my first post to this mail list. Forgive my noob questions, I am new to boost. I have read some documentations but still dont understand how io_service works. My problem is that I need two functions in my server class, listen() and handle() listen() is to accept all incoming connections and bind them with a handler function which accept a socket as argument. and handler will simply call io_service.run() ========================= class Server { io_service IOService; std::vector<boost:: ... :: socket> SocketVector; listen() { //blocking accept all incoming connection and bind socket with handleSocket } HandleRequest() { //io_service.run(); } } ============================ handleSocket(*Socket) { //handleSocket; } ============================== main() { boost::thread t1(&Server::listen, &myServer); boost::thread t2(&Server::HandleRequest, &myServer); } ==================================== my understanding is that everytime you instantiate a new socket object with a constructor including a io_service object, this socket object is associated with the io_service object, since I only have one io_service object, these socket object will be executed when I call io_service.run()but, the question is, how do i assign handle_function to those socket, I saw people use acceptor.async_accept(socket, boost::bind(handler, &socket)) like this, But I want to use accept rather than async_accept(), but the accept() function cant be used to bind a handler function to this socket Thank you

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c++ Bit Fields
by Chris Gem 08 Apr '13

08 Apr '13

Please forgive me if this question has been answered but I've searched for days now and cannot find it. How do I expose a c++ struct with a bit field to python using boost::python? When I try I get this error. error: invalid pointer to bit-field ‘frameHdr_s::hdrSize’ Here is the struct: #define DATA_SIZE 0x100 typedef struct frameHdr_s { #define USE_BIT_FIELDS #ifdef USE_BIT_FIELDS // Longword 0 uint32_t hdrSize : 16; ///< Size of the header uint32_t revMin : 8; ///< Frame Minor Version uint32_t revMaj : 8; ///< Frame Major Version #else // Longword 0 uint32_t hdrSize; ///< Size of the header uint32_t revMin ; ///< Frame Minor Version uint32_t revMaj ; ///< Frame Major Version #endif } frameHdr_t; typedef struct frame_t { frameHdr_t frame_header; ///< frame header uint8_t data[DATA_SIZE]; ///< Byte array of data } frame_t; Here is boost code to expose it: using namespace boost::python; BOOST_PYTHON_MODULE(api) { class_<frameHdr_t>("frameHdr_t") .def_readwrite("hdrSize", &frameHdr_t::hdrSize) ; class_<frame_t>("frame_t") .def_readwrite("frame_header", &frame_t::frame_header) ; class_<myClass>("myClass") .def("register_callback", &myClass::register_callback) .def("boo", &myClass::boo) .def("crap", &myClass::crap) ; } I know that with ctypes I can create the same struct as in c++: from ctypes import * class frameHdr_t(Structure): _pack_ = 1 _fields_=[ # Longword 0 ("hdrSize",c_uint32, 16), ("revMin",c_uint32, 8), ("revMaj",c_uint32, 8), ] DATA_SIZE = 0x100 class frame_t(Structure): _pack_ = 1 _fields_=[ ("frame_header",frameHdr_t), ("data",c_uint8 * DATA_SIZE), ] But how do I translate from the Python version of frame_t to the c++ version of frame_t? In summary, * How do I tell boost to expose a bitfield? * If that is not possible, how do I translate from Python frame_t to C++ frame_t using boot? (I don't want to wrap in C because I need to preserve the C++ness of the interface.) The code is attached. Thank you for your time, Chris

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type_erasure question
by Aleksandar Fabijanic 07 Apr '13

07 Apr '13

Looking at the type_erasure example: typedef any<boost::mpl::vector<copy_constructible<>, typeid_<>, addable<>> > any_type; any_type x(1.1); any_type y(1); any_type z(x + y); Apparently, without placeholders for x and y, this is undefined behavior. Am I interpreting it right? If so, shouldn't it fail to compile or at least throw an exception at runtime? Thanks, Alex

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