December 2012 - Boost-users

How to implement a custom hash function for __uint128_t?
by Scott Smedley 10 Dec '12

10 Dec '12

Hi all, How can I implement a hash function for a __uint128_t type that is compatible with Boost? I tried this: #include <boost/functional/hash.hpp> #include <unordered_set> #ifdef USE_64 typedef uint64_t MyId; // works fine #else typedef __uint128_t MyId; #endif inline std::size_t hash_value (const MyId &x) { // not a very good hash function, but I just want to get it working first! return static_cast<std::size_t>(x); } int main (int argc, char *argv[]) { std::unordered_set<MyId, boost::hash<MyId>> s; s.insert(42); } but I get 144 lines of errors (!) using g++-4.7.2 with Boost v1.51.0 on 64-bit Scientific Linux 6.2: error: no matching function for call to 'hash_value(const __int128 unsigned&)' Any pointers/help would be muchly appreciated. Scott. :)

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Re: [Boost-users] text_file_backend with append and rotate (Victor Yankee)
by Victor Whiskey Yankee 09 Dec '12

09 Dec '12

Anyone, Would someone show me what I am doing wrong setting up this logger? I posted on the boost log site too but got no reply there either. Thanks, Vic > Hello everyone! > > How to create a text_file_backend that appends to existing log file and > also has rotation. The init function below always creates a new file every > time I run my program no matter the rotation settings. > > I am using svn version 774 (latest as of Dec 5, 2012. I tried many ways but > no joy. There is not an example like this, and there does not seem to be a > test for appending either, so maybe it is not supported, but that would be > bad. So I must be doing something wrong. > > Here is my function to set up the logger (using my custom severity levels): > > void init() > { > typedef boost::log::sinks::synchronous_sink<boost::log::sinks::text_file_backend > FileSink_t; > > boost::shared_ptr< FileSink_t> mySink(new FileSink_t( > boost::log::keywords::file_name = "%Y%m%d_%H%M%S_%5N.log" > , boost::log::keywords::rotation_size = 16 * 1024 * 1024 /3 > , boost::log::keywords::time_based_rotation =boost::log::sinks::file::rotation_at_time_point(0,0,0) > , boost::log::keywords::auto_flush = true > , boost::log::keywords::open_mode=(std::ios::out |std::ios::app) // seems to have no effect > )); > > // this method of setting append does not seem to work either, so Imust be doing something wrong > mySink->locked_backend()->set_open_mode(std::ios::out|std::ios::app); > > > mySink->locked_backend()->set_file_collector(boost::log::sinks::file::make_collector( > boost::log::keywords::target = "logs" > , boost::log::keywords::max_size = 16 * 1024 * 1024 > , boost::log::keywords::min_free_space = 2 * 16 * 1024 * 1024)); > > mySink->set_filter(boost::log::filters::attr< LOGGING::LOG_LEVEL("Severity", std::nothrow) >= LOGGING::warning); > mySink->locked_backend()->scan_for_files(); mySink->set_formatter( > boost::log::formatters::format("[%1% | %2%] %3%") > % boost::log::formatters::date_time< boost::posix_time::ptime("TimeStamp") > % boost::log::formatters::attr< LOGGING::LOG_LEVEL >("Severity",std::nothrow) > % boost::log::formatters::message()); > > boost::log::core::get()->add_sink(mySink); > boost::log::core::get()->add_global_attribute("TimeStamp",boost::log::attributes::local_clock()); > }

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Boost Filesystem references in static/shared library
by Miguel Guedes 09 Dec '12

09 Dec '12

Hello List, I was using boost::filesystem previously in a project that built an executable but it has now grown and the requirements changed, and I now have to build a portion of the code as a library; preferably an so. Since I've started building code as a library I've been getting errors about invalid references to boost::filesystem. Here's how I'm building the library: $ g++ -DBOOST_ALL_NO_LIB -fPIC -lrt -lstdc++ -shared -pthread -lboost_system -lboost_thread -lboost_filesystem -L/usr/local/lib -ldl -lpthread -lstdc++ -lclang -o libomnis.so cout.o command_line_processor.o command_options_container.o commands_container.o command_base.o command_option_base.o command_option.o command_option_multi.o command_option_integer.o command_option_flag.o command_serve.o command_send.o command_help.o command_version.o register.o unsaved_file.o clang_parameters.o ustring_vector.o string_vector.o request_strings.o source_file.o reply.o omnisource.o omnis.o As you can see I've tried building it with (as well as without) the BOOST_ALL_NO_LIB macro defined. I then compile the main executable as given: $ g++ libomnis.so client.o omnis_command_line_processor.o request_handler.o request_handler_1.0.o request_parser.o server.o connection.o omnisource_loader.o omnis_app.o main.o -o omnis -pthread -lboost_system -lboost_thread -lboost_filesystem -L/usr/local/lib -ldl -lpthread -lstdc++ -lclang -L. -lomnis And this results in the following output: ./libomnis.so: undefined reference to `boost::filesystem2::detail::dir_itr_close(void*&, void*&)' ./libomnis.so: undefined reference to `boost::filesystem2::detail::dir_itr_first(void*&, void*&, std::string const&, std::string&, boost::filesystem2::file_status&, boost::filesystem2::file_status&)' ./libomnis.so: undefined reference to `boost::filesystem2::detail::dir_itr_increment(void*&, void*&, std::string&, boost::filesystem2::file_status&, boost::filesystem2::file_status&)' ./libomnis.so: undefined reference to `boost::filesystem2::detail::status_api(std::string const&, boost::system::error_code&)' ./libomnis.so: undefined reference to `boost::filesystem2::detail::not_found_error()' collect2: error: ld returned 1 exit status What am I missing here? PS: No errors occurred previously when I was just building the executable. -- Miguel

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Why is cref required in this nested bind example?
by Chris Stankevitz 08 Dec '12

08 Dec '12

Hello, Can someone please explain why a cref is needed in the last line of the attached code snippet? Thank you, Chris === #include <boost/bind.hpp> #include <boost/function.hpp> using boost::bind; using boost::cref; using boost::function; void a() { } void b(function<void()>) { } void f() { //bind(b, bind(a)); bind(b, cref(bind(a))); }

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boost shared_ptr with own dtor
by Philipp Kraus 08 Dec '12

08 Dec '12

Hello, I'm using boost::shared_ptr for using a C pointer. The ctor and all functions are called without any problem, but I have got a problem with the dtor. I need to call a C function on the dtor eg cptr_close( mypointer ) How can I this used with boost::shared_ptr? I need the cptr_close call on the pointer member of the dtor on the shared_ptr. Thanks a lot Phil

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[Interprocess] message queue Cannot Allocate Memory
by cons_Pavignani, Antonio 08 Dec '12

08 Dec '12

Dear all, I use the message queue. I create a queue inside a thread (called Thread A) and I use it in another thread (called Thread B). I get this error: Cannot Allocate memory. This is the code related to the Thread A: message_queue::remove(InterprocessQueueName.c_str()); message_queue mq(open_or_create,InterprocessQueueName.c_str(),MAX_INTERPROCESS_SEND_QUEUE_SIZE,CalculatingSizeStructure::maxSizeHMIExtMessage); for(;;) { try { unsigned int priority; std::size_t recvd_size; mq.receive(msgBuffer, CalculatingSizeStructure::maxSizeHMIExtMessage, recvd_size, priority); ... } catch (interprocess_exception &ex) { ... } } This is the code related to the Thread B: boost::interprocess::message_queue *mq = InterprocessQueueManager::getInstance()->openQueue("Library_Queue"); if((mq->try_send(&msgCmdSendStatusToLibraryInfoR,sizeof(LibraryInfo),0))==false) {... } I've looked for that exception, and it seems to be related to the POSIX queue. I've also tried some solutions without results. Any ideas? Thanks in advance, Best Regards Antonio

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Manually cleaning up TSS data in boost 1.49
by Andrew Harvey 08 Dec '12

08 Dec '12

Hi, I am using boost::thread for a plug-in that is loaded by a third-party Linux application. I have no control over the host's threading or when it chooses to unload my code. Unfortunately I experience a crash every time the host thread unloads the .so and terminates. I get the following backtrace: (gdb) bt #0 0x00007fffde12c460 in ?? () #1 0x00000032cf607889 in start_thread () from /lib64/libpthread.so.0 #2 0x00000032cf2e5ccd in clone () from /lib64/libc.so.6 Not much to go on... I am pretty confident the crash is happening in a pthread key destructor registered by Boost. The only parts of the boost::thread library I am currently using are the synchronization classes: shared_mutex, shared_lock, unique_lock, upgrade_lock, upgrade_to_unique_lock I'm not directly using any thread-specific storage myself. What I would like to do is force boost to call its TSS destructor in my plug-in's destroy_dso() function. Is this at all possible? Many thanks, - Andrew

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[boost][mpl] Detect a type sequence type
by Klaim - Joël Lamotte 07 Dec '12

07 Dec '12

Hi, I am writing some functions and classes that accept a sequence of type ( boost::mpl::vector/list currently) as template parameter. I'm looking for a way to enhance type checking by making sure the provided types are... type sequences. I didn't find anything relevant in standard or boost type_trait libraries. So far, I'm guessing there is no way to check that, mainly because such types would be template instances, which make checking this like checking if a type is an instance of a template which is impossible right now (as far as I know anyway). My question is: what are possible ways to enhance type checking on type sequence types? I know some boost developers around here make great efforts to make sure their meta programming libraries make early and good error reporting so maybe they have a solution? PS: I'm using Visual Studio 2012 so I can't use variadic template yet ;___; (can't rely on the CTP) Joel Lamotte

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[Graph] Labeled graph bug
by Kikohs xxx 07 Dec '12

07 Dec '12

Hello, I have created a labeled graph:

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Clients controlling server and other clients
by Gonzalo Garramuno 07 Dec '12

07 Dec '12

I am writing an application in which one of multiple clients need to control the server and the other clients. The example is the timeline of a flipbook player. If one client sets the timeline to 125, both the server and the other clients need to jump to frame 125. If the server's timeline is modified to 200, indeed the timeline needs to be set to the new value in all clients. I am puzzled on how to write this with asio. Any help is appreciated.

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Re: [Boost-users] [Graph] How to do multi source shortest path
by ratnesh kumar 07 Dec '12

07 Dec '12

Hi All, I need to use the parallel dijkstra for multiple source shortest path as mentioned before in this thread. I copied the part of last email below. Is this feature now implemented in BGL ? Thanks Ratnesh

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text_file_backend with append and rotate
by Victor Yankee 06 Dec '12

06 Dec '12

Hello everyone! How to create a text_file_backend that appends to existing log file and also has rotation. The init function below always creates a new file every time I run my program no matter the rotation settings. I am using svn version 774 (latest as of Dec 5, 2012. I tried many ways but no joy. There is not an example like this, and there does not seem to be a test for appending either, so maybe it is not supported, but that would be bad. So I must be doing something wrong. Here is my function to set up the logger (using my custom severity levels): void init() { typedef boost::log::sinks::synchronous_sink< boost::log::sinks::text_file_backend > FileSink_t; boost::shared_ptr< FileSink_t> mySink( new FileSink_t( boost::log::keywords::file_name = "%Y%m%d_%H%M%S_%5N.log" , boost::log::keywords::rotation_size = 16 * 1024 * 1024 /3 , boost::log::keywords::time_based_rotation = boost::log::sinks::file::rotation_at_time_point(0,0,0) , boost::log::keywords::auto_flush = true , boost::log::keywords::open_mode=(std::ios::out | std::ios::app) // seems to have no effect )); // this method of setting append does not seem to work either, so I must be doing something wrong mySink->locked_backend()->set_open_mode(std::ios::out|std::ios::app); mySink->locked_backend()->set_file_collector(boost::log::sinks::file::make_collector( boost::log::keywords::target = "logs" , boost::log::keywords::max_size = 16 * 1024 * 1024 , boost::log::keywords::min_free_space = 2 * 16 * 1024 * 1024 )); mySink->set_filter(boost::log::filters::attr< LOGGING::LOG_LEVEL >("Severity", std::nothrow) >= LOGGING::warning); mySink->locked_backend()->scan_for_files(); mySink->set_formatter( boost::log::formatters::format("[%1% | %2%] %3%") % boost::log::formatters::date_time< boost::posix_time::ptime >("TimeStamp") % boost::log::formatters::attr< LOGGING::LOG_LEVEL >("Severity", std::nothrow) % boost::log::formatters::message() ); boost::log::core::get()->add_sink(mySink); boost::log::core::get()->add_global_attribute("TimeStamp", boost::log::attributes::local_clock()); }

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Why does gcc require explicit template arguments with my boost::bind
by Chris Stankevitz 06 Dec '12

06 Dec '12

Hello, Below I implement a function "Chain" that takes two functions and executes them both. The first approach succeeds: direct function call. The second approach succeeds: call via bind with explicit template arguments The third and fourth approaches fail: call via bind without explicit template arguments (with/without boost::protect) Question: Why do I have to use explicit template arguments when using bind with Chain? Thank you, Chris === #include <boost/bind.hpp> #include <boost/function.hpp> template <typename TAFunc1, typename TAFunc2> void Chain(const TAFunc1& Func1, TAFunc2& Func2) { Func1(); Func2(); } void f() { } void foo() { boost::function<void()> x = boost::bind(f); boost::function<void()> y = boost::bind(f); Chain(x, y); boost::bind(Chain<boost::function<void()>, boost::function<void()> >, x, y)(); boost::bind(Chain, x, y)(); boost::bind(Chain, boost::protect(x), boost::protect(y))(); }

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Experience with dealing with warnings from the Clang toolset?
by Paul A. Bristow 06 Dec '12

06 Dec '12

I have added a little information on dealing with warnings when using the Clang toolset at https://svn.boost.org/trac/boost/wiki/Guidelines/WarningsGuidelines but I am sure there are people using Clang who can provide more detailed information and suggestions from their experiences. Please tell me if you have anything to add. Paul --- Paul A. Bristow, Prizet Farmhouse, Kendal LA8 8AB UK +44 1539 561830 07714330204 pbristow(a)hetp.u-net.com

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Boost::Asio read_until and streambuf usage
by Gonzalo Garramuno 06 Dec '12

06 Dec '12

I have a server that sends three lines, each of which have to be parsed independently. I am using read_until but have a problem with its usage. When read_until reads once, the streambuf seems to contain the three lines but not in the istream and only when I call read_until several times, I get the lines. I am wondering how can I safely read_until the buffer is empty (the 3 or more lines are read) and then exit the loop. boost::asio::streambuf buf; while( 1 ) { size_t reply_length = boost::asio::read_until( socket_, buf, '\n' ); std::istream is(&buf); std::string reply; std::getline(is, reply); // only 1 line obtained }

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Re: [Boost-users] boost msm - differed events
by Kamel Zaarouri, Mr 05 Dec '12

05 Dec '12

Hi guys, I realized that I asked a very unclear question yesterday. I will try to reformulate :) Let's say I have 2 states, an Active state and an Idle state. If I receive some events in Active state I would like to defer them and execute them when I go back to Idle state. But when I go back to Idle State is there a way to chose which previously deferred event to process? or is there a way to prioritize them or even ignore few of them? Thank you!

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C++11, boost::filesystem::path, no std::hash specialization
by Benjamin Kircher 05 Dec '12

05 Dec '12

Hi there, I cannot use boost::filesystem::path with an e.g. unordered_set because std::hash seems not to be specialized for this type. Is this intended? Should I file a bug? Or am I completely misguided? I use 1.52 libraries with -DBOOST_FILESYSTEM_NO_DEPRECATED. I searched the bug database but did not find anything relevant (other than this https://svn.boost.org/trac/boost/ticket/5650 ticket). Thanks in advance, -Benjamin

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Boost.Serialization type-dependent serialization
by Roman Suvorov 05 Dec '12

05 Dec '12

Hi! I have a list of objects of the following structure: > class Obj > { > // a number simple fields > int field1() const; > > // ... > > // reference to an object containing large amount of data > const blob_type & mega_blob() const; > }; The list is to be serialized in the following way: 1) simple fields of each object are to be serialized into a single xml file; 2) mega_blobs' are to be serialized into separate binary files. The idea of doing it is to write custom archive that has operator<< specialized for blob_type which does the magic. Following the Boost.Serialization reference (http://www.boost.org/doc/libs/1_52_0/libs/serialization/doc/archive_referen…) I wrote the code in order to proof the concept: http://pastebin.com/ekbXXvxF My test project is built using CMake and G++-4.6.3 (Debian Wheezy) (that seems to be ok - other code that uses Boost.Serialization compiles well): http://pastebin.com/WVRUKLD2 As a result I get the following linker errors: http://pastebin.com/rM05nkqw The questions: 1) am I using xml_oarchive_impl wrong way or that problem is not boost-related? 2) maybe there are more elegant ways of solving my task? Cheers, Suvorov Roman.

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Re: [Boost-users] Boost-users Digest, Vol 3288, Issue 1
by Shcherbina Vladimir 05 Dec '12

05 Dec '12

Hi, Could you try it with MS compiler and any release prior to the 1.52.0? -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of boost-users-request(a)lists.boost.org Sent: 04 December 2012 17:29 To: boost-users(a)lists.boost.org Subject: Boost-users Digest, Vol 3288, Issue 1 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: Boost 1.49.0 compilation issue (Marshall Clow) 2. Re: boost msm - Multiple differed events (Kamel Zaarouri, Mr) 3. [serialization] versioning for class nested within template class (Gabriel Redner) 4. Re: Asio and software interrupts (Steve Lorimer) 5. Spirit guidance needed (Arkadiy and Marina Vertleyb) 6. [boost][polygon]Errors with minkowski sum (renaud lepere) 7. Re: Spirit guidance needed (Igor R) 8. Experience with dealing with warnings from the Clang toolset? (Paul A. Bristow) ---------------------------------------------------------------------- Message: 1 Date: Mon, 3 Dec 2012 09:29:59 -0800 From: Marshall Clow <mclow.lists(a)gmail.com> To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] Boost 1.49.0 compilation issue Message-ID: <BA420D66-6A77-4CF9-AB4C-E1005A770684(a)gmail.com> Content-Type: text/plain; charset=us-ascii On Dec 2, 2012, at 1:47 AM, Shcherbina Vladimir <Vladimir.Shcherbina(a)elbitsystems.com> wrote: > I tried to compile this boost dependent class with VS2008 and VS2010 > (error lines are in bold) Another data point: I was able to successfully compile your code with clang. and the 1.52.0 release. -- Marshall Marshall Clow Idio Software <mailto:mclow.lists@gmail.com> A.D. 1517: Martin Luther nails his 95 Theses to the church door and is promptly moderated down to (-1, Flamebait). -- Yu Suzuki ------------------------------ Message: 2 Date: Mon, 3 Dec 2012 21:08:57 +0000 From: "Kamel Zaarouri, Mr" <kamel.zaarouri(a)mail.mcgill.ca> To: "boost-users(a)lists.boost.org" <boost-users(a)lists.boost.org> Subject: Re: [Boost-users] boost msm - Multiple differed events Message-ID: <E7E49CA8DA97024ABF8B81BBF85E325412D63A(a)EXMBX2010-3.campus.MCGILL.CA> Content-Type: text/plain; charset="us-ascii" Hi Guys, Let's say that we have 2 states, S1 and S2. with this transition table: S1 -> S2 on event Es2 S2 -> S1 on event Es1 also let's say that S1 can also accept Ev1 and Ev2 but S2 cannot accept them so it differs them. Now when let's say that S2 receives 2 events Ev1 and Ev2 and differs them. Now, when S2 goes back to S1 would S1 handle both events in order? or how does it work? Thanks, ------------------------------ Message: 3 Date: Mon, 3 Dec 2012 17:51:40 -0500 From: Gabriel Redner <gredner(a)gmail.com> To: boost-users <boost-users(a)lists.boost.org> Subject: [Boost-users] [serialization] versioning for class nested within template class Message-ID: <CAO0m-H+t-bfAOe7JoV27MEMeHPXs6pVzDV9yqJC1Csp2Av6ESA(a)mail.gmail.com> Content-Type: text/plain; charset=windows-1252 Hi folks, I am having trouble incrementing the serialization version of a regular class nested within a template class. I'm not sure if the problem is with boost or with my own understanding of the issue. My code looks like: ============================== template <typename A, typename B> struct Foo { struct Bar { int data1; int data2; private: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, unsigned int version) { ar & data1; if (version >= 2) { ar & data2; } else { data2 = 0; } } }; }; ============================== My attempt at setting the version looks like: ============================== namespace boost { namespace serialization { template <typename A, typename B> struct version<typename Foo<A, B>::Bar> { BOOST_STATIC_CONSTANT(unsigned int, value = 2); }; } // namespace serialization } // namespace boost ============================== However, g++ gives an error: ============================== main.cpp:31:8: error: template parameters not used in partial specialization: main.cpp:31:8: error: ?A? main.cpp:31:8: error: ?B? ============================== Strangely, clang 3.0 compiles the code but issues some warnings: ============================== main.cpp:31:8: warning: class template partial specialization contains template parameters that can not be deduced; this partial specialization will never be used struct version<typename Foo<A, B>::Bar> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.cpp:30:20: note: non-deducible template parameter 'A' template <typename A, typename B> ^ main.cpp:30:32: note: non-deducible template parameter 'B' template <typename A, typename B> ^ 1 warning generated. ============================== I'd appreciate any pointers! Thanks, -Gabe ------------------------------ Message: 4 Date: Tue, 4 Dec 2012 10:17:33 +1100 From: Steve Lorimer <steve.lorimer(a)gmail.com> To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] Asio and software interrupts Message-ID: <CAE-NPOiR0Z3rGhmfBftGxpRLrJHTBW=6eMjGac27SaW+OvgJVw(a)mail.gmail.com> Content-Type: text/plain; charset="iso-8859-1" On 4 December 2012 01:51, Joseph Sulewski <joemacher(a)gmail.com> wrote: > *When I call socket->bind I provide it with an endpoint. When I > create the endpoint I'm currently using the multicast address, what > should I use for the address? * > If you bind to INADDR_ANY then the OS will use its ip routing tables to work out which the best local nic to use is. You can force it to use a specific local nic by providing its address. Most applications will use INADDR_ANY *If I'm binding to multiple multicast addresses it doesn't make sense to > bind to one of them.* > Because UDP is connectionless there is no way for the kernel / network stack to know which pid to deliver datagrams to for a particular port unless you bind your socket's file descriptor to that port. (note, if you want to allow other file descriptors to be able to bind to that port you need to set SO_REUSEADDR to 1) > *Finally, it appears I can join multiple multicast groups but they > need to be the same port. Is this correct?* > The reason for this is as my previous point above. What you would do is create as many sockets as there are different ports, and have each socket join the multicast addresses which are on that port > >

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[Filesystem] Movable fstreams
by Szymon Gatner 04 Dec '12

04 Dec '12

Hi, Could move (via boost.move) support be added to file streams provided by filesystem library? Would be very useful when returning for example ifstream from function. Cheers, Simon -- Szymon Gatner The Lordz Games Studio www.thelordzgamesstudio.com

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Boost.Math - Statistical Distribution Explorer - updated to Boost 1.52
by Paul A. Bristow 04 Dec '12

04 Dec '12

Just to note that I have recently updated the Microsoft Windows C# 'app' that allows one to explore various properties of statistical distributions and calculate their Cumulative Distribution Function CDF, Probability Distribution Function PDF, or quantiles/percentiles. This revision includes some new distributions and all the bug fixes and improvements in Boost.Math for 1.52. I have also now aligned the application version numbering with Boost release numbering. For full information and download http://sourceforge.net/projects/distexplorer/ It works on all the 'this-millennium' versions of Windows. If anyone knows how to produce a *nix version, please contact me. Paul --- Paul A. Bristow, Prizet Farmhouse, Kendal LA8 8AB UK +44 1539 561830 07714330204 pbristow(a)hetp.u-net.com

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Spirit guidance needed
by Arkadiy and Marina Vertleyb 04 Dec '12

04 Dec '12

Hi all, Can somebody direct me to a part/facility inside the Spirit library to do the following: I need to pre-parce a boolean expression (once) and save it somewhere. Then I need to evaluate this expression (many times, performance important) based on different values of tokens. Will Spirit.Classic do? Or do I need to use any of the newer libraries inside Spirit? Thanks for any help. Arkadiy

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[boost][polygon]Errors with minkowski sum
by renaud lepere 04 Dec '12

04 Dec '12

I need to implement robust minkowski sum operations on polygons. I have seen that this could be implemented easily using boost::polygon, the tutorial is here http://www.boost.org/doc/libs/1_52_0/libs/polygon/doc/gtl_minkowski_tutoria… The example works fine, however i need more precision than "int" (32 bits on my plateform win32-msvc10-32bits). I tried to replace to replace int -> double typedef boost::polygon::point_data< int > point; with typedef boost::polygon::point_data< double > point; But this leads to strange errors deep into the code (operator< is "bad") if (!_Pred(_Left, _Right)) return (false); else if (_Pred(_Right, _Left)) _DEBUG_ERROR2("invalid operator<", _File, _Line); called after scan_data_.insert(*insert_itr); // line 1197 in scan_arbitrary.hpp What can i do to avoid it, if i use "long long" type it works but it sends a lot of warning at compile time. Any idea of what i should do ? Is "double" type supported ?

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Asio and software interrupts
by Joseph Sulewski 03 Dec '12

03 Dec '12

Hello, I’m use the Boost::Asio libraries to read data from multicast sockets. This is a high rate application that needs to listen to data coming on a large number of multicast addresses (up to 500 different addresses). I would like to funnel all the multicast traffic to a single class where the data can get handled very quickly. I have the code working now using the socket->async_receive_from() method but the system is getting bogged down handling a large number of software interrupts. 51% of the CPU time is spent handling software interrupts. I create each multicast socket (up to 500 of them) like so: socket = new udp::socket(io_service); socket->open(listenEndPoint.protocol()); socket->set_option(boost::asio::ip::udp::socket::resuse_address(true)); socket->bind(listenEndPoint); socket->set_option(boost::asio::ip::multicast::join_group(multicastAddress.to_v4())); Slightly after that I register for data like so: socket->async_receive_from(buffer,senderEndPoint,boost::bind(&EthernetCapture::receiveData,this,boost::asio::placeholders::bytes_transferred)); Is there a more efficient way to receive multicast data without incurring so many software interrupts? By the way this is for an application to run on 32 bit Linux for an embedded application. Thanks

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[serialization] versioning for class nested within template class
by Gabriel Redner 03 Dec '12

03 Dec '12

Hi folks, I am having trouble incrementing the serialization version of a regular class nested within a template class. I'm not sure if the problem is with boost or with my own understanding of the issue. My code looks like: ============================== template <typename A, typename B> struct Foo { struct Bar { int data1; int data2; private: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, unsigned int version) { ar & data1; if (version >= 2) { ar & data2; } else { data2 = 0; } } }; }; ============================== My attempt at setting the version looks like: ============================== namespace boost { namespace serialization { template <typename A, typename B> struct version<typename Foo<A, B>::Bar> { BOOST_STATIC_CONSTANT(unsigned int, value = 2); }; } // namespace serialization } // namespace boost ============================== However, g++ gives an error: ============================== main.cpp:31:8: error: template parameters not used in partial specialization: main.cpp:31:8: error: ‘A’ main.cpp:31:8: error: ‘B’ ============================== Strangely, clang 3.0 compiles the code but issues some warnings: ============================== main.cpp:31:8: warning: class template partial specialization contains template parameters that can not be deduced; this partial specialization will never be used struct version<typename Foo<A, B>::Bar> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.cpp:30:20: note: non-deducible template parameter 'A' template <typename A, typename B> ^ main.cpp:30:32: note: non-deducible template parameter 'B' template <typename A, typename B> ^ 1 warning generated. ============================== I'd appreciate any pointers! Thanks, -Gabe

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