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Oven, regular and Boost
by Robert Jones 10 Dec '12

10 Dec '12

The 'Oven' port... http://dl.dropbox.com/u/1682460/git/OvenToBoost/libs/range/doc/html/range_e… makes much of its 'regular' operator, which is used to fix this problem using boost::lambda::_1; for_each_(r | filtered(_1 % 2 == 0), f); // Error! Can't default construct/copy assign for_each_(r | filtered(regular(_1 % 2 == 0)), f); // OK However, AFAICS this is not a problem in current-ishBoost (1.47). Has this ever been a problem? Can anyone comment on its general provenance? Thx, Rob.

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[Range] Sliced... less than it could be.
by Robert Jones 10 Dec '12

10 Dec '12

I was disappointed to discover that I can't write range | filtered( some_predicate ) | sliced( n, m ) | ..... because sliced requires a random access range, and filtered produces a forward range! Piffle. It seems such a useful and obvious use-case. Is this restriction really necessary? Thx, Rob.

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[overloaded_function] Why does it define f_ as const?
by Felipe Magno de Almeida 10 Dec '12

10 Dec '12

Hello, I'm trying to use overloaded_function. But unfortunately it defines f_ as const, which makes it not Assignable. Which seems to me, like a unnecessary limitation. I looked at the docs, but couldn't find any mention of assignment nor a rationale for this behavior. Is there a specific reason for overloaded_function to not be Assignable? Regards, -- Felipe Magno de Almeida

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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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