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Re: [Boost-users] [boost][thread] Future returning 0xfeeefeee
by Stefan Strasser 14 Apr '13

14 Apr '13

Zitat von Klaim - Joël Lamotte <mjklaim(a)gmail.com>: > On Sun, Apr 7, 2013 at 1:02 AM, Klaim - Joël Lamotte > <mjklaim(a)gmail.com>wrote: > >> So the promise is destroyed before setting the value to the future. > > > Sorry, I meant: the promise is (a priori) guaranteed to be destroyed AFTER > having set the value to the future. > > Joel Lamotte > I was under the impression that the promise object itself has to be alive when the future result is used. and since you're emptying your queue on execution it's not. but considering that the promise object could be in another thread that was probably a false impression. Which compiler does this even work with yet? Both gcc and clang fail. clang on compilation, gcc compiles it but fails at runtime with a system_error exception and an invalid error code. so you might wanna consider compiler and library bugs, too.

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Re: [Boost-users] Can I implement asynchronous and non-blocking socket IO with boost.asio on LINUX?
by Marat Abrarov 14 Apr '13

14 Apr '13

> I think this implementation looks similar to ACE. The proactor > implementation varies depends on platforms. ACE uses native asynch IO > features for Windows, Solaris but not for LINUX. > I wanted to know if boost.asio implements asynch IO for LINUX not like > ACE. RTFM? http://www.boost.org/doc/libs/1_53_0/doc/html/boost_asio/overview/implementa tion.html > Then does proactor of boost.asio on LINUX work well? If it is portable I > guess it should though. > > Do people use proactor of boost.asio on LINUX? http://think-async.com/Asio/WhoIsUsingAsio As far as I know, the best performance at Linux can be achieved using "io_service-per-CPU design": http://www.boost.org/doc/libs/1_53_0/doc/html/boost_asio/examples.html#boost _asio.examples.http_server_2 Regards, Marat Abrarov.

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Can I implement asynchronous and non-blocking socket IO with boost.asio on LINUX?
by Journeyer J. Joh 14 Apr '13

14 Apr '13

Can I implement asynchronous and non-blocking (overlapped) socket IO with boost.asio on LINUX? If so please provide me some information for that. Thank you in advance! Best regards ---------------------------------------- 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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C++ and/or boost analog to .NET System.Version
by Michael Powell 13 Apr '13

13 Apr '13

Hello, I am curious is there an analog to System.Version in .NET? http://msdn.microsoft.com/en-us/library/system.version.aspx Basically a cloneable, comparable, equatable version composed of major, minor, build, revision. Or patch, build, or however you'd like to decompose the fields. I don't think it'd be hard to cook one up using say tuple<int, int, int, int> for instance, but if one already exists I'd like to save the effort. Thanks! Regards, Michael Powell

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Issue with asio::serial_port - async_write_some handler isn't firing
by Alex McClung 13 Apr '13

13 Apr '13

Hi, I'm trying to get a simple application up and running that sends and receives simple commands through a COM port to an Arduino hooked up to some sensors. Right now, I'm just trying to send the Arduino a simple command through a boost::asio::serial_port instance, although at some point I'll need to start reading from it as well. At any rate, I think I've got the basic premise down, but for some reason the WriteComplete function (see code below) isn't being called. After running the program, the output is: Open Sending command '.' Press any key to continue. I'm not 100% sure what's going on. The only thing I can think of is that the boost::asio::buffer(&command, sizeof(command)) statement is wrong. I'm not very familiar with these libraries, though, so I don't know what I would replace it with. I've included the code I'm using in case anyone can help me out. Thanks, -Alex --- #include "stdafx.h" #include <iostream> #include <boost\bind.hpp> #include <boost\asio.hpp> using namespace std; boost::asio::io_service gService; boost::asio::serial_port gPort(gService); void WriteComplete(const boost::system::error_code& error, std::size_t bytes_transferred) { cout << "Write complete." << endl; gPort.close(); } int _tmain(int argc, _TCHAR* argv[]) { gPort.open("COM3"); if(!gPort.is_open()) { cout << "Could not open com port." << endl; return 0; } cout << "Open" << endl; typedef boost::asio::serial_port_base asio_serial; gPort.set_option( asio_serial::baud_rate( 9600 ) ); gPort.set_option( asio_serial::flow_control( asio_serial::flow_control::none ) ); gPort.set_option( asio_serial::parity( asio_serial::parity::none ) ); gPort.set_option( asio_serial::stop_bits( asio_serial::stop_bits::one ) ); gPort.set_option( asio_serial::character_size( 8 ) ); char command = '.'; cout << "Sending command '" << command << "'" << endl; gPort.async_write_some( boost::asio::buffer(&command, sizeof(command)), boost::bind( &WriteComplete, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred ) ); cout << "Press any key to continue."; cin.ignore(); cin.get(); return 0; }

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

13 Apr '13

> > Actually, I try to use template variadic functions which can contains references, pointers and/or values which must be converted to boost::function0<void>. > > I tried to use forward() but I lose references with it. I tried ref() to but it make values interpreted as references (so ints are broken). So I'm looking for a magic way to use ref() only when needed by the arguments. > What do you mean by "when needed by the arguments?" How do you specify what should have ref added and what shouldn't? Well, I tried to make a template pseudo-code to determine which function it needs to use. Like this code that does not work: ///// Big code to make it working template<typename W,typename T> struct SignalArgumentValueConverter { }; template<typename T> struct SignalArgumentValueConverter<const boost::reference_wrapper<T>,T> { static const boost::reference_wrapper<T> convert(T&& t) { return boost::ref<T>(t); } }; template<typename T> struct SignalArgumentValueConverter<T&&,T> { static T&& convert(T&& t) { return std::forward<T&&>(t); } }; template<typename T> struct SignalArgumentTypeConverter { typedef typename std::conditional<std::is_reference<T>::value,const boost::reference_wrapper<T>,T&&>::type type; static type convert(T&& t) { return SignalArgumentValueConverter<type,T>::convert(std::forward<T&&>(t)); } }; ////// Little code to use it // Note: current is an iterator on a std::vector< boost::function<void(Args…)> > (*current)( SignalArgumentTypeConverter<Args>::convert(boost::forward<Args>(args))... ); This code does not compile and I think that I may break its code while I made some tests. Any idea to create something lile that (or even better) ? Regards, Yannick POTIN

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[program_options] Possible to compose notifier to void void function?
by Michael Powell 13 Apr '13

13 Apr '13

Hello, Is it possible? Something like the example identified here: http://stackoverflow.com/questions/7125666/what-is-boostprogram-optionsnoti… Except I'd like to hook up a void(void) notifier handler instead of the parameter. Thank ye... Regards, Michael Powell

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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

> > >> 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 ? Sorry, I lost context with what you're trying to do, but maybe you want to use boost::ref / std::ref in conjunction with boost::bind / std::bind, respectively? I think that should indicate to the binding framework to hold the bound values by reference rather than by value (if that's what you want). - Jeff Actually, I try to use template variadic functions which can contains references, pointers and/or values which must be converted to boost::function0<void>. I tried to use forward() but I lose references with it. I tried ref() to but it make values interpreted as references (so ints are broken). So I'm looking for a magic way to use ref() only when needed by the arguments. Regards, Yannick POTIN

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Difficulty using promises and futures
by Michael Powell 12 Apr '13

12 Apr '13

Hello, I would like to use promises and futures in our embedded app. We're targeting ArchLinux ARM. I believe we can build against a GCC 4.7.2 toolchain which has either C++0x or possibly even C++11 (somewhat) support. I am trying to setup a couple of simple issues to make it even compile, but am having trouble. boost::packaged_task<vector<int> > int_vect_pt_(simple_vector_getter); boost::unique_future<vector<int> > int_vect_f_ = int_vect_pt_.get_future(); boost::thread task(boost::move(int_vect_pt_)); boost::packaged_task<int> int_pt_(simple_getter); boost::unique_future<int> int_f_ = int_pt_.get_future(); boost::thread task(boost::move(int_pt_)); Error(s): Description Resource Path Location Type 'boost::move' is ambiguous ' Candidates are: boost::type move(boost::packaged_task<int> &) ' optics.cpp /detector/devices line 156 Semantic Error Description Resource Path Location Type 'boost::move' is ambiguous ' Candidates are: boost::type move(boost::packaged_task<std::vector<int,std::allocator<int>>> &) ' optics.cpp /detector/devices line 152 Semantic Error Can anyone help or otherwise advise? I've even got a "crude" future implementation in C# .NETCF for pity's sake... Anyway, if necessary, what did we do before promises/futures? ;-) Thank you... Regards, Michael Powell

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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

> >> 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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