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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