March 2009 - Boost-users - lists.boost.org

Socket iostream Question
by Anthrope 01 Apr '09

01 Apr '09

Hello all, I am developing a high-performance socket-based application using the boost asio library. The application implements a binary tcp-based protocol that a bi-directional exchange of fixed-size messages. To simplify the coding while not sacrificing flexibility or performance, I decided to use the TCP iostream classes. The approach seems to work well, and I like the fact that the streams are buffered and allow me control over when I flush them. There's one minor issue that I thought I would seek some guidance on: Diagnosing and reporting failures connecting to servers are problematic. Basically, if a connect fails, the only way to know about it is to check the fail bit of the iostream. It would be nice to know why a client is unable to connect. So, to that end, I thought I could construct the iostream object via the default constructor, grab its streambuf via the rdbuf() call and in turn grab a basic_socket object reference to the streambuf and then call connect() on it, i.e., tcp::iostream iStream ; boost::asio::basic_socket_streambuf<tcp>& buf(*(iStream.rdbuf())); boost::asio::basic_socket<tcp, stream_socket_service<tcp> >& mySock(buf) ; mySock.connect(endPoint, error) ; The call to connect() on mySock with the error_code argument enables me to the diagnose and report connection problems a bit better. Once the connection is established, we can resume using the iostream directly. I would like to hear from you as to whether this approach makes sense, and what the pitfalls might be. And, alternative approaches would be most welcome too! Thanks in advance, Prashanth Nandavanam -- View this message in context: http://www.nabble.com/Socket-iostream-Question-tp22805249p22805249.html Sent from the Boost - Users mailing list archive at Nabble.com.

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Is boost license GPL compatible?
by Tommy Nordgren 31 Mar '09

31 Mar '09

That is, is it possible to distribute a library distributed under the boost license together with a software package distributed under the GPL. ----------------------------------- See the amazing new SF reel: Invasion of the man eating cucumbers from outer space. On congratulations for a fantastic parody, the producer replies : "What parody?" Tommy Nordgren tommy.nordgren(a)comhem.se

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zip_iterator and sTL algorithms like random_shuffle
by Andreas Fabri 31 Mar '09

31 Mar '09

Hello, I have two vectors and want to random_shuffle them the same way using the zip_iterator. I thought the code below would do it, but when I execute it I see that both sequences get screwded up. What do I wrong? Best regards, andreas #include <vector> #include <boost/iterator/zip_iterator.hpp> #include <algorithm> #include <iostream> int main() { std::vector<int> I(8), J(8); for(int i = 0; i < I.size(); i++){ I[i] = J[i] = i; } std::random_shuffle(boost::make_zip_iterator(boost::make_tuple(I.begin(), J.begin())), boost::make_zip_iterator(boost::make_tuple(I.end(), J.end()))); for(int i = 0; i < I.size(); i++){ std::cout << I[i] << " " << J[i] << std::endl; } return 0; }

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[Q] scoped_ptr for forward declared classes
by V S P 31 Mar '09

31 Mar '09

Hello I have a situation where I have struct cmoney_impl_dtl; //hidden impl is in Cpp file struct myclass { boost::scoped_ptr<hidden_impl> myimpl_ptr; } The compiler complains that the struct hidden_impl must be fully defined in the header file (which I cannot do) ------------- c:\usr\local\boost.msvc2008\boost_1_38_0\boost\checked_delete.hpp(32) : error C2027: use of undefined type 'cmoney_impl_dtl' c:\dbt_money.hpp(38) : see declaration of 'cmoney_impl_dtl' c:\usr\local\boost.msvc2008\boost_1_38_0\boost\scoped_ptr.hpp(80) : see reference to function template instantiation 'void boost::checked_delete<T>(T *)' being compiled ------------- is there a way around this? I was trying to use shared_ptr there, but MSVC reports memory leak on those objects... so I must be doing something wrong there , and therefore just wanted to try a simple ptr. thanks in advance, Vlad -- V S P toreason(a)fastmail.fm -- http://www.fastmail.fm - Same, same, but different...

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warnings with boost::bind
by Hansi 31 Mar '09

31 Mar '09

Hello, I have a question. I use boost::bind with the following class: class B { int data; } class A { bool SetData(const B&){return true;}; } now when I make somewhere the following: A a; boost::bind<bool>(&A::SetData,&a); I get a warning 8>D:\boost\boost_1_34_1\boost/bind.hpp(1575) : warning C4180: qualifier applied to function type has no meaning; ignored 8> D:\boost\boost_1_34_1\boost/bind.hpp(1609) : see reference to class template instantiation 'boost::_bi::add_cref<Pm,I>' being compiled 8> with 8> [ 8> Pm=bool (__thiscall Microtec::Program::* )(const Microtec::TrackingInfo &), 8> I=1 8> ] 8> .\Program.cpp(2385) : see reference to class template instantiation 'boost::_bi::dm_result<Pm,A1>' being compiled 8> with 8> [ 8> Pm=bool (__thiscall Microtec::Program::* )(const Microtec::TrackingInfo &), 8> A1=bool 8> ] I think it is for the const reference. Is this a problem? Is there some way to avoid it (okay the way with pragma I know)? I use boost 1.34.1 and MSVC2005 Regards

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Cyclic includes when using smart pointers.
by Jared Lee Richardson 31 Mar '09

31 Mar '09

Hey, I'm having trouble with cyclic includes in a project I'm working on. This is my first attempt at a project that heavily uses boost, and specifically, smart pointers. I have the following situation, simplified down. Header file 1: class Test1 { vector<Test2Ptr> mTest2Objects; }; typedef boost::shared_ptr<Test1> Test1Ptr; Header file 2: class Test2 { vector<Test1Ptr> mTest1Objects; }; typedef boost::shared_ptr<Test2> Test2Ptr; Now normally I'd get around this easily by doing a forward declaration, but I can't do that with a smart pointer definition. How can I work around this? So far I have found ways to work around the above(Since that's not precisely what I'm doing), but when I start inlining functions it will become very difficult to work around. Obviously something is wrong with my include structure or how I am going about this, but I don't know what... Any help? Is there a way I can forward-declare smart pointers? How are complicated cyclic includes usually resolved, if forward declares aren't enough(i.e., inline files)? Thanks, Jared

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[concept check][mpl] (Conditional) Concept checking for functions
by Jesse Perla 31 Mar '09

31 Mar '09

One rough idea I had was that since I will always have boost::function declarations as the default type, I could try to see if the type F is compatible with the boost::function type? Could this be done in a simple metafunction similar to the following: template<class BoostF, class F> struct CheckFunctionCompatible { static void Check() { F f; BoostF fboost = f; //If this fails, then I am basically failing } }; But then if I instantiate, won't it also try to instantiate the constructor? template<class F> class { typedef CheckFunctionCompatible<boost::function<double (double)>, F> test_F_compatibility; }; Of course, this wouldn't work for detecting the signature of the function, but that is a 2nd order feature for me. Of course, this also assumes that F can be constructed with no parameters, but this also might be reasonable for me if there is no better solution. -Jesse

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TupleIt and zip_iterator
by Andreas Fabri 31 Mar '09

31 Mar '09

Was Anthony Williams TupleIt, mentioned in http://www.cpptalk.net/7-vt9657.html?postdays=0&postorder=asc&start=90 and distributed in http://groups.yahoo.com/group/boost/files/tupleit.zip) the precursor of the boost::zip_iterator? In contrast to the boost::zip_iterator an TupleIt iterator range can be sorted. What are the advantages of the zip_iterator, besides being in boost. andreas

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Re: [Boost-users] [wave]include not found
by Ein Held 31 Mar '09

31 Mar '09

Here we go: http://rapidshare.com/files/215649826/wave.zip.html or http://uploaded.to/?id=ndz0tn

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[Q] does map.erase destroy shared_ptr ?
by V S P 31 Mar '09

31 Mar '09

Hello, I am storing database streams as associated string tag as std::map< std::string, boost::shared_ptr<otl_stream> > once in a while I need to remove a stream based on the tag, so I do //find stream based on tag //close stream s->close //call map.erase can I expect that once I call map erase the destructor of the stream will get called? (for some reason I do not see my trace statement of the destructor, but the stream destruction are unfamiliar code to me.. so I may be just doing something wrong). thank you, Vlad -- V S P toreason(a)fastmail.fm -- http://www.fastmail.fm - Faster than the air-speed velocity of an unladen european swallow

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