March 2011 - Boost-users - lists.preview.boost.org

min and max preferring NaN
by Rhys Ulerich 10 Mar '11

10 Mar '11

'Afternoon, The usual std::min and std::max prefer numbers over NaNs per http://en.wikipedia.org/wiki/IEEE_754_revision#min_and_max. POSIX's fmin(3) does as well. Can anyone suggest a better implementation (chained ternary complaints aside) for a NaN-preferring min or max than brute force things akin to template<class T> inline const T& minnan(const T& a, const T& b) { return UNLIKELY((boost::math::isnan)(a)) ? a : (a < b) … [View More]

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async_read_some/async_write_some
by Marco Piacentini 10 Mar '11

10 Mar '11

Hi...this is my question: are there the concatenation of these functions be considered like a multithread approach on a socket? I try to explain myself better... I need to have a behaviour like the following: inside a process, one thread read over a scoket, and one thread write over the same socket... is it possible to make the same beahviour simply create a chain of async_read and Async_write? or I have to handle the socket with lock-unlock mechanism? thank you...

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Re: [Boost-users] [ASIO] async_accept : Error m_val 1.
by Cyprien DIOT 10 Mar '11

10 Mar '11

Thank you for your answer. You're right, with message member function, I get the "Already open" error. I don't really understand it, my source code is: void Server::receiving() { boost::system::error_code error; tcp::endpoint endp(tcp::v4(), 14242); acceptor = new tcp::acceptor(_io); acceptor->open(endp.protocol()); acceptor->set_option(tcp::acceptor::reuse_address(true)); acceptor->bind(endp); acceptor->listen(); _client = new tcp::socket(_io); _client->close(); … [View More]

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[uBLAS] Predefined subrange or project
by Ryan 10 Mar '11

10 Mar '11

Is it possible to predefine a subrange or project with a specific range so that when called I only had to pass in the matrix? I'm currently dealing with several 9x9 matrices that I need to access the 3x3 submatrix (topleft, topmiddle, topright, etc.). Is there a way to typedef or templatize a subrange or project so that I just need to pass the 9x9 matrix and get the topleft matrix? Example: typedef subrange(input_matrix, 0, 3, 0, 3) topleft; //This is what I want to somehow define. matrix… [View More]

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Re: [Boost-users] [ASIO] async_accept : Error m_val 1.
by Cyprien DIOT 10 Mar '11

10 Mar '11

I've made unit test for this problem. Server.h: #pragma once #include <boost/thread/thread.hpp> #include <boost/asio.hpp> #include <boost/array.hpp> #include <iostream> class Server { public: AssistGui(boost::asio::io_service &); ~AssistGui(void); void accept(const boost::system::error_code& e); void sendMsg(const char *msg, unsigned int size); private: boost::asio::io_service &io; boost::asio::ip::tcp::socket _client; boost::asio::ip::tcp::… [View More]

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[Boost] [Interprocess] Use of Boost.Move in interprocess affecting causing compilation errors with 1.46
by Lars Hagstrom 10 Mar '11

10 Mar '11

Hi all, I'm having a problem compiling some code with boost 1.46 that was compiling fine with 1.36 to 1.43 (or thereabouts). It appears that this is somewhat related to the use of Boost.Move in the Boost.Interprocess library. I have tried to read up a bit on Boost.Move, but have failed to quite understand what of it applies to me. Here is a small piece of code that will cause the compilation error (explanations below): ---------------------- #include <boost/interprocess/ containers/vector.… [View More]hpp> #include <boost/interprocess/containers/string.hpp> #include <boost/interprocess/managed_shared_memory.hpp> typedef boost::interprocess::basic_string < char, std::char_traits<char>, boost::interprocess::allocator < char, boost::interprocess::managed_shared_memory::segment_manager > > ShmString; class A { #if 0 public: A(const A&); A& operator=(const A&); #endif private: #if 1 ShmString m_name; #endif }; typedef boost::interprocess::vector < A, boost::interprocess::allocator < A, boost::interprocess::managed_shared_memory::segment_manager > > AVector; class B { public: void AddA(const A & a) {m_as.push_back(a);} private: AVector m_as; }; ---------------- g++ 4.4 compilation errors: ---------------- In file included from /usr/include/c++/4.4/memory:49, from /home/lars/boost_1_46_0/boost/interprocess/containers/container/vector.hpp:23, from /home/lars/boost_1_46_0/boost/interprocess/containers/vector.hpp:19, from mfp.cpp:1: /usr/include/c++/4.4/bits/stl_algobase.h: In static member function ‘static _OI std::__copy_move<false, false, std::random_access_iterator_tag>::__copy_m(_II, _II, _OI) [with _II = boost::container::constant_iterator<A, long int>, _OI = A*]’: /usr/include/c++/4.4/bits/stl_algobase.h:397: instantiated from ‘_OI std::__copy_move_a(_II, _II, _OI) [with bool _IsMove = false, _II = boost::container::constant_iterator<A, long int>, _OI = A*]’ /usr/include/c++/4.4/bits/stl_algobase.h:436: instantiated from ‘_OI std::__copy_move_a2(_II, _II, _OI) [with bool _IsMove = false, _II = boost::container::constant_iterator<A, long int>, _OI = A*]’ /usr/include/c++/4.4/bits/stl_algobase.h:468: instantiated from ‘_OI std::copy(_II, _II, _OI) [with _II = boost::container::constant_iterator<A, long int>, _OI = A*]’ /home/lars/boost_1_46_0/boost/interprocess/detail/move.hpp:1105: instantiated from ‘F boost::interprocess::copy_or_move(I, I, F, typename boost::disable_if<boost::interprocess::move_detail::is_move_iterator<I>, void>::type*) [with I = boost::container::constant_iterator<A, long int>, F = A*]’ /home/lars/boost_1_46_0/boost/interprocess/containers/container/detail/advanced_insert_int.hpp:53: instantiated from ‘void boost::container::containers_detail::advanced_insert_aux_proxy<T, FwdIt, Iterator>::copy_all_to(Iterator) [with T = A, FwdIt = boost::container::constant_iterator<A, long int>, Iterator = A*]’ mfp.cpp:46: instantiated from here /usr/include/c++/4.4/bits/stl_algobase.h:343: error: no match for ‘operator=’ in ‘* __result = __first.boost::container::constant_iterator<T, Difference>::operator* [with T = A, Difference = long int]()’ mfp.cpp:17: note: candidates are: A& A::operator=(A&) Which may not say too much, but if I change either the #if 0 to #if 1 or the #if 1 to #if 0 it suddenly compiles. So I'm thinking that the use of BOOST_MOVE_MACRO_COPYABLE_AND_MOVABLE(basic_string) in the interprocess string is somehow causing me to have to implement copy constructors and copy assignment operators in all classes that use them. Is this the way it is meant to be? I was fine with the compiler-generated ones before... Cheers Lars [View Less]

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[lambda] How to write a lambda functor that returns a new functor
by Sebastian Theophil 10 Mar '11

10 Mar '11

Hi, How can I write a lambda expression with two placeholders, one for the callable object, and one for the function argument, such that supplying the callable object first returns a unary function? In the example below, generate should be a lambda expression with the first placeholder for the callable object itself, and the second placeholder for the argument. Calling generate(c) should return a unary function that is only missing the function call argument. In fact, it somehow returns type … [View More]

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boost::asio multiprocess
by Marco Piacentini 10 Mar '11

10 Mar '11

Hi guys...I would to make a simple multi process (not thread) server. I've seen the iterative example in which it handles one request at a time. Instead I need to handle more requests(more on less 10) at the same time. In the classic c and c++ examples, I've seen that the server is designed like the following: int listensd, connsd; // listening socket and conection socket pid_t pid; //process id listensd=socket(....); bind(listensd,...); listen(listensd,...); for(;;) { connsd=… [View More]

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program_options and BOOST_ALL_NO_LIB=1
by Gianni Ambrosio 10 Mar '11

10 Mar '11

Dear All, I have a simple test using program_options but even if I set BOOST_ALL_NO_LIB=1 the linker gives me errors. Any idea? Regards Gianni

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lambda::var( i )++
by er 10 Mar '11

10 Mar '11

Hello, Is there a variant of this int i = 0; lambda::var( i )++; in which I can do away with the external variable, i? In other words, a nullary functor that returns 0, 1, 2, successively? Thanks.

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