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[serialization]const member when using boost serialization
by Ray Zhang 17 Feb '09

17 Feb '09

Hi, I got a problem when i use boost:: serialization lib --- whether a const data member could be serialized? For example, class A { const int a; } how can i serialize 'a' by using boost? Best Regards. Ray Zhang. Tsinghua Univ. P.R.China

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[boost-users][bind]
by Igor R 17 Feb '09

17 Feb '09

Hello, Could you please explain what causes the following warning and how to avoid it (boost 1.36, MSVC9.0SP1): typedef boost::weak_ptr<Task> TaskWeakPtr; typedef std::vector<TaskWeakPtr> TaskWeakPtrs; TaskWeakPtrs tasks_; TaskWeakPtrs::iterator toRemove = std::remove_if(tasks_.begin(), tasks_.end(), !boost::bind(&TaskWeakPtr::lock, _1)); 1>../boost\boost/bind.hpp(1643) : warning C4180: qualifier applied to function type has no meaning; ignored 1> ../boost\boost/bind.hpp(1677) : see reference to class template instantiation 'boost::_bi::add_cref<Pm,I>' being compiled 1> with 1> [ 1> Pm=boost::shared_ptr<Task> (__thiscall boost::weak_ptr<Task>::* )(void), 1> I=1 1> ] 1> .\TaskMaker.cpp(90) : see reference to class template instantiation 'boost::_bi::dm_result<Pm,A1>' being compiled 1> with 1> [ 1> Pm=boost::shared_ptr<Task> (__thiscall boost::weak_ptr<Task>::* )(void), 1> A1=boost::arg<1> 1> ] Thank you!

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[boost.propertymap] queries
by Sean Farrow 17 Feb '09

17 Feb '09

Hi: I have two queries about boost.Property map: 1. I am in the middle of writing a class, and have an array with strings in. I would like to be able to have a series of properties in the class, and have these retrieved from different indexes of the array, so for example Comments [array index 1]. Is this possible with boost.Property Map 2 if the answer is yes to the first question, how would this be achieved? Any help appreciated Cheers Sean.

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Re: [Boost-users] Remove edge
by Gianni Loiacono 16 Feb '09

16 Feb '09

Hi Michael, thanks for the answer. Can you write me an example for to use the remove_edge_if() function? I have read the docs on the site, but there isn't an example :( Thanks a lot Passa a Yahoo! Mail. La webmail che ti offre GRATIS spazio illimitato, antispam e messenger integrato. http://it.mail.yahoo.com/

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[Serialize] Problem creating boost::archive::text_iarchive
by Javier Sanz 16 Feb '09

16 Feb '09

Hello, I'm getting problems creating a boost::archive::text_iarchive with boosts version 1.35.0 and Visual C++ Studio 2005 (Version 8). When I do so I get a std::bad_alloc exception. The code is as follows: void Serialize::deserialize(std::ifstream &modelFile, CoreModel &c) { try { boost::archive::text_iarchive ia(modelFile); // This line throws the exception (I've seen it with the debugger) ia >> c; } catch (std::exception& ex) { // I catch the bad_alloc here } } And this code si called this way: ... for (...) { modelFile.open(model_name.c_str(), std::ios::binary); if (modelFile.is_open() == false) { // ... We deal with the error but it does not get into here } CoreModel model; Serialize::deserialize(modelFile, model); .... } With the debugger I have seen that the exception is thrown into the method text_iarchive_impl<Archive>::load. The method basic_text_iprimitive::load is not setting the size of the string and when the string resize is done the value is huge (is garbage actually) and it throws the std::bad_alloc. Digging into the mailing list I have seen a thread that explains the same problem: http://lists.boost.org/boost-users/2006/03/18032.php But the solution proposed there does not fit me (As far as I can see). /Thanks Francisco Javier Sanz Olviera

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Remove edge
by Gianni Loiacono 16 Feb '09

16 Feb '09

Hi all, I have defined my graph like this: typedef adjacency_list<vecS, vecS, undirectedS,NodoProperty, ArcoProperty> Graph2; And also: graph_traits < Graph2 >::edge_iterator ei, ei_end; Now, I want to delete all edges where the capacity is less than 10. Than I have write this code: for (tie(ei, ei_end) = edges(g); ei != ei_end; ++ei) { if (capacity2[*ei] < 10) { remove_edge(source(*ei,g),target(*ei,g),g); } } But the program after 2 cicles....it crashs :(....Why? Thanks a lot Passa a Yahoo! Mail. La webmail che ti offre GRATIS spazio illimitato, antispam e messenger integrato. http://it.mail.yahoo.com/

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boost::asio handler based on received data
by Abdo Haji-Ali 16 Feb '09

16 Feb '09

Greetings, A server that I'm communicating with sends two types of messages identified by an ID. The first message type is sent automatically on specific events. The second type is sent in response to commands. I want to provide an interface that notifies the user when events occur (asynchronously) and at the same time enable performing commands. My first implementation did this (pseudocode): // In initialization socket.async_receive(buffer, event_handler); // In send_command socket.send(command_buffer); socket.receive_async(response_buffer, user_response_handler); event_handler() { user_event_handler(); socket.async_receive(buffer, event_handler); } The problem here is that 'event_handler' might (or will?) receive the response message. An additional problem is that these messages have no specific order. In other words, the following sequence might occur: - Send command (A) - Send command (B) - Receive event notification - Receive response (A) - Receive response (B) A possible solution might be the following: // In initialization socket.async_receive(buffer, msg_handler); // In send_command socket.send(command_buffer); handlers_queue.enqueue(user_command_handler); socket.receive_async(response_buffer, msg_handler); // Line(3) msg_handler() { if (event) user_event_handler(); else handlers_queue.dequeue() (); // Call first user handler socket.async_receive(buffer, msg_handler); } I want to know if boost::asio provides a better way to solve this problem. I'm particularly interested if writing a custom io service can help me in this situation. Thanks you, -- Abdo Haji-Ali Programmer In|Framez

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[Lambda] Misplaced "const" causes runtime error?
by Paul Baker 16 Feb '09

16 Feb '09

Hi, The following program, as expected, outputs "1 1 1": #include <algorithm> #include <iostream> #include <vector> #include <boost/mem_fn.hpp> #include <boost/bind.hpp> #include <boost/lambda/bind.hpp> int main() { std::vector<std::pair<int, int> > pairs; pairs.push_back(std::make_pair(1, 1)); std::vector<int> result; std::transform(pairs.begin(), pairs.end(), std::back_inserter(result), boost::mem_fn(&std::pair<int, int>::first)); std::transform(pairs.begin(), pairs.end(), std::back_inserter(result), boost::bind(&std::pair<int, int>::first, _1)); std::transform(pairs.begin(), pairs.end(), std::back_inserter(result), boost::lambda::bind(&std::pair<int, int>::first, boost::lambda::_1)); std::cout << result[0] << ' ' << result[1] << ' ' << result[2]; } Changing "std::pair<int, int>" to "std::pair<const int, int>" on the line using boost::mem_fn or the line using boost::bind causes a compile-time error. However, performing the same change on the line using boost::lambda::bind leads to a successful compile - yet at run-time result[2] is set to a seemingly random value. This has been tested on Visual C++ 7.1 SP1, 8.0 SP1 and 9.0 SP1. Is this expected behaviour? I was expecting to see either a compile-time error or run-time success. Thanks

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[boost-users][signals]
by Germán Diago 16 Feb '09

16 Feb '09

Hello. I'm trying to implement a similar system to signals/slots found in qt, with connections at runtime. Now I need to know the argument types for a given signal, like boost::function<>::first_arg_type and so on. Is this possible, and how? thank you very much.

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[asio] read with transfer_at_least(300) return after 256 characters with no error
by tomasz jankowski 16 Feb '09

16 Feb '09

hello, how it is possible that size = boost::asio::read(socket_, boost::asio::buffer(serverReply_,300),boost::asio::transfer_at_least(300)); return with no error after reading 256? thanks, tom ---------------------------------------------------- Inżynierskie Targi Pracy 26.02.2009 http://klik.wp.pl/?adr=http%3A%2F%2Fwww.itp.BEST.krakow.pl&sid=643

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