September 2010 - Boost-users

Serialization of functors and MPL
by Anonymous user 16 Sep '10

16 Sep '10

�Hello everybody,�I'm currently trying to serialize functors.Apparently, it is not possible to serialize boost::function objects,is it possible to find a way to serialize pointer to function ? (in order to make working the example below*)If it is definitively not possible, is there a way to 'register' a relation betwwen objects and functor ? (using MPL library).The idea is to rebuild the boost function according to the 'Object and 'Type' class of the template'.�Example:��mpl::pair<Object,Function> container;serialize(){boost::function<Type ()>�m_getter=mpl::at<�container,Object>;}��*Here is the problem that �I'm trying to resolve:�MyObject�myObject("before");SetCommand<std::string,MyObject> SetCommand(myObject,&MyObject::setName,&MyObject::getName,"after");�SetCommand.do(); � // call functor 'MyObject::setName("after")'SetCommand.undo();�// call functor 'MyObject::setName("before")' template<typename Type,typename Object>class�SetCommand : public Command{ ��public:�� template�<typename�Setter,�typename�Getter>�� SetCommand(Object& o,�const�Setter& setter,�const�Getter& getter,�const�Type& value) :� � � � � ��Command(),� � � � � ��m_getter(boost::bind(getter, &o)),�� m_setter(boost::bind(setter, &o, _1)),� � � � � ��initialValue(m_getter()),� � � � � ��finalValue(value)� � � � {� � � � }�virtual�void�undo()� � � � {� � � � � ��m_setter(initialValue) ;� � � � }�� virtual�void�do()� � � � {� � � � � ��m_setter(finalValue) ;� � � � }�� private: friend�class�boost::serialization::access; SetCommand(){} template�<class�Archive>� void�serialize( Archive & ar,�const�unsigned�int�version ) { ��ar & m_getter;ERROR -> does not compile !!! ��ar & m_setter;ERROR -> does not compile !!! �� ar &�initialValue; �� ar &�finalValue; } boost::function<Type ()>�m_getter�;� � � ��boost::function<void�(Type)>�m_setter�;�� Type�initialValue�;� � � � Type�finalValue�;}; Thanks in advance. -------------------------------------------------------------- Ovi Mail: Making email access easy http://mail.ovi.com

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questions on PBGL
by Raghava Mutharaju 16 Sep '10

16 Sep '10

Hello Boost users, I am looking at Parallel Boost Graph Library (PBGL) to check whether it fits our project needs. I have a few questions on PBGL. 1) How does PBGL know about the size of the cluster -- its IP address, name? 2) What is the performance of it -- are there any other numbers apart from ones in the paper http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.107.5681? Thank you. Regards, Raghava.

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HTTP Parser
by Anand Patel 16 Sep '10

16 Sep '10

All, I am looking into developing an HTTP Proxy with content filtering and other mechanism as a fun project. Is there anything available in BOOST or in other libraries that I can read upon and use them. Specifically, I need to have HTML Parser and some sort of Proxy implementation. Few features that I aiming for are: 1. Intercept request on port 80. 2. Retrieve entire page and parse the page and check with current rules. 3. URL checking with current policy. Thanks, -AP

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Connection refused after close then open.
by Doak, Roger (GE Healthcare) 16 Sep '10

16 Sep '10

I'm trying to limit the connections made to the server. So after creating the acceptor and accepting MAX connections I closed the acceptor. Further connections are properly rejected. However after one of the connections is closed by the client I attempt to re-open the acceptor but further connections are still rejected? Create and open: m_acceptor(m_ioService, m_endpoint = resolve(m_ioService, host, port), true) Async accept: m_acceptor.async_accept(connection->socket(), boost::bind(&IpServer::handleAccept, this, aph::error, connection)); Close after max connections: m_acceptor.close(); Reopen when a connection is available: m_acceptor.open(m_endpoint.protocol()); m_acceptor.set_option(boost::asio::ip::tcp::acceptor::reuse_address(true )); m_acceptor.bind(m_endpoint); m_acceptor.listen(); Thanks for your time. Roger

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[DateTime] local_adjustor for run-time
by Igor R 16 Sep '10

16 Sep '10

Hello, I'm writing a client application that receives from a server UTC timestamps and the server local time-zone. I have to display this time in my client app in terms of the server time-zone (i.e. the server local time should be displayed, not the client one). For this purpose I intended to use local_adjustor, but I see it wants compile-time time-zone value. Is there a similar facility that allows run-time parameters? Thanks.

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[Proto] Default-constructing a proto::terminal
by Roland Bock 16 Sep '10

16 Sep '10

Hi, I have a class which has boost::proto::terminal members like this: struct _table { struct id { id(); // default constructible /*...*/ }; boost::proto::terminal<id> id_terminal; }; _table table; Will table.id_terminal be constructed correctly? I am asking because in Proto's documentation terminals are always instantiated with curly braces, e.g.: typedef proto::terminal<int>::type int_; int_ i = {42}, j = {24}; template<int I> struct placeholder {}; proto::terminal<placeholder<0> >::type const _1 = {{}}; proto::terminal<placeholder<1> >::type const _2 = {{}}; Thanks and regards, Roland

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OpenMP and Boost - can they be used together?
by Max S. Kaznady 16 Sep '10

16 Sep '10

Hello, I wrote a simple parallel program which computes the sum of elements across a matrix using Boost. When I use OpenMP, the program runs give different sums. When I use just simple arrays like double array[N][N], instead of boost::numeric::ublas::matrix<double>, the code work just fine and as expected. Does anyone know what is going on? It looks like the score function is not being modified properly, because Boost array returns just fine. The function compute_score() creates a matrix and computes the sum of its elements in parallel, copying the result to matrix temp and then printing temp, to make sure that the results can be copied in parallel too. The function is run infinitely many times, and if its return values differ then the program exits. [code] #include <iostream> #include <omp.h> #include <boost/numeric/ublas/io.hpp> #include <boost/numeric/ublas/matrix.hpp> #define ENABLE_OPENMP_SCORE 1 #define N 10 #define NUMTHREADS 2 using std::cout; using std::endl; using boost::numeric::ublas::matrix; double compute_score() { matrix<double> data1(N, N); for (unsigned i = 0; i < N; ++i) for (unsigned j = 0; j < N; ++j) data1(i, j) = i * N + j; double sc = 0.0; unsigned i, j; matrix<double> temp(N, N); #pragma omp parallel \ shared(sc,temp) \ private(i,j) \ if (ENABLE_OPENMP_SCORE) { omp_set_num_threads(NUMTHREADS); #pragma omp master sc = 0.0; #pragma omp for reduction(+:sc) schedule(static) collapse(2) nowait for (i = 0; i < N; ++i) { for (j = 0; j < N; ++j) { temp(i, j) = data1(i, j); sc += data1(i, j); } } } cout << temp << endl; return sc; } int main(void) { double oldval = compute_score(), newval; cout.precision(32); cout << "--" << endl; while (1) { newval = compute_score(); cout << "--" << endl; if (newval != oldval) { cout << " newval - oldval = diff, " << newval << " - " << oldval << " = " << newval - oldval << endl; exit(1); } oldval = newval; } return 0; } [/code] This problem is driving me insane... the code is really simple, but for some reason after using Boost it does not function as expected. Cheers, Max

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[Serialization] Encrypting an xml archive
by Sean Farrow 16 Sep '10

16 Sep '10

Hi: Has anyone had the need to encrypt an xml or binary archive? If so what is the best way of going about it? Do I need to create a totally new archive class, or can I just derive from another one of boosts archive classes, if yes which methods should be overridden? Thanks for any pointers Regards Sean.

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Editable XML Serialization
by Anne van Rossum 16 Sep '10

16 Sep '10

Dear list members, I guess it's one of the hardest search terms around but I would like to know if there is any editable XML serialization provided by Boost or other C++ libraries. And I don't mean the kind of thing that requires you to go jumping around through trees, with iterators etc. I don't want to see any iterator! I really iike the XML serialization method that boost::serialization provides: //! Give boost serialization libraries access to private fields friend class boost::serialization::access; //! Tell which private fields to serialize template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & boost::serialization::make_nvp("Phase", phase); ar & boost::serialization::make_nvp("Period", period); ar & boost::serialization::make_nvp("DutyCycle", dutycycle); } Just adding this to a file, and then: xml_out << boost::serialization::make_nvp("ApplicationConfig", config); Or: xml_in >> boost::serialization::make_nvp("ApplicationConfig", config); It's awesome! I don't need to care about descending trees, etc. However, the default serialization class does not allow for different orders of the XML tags, etc. It doesn't use the "ApplicationConfig" string, but just assumes that XML tag should be there if this read operation. If you change anything in the XML file, it is likely you will get a segfault, and you won't know what is causing the problem exactly. It would be so great if there is something like this in which the XML files can actually be edited! I am almost sure that there should be something like that, but I can't find it. Thanks in advance, Anne

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ASIO Win32 Thread not terminated
by Manuel Drews 16 Sep '10

16 Sep '10

Hi all, I have a question regarding boost::asio: if I run the example boost_asio/example/http/client/async_client.cpp on a Windows 7 or Vista and set a breakpoint on the very last line (return 0;), VisualStudio tells me that (apart from the Main Thread) two Threads named Win32 Thread are still running. Since the whole ASIO code is within the try block, everything connected to the sockets should be terminated when leaving the block, right? I get this behaviour also in a custom project, where I explicitly call close on the socket. My concern is, that a project which uses a lot of socket connections will end up with a dozen or more lingering threads. How can I avoid that? Thanx in advance Manuel -- GMX DSL SOMMER-SPECIAL: Surf & Phone Flat 16.000 für nur 19,99 Euro/mtl.!* http://portal.gmx.net/de/go/dsl

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