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boost fusion and/or boost parameter: open ended question about constructing object from a string
by e r 10 Sep '08

10 Sep '08

hi, here's what i'd like to do A] hpp: struct my{ template<typename ArgPack> my(const ArgPack& args):n_(args[tag::n]),k_(args[tag::k]){} } struct argpack{ arglist<???> operator()(const string& str){???} } cpp: string str("n=2; k=1"); my(argpack(str)); In words,I'm looking to construct an ArgPack from a string, what's the appropriate library for this? Does it seem like I should invest in Boost Spirit? B] The above is a simplified version of what i really need, which is, potentially, 1) having to construct a large number of objects (to be pushed at the back of a container) 2) each object taking a large number arguments (not just n and k as above) 3) each object an instance of one of a set of classes (my0,my1,my2,...,myN) each with its specific argument tags (keywords). So I'd like to put all these arguments in a file, each line corresponding to an object, rather than have a messy cpp file. this is all very open-ended, but so reads the subject title... thanks!

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fusion/adapted/mpl.hpp
by e r 10 Sep '08

10 Sep '08

Hi, I would need this: // a) typedef fusion::vector<...> input0_type; typedef mpl::transform( input0_type, F0 )::type result0_type; //b) typedef fusion::vector<...> resul1_type; result1_type result1 = fusion::transform( result0_type(), f1 ); Of course a) is not allowed, but I guess I can do: // a) typedef mpl::vector<...> mpl_input0_type; //same elements as input0_type typedef mpl::transform( mpl_input0_type, F0 )::type mpl_result0_type; //b) #include <boost/fusion/adapted/mpl.hpp> #include <boost/fusion/include/mpl.hpp> typedef fusion::vector<...> resul1_type; result1_type result1 = fusion::transform( mpl_result0_type(),//? f1 ); in my case, result1_type = input0_type. So I have to define input0_type and mpl_input0_type separately although they convey the same information. i'd like to get rid of this redundancy. I wished there existed a metafun fusion_to_mpl such that MPL_ASSERT((is_same<fusion_to_mpl<input0_type>::type,mpl_input0_type>)) so that the 1st version of a) could be replaced by typedef mpl::transform( fusion_to_mpl<input0_type>::type, F0 )::type mpl_result0_type; and keep the second version of b) any help appreciated. thanks!

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Re: [Boost-users] [bind] [multi-index] Create type of pointer to overloaded erase method
by JOAQUIN M. LOPEZ MUÑOZ 10 Sep '08

10 Sep '08

________________________________________ De: boost-users-bounces(a)lists.boost.org [boost-users-bounces(a)lists.boost.org] En nombre de Steven Watanabe [watanabesj(a)gmail.com] Enviado el: miércoles, 10 de septiembre de 2008 18:54 Para: boost-users(a)lists.boost.org Asunto: Re: [Boost-users] [bind] [multi-index] Create type of pointer to overloaded erase method > AMDG > > Peter Barker wrote: > > RecordsContainer::size_type (RecordsContainer::*erase)(unsigned int) = > > &RecordsContainer::erase; > > > > but it failed to compile. Visual Studio 2003 gives me the following > > error on the above line: > > <snip> > > > > The following compiles for me with msvc 9.0 > > int main() { > RecordsContainer::size_type (RecordsContainer::*erase)(unsigned int) = > &RecordsContainer::erase; > } Oddly enough, it fails with MSVC++ 8.0 (though it shouldn't since your call_traits analysis is correct): error C2440: 'initializing' : cannot convert from 'overloaded-function' to 'boost::multi_index::detail::ordered_index<KeyFromValue,Compare,SuperMeta, TagList,Category>::size_type (__thiscall boost::multi_index::multi_index_container<Value,IndexSpecifierList>::* )(unsigned int)' [...] The following is bulletproof and has the added benefit of its immunity against future slight changes in the interfaces (like, for instance, erase(key) getting templatized): template<typename Container,typename Key> typename Container::size_type container_erase(Container& c,const Key& k) { return c.erase(k); } int main() { RecordsContainer::size_type (*erase)(RecordsContainer&,const unsigned int&) = &container_erase; } Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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[serialization] How to deal with bit fields?
by Sebastian Knopp 10 Sep '08

10 Sep '08

Hello, I am a new user of the serialization library and find it is a very comfortable solution. But I met a problem concerning the serialization of bit fields. For example, look at the following: struct A { int a : 1; int b : 7; }; Serialization using the following code does not work, because bitfields can not be passed by reference. template<class Archive> void serialize(Archive& ar, A& theA, const unsigned int version) { ar & make_nvp("a", theA.a); ar & make_nvp("b", theA.b); } So, I use this workaround: template<class Archive> void serialize(Archive& ar, A& theA.a, const unsigned int version) { bool myA; int myB; if (!Archive::is_loading::value) { myA = (theA.a == 1); myB = theA.b; } ar & make_nvp("a", myA); ar & make_nvp("b", myB); if (Archive::is_loading::value) { theA.a = myA ? 1 : 0; theA.b = myB; } } Do you have any suggestions how a more elegant solution could look like? Thanks and bye, Sebastian Knopp

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[dataflow] Filter with multiple slots
by Manuel Jung 10 Sep '08

10 Sep '08

Hey, I want to define my own filter, which can take different signatures. It should take a Url (e.g. std::string, for me an unicode type) and use a difault timeout or it should take both. There is an tutorial for multiple slots, when using a consumer, but i need a filter and i am wondering how i should define the signature of the filter then? (overlaoding of the operator() method needs to be done of course. Kind Regards Manuel

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static linkage of filesystem lib under linux
by Ottmar Buennemeyer 10 Sep '08

10 Sep '08

Hello, We have problems with using the static filesystem lib under linux. We use filesystem as static library in a shard library. Example: libfilesystem.a used for shared library libTestBoostStatic.so No errors during build of library libTestBoostStatic.so. Afterwards we use libtest.so in the application UseTestBoostStatic. During the linking of the application we get the following error message: Invoking: GCC C++ Linker g++ -L/home/ROSENINSPECTION/AlKeller/src/SDES/Test/TestBoostStatic/Debug -L/usr/lib64 -Wl,-static -lboost_filesystem-mt -lboost_regex-mt -Wl,-call_shared -o"UseTestBoostStatic" ./UseTestBoostStatic.o -lTestBoostStatic /home/ROSENINSPECTION/AlKeller/src/SDES/Test/TestBoostStatic/Debug/libTestBoostStatic.so: undefined reference to `boost::filesystem::detail::dir_itr_increment(void*&, void*&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, boost::filesystem::file_status&, boost::filesystem::file_status&)' /home/ROSENINSPECTION/AlKeller/src/SDES/Test/TestBoostStatic/Debug/libTestBoostStatic.so: undefined reference to `boost::filesystem::detail::dir_itr_close(void*&, void*&)' /home/ROSENINSPECTION/AlKeller/src/SDES/Test/TestBoostStatic/Debug/libTestBoostStatic.so: undefined reference to `boost::filesystem::detail::dir_itr_first(void*&, void*&, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, boost::filesystem::file_status&, boost::filesystem::file_status&)' /home/ROSENINSPECTION/AlKeller/src/SDES/Test/TestBoostStatic/Debug/libTestBoostStatic.so: undefined reference to `boost::filesystem::detail::not_found_error' collect2: ld returned 1 exit status make: *** [UseTestBoostStatic] Error 1 We use the boost version 1.34.1 GCC Version: 4.1.2 20061115 (pre release) What's wrong with our configuration? Thanks in advance, Ottmar

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[Boost_users][date_time] Updating ptime after it's been constructed
by Ryan McConnehey 10 Sep '08

10 Sep '08

Hi, Currently I'm creating a boost date_time object as follows: boost::shared_ptr<boost::posix_time::ptime> time(new boost::posix_time::ptime(boost::posix_time::microsec_clock::local_time())); Now that the ptime object has been created how do I update the boost pointer with a new local_time? There doesn't seem to be any function calls or operators that allow the setting of time. The only operators seem to allow you to offset the time not replace it. Ryan

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Re: [Boost-users] Comparing two vectors element by element
by Gevorg Voskanyan 10 Sep '08

10 Sep '08

Sean Farrow wrote: > It's not allower, the sizes aren't identical. > Sean. Then I think you can perfectly use the function below: bool bitset_vector_less( const std::vector< std::bitset< 6 > > & lhs, const std::vector< std::bitset< 6 > > & rhs ) { assert( lhs.size() == rhs.size() ); return std::equal( lhs.begin(), lhs.end(), rhs.begin(), BitSetComp() ); } where BitSetComp is the predicate you have shown earlier. HTH, Gevorg

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Periodic Timer
by amit khandelwal 10 Sep '08

10 Sep '08

I see that we have a deadline timer in boost. I am looking for a periodic timer. I see that there is a sample code in boost website to simulate a periodic timer. Over a period of time I think it will probably cause some slippage. I am looking at microsecond granularity Can someone please advise? #include <iostream> #include <boost/asio.hpp> #include <boost/thread.hpp> #include <boost/bind.hpp> #include <boost/date_time/posix_time/posix_time.hpp> class printer { public: printer(boost::asio::io_service& io) : timer1_(io, boost::posix_time::microseconds(10)), count_(0) { timer1_.async_wait(boost::bind(&printer::print1, this)); } ~printer() { std::cout << "Final count is " << count_ << "\n"; } void print1() { if (count_ < 100) { timer1_.expires_at(timer1_.expires_at() + boost::posix_time::microseconds(10)); timer1_.async_wait(boost::bind(&printer::print1, this)); std::cout << "Timer 1: " << count_ << "\n"; ++count_; } } private: boost::asio::deadline_timer timer1_; int count_; }; int main() { boost::asio::io_service io; printer p(io); boost::thread t(boost::bind(&boost::asio::io_service::run, &io)); io.run(); t.join(); return 0; } -- ------------------------------------------------------------------- Ph : (732) 647 5679 Email: khandelwal.amit(a)gmail.com Web: http://khandelwal.amit.googlepages.com/home -------------------------------------------------------------------

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[graph] Overkill to use graph library for 'small' graphs?
by Rainer Thaden 10 Sep '08

10 Sep '08

Hi all, I have to manage connections between different items in an audio control software. Currently, I am using several maps to manage "connections". I was thinking of using a graph for this but there are several questions arising. Maybe, someone can enlighten this: I am controlling a hardware which has several inputs and outputs and between it a layer of nodes. The inputs are connected to the nodes as well as the outputs. An input can be connected to several nodes, an output only to one node. So, the graph has to represent connections between inputs, nodes, and outputs. (Actually, there are more layers, but to keep it simple I show only these 3). The inputs, outputs, etc. in the end are integers, which are sent to the device. I represent them as enums. So I have, e.g. enum Inputs{ Input1 = 0, Input2, InputNone }; enum Nodes{ NodeM=0, NodeN, NodeNone }; enum Outputs{ AnalogOut1 = 0, AnalogOut2 OutputNone }; Now, to use graphs, I have to define vertices. These have to be of "one" type, as far as I understand that. How do I use the enums as shown above? A vertice-value may be in enum Inputs or Nodes or Outputs. Do I have to use a graph with elements of type ints and cast them to my enums? From the introduction to BGL, modified: const int num_vertices = InputNone + NodeNone + OutputNone; // writing out the edges in the graph typedef std::pair<int, int> Edge; Edge edge_array[] = { Edge(Input1,NodeM), Edge(Input2,NodeN), Edge(AnalogOut1,NodeM), Edge(AnalogOut2,NodeN)}; const int num_edges = sizeof(edge_array)/sizeof(edge_array[0]); // declare a graph object Graph g(num_vertices); // add the edges to the graph object for (int i = 0; i < num_edges; ++i) add_edge(edge_array[i].first, edge_array[i].second, g); When I e.g. need all vertices, connected to NodeM, I get two ints. One of them represents a member of enum Inputs, the other one a member of enum Outputs. Their numbers overlap, so I can not tell which is an Input and which is an Output (the hardware device needs the numbers starting from 0). Any idea how do solve this? Secondly, is there a big advantage of using a graph? There are about 25 different inputs, 8 nodes and 10 outputs and 2-3 additional layers. It may be more elegant to use one graph instead of several maps. I can not estimate the effort and performance of the graph. Would it be overkill in both, performance and time to implement to use a graph for that? Thanks in advance and regards, Rainer

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