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[signals2] analysing the signature
by Igor R 08 Feb '10

08 Feb '10

Hello, typedef signal<void (MyObject)> signal_type; Is there a way to get the type of the 1st argument, i.e. something that would return MyObject as a type. Thanks.

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Serialization of a unordered_map
by Basti Korf 08 Feb '10

08 Feb '10

Hallo, I just wondered, why there is no possibility to serialize a unordered map. Since the STL map is serialized, i take the file for it and changed all maps to boost::unordered_map (multimap). Or is there a better way, i just did not see? Here is the code: #ifndef BOOST_SERIALIZATION_UNORDEREDMAP_HPP #define BOOST_SERIALIZATION_UNORDEREDMAP_HPP // MS compatible compilers support #pragma once #if defined(_MSC_VER) && (_MSC_VER >= 1020) # pragma once #endif /////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8 // serialization/map.hpp: // serialization for stl map templates // (C) Copyright 2002 Robert Ramey - http://www.rrsd.com . // Use, modification and distribution is subject to the Boost Software // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) // See http://www.boost.org for updates, documentation, and revision history. #include <boost/unordered_map.hpp> #include <boost/config.hpp> #include <boost/serialization/utility.hpp> #include <boost/serialization/collections_save_imp.hpp> #include <boost/serialization/collections_load_imp.hpp> #include <boost/serialization/split_free.hpp> namespace boost { namespace serialization { template<class Archive, class Type, class Key, class Compare, class Allocator > inline void save( Archive & ar, const boost::unordered_map<Key, Type, Compare, Allocator> &t, const unsigned int /* file_version */ ){ boost::serialization::stl::save_collection< Archive, boost::unordered_map<Key, Type, Compare, Allocator> >(ar, t); } template<class Archive, class Type, class Key, class Compare, class Allocator > inline void load( Archive & ar, boost::unordered_map<Key, Type, Compare, Allocator> &t, const unsigned int /* file_version */ ){ boost::serialization::stl::load_collection< Archive, boost::unordered_map<Key, Type, Compare, Allocator>, boost::serialization::stl::archive_input_map< Archive, boost::unordered_map<Key, Type, Compare, Allocator> >, boost::serialization::stl::no_reserve_imp<boost::unordered_map< Key, Type, Compare, Allocator > > >(ar, t); } // split non-intrusive serialization function member into separate // non intrusive save/load member functions template<class Archive, class Type, class Key, class Compare, class Allocator > inline void serialize( Archive & ar, boost::unordered_map<Key, Type, Compare, Allocator> &t, const unsigned int file_version ){ boost::serialization::split_free(ar, t, file_version); } // multimap template<class Archive, class Type, class Key, class Compare, class Allocator > inline void save( Archive & ar, const boost::unordered_multimap<Key, Type, Compare, Allocator> &t, const unsigned int /* file_version */ ){ boost::serialization::stl::save_collection< Archive, boost::unordered_multimap<Key, Type, Compare, Allocator> >(ar, t); } template<class Archive, class Type, class Key, class Compare, class Allocator > inline void load( Archive & ar, boost::unordered_multimap<Key, Type, Compare, Allocator> &t, const unsigned int /* file_version */ ){ boost::serialization::stl::load_collection< Archive, boost::unordered_multimap<Key, Type, Compare, Allocator>, boost::serialization::stl::archive_input_multimap< Archive, boost::unordered_multimap<Key, Type, Compare, Allocator> >, boost::serialization::stl::no_reserve_imp< boost::unordered_multimap<Key, Type, Compare, Allocator> > >(ar, t); } // split non-intrusive serialization function member into separate // non intrusive save/load member functions template<class Archive, class Type, class Key, class Compare, class Allocator > inline void serialize( Archive & ar, boost::unordered_multimap<Key, Type, Compare, Allocator> &t, const unsigned int file_version ){ boost::serialization::split_free(ar, t, file_version); } } // serialization } // namespace boost #endif // BOOST_SERIALIZATION_UNORDEREDMAP_HPP Best regards, SK -- GRATIS für alle GMX-Mitglieder: Die maxdome Movie-FLAT! Jetzt freischalten unter http://portal.gmx.net/de/go/maxdome01

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Compilation/syntax error Boost.Lambda
by Joost Kraaijeveld 07 Feb '10

07 Feb '10

Hi, The code below does not compile and gives me 2 errors that, whatever I try, do not want to disappear. What am I doing wrong? TIA The errors: g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"Main.d" -MT"Main.d" -o"Main.o" "../Main.cpp" ../Main.cpp: In function ‘std::map<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > > getObjects(const Predicate&)’: ../Main.cpp:34: error: no matching function for call to ‘bind(<unresolved overloaded function type>, std::map<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >*&, std::pair<boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::action<2, boost::lambda::function_action<2, boost::lambda::detail::unspecified> >, boost::tuples::tuple<const std::basic_string<char, std::char_traits<char>, std::allocator<char> > std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >::* const, const boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> > >, boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::action<2, boost::lambda::function_action<2, boost::lambda::detail::unspecified> >, boost::tuples::tuple<std::basic_string<char, std::char_traits<char>, std::allocator<char> > std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >::* const, const boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> > > >&)’ ../Main.cpp: In function ‘int main(int, char**)’: ../Main.cpp:46: error: no match for ‘operator<<’ in ‘boost::lambda::operator<<(A&, const boost::lambda::lambda_functor<Arg>&) [with A = std::ostream, Arg = boost::lambda::lambda_functor_base<boost::lambda::action<2, boost::lambda::function_action<2, boost::lambda::detail::unspecified> >, boost::tuples::tuple<const std::basic_string<char, std::char_traits<char>, std::allocator<char> > std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >::* const, const boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> >](((const boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::action<2, boost::lambda::function_action<2, boost::lambda::detail::unspecified> >, boost::tuples::tuple<const std::basic_string<char, std::char_traits<char>, std::allocator<char> > std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >::* const, const boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> > >&)(& boost::lambda::bind(const Arg1&, const Arg2&) [with Arg1 = const std::basic_string<char, std::char_traits<char>, std::allocator<char> > std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >::*, Arg2 = boost::lambda::lambda_functor<boost::lambda::placeholder<1> >](((const boost::lambda::lambda_functor<boost::lambda::placeholder<1> >&)((const boost::lambda::placeholder1_type*)boost::lambda::<unnamed>::_1)))))) << std::endl’ ../Main.cpp: In function ‘std::map<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > > getObjects(const Predicate&) [with Predicate = boost::function<bool(std::string)>]’: ../Main.cpp:45: instantiated from here ../Main.cpp:28: error: no matching function for call to ‘bind(<unresolved overloaded function type>, std::map<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >*, std::pair<boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::action<2, boost::lambda::function_action<2, boost::lambda::detail::unspecified> >, boost::tuples::tuple<const std::basic_string<char, std::char_traits<char>, std::allocator<char> > std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >::* const, const boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> > >, boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::action<2, boost::lambda::function_action<2, boost::lambda::detail::unspecified> >, boost::tuples::tuple<std::basic_string<char, std::char_traits<char>, std::allocator<char> > std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >::* const, const boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> > > >)’ make: *** [Main.o] Error 1 The code: #include <iostream> #include <map> #include <boost/lambda/lambda.hpp> #include <boost/lambda/algorithm.hpp> #include <boost/lambda/bind.hpp> #include <boost/lambda/if.hpp> #include <boost/function.hpp> using namespace std; using namespace boost; using namespace boost::lambda; map<string, string> objects; template< typename Predicate > map<string, string> getObjects( const Predicate& aPredicate) { map<string, string> matchedObjects; for_each( objects.begin(), objects.end(), if_then( bind(aPredicate, boost::lambda::_1) , bind(&map<string, string>::insert, &matchedObjects , make_pair(bind(&map<string, string>::value_type::first, _1),bind(&map<string, string>::value_type::second,_1))))); return matchedObjects; } int main( int argc, char* argv[]) { objects.insert(make_pair("one","value")); objects.insert(make_pair("two","value")); objects.insert(make_pair("three","value")); function< bool (string)> predicate = _1 == "value"; map<string, string> matchedObjects = getObjects(predicate); for_each(matchedObjects.begin(),matchedObjects.end(),cout << bind(&map<string, string>::value_type::first, _1) << endl); } -- Groeten, Joost Kraaijeveld Askesis B.V. Molukkenstraat 14 6524NB Nijmegen tel: 024-3888063 / 06-51855277 fax: 024-3608416 web: www.askesis.nl

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[proto] Handling String Terminals
by David A. Greene 07 Feb '10

07 Feb '10

If I have a grammar like this: typedef boost::proto::literal<std::string>::type StringTerminal; typedef or_< StringTerminal, ... > Rule; and I do this: checkMatch<Rule>(boost::proto::lit(std::string("str"))); checkMatch<Rule>(std::string("str")); checkMatch<Rule>("str"); where checkMatch is a wrapper around matches<>, the first line is the only one that passes. This is presumably because the string needs to be "protoized" and to match StringTerminal it has to be cast to std::string explicitly. This is rather ugly for constructs like this: term["str"] => term[lit(string("str"))] I would really rather not have to do the lit(string()) thing. Is there a good strategy to avoid this clutter? I could predefine literals like this: StringTerminal strlit = {{"str"}}. term[strlit] but that's a bit burdensome on the user. Would the same massaging be needed for, say, term + "strlit" Perhaps I can reformulate the grammar to avoid the cluttter by using constructs that promote constants to proper proto terminals. Any advice? Thanks! -Dave

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Asio - Joining Sync to Async
by John D 07 Feb '10

07 Feb '10

Hello I am writing to ask if it is possible to do the following. I have a persistently connected async socket held lively with keep alives. I would like to take in a new synchronous connection and make the async socket the end point for form a relay. Wondering is this even possible and if so how would be a good approach to it. Thank you, John

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BoostCon 2010 tentative, fully scheduled program available
by Hartmut Kaiser 06 Feb '10

06 Feb '10

Hey all, The first tentative, fully scheduled program for BoostCon 2010 is now available at http://www.boostcon.com/program. We're quite fond of this program and we believe it contains something for almost everybody. We hope to convince you to join us at BoostCon 2010, May 10-14th, in the beautiful Aspen. For registration, accommodation, and more information please visit the conference website at http://www.boostcon.com. Please note the reduced early registration fee! Regards Hartmut Program Chair BoostCon 2010 --------------- Meet me at BoostCon www.boostcon.com

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PP: BOOST_PP_CAT concatenate an argument with a whitespace
by Hicham Mouline 06 Feb '10

06 Feb '10

Hi, BOOST_PP_CAT( MACRO1, MACRO2 ); MACRO1 expands to double MACRO2 expands to x BOOST_PP_CAT( MACRO1, MACRO2 ); therefore expands to doublex; I am trying to get the statement double x; I couldn't find any macro that expands to whitespace? I am missing something obvious here Regards,

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Standard error handler in gil jpeg_io extension calls exit()
by Peter Goetz 06 Feb '10

06 Feb '10

Hi, I'm using the gil jpeg_io extension like this: gil::rgb8_image_t img; gil::jpeg_read_image("test.jpg",img); As it turned out, if "test.jpg" is not a jpeg the program will quit with the message: "Not a JPEG file: starts with 0x6b 0x6a" although I put a try-catch-block around it. Digging a bit deeper, I found, that this is because in boost/gil/extension/io/jpeg_io_private.hpp the jpeg_reader::init() function uses the standard error handler: _cinfo.err=jpeg_std_error(&_jerr); which calls the exit() function. I'd prefer to have an exception and handle the exception in my main program rather than in the library. Is there a way to do that? To me it seems there's no other way than modifying the jpeg_io_extension. Or am I missing something? Any help is very appreciated! Peter

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[proto] transform for a templated proto::terminal type
by Manjunath Kudlur 06 Feb '10

06 Feb '10

Hello, I have some proto::terminal's as follows : template<typename T> struct Var { unsigned int id; }; typedef proto::terminal<Var<int> >::type int32_; typedef proto::terminal<Var<float> >::type float_; typedef proto::terminal<Var<double> >::type double_; I can write a callable transform, with templated operator() functions to handle each Var<> type as follows : struct _var_tostr : proto::callable { typedef std::string result_type; template<typename T> result_type operator()(variables::Var<T> const &v) const { std::stringstream sout; sout << "S" << v.id; return sout.str(); } template<typename T> result_type operator()(variables::VecVar<T> const &v) const { std::stringstream sout; sout << "V" << v.id; return sout.str(); } }; To activate the transform, I end up writing one rule for each Var<> type as follows : struct var_tostr : proto::or_< proto::when<proto::terminal<variables::Var<int> >, _var_tostr(proto::_value)> ,proto::when<proto::terminal<variables::Var<float> >, _var_tostr(proto::_value)> ,proto::when<proto::terminal<variables::Var<double> >, _var_tostr(proto::_value)> > { }; This gets cumbersome when I have more Var<> types. Is there a way to not list each Var<> type in the grammar? That is, I want to match any Var<T> and just call the _var_tostr(proto::_value) transform. How can I accomplish this? Thanks, Manjunath

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[Serialization] Speedding up client-server communication
by Ruediger Berlich 06 Feb '10

06 Feb '10

Hi there, I am in the process of speeding up communication between a server and its clients. Communication involves serialized class data. Messages can be as large as 100 kilobytes. I have done some measurements which have shown that, in a cluster with Gigabit networking, most overhead of the parallelisation seems to come from the Broker infrastructure and the process of (de-)serialization. Network latency and/or bandwidth seems to play only a minor role in this environment. Hence, apart from optimizing my broker, I'm looking for ways to optimize the serialization process, as used in my application. As messages are discarded as soon as they reach the recipient, versions of serialized data do not play an important role. Apart from decreasing the frequency and size of data exchanges and using binary transfers in a homogeneous environment, another way of speeding up the application seems to be the "Class Information" section discussed e.g. in http://www.boost.org/doc/libs/1_41_0/libs/serialization/doc/special.html . Also, BOOST_IS_BITWISE_SERIALIZABLE(my_class) might help. One question I have about this is whether a std::vector<POD> would be accessible to this optimization ? I use quite a few of them. Do you have further suggestions for ways of influencing the Boost.Serialization library ? Thanks and Best Regards, Ruediger

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