September 2010 - Boost-users

asio multicast receiver takes all traffic addressed to the same port (example/multicast/receiver.cpp)
by Yuri T. 09 Sep '10

09 Sep '10

Hi, In my network there are multiple multicast streams with different addresses, but with the same port. I tried to run an example from the asio library (example/multicast/receiver.cpp). In Windows it works fine but in linux if you run multiple copies of the application they receive all packets arriving on the specified port and ignore the broadcast address. How to filter packets by multicast address? (senderEndpoint contain real IP, not multicast)

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issues when linking a library that uses boost classes
by Sean Farrow 08 Sep '10

08 Sep '10

Hi: I've recently written a library that uses boost classes internally. The library (the release version) uses the visual studio multi-threaded static library. When I try to use the class in another program that uses boost classes it appears the relevant parts of the library don't get linked in. After specifying the lib on the linker tab (i.e the one that I've built) the build goes fine, but I get an excdeption when the app is run. Any ideas? I can replicate this with two projects, visual studio 2008, boost 1.44 release. If anybody wants to take a look at the solution, I'm happy to send off-list. Cheers Sean.

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Re: [Boost-users] fusion::vector with 1 element, fusion::transform, boost::variant and boost::optional
by Hicham Mouline 08 Sep '10

08 Sep '10

> -----Original Message----- > From: Hicham Mouline [mailto:hicham@mouline.org] > Sent: 09 September 2010 04:49 > To: 'boost-users(a)lists.boost.org' > Subject: fusion::vector with 1 element, fusion::transform, > boost::variant and boost::optional > > Hello, > I have this error w msvc2008: I attach here a compilable cpp file. same error with g++4.4 regards,

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Incorrect handling of synthesized attributes in Spirit.
by Preeti Khurana 08 Sep '10

08 Sep '10

I am trying to parse the lines :: 10.1.1.1/32 10.10.1.1 29/nolabel 10.7.7.7/32 150.2.2.2 nolabel/30 Which are space separated and putting them in a vector of strings :: sp %= lit(' '); ip_address %= +char_("0-9") >> char_('.') >> +char_("0-9") >> char_('.') >> +char_("0-9") >> char_('.') >> +char_("0-9") >> *char_("/") >> *char_("0-9"); data %= *sp >> ( xr_special | ip_address | +lit("/") | +char_("0-9A-Za-z()")); start %= +(data ) >> *sp >> eoi; qi::rule<Iterator, void()> sp; qi::rule<Iterator, std::string()> ip_address; qi::rule<Iterator, std::string()> data; qi::rule<Iterator, test::Parsed_Rec()> start; (Parsed Rec carries a vector of strings ) Grammar is able to parse the lines but while parsing 29 in first line & 30 in last line, the attributes are incorrectly filled. The attributes are filled twice ( Debug File for this is debug_file_incorrect). Snippet :: <data> <try> 29/nolabel</try> <xr_special> <try>29/nolabel</try> <fail/> </xr_special> <ip_address> <try>29/nolabel</try> <fail/> </ip_address> <success>/nolabel</success> <attributes>[[2, 9, 2, 9]]</attributes> </data> While if I change my grammar to explicitly fill the attributes, they are filled correctly. File attached : debug_file_correct data = *sp >> ( xr_special | ip_address[_val= _1] | +lit("/") | +char_("0-9A-Za-z()")[_val+= _1] ); <data> <try> 29/nolabel</try> <xr_special> <try>29/nolabel</try> <fail/> </xr_special> <ip_address> <try>29/nolabel</try> <fail/> </ip_address> <success>/nolabel</success> <attributes>[[2, 9]]</attributes> </data> Thanks Preeti

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fusion::vector with 1 element, fusion::transform, boost::variant and boost::optional
by Hicham Mouline 08 Sep '10

08 Sep '10

Hello, I have this error w msvc2008: error C2664: 'nicohich::systems::make_parameters_for_simulate<parameters_t>::type::type(c onst boost::fusion::vector1<T0> &)' : cannot convert parameter 1 from 'const parameters_1_n_seq_t' to 'const boost::fusion::vector1<T0> &' 1> with 1> [ 1> parameters_t=my_ns::systems::ns1::parameters, 1> T0=boost::variant<std::vector<double>, my_ns::range_incr<double>, my_ns::range<double>,double> 1> ] 1> and 1> [ 1> T0=boost::variant<std::vector<double>, my_ns::range_incr<double>, my_ns::range<double>,double> 1> ] 1> Reason: cannot convert from 'const parameters_1_n_seq_t' to 'const boost::fusion::vector1<T0>' 1> with 1> [ 1> T0=boost::variant<std::vector<double>, my_ns::range_incr<double>, my_ns::range<double>,double> 1> ] 1> No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called where parameters_1_n_seq_t which is a result of a metafunction invocation is: (as determined at runtime by typeid(parameters_1_n_seq_t).name(), I manually edited out the namespaces and trailing boost templates args ): fusion::transform_view< fusion::vector1< optional< variant< std::vector<double>, my_ns::range_incr<double>, my_ns::range<double>, double > > >, deoptionalize_item, void_ > where struct deoptionalize_item { typedef deoptionalize_item Self; template<typename Sign> struct result; // primary template template<typename T> // template spec struct result<Self( const boost::optional<T>& )> { typedef const T& type; }; template <typename T> const T& operator()( const boost::optional<T>& rhs ) const { return *rhs; } }; my_ns::systems::ns1::parameters is defined as: namespace systems { struct base_parameters { double x; }; namespace ns1 { struct parameters : public base_parameters { // double y }; } } // at global namespace BOOST_FUSION_ADAPT_STRUCT( my_ns::systems::ns1::parameters, (double, x) // (double, y) ) Previously, parameters held the field y, and this error didn't happen. Regards,

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trick to print a type at compile-time
by Hicham Mouline 08 Sep '10

08 Sep '10

Hello, Is there a way to print the type returned by a metafunction typedef some_metafunction<T>::type result_type; during compile-time (probably via triggering a compilation error). I almost recall some sort of static assertion (mpl ?) to do this. regards,

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serialization of c++0x or boost unordered_map
by William Oquendo 08 Sep '10

08 Sep '10

Dear all, I would like to know if is there a canonical way to use serialization for c++0x or boost unordered_map, like the provided for standards vectors with the file boost/serialization/vector.hpp . Thanks in advance. Best regards / Cordialmente, -- William Oquendo Phd Candidate Simulation Of Physical Systems Group Universidad Nacional de Colombia Linux User # 321481 ********************* Este correo puede carecer de tildes o eñes ya que el teclado no contiene estos caracteres. Presento excusas por eso. *********************

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[Random] uniform_real, min/max at end of value range
by Ruediger Berlich 08 Sep '10

08 Sep '10

Hi there, from what I can see, uniform_real(min,max) essentially does this: fp_type result = uniform_fp_between_0_and_1 * (max - min) + min; // (1) (1) will fail e.g. if the distance between min and max is > std::numeric_limits<fp_type>::max() While writing unit tests for my code I have come across exactly this situation. My application would not suffer much from reducing the allowed value range for my variables to < +/-0.5*std::numeric_limits<fp_type>::max() . However I feel that this would be a bit artificial. Hence I was wondering whether code like the following made more sense (although it is certainly not as efficient): /**********************************************************/ fp_type uniform_real(const fp_type& min, const fp_type& max) { // Check that min and max have appropriate values assert(min<=max); if(min >= fp_type(0.) || max <= fp_type(0.)) { // (max-min) is valid return uniform_01() * (max - min) + min; } else { // Some values will fail (max-min) // We know: min<0., max>0. assert(min<0); assert(max>0); // Calculate a random number in the range [0,1[ fp_type fraction = uniform_01(); // Calculate the fraction of the distance of min from 0. volatile fp_type minFraction = -fraction*min; // Calculate the fraction of the distance of max from 0. volatile fp_type maxFraction = fraction*max; // // The start of the scale volatile fp_type result = min + minFraction; // Add maxFraction to the result. result += maxFraction; return result; } } /**********************************************************/ Essentially, in cases where (max-min) could be larger than the allowed value range, the distance to 0 of each max and min is individually multiplied with a fp random number in the range [0,1[ . The resulting values are then added seperately to min. There should be no situation where an attempt is made to create a value larger than the allowed value range ... unless the compiler optimizes this to "result=min+minFraction+maxFraction;" or worse. volatile might or might not prevent this, I am not sure (seems to work with g++ 4.4.3, though). What is your view on this ? Are there different/better approaches in Boost that I could use ? Best Regards, Ruediger

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insert_iterator() for Unordered Containers
by Hossein Haeri 08 Sep '10

08 Sep '10

Dear all, Is there any insert_iterator (the std Iterator Adaptor) for unordered containers? I am especially interested in unordered_map. TIA, --Hossein

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BOOST_FUSION_ADAPT_STRUCT for empty structs
by Hicham Mouline 08 Sep '10

08 Sep '10

Hello I have this situation: namespace X { struct base_parameters { double skid; }; namespace XX { struct derived_parameters: public base_parameters { double old_field; }; } } // at global namespace BOOST_FUSION_ADAPT_STRUCT( X::XX::parameters, (double, skid) //(double, old_field) ) boost 1.44 Is this supposed to work? I'm getting a compile error which I can't understand and 1 change that I've done is remove the only field that was before in derived_parameters. Regards,

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