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boost serialization stream error question
by Gabe Sibley 01 Feb '10

01 Feb '10

Dear All, I'm using boost serialization and have come across issues with "steam error" when I try to deseriailze from an xml or text archive. Binary archives are fine, but I can't use binary because my users need xml archives. The problem is caused by double values less than DBL_MIN. Apparently, streaming such values in causes the input stream fail_bit to be set, which causes the serialization lib to throw an exception. One work around is to make sure all double values are clamped and finite when the archive is created. I can live with this, esp. since I have algorithms that will from time to time produce non-finite results. So far what I've done is just replace BOOST_SERIALIZATION_NVP macro with the following MAKE_NVP macro that calls "FixReal": #define BOOST_SERIALIZATION_NVP(name) \ boost::serialization::make_nvp(BOOST_PP_STRINGIZE(name), name ) // Use this macro instead of BOOST_SERIALIZATION_NVP because it fixes doubles that are not streamable. // That is, it fixes double values that cause streaming errors. #define MAKE_NVP(name) \ boost::serialization::make_nvp(BOOST_PP_STRINGIZE(name), FixReal(name) ) // note the call to FixReal // does nothing -- just pass all non-double types through template<class T> inline T& FixReal( T& t ) { return t; } /// Routine to make sure doubles are streamable -- Nan, Inf, etc. cause stream errors, so we prevent them. inline double& FixReal( double& d ) { if( d < DBL_MIN ) { d = DBL_MIN; } if( d > DBL_MAX ) { d = DBL_MAX; } if( std::isnan(d) ) { d = 0; } if( std::isinf(d) ){ d = DBL_MAX; } return d; } /// We also need to fix double arrays. The ugly syntax is because // we have to pass and return a reference to an array. inline double (&FixReal( double (&d)[2] ))[2] { for( size_t ii = 0; ii < 2; ii++ ){ FixReal(d[ii]); } return d; } Ok, here's my question: How can I get the "FixReal" functionality above without having to write a specialized function for every possible double signature? For instance, I don't want to have to write inline double (&FixReal( double (&d)[3] ))[3] inline double (&FixReal( double (&d)[4] ))[4] ... etc. or any of the other POD double signatures possible. I just want the serialization library to fix the errant double values when I create the archive. I guess I could modify the "void save(const double t)" function in basic_text_oprimitive.hpp to check all doubles, but that seems like a bad plan. Any suggestions? thanks for your help, Gabe

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Strange output from boost::exception diagnostic_information
by pholding 01 Feb '10

01 Feb '10

-------------------------------------------------------------------------------- I've been having a look at the diagnostic_information function in the boost exception library, but seem to be getting a strangely formatted output. The code I'm using is as follows Code: #include <boost/exception/diagnostic_information.hpp> #include <stdexcept> #include <iostream> void myerror(){ throw boost::enable_error_info(std::range_error("blah")); } int main(){ try{ myerror(); } catch(boost::exception & e){ std::cerr << diagnostic_information(e) << std::endl; } return 0; }The output is as follows: Quote: Throw in function (unknown) Dynamic exception type: N5boost16exception_detail19error_info_injectorISt1 1range_errorEE std::exception::what: blah What I don't understand is why I'm getting N5, 16, 19, ISt11 and EE between the details of the exception type. To rule out my code, I compiled the example_io.cpp file provided in the boost example documentation and I'm getting a similar output. Does anyone what is causing the strange characters displayed? I'm running Ubuntu 9.10 and the version of g++ is 4.4.1 -- View this message in context: http://old.nabble.com/Strange-output-from-boost%3A%3Aexception-diagnostic_i… Sent from the Boost - Users mailing list archive at Nabble.com.

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Re: [Boost-users] [BGL] Color Maps
by pablo barrio lópez-cortijo 31 Jan '10

31 Jan '10

Hi Andrew, thanks for your help. > I would recommend using the named parameter version of the call since it lets you omit optional parameters. It seems like the right approach. So now my code is as follows: typedef graph_traits<graph_t>::vertex_descriptor Vertex; Vertex source; ... some code that finds the appropriate vertex // DFSActions is the DFS visitor, with actions on vertex discover and finish DFSActions actions(this); // Calling DFS with named parameters depth_first_search(*g, visitor(actions), root_vertex(source)); Problem: the code doesn't compile, and I'm sure the fault is in "root_vertex(source)". This is the (very synthesized) error thrown by the compiler: property_map.hpp: In instantiation of ‘boost::property_traits<boost::bgl_named_params<long unsigned int, boost::root_vertex_t, boost::no_property> >’: depth_first_search.hpp:192: instantiated from ‘void boost::depth_first_search( long line ) [ with REALLY long line ]’ depth_first_search.hpp:222: instantiated from ‘void boost::depth_first_search( long line ) [ with REALLY long line ]’ graphdef.cpp:134: instantiated from here graphdef.cpp:134: instantiated from here property_map.hpp:31: error: no type named ‘key_type’ in ‘struct boost::bgl_named_params<long unsigned int, boost::root_vertex_t, boost::no_property>’ property_map.hpp:33: error: no type named ‘reference’ in ‘struct boost::bgl_named_params<long unsigned int, boost::root_vertex_t, boost::no_property>’ property_map.hpp:34: error: no type named ‘category’ in ‘struct boost::bgl_named_params<long unsigned int, boost::root_vertex_t, boost::no_property>’ And many other errors, but this is the first one. To check if the problem was in my "source" vertex, I changed the call to DFS with the default value for the root_vertex (looked up in the header file): depth_first_search(*g, visitor(actions), root_vertex(*vertices(*g).first)); The error keeps showing. Having a look at the DFS source code, it seems that the named param function expects a root_vertex of type root_vertex_t, which appears several times in the error msg. The Boost docs specify a type of graph_traits<graph_t>::vertex_descriptor, which is what I'm using now. I suppose it's the same type, but I've not found the type definition. I'm sure it must be a very stupid mistake, but I can't see it. Any clues?

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[circular_buffer] Serialization support for circular_buffer
by Brian Wood 31 Jan '10

31 Jan '10

B"H Shalom, Boost, The C++ Middleware Writer now supports marshalling circular_buffers. This is done by transmitting a circular buffer's capacity, then size, followed by it's elements. An example of the code used when marshalling a circular_buffer is here -- http://webEbenezer.net/posts/cirbuf.hh. -- Brian Wood http://www.webEbenezer.net (651) 251-9384

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Can someone provide an Asio Serial Port example?
by Jeff 30 Jan '10

30 Jan '10

I would like to use Asio to connect to a microcontroller to send and read from, but there are no serial_port samples available. For instance, I would like to type an ‘a’ into the keyboard and have the microcontroller return 1. The microcontroller is already programmed for this but I need to create an interface for it. A sample that does this or any working sample at all would be sincerely appreciated. Thank you, Jeff

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std::list customization
by Etienne Philip Pretorius 30 Jan '10

30 Jan '10

Hello List, I know this is not boost specific, but I would appreciate any comments about the following. I have a specific set of values stored in a std::list<unsigned char>. As expected I can delete and add items anywhere, since I am using the std::list object rearrange its own contents. But here is the problem - when I have already decided that item at position 13 should always remain at position 13 if the list has 13 or more objects in it... If I remove an item from the beginning then the item at position 13 becomes the item at position 12, while this is undesired - the effect of shifting everything else on by one value is desired. Some examples of what I require: Fixed position marked with []. a,b,c,[d],e,f pop_front() is called b,c,e,[d],f This list object should also work when inserting items and keep those with fixed positions at their position if the object size allows it. Any suggestions, Ideas on how to implement this would be greatly appreciated. Kind Regards, Etienne

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[mpl - function_types] Generate typedef from operator() of a functor
by Olivier Tournaire 30 Jan '10

30 Jan '10

Hi all, Given an mpl sequence of types such as: typedef mpl::vector<T0, T1, T2, T3> arg_types; 1) the users of my library provide functors such as F (where T0 and T1 may have been any of the types of arg_types: class F { typedef mpl::pair<T0,T1> signature_type; double operator()(const T0& t0, T1& t1); }; is there a way to generate signature_type automatically ? 2) if the operator() is overloaded, the user class currently has to typedef an mpl::vector of mpl::pairs such as class G { typedef mpl::vector<mpl::pair<T2,T3>, mpl::pair<T1,T1>, mpl::pair<T3,T1> > signature_type; double operator()(const T2& t2, T3& t3); double operator()(const T1& t1, T1& t1); double operator()(const T3& t3, T1& t1); }; in this case, is it also possible to generate signature_type automatically ? Regrads, Olivier

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[function_types] About parameter_types
by Olivier Tournaire 30 Jan '10

30 Jan '10

Hi all, I am trying to extract the parameters types of a given function/functor in a mpl sequence. Digging boost libraries, I came across function_types, and in particular parameter_types, which might be the right tool. However, I cannot figure how to use it. Could you please help ? Suppose I have: void foo(int, double); And would like to generate the following sequence: mpl::vector<int, double> How can I do that ? Regards, Olivier

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[doc] Add "Last Update" information
by Marco Guazzone 30 Jan '10

30 Jan '10

Dear Boosters, In my opinion it would be very helpful if the documentation include for each library the version of the last update. For instance, one could add this information in the summary page (http://www.boost.org/doc/libs/1_41_0) --- [snip] --- uBLAS uBLAS provides matrix and vector classes ... Author(s)...........Joerg Walter and Mathias Koch First Release...1.29.0 -> Last Update......1.40.0 <- Standard Build & Link......Header only Categories........Math and numerics --- [/snip] --- The reason for this is that it should simplify the discovery of what version of Boost one needs for his own software project. As a matter of fact, the use of "First Release" might not be sufficient because after the initial release of a library many other features could have been added. So the need for this additional piece of information. What do you think? Regards, -- Marco

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asio UDP local port binding issue on Windows
by akos＠maroy.hu 30 Jan '10

30 Jan '10

Hi, I seem to encounter an issue when using boost asio. I'm trying to create a UDP client-server environment, where for the client I'm creating an asio socket like this: io_service _io_service; ip::udp::socket _socket(_io_service, ip::udp::v4()); my expectation at this point is that the _socket is created, and it can send and receive UDP packets. this includes receiving packets, which also means that the socket is bound to some random port on the local network interface. now this is all true on Linux and MacOS, but on Windows, the socket does not seem to bind to a port. interestingly, for _socket.is_open() I get true in return. but for _socket.local_endpoint(), I get an error excaption with the error code 10022, which is defined as WSAEINVAL. I also tried the following, and got the same results: io_service _io_service; ip::udp::socket _socket(_io_service); _socket.open(ip::udp::v4()); is my assumption that the above should result in a socket bound to a local random port incorrect? Akos

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