June 2008 - Boost-users - lists.boost.org

[BGL][Graph][vertex_descriptor] how do I get my vertex_descriptor?
by Andrew Schweitzer 22 Jun '08

22 Jun '08

This is probably in the Graph doc / book somewhere, but after a few hours poking around didn't find it... I added a bunch of vertices, each with a "unique id" property that comes from our system. Then I want to add the edges. Given the "unique id" from our system for the From and To vertices of the edge, how do I convert those "unique ids" into vertex_descriptors that can be passed to add_edge? tx Andy

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boost::any and boost::lexical_cast
by Chris Ross 22 Jun '08

22 Jun '08

I'm having some problems getting boost::lexical_cast to work for me. I have an abstract class, and it calls a pure virtual function which returns a boost::any. I don't know the type of the boost::any, but in the place I'm working now, I pretty much can assume it's boolean, but it could be a 'bool' data type, or an 'int', or a 'short', or any other thing depending on how the boost::any that the method returned to me was constructed. When I try to use boost::lexical_cast<int>(anyvar), I get compile errors as: /usr/local/boost/include/boost/lexical_cast.hpp: In member function ‘bool boost::detail::lexical_stream<Target, Source, Traits>::operator<<(const Source&) [with Target = int, Source = boost::any, Traits = std::char_traits<char>]’: /usr/local/boost/include/boost/lexical_cast.hpp:1146: instantiated from ‘Target boost::detail::lexical_cast(typename boost::call_traits<Source>::param_type, CharT*, size_t) [with Target = int, Source = boost::any, bool Unlimited = true, CharT = boost::lexical_cast::char_type]’ /usr/local/boost/include/boost/lexical_cast.hpp:1170: instantiated from ‘Target boost::lexical_cast(const Source&) [with Target = int, Source = boost::any]’ ../db.cc:51: instantiated from here /usr/local/boost/include/boost/lexical_cast.hpp:588: error: no match for ‘operator<<’ in ‘((boost::detail::lexical_stream<int, boost::any, std::char_traits<char> >*)this)->boost::detail::lexical_stream<int, boost::any, std::char_traits<char> >::stream << input’ /usr/lib/gcc/x86_64-redhat-linux/4.3.0/../../../../include/c ++/4.3.0/ostream:112: note: candidates are: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>& (*)(std::basic_ostream<_CharT, _Traits>&)) [with _CharT = char, _Traits = std::char_traits<char>] (and more "candidates are" output lines) Line 51 of db.cc is: int v = boost::lexical_cast<int>(is); I know in this case that the subclass is returning a boost::any<int64_t>. And, if I use boost::any_cast<int_64t>(is), I get the right value out. But, if I use boost::any_cast<int>(is) it throws a bad_any_cast, so I assume I need lexical_cast, or something like that, in here since I don't know the source type. Can anyone else figure out why the above compile fails? - Chris

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a question regarding automatic test module registration
by Ákos Maróy 22 Jun '08

22 Jun '08

Hi, I'm trying to use the boost unit test framework, and I have a question regarding automatic test module registration and the automatic definition of the init_unit_test_suite() function. I'm organizing unit tests into a range of source files: tests1.cpp tests2.cpp where each file is set up as follows: #define BOOST_TEST_MODULE moduleX #include <boost/test/unit_test.hpp> BOOST_AUTO_TEST_CASE(test1) { ... } BOOST_AUTO_TEST_CASE(test2) { ... } and I'm linking this all with -lboost_unit_test_framework-mt -lboost_test_exec_monitor-mt Intersestingly, as soon as I have two or more test module files, I get the following linker error: /usr/include/boost/test/unit_test_suite.hpp:187: multiple definition of `init_unit_test_suite(int, char**)' debug/testGeometry.o:/usr/include/boost/test/unit_test_suite.hpp:187: first defined here This seems to be a bit counter-intuitive - after all, isn't one supposed to be able to use a number of test modules as above? (for me, intuitively, yes :) but if this is not the intended way of using the boost unit test library, how would one go about this using auto-registration? it would be really nice to spare the hassle of manual registration, but still be able to partition test cases into separate modules / files. Akos

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Re: [Boost-users] boost::any and boost::lexical_cast
by Igor R 22 Jun '08

22 Jun '08

> Does anyone have a suggestion as to how I can get a value out of a > boost::any for which I don't know the specific type stored in it? Probably, the most safe way is just to change boost::any to boost::variant ?

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[mpl][fusion] non-unique keys in map?
by Danny Havenith 22 Jun '08

22 Jun '08

Hello all, I've encountered some behaviour of maps in both fusion and mpl that I did not expect, when inserting elements with the same key. Both libraries behave the same. To illustrate, I wrote the code below (full source at the end of this post), where I create a map with a single element an then insert an element with the same key (int_<1>). I expected the size<> of the resulting map to be 1. Instead, the size is 2. (all on msvc9 and gcc 4.1.2 (MinGW), boost 1.35 and svn_head) ----------------------------------- typedef pair< int_<1>, vector< int> > first_element; typedef pair< int_<1>, vector< int, int> > second_element; typedef map< first_element> first_map; typedef insert< first_map, second_element>::type second_map; // it prints "2", I expected "1". std::cout << size< second_map>::type() << std::endl; ----------------------------------- Generally, when I inspect the type of the resulting map after several inserts, I see that all inserted elements are still there. What is wrong with the above code? What should I do if I wanted the original entry to be replaced with the new one? Danny. ------source------- #include <iostream> #include <boost/mpl/vector.hpp> #include <boost/mpl/int.hpp> #include <boost/mpl/insert.hpp> #include <boost/mpl/pair.hpp> #include <boost/mpl/size.hpp> #include <boost/mpl/count.hpp> #include <boost/mpl/map.hpp> #include <boost/fusion/include/map.hpp> #include <boost/fusion/include/insert.hpp> #include <boost/fusion/include/count.hpp> #include <boost/fusion/include/vector.hpp> #include <boost/fusion/sequence/intrinsic/size.hpp> #include <utility> // std::pair //#define USE_FUSION int main(int argc, char* argv[]) { #ifdef USE_FUSION using namespace boost::fusion::result_of; using std::pair; using boost::fusion::vector; using boost::fusion::map; #else using namespace boost::mpl; #endif using boost::mpl::int_; typedef pair< int_<1>, vector< int> > first_element; typedef pair< int_<1>, vector< int, int> > second_element; typedef map< first_element> first_map; typedef insert< first_map, end< first_map>::type, second_element>::type second_map; std::cout << size< second_map>::type() << std::endl; return 0; }

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getting back information about a serialized class from a binary archive
by Ivan Gonzalez 21 Jun '08

21 Jun '08

Dear all, I'm using the serialization library to serialize some classes to a binary archive. These classes are basically arrays of some numerical type. As an example say they are doubles. Later I would like to read one of these binary archives into the same structure but using another numerical type, to which you could promote the first one. Say for example std::complex<double>. If I was using a simply a text file, I could read the double, without caring about its original type, into the new type because it will be automatically promoted. You can not do this with the binary file. So my question is, is there any way to extract information about the class stored in the binary archive, in this case the numerical type of the array? I thought in using the version number of the class to label the original type, is this the only way? In coding: template<class T> struct SimpleClass{ typedef T num_type; num_type data_; template<class Archive> void serialize(Archive ar, const unsigned int version) { ar & data_; } }; Now given a binary archive containing a instance of SimpleClass<double>, how to read it to an instance of SimpleClass<std::complex<double> > ? If I could get directly from the file the type SimpleClass::num_type then I could write a constructor in the SimpleClass to promote one to the other. Thanks in advance. Best, Ivan

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[interprocess] boost::interprocess::basic_string and VS2005 watch window
by Jason Sachs 20 Jun '08

20 Jun '08

I am trying to debug some work with basic_string<>s in shared memory with Micro$oft VS2005. does anyone have an expression for the autoexp.dat file that works with boost interprocess basic_strings to view the string it contains? I'm fighting some weird bug. (also is there a problem with this listserver? I sent a msg to it twice & it appears to have disappeared into the ether)

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[boost-users][hash] adding hash_value to boost namespace(s)?
by Igor R 20 Jun '08

20 Jun '08

Hi, I'd like to define hash_value() for some types defined in Boost, in order to use those types in hashed containers. It seems that the only way to do this is to define hash_value() in namespace boost, or the inner namespaces (where the desired type is defined) - isn't it? Is this legal? Thank you, Igor'.

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Message Queues with Strings instead of Integers
by Julian Magnone 20 Jun '08

20 Jun '08

Hi, We are serializing an object to a string and then we want to send it to another process using MQ. When received, it's deserialized and the original object is reconstructed again. We are trying to use message_queue from Boost Interprocess but we still having some troubles sending String messages. (I've been noticed about the boost examples using integers) The first issue is about std::string. I read on boost documentation that MQ do not works with std::string so my first attempt was to use boost::interprocess:string. However, I've received library error while trying to use interprocess::string, so I tried to use std::string and mysteriously it worked fine. After we change the application to another machine with the same configuration, it didn't work again, so I guessed that's the clue why std::string is not guarantee to work in all cases. My question is, what should be the right way to transmit a string message using MQ? Thanks in advance, Julian Magnone

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[serialization] class names in xml archives
by Kabanov, Alexander 20 Jun '08

20 Jun '08

Hi I have recently began familiarising myself with the serialization library (Boost 1.35). I am specifically interested in XML serialization. This is probably a trivial question: can you get the actual name of the class to appear in the opening tag of the class instance? All I get so far is the class_id for the first instance and class_id_reference thereafter. This does make sense, of course, but I would like to know if this really is the default behaviour, and if it is, can it be changed to display the class name? Thanks Alexander Kabanov

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