April 2009 - Boost-users - lists.boost.org

[graph]
by liquid 21 Apr '09

21 Apr '09

I'd like to have unique vertices in a graph based on index of type std::string. I did the following coding. typedef property<edge_weight_t,float> EProperty; typedef property<vertex_index_t,string> VIndex; typedef adjacency_list<setS,listS,directedS,VIndex,EProperty> Graph; typedef property_map<Graph, vertex_index_t>::type VIndexMap; graph_traits<Graph>::vertex_descriptor addv(property_traits<VIndexMap>::value_type v,Graph &g) { graph_traits<Graph>::vertex_descriptor vd; vd = add_vertex(VIndex(v),g); return vd; } Does "add_vertex" check the existence of added vertices of given index? No, it doesn't. Or I do something wrong. Regards liquid

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boost variant compile time visitation: verification
by Hicham Mouline 21 Apr '09

21 Apr '09

Hello, #include <iostream> #include <boost/variant/variant.hpp> typedef boost::variant<int, double, char> VT; struct print_type : public boost::static_visitor<const char*> { const char* operator()( int ) { return "int"; } const char* operator()( double ) { return "double"; } const char* operator()( char ) { return "char"; } }; int main() { VT v('c'); std::cout<< v.apply_visitor( print_type() ) <<std::endl;; } If I understood the doc correctly, the visitation is supposed to be compile-time, that is, v.apply_visitor( print_type() ) is already "char" before the program start... Is this right? If so, is there a way to see this in the binary executable file? Maybe viewing symbols? I have access to vs2005 and g++3/4 /linux platforms. It would be so fantastic if compilers output _also_ the C++ source resulting from the template machinery! Best regards,

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unordered_map serialization
by gtsml owevwr 21 Apr '09

21 Apr '09

Hi, I cannot find any serialization code for unordered_map in boost, am I missing something? I'm using boost 1.36, header <boost/unordered_map.hpp>. I could not find anything in 1.38 neither. Is the header <boost/serialization/hash_map> related? I have to say that I'm a bit confuse with the whole TR1 stuff (it seems to be related). Anyway, I can still convert to a list and serialize I guess, but if there's already something somewhere... Any suggestion welcome, Frank

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[Boost-announce] Review Conclusion - Futures Library
by Tom Brinkman 20 Apr '09

20 Apr '09

Review Conclusion - Futures Library Braddock Gaskill http://braddock.com/~braddock/future Anthony Williams http://www.justsoftwaresolutions.co.uk/files/n2561_future.hpp The lack of examples and documentation made them difficult to review. Nevertheless, Anthony Williams futures library did receive almost unanimous and enthusiastic support. Unfortunately, the depth of the support was very shallow. I just finished my first read of Anthony's book "C++ Concurrency in Action and acknowledge his expertise in the areas of multi threaded and parallel programming. (http://www.manning.com/williams/) Anthony is the maintainer of boost::threads. Anthony's Future library has been approved for the next major release of c++ standard. Conclusion Braddock Gaskill - Rejected Anthony Williams - Approved Anthony's Futures library is approved for inclusion into boost::threads. As he is the maintainer of that library, he should be given maximum latitude about how that is to be done. In the future, if Anthony wants to re-publish the library as a top-level boost library, then he needs to resubmit it again with samples and test cases, which are lacking. Requirements As per the usual boost library requirements, examples and test cases are needed. Anthony should also improve the documentation, which should not be a problem as he is a prolific author in the area of multi threaded programming. Review Manager Tom Brinkman _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost-announce

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[date_time] runtime error with intel c++ 11.0.072 (win32) and ptime's time_from_string()
by Edward Rankin 20 Apr '09

20 Apr '09

Hi all, I have encountered a runtime error when date_time tries to parse a time from a delimited string when compiled with intel c++ 11 in release mode. The following code is what I used to replicate the error: int main(int argc, char** argv) { using namespace boost::posix_time; ptime first = microsec_clock::local_time(); std::string temp = to_simple_string(first); ptime second = time_from_string(temp); // it crashes here } It works when using msvc9's compiler in debug and release mode and intel c++ 11 debug mode. Any idea how to resolve this? Thanks, Edward

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[concept check][mpl] (Conditional) Concept checking for functions
by Jesse Perla 20 Apr '09

20 Apr '09

I have a variety of user defined function objects that I will need to call. Take the following examples:template<int N1, int N2 = 0> struct Func1{ double operator()(boost::array<double, N1>& x1, boost::array<double, N2>& x2){...}}; template<int N1> struct Func2{ double operator()(boost::array<double, N1>& x){...}}; With a function such as template<int N1, int N2 = 0, class F = boost::function<double (boost::array<double, N1>& x1, boost::array<double, N2>& x2)> class DPP{ void solve(){...... uses F...to be discussed} }; I have a few questions: 1) Is there a relatively easy way to use boost concept check to verify that F follows the first function signature so that I can detect compile time the problem? I can't figure out how to do it from the concept check docs, and they say they are out of date. Usage I want to check in the instantiation of DPP: F f; f(boost::array<double, N1>& x1, boost::array<double, N2>& x2) 2) I want the user to be able to pass in a simplified function type if N2 = 0 I assume that to call the actual function I would have some kind of impl function with partial specialization such as: template<bool use_simplified, int N1, int N2> struct use_f_impl(); template<int N1, int N2> struct use_f_impl<true, N1, N2>{ static double use_f() { STATIC_ASSERT(N2 == 0); F f; boost::array<double, N1> x; return f(x); } }; template<int N1, int N2> struct use_f_impl<false, N1, N2>{ static double use_f() { F f; boost::array<double, N1> x1; boost::array<double, N2> x2; return f(x1, x2); } }; And then in my solve() function I go: double val = use_f<(N2 == 0, N1, N2)>::use_f(); Is this the right idiom, pattern, etc? Do I need to use the struct with a static function since function templates don't have partial specialization? 3) Now what if I want to do a concept check on the F passed into DPP? It has to be conditional on the N2 value now. How would I do this? 4) Lets say that I don't want to force them to use the simplified version of the function signature if they don't want to. Can I automatically detect the signature and put it into a flag integer in the class? i.e. inside of the DPP class: static bool use_simple = IsSimple<F>::value; Then pass in the use_simple value when calling use_f_impl. If so, what would the IsSimple metafunction look like and can concept check help? Thanks, Jesse

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[interprocess] 32 to 64 bit ?
by Stephan Menzel 20 Apr '09

20 Apr '09

Hi there, before holidays kick in I wondered whether I go for a strange problem in my usage of interprocess. Im using it within boost 1.38 on windows, msvc. Basically, I transfer data between two processes, which works great. So far, both have been built 32 bit release. But now since I exclusively use supposedly safe data types in the shared mem such as boost::uint32_t and friends I was wondering whether it's possible to have the data retrieving process built in 64 bit and access the same buffer. I just gave it a shot and it behaves different to what I had hoped for. In blocks during finding a struct with in a shared segment. ret = segment->find<struct my_buffer>(unique_instance).first; This operation blocks on a mutex in segment_manager.hpp: #ifdef BOOST_INTERPROCESS_RVALUE_REFERENCE scoped_lock<rmutex> #else detail::move_return<scoped_lock<rmutex> > #endif priv_get_lock(bool use_lock) { scoped_lock<rmutex> local(m_header, defer_lock); if(use_lock){ local.lock(); // <----- here! } return local; } .. never to return. The code is the same as in my 32 - 32 bit versions and known to work. Now I'm wondering, is this supposed to work or is 32 to 64 bit transfer not supported at all? Is this a bug or a feature? Do I have to have both applications in a 64 bit version? Cheers, Stephan

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[repost][threads] recursive shared_mutex
by JOAQUIN M. LOPEZ MUÑOZ 20 Apr '09

20 Apr '09

Hi, allow me to repost this query of mine that went without much attention at first try... As the docs do not explicitly say otherwise, I guess I must assume that boost::shared_mutex is not recursive with respect to unique ownership, that is, the following behavior ensues: shared_mutex mutex; lock_guard<shared_mutex> lock1(mutex); lock_guard<shared_mutex> lock2(mutex); // DEADLOCK Is this so? In case boost::shared_mutex is indeed non-recursive, I've read the following assertion on Hinnant's paper N2406 (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2406.html ): "A recursive shared mutex could be built upon shared_mutex if desired, but this is not proposed." Does anyone has a reference on how to construct a recursive shared_mutex from a non-recursive one? Thank you, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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[lexical_cast] How is the degenerate case handled?
by Robert Jones 20 Apr '09

20 Apr '09

If you use lexical_cast to cast between identical types, eg. lexical_cast< int >( 4 ); does it go through all the machinery of streaming out and back, or does it short circuit? In those circumstances, does the type need to be streamable? Thanks, Rob.

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Serialization of intrusive_ptr's?
by Jared Lee Richardson 20 Apr '09

20 Apr '09

Hey, quick question, what do I need to do to serialize intrusive_ptr's? I don't see anything in the serialization documentation to indicate that it supports it, does it? If not, is there an easy way? Or do I need to serialize the raw pointers and re-construct the intrusive_ptr's one by one? I'm storing intrusive_ptr's inside std container classes(map, list). Thanks, Jared

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