May 2010 - Boost-users - lists.preview.boost.org

[Function][Bind] Strange problem with g++ 4.5
by Maxime van Noppen 17 May '10

17 May '10

Hi, I've got a very strange problem with Boost.Function used in conjunction with Boost.Bind with g++ 4.5.0. Here is the minimal test case: ----------------gtest.cc--------------------------------- #include <boost/bind.hpp> #include <boost/function.hpp> #include <iostream> int fun(const int* id) { std::cout << "id: " << id << std::endl; std::cout << *id << std::endl; return 0; } int main() { typedef boost::function<int ()> func_t; int id = 42; std::cout << "id: " << &id << std::endl; func_t f = boost::bind(&fun, &id); //std::cout << f << std::endl; func_t g = f; g(); return 0; } ------------------------------------------------- When compiled with -O2 the program crashes: ------------------------------------------------- $ g++ -O2 gtest.cc && ./a.out id: 0x7fff3f7f85ec id: 0 Segmentation fault ------------------------------------------------- The problem seems to be inlining, when compiled with -O0 or -O2 -fno-inline everything works fine: ------------------------------------------------- $ g++ -O2 -fno-inline gtest.cc && ./a.out id: 0x7fff32b81a9c id: 0x7fff32b81a9c 42 $ g++ -O0 gtest.cc && ./a.out id: 0x7fff960b270c id: 0x7fff960b270c 42 ------------------------------------------------- What is very strange is that if I uncomment the std::cout of f everything works fine: ------------------------------------------------- $ g++ -O2 gtest.cc && ./a.out id: 0x7fff738619ac 1 id: 0x7fff738619ac 42 ------------------------------------------------- If the Boost.Function is not copied to g (ie, use f) everything works. Everything works fine with g++ (GCC) 4.4.3 20100316 (prerelease). I'm using Linux x86_64 with boost 1.42 and 1.43. Any idea of what may be going wrong here? -- Maxime

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Re: [Boost-users] [Asio]Question about error_code when socket::close
by Comet 17 May '10

17 May '10

> void Read() { > // this line is very slow, > // because boost::bind(&Session::HandleRead,shared_from_this(), ...) > // causes extra new/delete operations My test result: ---------------------------------- raw ptr version ------------------------ a.cc: class A { public: void f() {} }; int main() { A a; boost::function<void ()> f; for (size_t i = 0; i < 100000000; ++i) { f = boost::bind(&A::f, &a); } } gcc a.cc -O2 time ./a.out real 0m1.235s user 0m1.232s sys 0m0.000s ------------------------------------ shared_ptr version ---------------------- a.cc: class A { public: static void f(boost::weak_ptr<A>) {} }; int main() { boost::shared_ptr<A> a = boost::make_shared<A>(); boost::function<void ()> f; for (size_t i = 0; i < 100000000; ++i) { f = boost::bind(&A::f, a); } } gcc a.cc -O2 time ./a.out real 0m25.925s user 0m25.898s sys 0m0.000s

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linking for release, has debug baggage
by Dan Bloomquist 17 May '10

17 May '10

Hi, I have a large project and for what ever reason if I add xpressive.hpp in my precompiled header, it completly kills intelligence. So I figured I'd move the stuff I want to use off to a lib. Works fine in debug but if I build the release, this lib tries to link in the Microsoft debug libs. In my project: 1>mfcs90.lib(nolib.obj) : warning LNK4098: defaultlib 'mfc90d.lib' conflicts with use of other libs; use /NODEFAULTLIB:library 1>mfcs90.lib(nolib.obj) : warning LNK4098: defaultlib 'mfcs90d.lib' conflicts with use of other libs; use /NODEFAULTLIB:library and just this one in the test solution: 1>msvcrt.lib(cinitexe.obj) : warning LNK4098: defaultlib 'msvcrtd.lib' conflicts with use of other libs; use /NODEFAULTLIB:library I have been able to recreate the problem in a small solution that should not dependent on my directories other than setting the boost path: <http://lakeweb.net/downloads/RaVpath.zip> (20k) vc 2008 (9.0) boost 1_42 And I don't know, this may have nothing to do with boost, but I have other dlls and libs without this problem. It is coming from 'boost::filesystem' as best as I can determine. And maybe someone has seen this before and knows off the top of their head. Thanks, Dan.

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[thread] Reader/Writer starvation
by Jérémy Coulon 17 May '10

17 May '10

Hi, According to the documentation of Boost 1.34 (before the major rewrite of boost::thread), the read/write lock was offering different scheduling policies. Some of those policies were providing a solution to the starvation problem that usually occurs with this kind of lock. http://www.boost.org/doc/libs/1_34_1/doc/html/thread/concepts.html#thread.c… http://www.boost.org/doc/libs/1_34_1/doc/html/thread/concepts.html#thread.c… But I don't find any reference to starvation and scheduling policies in the current Boost documentation (1.37). So, I am wondering if this starvation problem is solved in the current boost::thread implementation ? What scheduling policy is actually the default one ? Can the documentation be improved ? Thanks. Jeremy

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Re: [Boost-users] [Asio]Question about error_code when socket::close
by 鑫炜廖 17 May '10

17 May '10

Igor R <boost.lists <at> gmail.com> writes: > > > I want to distinguish the error_code set by calling socket::close from any other ways (like system error, network > > error, etc), otherwise, I can't determine whether I should delete the object in async handlers, because > some have already been deleted after I call socket::close. If boost::asio::error::operation_aborted > definitely means "socket::close is called", I can distinguish this situation. > > It seems to be rather error-prone approach. One day, when your > application will have grown a bit, you'll find yourself hunting weird > segfaults / access-violations. > But when should I delete the object after I call socket::close? May be there's no async handler, so just deleting object in handlers leads to memory leak. > > I've tried using boost::weak_ptr with boost::bind,but the performance decrease dramatically. > > Did you run a performance profiler with fully-optimized application > and really discovered that the bottle-neck is in shared_ptr's?! This > would be really surprising... > I've tested it separately, when binding a weak_ptr/shared_ptr with a member function, it will cause extra new/delete operations, but raw pointer will not(gcc 4.4.1, boost 1.4.3).The former way is about 20 times slower,as a frequently operation, it seems not acceptable.

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Re: [Boost-users] [fusion]simple fusion seq_size fails to compile
by Pete Bartlett 16 May '10

16 May '10

>Compilation of attachment 1 with gcc-4.5, produces errors in attachment 2. When the >'#if 1' on line 24 is changed to '#if 0', it compiles OK. > >What am I doing wrong? > >TIA. In the second "inner" instantiation of seq_size (ie the one taking in an empty sequence), what return type /could/ pop_front have? So intuitively a compile error is what I would expect here - and I think a literal reading of the documentation agrees because an empty sequence does not satisfy the fusion Sequence concept.

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[fusion]simple fusion seq_size fails to compile
by Larry Evans 16 May '10

16 May '10

Compilation of attachment 1 with gcc-4.5, produces errors in attachment 2. When the '#if 1' on line 24 is changed to '#if 0', it compiles OK. What am I doing wrong? TIA. -regards, Larry /home/evansl/download/gcc/4.5-20100408/install/bin/g++ -c -Wall -ftemplate-depth-300 -O0 -g3 -fno-inline -std=gnu++0x -I/home/evansl/prog_dev/boost-svn/ro/trunk -DTEMPLATE_DEPTH=300 fusion_list_nil_function_specialization.cpp -MMD -o /home/evansl/prog_dev/boost-svn/ro/trunk/sandbox-local/build/gcc4_5n/sandbox/variadic_templates/libs/composite_storage/sandbox/fusion_list_nil_function_specialization.o In file included from /home/evansl/prog_dev/boost-svn/ro/trunk/boost/fusion/container/list/cons_iterator.hpp:14:0, from /home/evansl/prog_dev/boost-svn/ro/trunk/boost/fusion/container/list/cons.hpp:16, from /home/evansl/prog_dev/boost-svn/ro/trunk/boost/fusion/container/list.hpp:10, from fusion_list_nil_function_specialization.cpp:4: /home/evansl/prog_dev/boost-svn/ro/trunk/boost/fusion/container/list/detail/next_impl.hpp: In instantiation of 'boost::fusion::extension::next_impl<boost::fusion::cons_iterator_tag>::apply<boost::fusion::cons_iterator<boost::fusion::void_> >': /home/evansl/prog_dev/boost-svn/ro/trunk/boost/fusion/iterator/next.hpp:52:9: instantiated from 'boost::fusion::result_of::next<boost::fusion::cons_iterator<boost::fusion::void_> >' /home/evansl/prog_dev/boost-svn/ro/trunk/boost/fusion/iterator/detail/distance.hpp:36:9: instantiated from 'boost::fusion::distance_detail::next_distance<boost::fusion::cons_iterator<boost::fusion::void_>, boost::fusion::cons_iterator<const boost::fusion::nil> >' /home/evansl/prog_dev/boost-svn/ro/trunk/boost/mpl/eval_if.hpp:38:31: instantiated from 'boost::mpl::eval_if<boost::fusion::result_of::equal_to<boost::fusion::cons_iterator<boost::fusion::void_>, boost::fusion::cons_iterator<const boost::fusion::nil> >, boost::mpl::identity<mpl_::int_<0> >, boost::fusion::distance_detail::next_distance<boost::fusion::cons_iterator<boost::fusion::void_>, boost::fusion::cons_iterator<const boost::fusion::nil> > >' /home/evansl/prog_dev/boost-svn/ro/trunk/boost/fusion/iterator/detail/distance.hpp:46:5: instantiated from 'boost::fusion::distance_detail::linear_distance<boost::fusion::cons_iterator<boost::fusion::void_>, boost::fusion::cons_iterator<const boost::fusion::nil> >' /home/evansl/prog_dev/boost-svn/ro/trunk/boost/fusion/iterator/distance.hpp:37:13: instantiated from 'boost::fusion::extension::distance_impl<boost::fusion::cons_iterator_tag>::apply<boost::fusion::cons_iterator<boost::fusion::void_>, boost::fusion::cons_iterator<const boost::fusion::nil> >' /home/evansl/prog_dev/boost-svn/ro/trunk/boost/fusion/iterator/distance.hpp:66:9: instantiated from 'boost::fusion::result_of::distance<boost::fusion::cons_iterator<boost::fusion::void_>, boost::fusion::cons_iterator<const boost::fusion::nil> >' /home/evansl/prog_dev/boost-svn/ro/trunk/boost/fusion/view/iterator_range/iterator_range.hpp:33:74: instantiated from 'boost::fusion::iterator_range<boost::fusion::cons_iterator<boost::fusion::void_>, boost::fusion::cons_iterator<const boost::fusion::nil> >' fusion_list_nil_function_specialization.cpp:25:52: instantiated from 'unsigned int seq_size(const FusionSeq&) [with FusionSeq = boost::fusion::iterator_range<boost::fusion::cons_iterator<const boost::fusion::nil>, boost::fusion::cons_iterator<const boost::fusion::nil> >]' fusion_list_nil_function_specialization.cpp:25:52: instantiated from 'unsigned int seq_size(const FusionSeq&) [with FusionSeq = boost::fusion::list<int>]' fusion_list_nil_function_specialization.cpp:35:45: instantiated from here /home/evansl/prog_dev/boost-svn/ro/trunk/boost/fusion/container/list/detail/next_impl.hpp:37:54: error: invalid use of incomplete type 'struct boost::fusion::extension::next_impl<boost::fusion::cons_iterator_tag>::apply<boost::fusion::cons_iterator<boost::fusion::void_> >::cons_type' /home/evansl/prog_dev/boost-svn/ro/trunk/boost/fusion/container/list/list_fwd.hpp:15:12: error: forward declaration of 'struct boost::fusion::extension::next_impl<boost::fusion::cons_iterator_tag>::apply<boost::fusion::cons_iterator<boost::fusion::void_> >::cons_type' /home/evansl/prog_dev/boost-svn/ro/trunk/boost/fusion/container/list/detail/next_impl.hpp:45:17: error: invalid use of incomplete type 'struct boost::fusion::extension::next_impl<boost::fusion::cons_iterator_tag>::apply<boost::fusion::cons_iterator<boost::fusion::void_> >::cons_type' /home/evansl/prog_dev/boost-svn/ro/trunk/boost/fusion/container/list/list_fwd.hpp:15:12: error: forward declaration of 'struct boost::fusion::extension::next_impl<boost::fusion::cons_iterator_tag>::apply<boost::fusion::cons_iterator<boost::fusion::void_> >::cons_type' ,,,

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[statechart] transition exception
by Christophe Bourez 16 May '10

16 May '10

Hi, Is it possible to transit<> back to the source state when an exception is thrown by the handler of a transition ? Pls, note that the handler of the transition can be used by several transitions in the state diagram. The state machine, being in a transition, is between two stable states. The exception can be handled by the innermost common outer state (or anyone above). In an handler of this state, is it possible to force transit<> to the source state of the transition that throws the exception ? Or is it possible to manage it differently ? Thank you for your help, Christophe

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Problem with "prod" function
by gicatena＠libero.it 16 May '10

16 May '10

The following code is not working for me: --------------------------------------- using namespace boost::numeric::ublas; matrix<double> m (3, 3); matrix<double> o (3, 3); for (unsigned i = 0; i < m.size1 (); ++ i) for (unsigned j = 0; j < m.size2 (); ++ j) { m (i, j) = 3 * i + j; o (i, j) = 3 * i + j; } std::cout << m << o << std::endl; matrix_vector_binary2< matrix_row< matrix<double> >, matrix<double>, double > D; D = prod(row(m, 1),o); --------------------------------------- the error is 1>c:\program files (x86) \boost\boost_1_42\boost\numeric\ublas\matrix_expression.hpp(3809) : error C2825: 'F': must be a class or namespace when followed by '::' 1> c:\users\alex\desktop\testngage\testngage\testngage.cpp(21) : see reference to class template instantiation 'boost::numeric::ublas:: matrix_vector_binary2<E1,E2,F>' being compiled 1> with 1> [ 1> E1=boost::numeric::ublas::matrix_row<boost::numeric::ublas:: matrix<double>>, 1> E2=boost::numeric::ublas::matrix<double>, 1> F=double 1> ] 1>c:\program files (x86) \boost\boost_1_42\boost\numeric\ublas\matrix_expression.hpp(3809) : error C2039: 'result_type' : is not a member of '`global namespace'' 1>c:\program files (x86) \boost\boost_1_42\boost\numeric\ublas\matrix_expression.hpp(3809) : error C2146: syntax error : missing ';' before identifier 'value_type' 1>c:\program files (x86) \boost\boost_1_42\boost\numeric\ublas\matrix_expression.hpp(3809) : error C4430: missing type specifier - int assumed. Note: C++ does not support default- int 1>c:\program files (x86) \boost\boost_1_42\boost\numeric\ublas\matrix_expression.hpp(3810) : error C2146: syntax error : missing ';' before identifier 'const_reference' 1>c:\program files (x86) \boost\boost_1_42\boost\numeric\ublas\matrix_expression.hpp(3810) : error C4430: missing type specifier - int assumed. Note: C++ does not support default- int 1>c:\program files (x86) \boost\boost_1_42\boost\numeric\ublas\matrix_expression.hpp(3810) : error C4430: missing type specifier - int assumed. Note: C++ does not support default- int 1>c:\program files (x86) \boost\boost_1_42\boost\numeric\ublas\matrix_expression.hpp(3811) : error C2146: syntax error : missing ';' before identifier 'reference' 1>c:\program files (x86) \boost\boost_1_42\boost\numeric\ublas\matrix_expression.hpp(3811) : error C4430: missing type specifier - int assumed. Note: C++ does not support default- int 1>c:\program files (x86) \boost\boost_1_42\boost\numeric\ublas\matrix_expression.hpp(3811) : error C4430: missing type specifier - int assumed. Note: C++ does not support default- int 1>c:\users\alex\desktop\testngage\testngage\testngage.cpp(21) : error C2512: 'boost::numeric::ublas::matrix_vector_binary2<E1,E2,F>' : no appropriate default constructor available 1> with 1> [ 1> E1=boost::numeric::ublas::matrix_row<boost::numeric::ublas:: matrix<double>>, 1> E2=boost::numeric::ublas::matrix<double>, 1> F=double 1> ] 1>c:\users\alex\desktop\testngage\testngage\testngage.cpp(23) : error C2679: binary '=' : no operator found which takes a right-hand operand of type 'boost:: numeric::ublas::matrix_vector_binary2<E1,E2,F>' (or there is no acceptable conversion) 1> with 1> [ 1> E1=boost::numeric::ublas::matrix_row<boost::numeric::ublas:: matrix<double>>, 1> E2=boost::numeric::ublas::matrix<double>, 1> F=boost::numeric::ublas::matrix_vector_prod2<boost::numeric:: ublas::matrix_row<boost::numeric::ublas::matrix<double>>,boost::numeric::ublas:: matrix<double>,double> 1> ] 1> c:\program files (x86) \boost\boost_1_42\boost\numeric\ublas\matrix_expression.hpp(4075): could be 'boost::numeric::ublas::matrix_vector_binary2<E1,E2,F> &boost::numeric::ublas:: matrix_vector_binary2<E1,E2,F>::operator =(const boost::numeric::ublas:: matrix_vector_binary2<E1,E2,F> &)' 1> with 1> [ 1> E1=boost::numeric::ublas::matrix_row<boost::numeric::ublas:: matrix<double>>, 1> E2=boost::numeric::ublas::matrix<double>, 1> F=double 1> ] 1> while trying to match the argument list '(boost::numeric::ublas:: matrix_vector_binary2<E1,E2,F>, boost::numeric::ublas::matrix_vector_binary2<E1, E2,F>)' 1> with 1> [ 1> E1=boost::numeric::ublas::matrix_row<boost::numeric::ublas:: matrix<double>>, 1> E2=boost::numeric::ublas::matrix<double>, 1> F=double 1> ] 1> and 1> [ 1> E1=boost::numeric::ublas::matrix_row<boost::numeric::ublas:: matrix<double>>, 1> E2=boost::numeric::ublas::matrix<double>, 1> F=boost::numeric::ublas::matrix_vector_prod2<boost::numeric:: ublas::matrix_row<boost::numeric::ublas::matrix<double>>,boost::numeric::ublas:: matrix<double>,double> 1> ] where am I getting wrong?

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[MPL] searching a vector at runtime
by Alexander Lamaison 16 May '10

16 May '10

I'm trying to recursively traverse an MPL vector_c but I'm not sure what the base-case type should be. I want to pick a type from a mpl::vector at runtime and use it to dispatch a call to an overloaded function. Basically tag-dispatch with the tags being looked up in an MPL collection. The runtime value is an unsigned it so I just store unsigned ints in a vector_c. Then I want to traverse this vector and compare each item to the runtime value. If I find a match, I want to use it to call an overloaded function. Here's how I'm trying to do it so far: template<typename ID> class message { ... } template<typename Sequence> // MAP is a vector_c struct dispatcher { template<typename T> static result dispatch(T* obj, unsigned int message_id, int arg) { typedef boost::mpl::front<Sequence>::type head; typedef boost::mpl::pop_front<Sequence>::type tail; if (head::value == message_id) return obj->handle(message<head::value>, arg); else return dispatcher<tail>::dispatch(obj, message_id, arg); } }; template<> struct dispatcher<boost::mpl::void_> // WHAT SHOULD THIS TYPE BE? { template<typename T> static result dispatch(T* obj, unsigned int message_id, int arg) { return obj->default_message_handler(message_id, arg); } }; struct handler { result handle(message<MESSAGE1>) { /* do stuff 1 */ } result handle(message<MESSAGE2>) { /* do stuff 2 */ } result default_message_handler(unsigned int id, int arg) {} } I'm stuck on what to make the dispatcher base case which is reached when pop_front is called on a list with one item. At first I though the resulting type was void_ but apparently this doesn't match. I'm new to MPL. Can someone explain what I'm doing wrong here or if there's an altogether better way? Many thanks. Alex Lamaison

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