April 2012 - Boost-users - lists.preview.boost.org

[BLL] Problem with print vector elements.
by mik 12 Apr '12

12 Apr '12

Hi, I'm trying to use thew BLL for the first time and I've the following program: class Date { public: Date(long d): _lDate(d) {} long getDate() const { return _lDate; } [...] private: long _lDate; }; std::ostream& operator<<(std::ostream &s, const Date &x) { [...] } struct C { C(long d): date(d) {} Date date; }; int main() { const C c(46000); std::cout << boost::bind(&C::date, boost::lambda::_1)(c) << std::endl; std::vector<C> cont(1, C(46000)); std::for_each(cont.begin(), cont.end(), std::cout << boost::bind(&C::date, boost::lambda::_1)); return 0; } The first std::cout is ok. But for the second one nested int the for_each I get this message error: error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'boost::_bi::bind_t<R,F,L>' (or there is no acceptable conversion) with [ R=const Date &, F=boost::_mfi::dm<Date,C>, L=boost::_bi::list1<boost::arg<1>> ] C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\INCLUDE\ostream(653): could be 'std::basic_ostream<_Elem,_Traits> &std::operator <<<char,std::char_traits<char>>(std::basic_ostream<_Elem,_Traits> &,const char *)' [found using argument-dependent lookup] with [ _Elem=char, _Traits=std::char_traits<char> ] Can you help me? Thank you, Mirko **

2 2

boost arm compilation
by Bisegni Claudio 12 Apr '12

12 Apr '12

Hi all, i have some problem compiling boost on arm. i can compile package individually but when i use "install" i go segmentation fault after a some times. So i have compiled by every library and i have installed by handle all file. after that compiling my code with boost i got this error: /usr/local/include/boost/cstdint.hpp:104: error: '::int_least8_t' has not been declared /usr/local/include/boost/cstdint.hpp:105: error: '::int_fast8_t' has not been declared /usr/local/include/boost/cstdint.hpp:106: error: '::uint8_t' has not been declared /usr/local/include/boost/cstdint.hpp:107: error: '::uint_least8_t' has not been declared /usr/local/include/boost/cstdint.hpp:108: error: '::uint_fast8_t' has not been declared /usr/local/include/boost/cstdint.hpp:111: error: '::int_least16_t' has not been declared /usr/local/include/boost/cstdint.hpp:112: error: '::int_fast16_t' has not been declared /usr/local/include/boost/cstdint.hpp:113: error: '::uint16_t' has not been declared /usr/local/include/boost/cstdint.hpp:114: error: '::uint_least16_t' has not been declared /usr/local/include/boost/cstdint.hpp:115: error: '::uint_fast16_t' has not been declared /usr/local/include/boost/cstdint.hpp:118: error: '::int_least32_t' has not been declared /usr/local/include/boost/cstdint.hpp:119: error: '::int_fast32_t' has not been declared /usr/local/include/boost/cstdint.hpp:120: error: '::uint32_t' has not been declared /usr/local/include/boost/cstdint.hpp:121: error: '::uint_least32_t' has not been declared /usr/local/include/boost/cstdint.hpp:122: error: '::uint_fast32_t' has not been declared /usr/local/include/boost/cstdint.hpp:127: error: '::int_least64_t' has not been declared /usr/local/include/boost/cstdint.hpp:128: error: '::int_fast64_t' has not been declared /usr/local/include/boost/cstdint.hpp:129: error: '::uint64_t' has not been declared /usr/local/include/boost/cstdint.hpp:130: error: '::uint_least64_t' has not been declared /usr/local/include/boost/cstdint.hpp:131: error: '::uint_fast64_t' has not been declared /usr/local/include/boost/cstdint.hpp:135: error: '::intmax_t' has not been declared /usr/local/include/boost/cstdint.hpp:136: error: '::uintmax_t' has not been declared someone has some idea on how resolve this issue? thank in advanced

3 2

Prim's algorithm with custom weights?
by John asdf 11 Apr '12

11 Apr '12

I feel like I explain the problem well with my question on stackoverflow but it's not getting much response. http://stackoverflow.com/questions/10098437/c-boost-prims-algorithm-with-cu… If anyone can help I would greatly appreciate it.

2 1

[Variant] recursive_wrapper and ambiguous convert_construct()
by Florian Goujeon 11 Apr '12

11 Apr '12

Hello, I'm modelizing a syntax tree using boost::variant, std::tuple and std::vector. This syntax tree has a lot of cyclic dependencies, so I have to use boost::recursive_wrapper along with forward declarations. I've encountered a case that my compiler (GCC 4.7) refuses to build. Here is the source code: http://pastebin.com/3a5xU06x (it's pretty short) Here is the compilation error message: http://pastebin.com/Zpa3TCp2 (Of course, reordering the declarations would solve the problem in this example, but it's not the point. This is a constraint I can't get rid of in my whole project.) The compiler complains about an ambiguous call of convert_construct() in Boost's source code, where a comment says: NOTE TO USER : Compile error here indicates that the given type is not unambiguously convertible to one of the variant's types (or that no conversion exists). c can be converted to boost::recursive_wrapper<c_fwd> though. Where is the ambiguity? I really don't know what to do. Help would be appreciated. Thank you.

3 5

Two days left to save on BoostCon / C++Now! 2012
by Dave Abrahams 11 Apr '12

11 Apr '12

Just a quick reminder to everyone that early-bird registration closes at the end of this week. After Friday, the price goes up by $100. Spots are limited and registrations have been coming in faster than in past years. http://cppnow.org Cheers! -- Dave Abrahams BoostPro Computing http://www.boostpro.com

1 0

Boost.Locale: normalized concatenation?
by Narcoleptic Electron 11 Apr '12

11 Apr '12

I'm a happy user of boost.locale, but there is a use case that I can't see a solution for. I would like to concatenate two long, canonically normalized (NFC) UTF-8 strings. It seems that the only way to currently do this is by calling boost::locale::normalize on the resulting string. This is wasteful, as it requires walking the entire string when only a well-defined substring of each (at the boundary) can possibly require modification. The ideal solution would be for boost.locale to expose something like ICU's unorm2_normalizeSecondAndAppend, which takes advantage of normalization guarantees in the Unicode standard to only normalize the boundary where it is required. Does this capability already exist in boost.locale? Thanks.

2 2

Best practice for singletons?
by Chris Cleeland 11 Apr '12

11 Apr '12

There are many ways to skin the singleton cat. In fact, boost itself sports several--some publicly exposed, some in "detail". I'm wondering if any one or two of these might be considered to be the current state-of-the-art with regard to implementing a singleton. I can certainly "roll my own" as I've done in the past, but if I can stand on the shoulders of giants and since I already have an accepted dependency on boost, I definitely prefer that. I do not wish to engage in any religious wars regarding singletons--I'm aware that they have their evils. Thanks much! -- Chris Cleeland

2 2

memory leak with boost asio and openssl
by Paul Bergen 11 Apr '12

11 Apr '12

I've written an HTTP daemon (like Apache) with Boost that takes https connections with openssl. Everything is working fine, except that it's leaking memory. Valgrind shows the leak is always in the openssl functions, and the backtrace shows it always starts inside boosts architecture. The backtraces are something like (this is heavily cleaned up since they're huge): CRYPTO_malloc openssl_stream_service::ssl_wrap openssl_operation::async_read_handler boost_asio_handler_invoke_helpers::invoke strand_service::dispatch asio_handler_invoke task_io_service::do_one io_service::run thread_proxy start_thread clone In my code I have a single 'server' class, I have a single instance of boost::asio::ssl::context(_io_service,boost::asio::ssl::context::sslv23) which I setup one time in my server's constructor (setting use_certificate_chain_file, etc). I also have an boost::asio::io_service and a boost::asio::ip::tcp::acceptor. An instance of my Connection class is created for each inbound connection, and it has a boost ssl_socket, which gets the io_service and context (by reference). Naturally lots and lots of other code too, and it's all working. My Connection objects are properly deleted when the connection is done, and so is the boost ssl_socket. And I call ssl_socket::shutdown(ip::tcp::socket::shutdown_both, ec) before deleting the socket. But it seems that's not enough to free all the memory. Valgrind shows there are no stray copies of any of my objects or of any boost objects that I created. Just all these openssl calls that originate within the boost framework. What's very strange is that the number of allocations leaked doesn't correspond to the number of connections. If my app starts and exits with no connections, there are only some leaks in static constructors, which, from what I read, is a known bug in openssl. But after there is 1 connection, there are about 6 new leaks similar to that stack trace above. After there are 10 connections, there are 16 leaks. But after 40 connections, there are only 18 leaks. So the leaks grows gradually, but over time it does keep growing until my app runs out of memory. Anybody know what cleanup functions I might not be calling to free up the memory? Thanks.

1 0

[Interprocess] Collection of base shared_ptr
by Aaron_Wright＠selinc.com 11 Apr '12

11 Apr '12

I'm using Boost 1.49, and Visual Studio 10. I'm having a hard time figuring out how to store a shared_ptr to a derived class in a collection of shared_ptr to the base class. This is something I do all the time with normal shared pointers. This is my code: { struct Base {}; struct Derived : public Base {}; typedef boost::interprocess::managed_shared_ptr < Base, boost::interprocess::managed_shared_memory >::type Base_ptr; typedef boost::interprocess::deque < Base_ptr, boost::interprocess::managed_shared_memory::allocator< Base_ptr >::type > Queue; struct shm_remove { shm_remove() { boost::interprocess::shared_memory_object::remove("testing"); } ~shm_remove() { boost::interprocess::shared_memory_object::remove("testing"); } } remover; boost::interprocess::managed_shared_memory shared_memory( boost::interprocess::create_only, "testing", 65536); Queue* queue = shared_memory.construct< Queue >(boost::interprocess::anonymous_instance)( shared_memory.get_allocator< Base_ptr >()); queue->push_back( bi::make_managed_shared_ptr< Derived >( shared_memory.construct< Derived >(bi::anonymous_instance)(), shared_memory)); } The compiler tells me a bunch of cryptic stuff, I think it has to do with the different deleter types: boost/container/deque.hpp(1040): error C2664: 'boost::interprocess::shared_ptr<T,VoidAllocator,Deleter>::shared_ptr(const boost::interprocess::offset_ptr<PointedType,DifferenceType,OffsetType,OffsetAlignment> &,const VoidAllocator &,const Deleter &)' : cannot convert parameter 1 from 'const boost::interprocess::shared_ptr<T,VoidAllocator,Deleter>' to 'const boost::interprocess::offset_ptr<PointedType,DifferenceType,OffsetType,OffsetAlignment> &' 5> with 5> [ 5> T=Base, 5> VoidAllocator=boost::interprocess::allocator<void,boost::interprocess::segment_manager<char,boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>,boost::interprocess::iset_index>>, 5> Deleter=boost::interprocess::deleter<Base,boost::interprocess::segment_manager<char,boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>,boost::interprocess::iset_index>>, 5> PointedType=Base, 5> DifferenceType=ptrdiff_t, 5> OffsetType=size_t, 5> OffsetAlignment=0 5> ] 5> and 5> [ 5> T=Derived, 5> VoidAllocator=boost::interprocess::allocator<void,boost::interprocess::segment_manager<char,boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>,boost::interprocess::iset_index>>, 5> Deleter=boost::interprocess::deleter<Derived,boost::interprocess::segment_manager<char,boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>,boost::interprocess::iset_index>> 5> ] 5> and 5> [ 5> PointedType=Base, 5> DifferenceType=ptrdiff_t, 5> OffsetType=size_t, 5> OffsetAlignment=0 5> ] 5> Reason: cannot convert from 'const boost::interprocess::shared_ptr<T,VoidAllocator,Deleter>' to 'const boost::interprocess::offset_ptr<PointedType,DifferenceType,OffsetType,OffsetAlignment>' 5> with 5> [ 5> T=Derived, 5> VoidAllocator=boost::interprocess::allocator<void,boost::interprocess::segment_manager<char,boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>,boost::interprocess::iset_index>>, 5> Deleter=boost::interprocess::deleter<Derived,boost::interprocess::segment_manager<char,boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>,boost::interprocess::iset_index>> 5> ] 5> and 5> [ 5> PointedType=Base, 5> DifferenceType=ptrdiff_t, 5> OffsetType=size_t, 5> OffsetAlignment=0 5> ] 5> No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called 5> test.cpp(94) : see reference to function template instantiation 'void boost::container::deque<T,A>::push_back<boost::interprocess::shared_ptr<Derived,VoidAllocator,Deleter>>(const BOOST_MOVE_TEMPL_PARAM &)' being compiled 5> with 5> [ 5> T=Base_ptr, 5> A=boost::interprocess::allocator<Base_ptr,boost::interprocess::segment_manager<char,boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>,boost::interprocess::iset_index>>, 5> VoidAllocator=boost::interprocess::allocator<void,boost::interprocess::segment_manager<char,boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>,boost::interprocess::iset_index>>, 5> Deleter=boost::interprocess::deleter<Derived,boost::interprocess::segment_manager<char,boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>,boost::interprocess::iset_index>>, 5> BOOST_MOVE_TEMPL_PARAM=boost::interprocess::shared_ptr<Derived,boost::interprocess::allocator<void,boost::interprocess::segment_manager<char,boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>,boost::interprocess::iset_index>>,boost::interprocess::deleter<Derived,boost::interprocess::segment_manager<char,boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>,boost::interprocess::iset_index>>> 5> ] --- Aaron Wright

4 8

[boost::python] problems wrapping a base class
by Andy Falanga (afalanga) 10 Apr '12

10 Apr '12

HI, I'm working on exposing what should be a factory to create derived objects using the standard pattern for such a factory. In short, I have something like the following: Class Base { // some private member variables Public: Virtual void Func1() =0; Virtual void Func2(); }; Class Derv1 : public Base { // override Func1() // override Func2() }; Class BaseWrapper : public Base, boost::python::wrapper<Base> { Void Func1() { Get_override("Func1")(); } Void Func2() { If(boost::python::override func = get_override("Func2")) { Func(); Return; } Base::Func2(); } }; Base* Factory(int selector) { // return derived classes base on selector } BOOST_PYTHON_MODULE(myMod) { Class_<Derv1, bases<Base> >("Derived") .def("Func1", &Derived::Func1) .def("Func2", &Derived::Func2) ; Class_<BaseWrapper, boost::noncopyable>("BaseWrapper") .def("Func1", pure_virtual(&Base::Func1)) .def("Func2", &Base::Func2, &BaseWrapper::Func2) ; Def("Factory", Factory); } Everything compiles now but I'm getting the following error: RuntimeError: extension class wrapper for base class class Base has not been created yet This comes when I try to import this module into the python interpreter. What exactly am I missing? I'm following instructions from here: http://www.boost.org/doc/libs/1_48_0/libs/python/doc/tutorial/doc/html/pyth… Some references I've found from Google thus far suggest that the problem is with linking order. However, how to specify linking order when that is determined dynamically during build? (I'm using Visual Studio 2010) Any help is greatly appreciated. Thanks, Andy

1 0

boost.multi_index & IPC
by 陈海峰 10 Apr '12

10 Apr '12

typedef managed_shared_memory::allocator<char>::type char_allocator; typedef basic_string<char, std::char_traits<char>, char_allocator>shm_string; struct quote { public: int market; int kind; shm_string seccode; shm_string secname; float price; float zf; quote(int market_, int kind_, const char* seccode_, const char_allocator& a, const char* secname_, const char_allocator& b, float price_, float zf_): market(market_),kind(kind_), seccode(seccode_, a), secname(secname_, b), price(price_), zf(zf_) {} }; typedef boost::multi_index::composite_key<quote, BOOST_MULTI_INDEX_MEMBER(quote, int, market), BOOST_MULTI_INDEX_MEMBER(quote, shm_string, seccode) >comp_key_search; typedef boost::multi_index::composite_key_compare< std::greater<int>, std::greater<shm_string> >comp_key_compare_search; typedef boost::multi_index::composite_key<quote, BOOST_MULTI_INDEX_MEMBER(quote, float, price), BOOST_MULTI_INDEX_MEMBER(quote, int, market), BOOST_MULTI_INDEX_MEMBER(quote, shm_string, seccode) >comp_key_sortbyprice; typedef boost::multi_index::composite_key_compare< std::greater<float>, std::greater<int>, std::greater<shm_string> >comp_key_compare_sortbyprice; typedef boost::multi_index::multi_index_container< quote, boost::multi_index::indexed_by< boost::multi_index::ordered_non_unique<comp_key_search, comp_key_compare_search>, boost::multi_index::ordered_non_unique<comp_key_sortbyprice, comp_key_compare_sortbyprice> >, managed_shared_memory::allocator<quote>::type >quote_mic; int main() { /* struct shm_remove { shm_remove() { shared_memory_object::remove("MySharedMemory"); } ~shm_remove(){ shared_memory_object::remove("MySharedMemory"); } } remover; */ managed_shared_memory segment(open_only,"MySharedMemory"); quote_mic *quotes = segment.find_or_construct<quote_mic> ("My MultiIndex Container") //Container's name in shared memory ( quote_mic::ctor_args_list(), //, segment.get_allocator<quote>()); //Ctor parameters quote_mic::allocator_type(segment.get_segment_manager())); quote_mic::nth_index<0>::type& idx_search = quotes->get<0>(); quote_mic::nth_index<1>::type& idx_sortbyprice = quotes->get<1>(); int count = 0; char_allocator ca1(segment.get_allocator<char>()); // 查询股票实时行情 shm_string seccode("600000", ca1); count = idx_search.count(boost::tuples::make_tuple(1, seccode)); quote_mic::nth_index<0>::type::iterator it = idx_search.find(boost::tuples::make_tuple(1, seccode)); for (int i=0; i<count; i++) { std::cout << it->seccode << std::endl; it++; } std::vector<quote> result; BOOST_FOREACH(const quote& q, idx_sortbyprice) { int kind = q.kind; if (kind == 1 || kind == 11) { // std::cout << "市场" << q.market << ",类别" << q.kind << ", " << q.secname << ",最新价" << q.price << std::endl; result.push_back(q); this statement will compile error, why? how to write? } else { // std::cout << "过滤：市场" << q.market << ",类别" << q.kind << ", " << q.secname << ",最新价" << q.price << std::endl; } } return 0; }

3 3

boost serialization skip a node
by ujoimro 10 Apr '12

10 Apr '12

Hello, I am working on a config file format, which is a collection of several xml "config file" classes. I would like to save them in a single file like this: oarchive << NVP(filters); oarchive << NVP(processor); oarchive << NVP(segmentation); However, it does make sense te use the "processor" class without the filters or the segmentation. Is there a simple way to skip some nodes in Boost.Serialization.XML? Or to refer to nodes by their name? iarchive >> NVP(processor); Thank You for Your help, LM

1 0

Including Boost 1.48.0 "qi.hpp" header file
by devika R S 10 Apr '12

10 Apr '12

Hi All, This post is regarding the issue we saw on IBM compiler using BOOST 1.48 version. Here is the sample code where we are trying to just include the header file "boost/spirit/include/qi.hpp>". *********************************Example Code************************************* #include <iostream> #include <boost/spirit/include/qi.hpp> main() { using namespace std; std::cout<<"test"<<"\n"; } *********************************END************************************************** When we compile this code on IBM with the compiler* : IBM XL C/C++ for AIX, V11.1 (5724-X13) Version: 11.01.0000.0000 *we end up with below error: xlC -I /usr/include/boost/1_48_0 -o dump test_prog.cpp - *xlC: 1501-230 (S) Internal compiler error; please contact your Service Representative. For more information visit:* - *http://www.ibm.com/support/docview.wss?uid=swg21110810* But this code works absolutely fine on g++ Linux. Looks like the inclusion of this header file on IBM platform is causing the issue. Is this is a known bug ?Is any patch available ? Thanks, Abc

2 1

problems with Boost.Thread on VS10
by John M. Dlugosz 10 Apr '12

10 Apr '12

I'm trying to use a packaged_task, and get an error on creation. template<typename R,typename F> struct task_object: task_base<R> { F f; task_object(F const& f_): // << refers to look here f(f_) {} #ifndef BOOST_NO_RVALUE_REFERENCES task_object(F&& f_): // <<<< Error here f(f_) {} E:\boost_1_49\boost/thread/future.hpp(1251): error C2535: 'boost::detail::task_object<R,F>::task_object(F)' : member function already defined or declared with [ R=size_t, F=std::tr1::_Bind<size_t,size_t,std::tr1::_Bind1<std::tr1::_Callable_fun<size_t (__cdecl *const )(std::string &),false>,const char *>> & ] E:\boost_1_49\boost/thread/future.hpp(1247) : see declaration of 'boost::detail::task_object<R,F>::task_object' with [ R=size_t, F=std::tr1::_Bind<size_t,size_t,std::tr1::_Bind1<std::tr1::_Callable_fun<size_t (__cdecl *const )(std::string &),false>,const char *>> & ] So I'm thinking that VS10 (Microsoft Visual Studio 2010) has problems overloading the constructor with (T const&) and (T&&) ? But shouldn't someone have noticed that long ago? Any ideas here? Thanks, —John

4 16

[Boost.Thread] unique_future without && ?
by John M. Dlugosz 09 Apr '12

09 Apr '12

My code needs to be compatible with a platform that doesn't have rvalue references available, for the time being. I've avoided explicit uses of move and made my && arguments fall back to const&. But I'm not sure about returning a unique_future. I see that unique_future<T> has a special move-the-guts type, with an implicit conversion operator and a constructor. But do I need to do anything special to declare a function returning one, and likewise the return statement itself? The code in packaged_task ( unique_future<R> packaged_task<R>::get_future() ) is not conditionally compiled based on BOOST_NO_RVALUE_REFERENCES, so I'm supposing that it just works by itself. Is that correct? But maybe it only works by itself in some cases? In that code, the return statement names a constructor directly. return unique_future<R>(task); In my code, I'm returning a unique_future that I already made somewhere else (actually, the result of another function call) so it would be wanting to call the copy constructor, I would think. So if I write unique_future<int> foo(); unique_future<int> bar() { return foo(); } what _should_ happen is that the existing value uses a user-defined conversion to construct the "copy", right? So I should expect this to work correctly if the thing I'm returning is already exactly the right type, as well as when naming the constructor directly. —John

3 8

split_iterator not working with a reference to const std::string
by asif saeed 09 Apr '12

09 Apr '12

Hi, Here is my code: struct CharIterator { CharIterator( const std::string &s, char_t const *delimiters) : s_(s), begin_(boost::algorithm::split_iterator<std::string::iterator>(s, boost::token_finder(boost::is_any_of(delimiters), boost::token_compress_off))), end_(boost::algorithm::split_iterator<std::string::iterator>()), i_(begin_) { } const std::string s_&; boost::algorithm::split_iterator<std::string::iterator> begin_, end_, i_; }; The compile gives me an error on parameter 1 of the above constructor. It compiles fine if I change "const std::string &s" to "std::string s" - that is, pass by value. I just want to store a reference to a string. Could you help me on this? Best regards, Asif

2 1

Clang "blocks" and function<>
by John M. Dlugosz 08 Apr '12

08 Apr '12

I wonder if there is anything already in Boost's implementation of the function template (that is exposed as std::tr1::function if you use Boost.TR1) that allows Clang's lambda-like "blocks" to be assigned to a function? Or, has anyone already fiddled with that and willing to share? —John reference: http://clang.llvm.org/docs/BlockLanguageSpec.txt

1 0

C++ Now! Early Bird Registration Ending Soon
by Jon Kalb 08 Apr '12

08 Apr '12

The fifteenth of this month is the end of Early Bird registration. Register by the end of next week to reserve your place and save on registration. Featuring 3 keynote speakers headlining 3 tracks of 50+ session brought to by 35+ presenters, this year¹s conference is our largest and most ambitious. What isn¹t bigger is the registration fee. If you beat the April 15th deadline you can enjoy the conference offering the most complete C++11 tutorial coverage of the year and save money too. See you in Aspen! Registration: http://cppnow.eventbrite.com/?ref=ecount Jon

1 0

mpl documentation question
by Robert Ramey 07 Apr '12

07 Apr '12

Documentation for mpl::less<T> has the following section: Expression semantics For any Integral Constants c1 and c2: typedef less<c1,c2>::type r; Return type:Integral Constant. Semantics:Equivalent to typedef bool_< (c1::value < c2::value) > r; typedef less<c1,c2> r; // a Return type:Integral Constant. Semantics:Equivalent to struct r : less<c1,c2>::type {}; //b if //a is used then the following yields bool_<true> is_same< less<c1, c2>, r> if // b is used then the following yields bool_<false> is_same< less<c1, c2>, r> So in what sense are //a and // b equivalent? Robert Ramey

3 6

Is boost::asio::io_service thread safety?
by 文凯 07 Apr '12

07 Apr '12

My code like this: #include <iostream> #include <map> #include <boost/asio.hpp> #include <boost/bind.hpp> #include <boost/thread.hpp> #include <boost/date_time/posix_time/posix_time.hpp> namespace ba = boost::asio; namespace bp = boost::posix_time; typedef std::map<int, ba::deadline_timer*> timer_map; timer_map g_timers; boost::mutex g_timers_lock; ba::io_service g_ios; void on_timer(int id) { { boost::mutex::scoped_lock lock(g_timers_lock); timer_map::iterator it = g_timers.find(id); assert(it != g_timers.end()); g_timers.erase(id); } // std::cout << "delete timer " << id << std::endl; } int main(void) { boost::thread trd(boost::bind(&ba::io_service::run, &g_ios)); trd.detach(); int count = 0; for (;;) { for (int i = 0; i < 100; i++) { ba::deadline_timer* pt = new ba::deadline_timer(g_ios, bp::seconds(1)); pt->async_wait(boost::bind(&on_timer, count)); boost::mutex::scoped_lock lock(g_timers_lock); g_timers.insert(std::make_pair(count++, pt)); } usleep(20000); } return 0; } ================================== I know, I should lock the g_timers, but should I lock the g_ios? I mean these lines: ba::deadline_timer* pt = new ba::deadline_timer(g_ios, bp::seconds(1)); pt->async_wait(boost::bind(&on_timer, count)); Are thread safety? It reference the g_ios, and will it call g_ios.add_job(this_timer) ..etc.. ? -- Cheers & KaiWen

2 1

[regex] fails to work with ICU
by valery O 07 Apr '12

07 Apr '12

Hi, I cannot make boost :: regex and ICU work together. I installed icu4c 4_8_1_1 in /usr/local, then boost_1_49_0 libraries, in /usr/local/boost. I used bjam with "-sHAVE_ICU=1". It built successfully with a message "-has_icu builds: yes". So it means boost libraries found icu, and can use it. But it wouldn't. If I add header #include"boost/regex/icu.hpp" to file main.cpp ( In Xcode ) and compile, I receive 451 errors beginning with: > >> /usr/local/boost_1_49_0/boost/regex/icu.hpp:22:28: error: >> unicode/utypes.h: No such file or directory > > /usr/local/boost_1_49_0/boost/regex/icu.hpp:23:27: error: unicode/uchar.h: >> No such file or directory > > /usr/local/boost_1_49_0/boost/regex/icu.hpp:24:26: error: unicode/coll.h: >> No such file or directory > > In file included from >> /Users/spaset/Documents/Myprograms/MarcoPolo77OLD/main.cpp:10: > > /usr/local/boost_1_49_0/boost/regex/icu.hpp:44: error: 'UChar32' does not >> name a type > > /usr/local/boost_1_49_0/boost/regex/icu.hpp:46: error: 'char_type' was not >> declared in this scope > > /usr/local/boost_1_49_0/boost/regex/icu.hpp:46: error: template argument 1 >> is invalid > > > If I open file /usr/local/boost_1_49_0/boost/regex/icu.hpp I got the similar messages: > unicode/utypes.h: No such file or directory > > unicode/uchar.h: No such file or directory > > unicode/coll.h: No such file or directory > > > So /usr/local/boost_1_49_0/boost/regex/icu.hpp does not see unicode > headers > in /usr/local/include/unicode, even though bjam says "- has_icu builds: > yes". > Can someone tell me what is wrong? > Thanks a lot for help! > > My details: > Mac OSX 10.6.8 > IDE - Xcode 3.2 > > egersheldster. > >

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Cray C++ compiler errors
by Nico Schlömer 07 Apr '12

07 Apr '12

Hi all, has anyone succeeded in compiling Boost with the Cray C++ compiler? I'm using Boost 1.47.0 and get error messages of the type ====================== *snip* ====================== CC-439 crayc++: ERROR File = /usr/common/usg/boost/1.47.0/include/boost/type_traits/is_rvalue_reference.hpp, Line = 21 A greater-than character (">") is expected. BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC1_1(typename T,is_rvalue_reference,T&&,true) ^ ====================== *snap* ====================== and ====================== *snip* ====================== CC-40 crayc++: ERROR File = /usr/common/usg/boost/1.47.0/include/boost/type_traits/add_rvalue_reference.hpp, Line = 46 An identifier is expected. typedef T&& type; ^ ====================== *snap* ====================== All hints appreciated. Cheers, Nico

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[preprocessor] having trouble using reentrant macros
by Rob Desbois 07 Apr '12

07 Apr '12

I'm unable to use the reentrant macros for iteration currently..I think I'm probably misunderstanding their usage, and a push in the right direction would be much appreciated. My need is to iterate through a sequence, then iterate through a sequence nested within each element. As I understand, I should be able to call (e.g.): * BOOST_PP_SEQ_FOR_EACH(OP, data, seq) to iterate through the outer sequence * then in OP(r, data, elem) call BOOST_PP_SEQ_FOR_EACH_R(r, OP2, data, elem) For me this keeps producing rubbish with a lot of non-expanded macro names embedded. I've reduced this down to a minimal example iterating over a 2-dimensional sequence; I know the final line isn't valid C++, I'm just checking preprocessing results at this stage. #include <boost/preprocessor/seq/transform.hpp> #define INNER(s, data, elem) <elem> #define MIDDLE(s, data, seq) BOOST_PP_SEQ_TRANSFORM_S(s, INNER, data, seq) #define OUTER(seqseq) BOOST_PP_SEQ_TRANSFORM( MIDDLE, _, seqseq) outer gives: OUTER( ((a) (b) (c)) ((i) (j) (k)) ((x) (y) (z)) ) Resultant output of this, with preprocessor line directives and empty lines removed, is: outer gives: ( BOOST_PP_SEQ_TAIL_I BOOST_PP_TUPLE_ELEM_3_2 BOOST_PP_SEQ_TRANSFORM_O(5, BOOST_PP_SEQ_TRANSFORM_O(4, BOOST_PP_SEQ_TRANSFORM_O(3, ( INNER , _, (nil)), a), b), c)) ( BOOST_PP_SEQ_TAIL_I BOOST_PP_TUPLE_ELEM_3_2 BOOST_PP_SEQ_TRANSFORM_O(6, BOOST_PP_SEQ_TRANSFORM_O(5, BOOST_PP_SEQ_TRANSFORM_O(4, ( INNER , _, (nil)), i), j), k)) ( BOOST_PP_SEQ_TAIL_I BOOST_PP_TUPLE_ELEM_3_2 BOOST_PP_SEQ_TRANSFORM_O(7, BOOST_PP_SEQ_TRANSFORM_O(6, BOOST_PP_SEQ_TRANSFORM_O(5, ( INNER , _, (nil)), x), y), z)) For reference, I am using the following: boost 1.46.00 g++ (GCC) 4.6.3 20120306 (Red Hat 4.6.3-2) TIA --rob

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[MSM] multiple visitors / signatures, and visitors by ref in submachines
by Albert Gil Moreno 06 Apr '12

06 Apr '12

Hi, I think that the visitors and the flags ideas of the MSM are very generic and easy to use. So, great! But, there is a way to define multiple visitors for a single state (base)? I think that it is not possible because the visitors mechanism is based on a "simple/single typedef" and not on an "listed typedef"... isn't it? So, why the visitors are not like flags? I mean, why not to use an "accept_sig_list" instead of a single "accept_sig"? Why is not possible a code like the following: struct my_visitable_state { typedef mpl::vector< args<void, VisitorType1&>, args<void, VisitorType2&> > accept_sig_list; void accept(VisitorType1&) const {} void accept(VisitorType2&) const {} }; By the way... I think that the usage of boost::ref() is not propagated to the submachines...? I've found that when my state machine is also in a submachine, the visitor of the state machine is passed by reference, but the submachine is passed always by value... is this a bug? (just using a pointer solved my needs, so just to report...) Thanks, Albert

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[MSM] state transitions and exceptions
by Stephan Menzel 06 Apr '12

06 Apr '12

Everyone, I did just get around to give the MSM a first shot and I have say I am impressed at the neat design, the ease of use, "understandability", tutorial ... exceptional work. Really great and it helped me a great deal so far. So thanks a bunch for this teriffic addition to boost. That's the kind of stuff I love boost for. There is one question however that puzzles me. How can / do I prevent state transistions when a transition function throws? Most transition functions are defined like that: void so_transition(event::Cause const &e) { methodCausingAnException(); } The tutorial only mentions this at the very end of the back-end docs and this is not clear to me. I have stuff inside my transitions that may throw and the example text mentiones other valid examples (like connect() logic). So what am I supposed to do here? This? void so_transition(event::Cause const &e) { try { methodCausingAnException(); } catch (const std::exception &sex) { return ??? } } The type is void and I can't return anything that would prevent the transition. Or should I just let the exception pass? What is the correct way? Suggestions are appreciated, Stephan

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