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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

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[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

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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

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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

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

08 Apr '12

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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

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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

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[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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