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[type_traits] is_convertible bug with gcc 4.3.0
by Terry G 09 Nov '08

09 Nov '08

I'm playing with move semantics (still/again). The following program compiles and runs fine with msvc8 but does not compile with gcc 4.3.0 when ENABLE_IS_CONVERTIBLE_CHECK is defined. Should it? The problem has something to do with U's copy constructor being private. I've inluded the compiler output below too. terry ============================================ #include <boost/type_traits.hpp> #include <boost/utility/enable_if.hpp> #include <cassert> template <typename T> class move_from { private: T* _source; public: explicit move_from(T& x) : _source(&x) { } T& get() const { return *_source; } }; // move_from #define ENABLE_IS_CONVERTIBLE_CHECK template <typename T> inline move_from<T> move(T& x #ifdef ENABLE_IS_CONVERTIBLE_CHECK , typename boost::enable_if< boost::is_convertible<move_from<T>, T> >::type* = 0 #endif ) { return move_from<T>(x); } template <typename T> class U { T* _ptr; public: void reset(T* p=0) { delete _ptr; _ptr = p; } T* release() { T* rval = _ptr; _ptr = 0; return rval; } U() : _ptr(0) { } U(T* x) : _ptr(x) { } U(move_from<U> x) : _ptr(x.get().release()) { } U& operator=(move_from<U> x) { reset(x.get().release()); } T* get() const { return _ptr; } T* operator->() const { return get(); } T& operator*() const { return *get(); } private: explicit U(const U&); U& operator=(const U&); }; // U int main() { U<int> x(new int(1234)); U<int> z(move(x)); // Seems to convert ok here. assert(*z == 1234); assert(!x.get()); return 0; } // main ============================================ In file included from c:/boost/boost/type_traits.hpp:38, from bug.cpp:1: c:/boost/boost/type_traits/is_convertible.hpp: In instantiation of ' const bool boost::detail::is_convertible_basic_impl< move_from<U<int> >&, U<int> >::value' : c:/boost/boost/type_traits/is_convertible.hpp:295: instantiated from ' const bool boost::detail::is_convertible_impl< move_from<U<int> >, U<int> >::value' c:/boost/boost/type_traits/is_convertible.hpp:418: instantiated from 'boost::is_convertible<move_from<U<int> >, U<int> >' c:/boost/boost/utility/enable_if.hpp:36: instantiated from 'boost::enable_if< boost::is_convertible<move_from<U<int> >, U<int> >, void >' bug.cpp:46: instantiated from here c:/boost/boost/type_traits/is_convertible.hpp:136: error: no matching function for call to 'U<int>::U(U<int>)' bug.cpp:34: note: candidates are: U<T>::U(move_from<U<T> >) [with T = int] bug.cpp:33: note: U<T>::U(T*) [with T = int] c:/boost/boost/type_traits/is_convertible.hpp:136: error: initializing argument 1 of ' static boost::type_traits::yes_type boost::detail::checker<T>::_m_check(T, int) [with T = U<int>]' from result of 'U<T>::U(move_from<U<T> >) [with T = int]'

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A lot of warnings with Boost.Filesystem
by ancode tran 08 Nov '08

08 Nov '08

Dear boosters, I got 25 warnings in total from "boost/filesystem/path.hpp" and "boost/filesystem/operations.hpp" about "comparison between signed and unsigned integer expressions". This is because the type of dot<Path>::value (and the likes, e.g slash<Path>::value) is char regardless of the type of Path::value_type, which is an unsigned integral type in case of wchar_t. Obviously, they are not errors but for me, these 25 warnings are too much and unfriendly. I hope this will be fixed in future version of Boost. Thank you for reading this. Best regards, An P.S: I use gcc(winxpsp2/linux) + boost 1.36.0 + stlport 5.1.6 --------------------------------- Đặt ngay địa chỉ email mới! Lấy ngay địa chỉ email bạn từng muốn có trước khi có người khác nhanh tay hơn!

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asio 10022 error
by Amit Sonawane 08 Nov '08

08 Nov '08

Hi, I am using boost 1.36.0 asio. I have to connect to several ip/ports within my application, asio successfully connects to some ips/ports while it throws an error with code 10022, "An invalid argument was supplied". In my case the ip/ports supplied are on the same ip i.e. same server. Any ideas what I could be doing wrong? Esta mensagem pode conter informação confidencial e/ou privilegiada. Se você não for o destinatário ou a pessoa autorizada a receber esta mensagem, não deverá utilizar, copiar, alterar, divulgar a informação nela contida ou tomar qualquer ação baseada nessas informações. Se você recebeu esta mensagem por engano, por favor avise imediatamente o remetente, respondendo o e-mail e em seguida apague-o. Agradecemos sua cooperação. This message may contain confidential and/or privileged information. If you are not the addressee or authorized to receive this for the addressee, you must not use, copy, disclose, change, take any action based on this message or any information herein. If you have received this message in error, please advise the sender immediately by reply e-mail and delete this message. Thank you for your cooperation.

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Concurrency and session termination in boost::asio
by Scott Gifford 08 Nov '08

08 Nov '08

Hello, I'm experimenting with boost::asio as the basis for communications and event handling for a network server. The server will support many clients, and should scale well to machines with multiple processors/cores, so I'd like to use thread pools to execute requests. I've done this by calling io_service.run() from multiple threads, which seems to be the normal way to do it. Each client session always has an asynchronous read operation waiting for new commands. If the server has a notification for a thread, it will send it by starting an asynchronous write on that session. Notifications can come at any time, not just in response to a request, so it is common for a session to simultaneously have oustanding asynchronous read and write requests. Sessions are terminated when the socket is closed or when the client sends a quit command. I'm trying to make sure that my handling of session termination is threadsafe. It seems that the normal way to handle this is to detect an error or end-of-file in an asynchronous event handler, then delete the object to end the session. Because my server is using a threadpool and waiting for both read and write events, it is possible for a read and write callback to be running concurrently on different CPUs. In that case, if one of those callbacks detects an error and deletes the object, the other will continue running using an invalid object. In a simple echo server I wrote to learn about boost::asio, I can see these invalid accesses when running under valgrind with a large number of clients, so unless I have made an error in my server, this appears to be a real problem. I rewrote it to have write errors handled by closing the session, which causes the read callback to run, notice the session has been closed, and delete the object. This seemed to solve the problem, but it still seems there is a potential problem if the read callback finishes deleting the object while the write callback is running. Is there a better way to handle session termination? Can I use io_service::strand to prevent this by having the readers and writers for the same session running in the same strand? Thanks for any thoughts! ----Scott.

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[trunk] Support for Intel-linux 11.0?
by Mikko Vainio 08 Nov '08

08 Nov '08

Dear boosters, Is someone out there working on fixes required for boost to work with the brand-new Intel Compiler v11.0 for linux? Should we users wait for a few days before start making tickets for the observed errors? Anyway, here's one to start with: /usr/local/include/boost/type_traits/is_class.hpp(129): error: namespace "boost" has no member "remove_cv" BOOST_TT_AUX_BOOL_TRAIT_DEF1( ^ Cheers, Mikko

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[signals2][review] The review of the signals2 library is scheduled to end on Monday, November 10th
by Stjepan Rajko 08 Nov '08

08 Nov '08

Hello, The review of the signals2 library is scheduled to end on Monday, November 10th. We have had some good discussion so far and a couple of reviews. I hope the remaining few days will provide enough time to others that were planning on submitting a review. If anyone needs any more discussion time or time to write the review, please let me know (so we can see about extending the review period, or so that I know to wait for your review longer). Kind regards, Stjepan

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[phoenix] another problem with member_variable bind
by Christian Henning 07 Nov '08

07 Nov '08

Hi there, I'm trying to multiply a factor to my probabilities by using the std::transform algorithm. But it results in a compiler error. #include <boost/spirit/include/phoenix_algorithm.hpp> #include <boost/spirit/include/phoenix_bind.hpp> #include <boost/spirit/include/phoenix_container.hpp> #include <boost/spirit/include/phoenix_core.hpp> #include <boost/spirit/include/phoenix_function.hpp> #include <boost/spirit/include/phoenix_fusion.hpp> #include <boost/spirit/include/phoenix_object.hpp> #include <boost/spirit/include/phoenix_operator.hpp> #include <boost/spirit/include/phoenix_scope.hpp> #include <boost/spirit/include/phoenix_statement.hpp> #include <boost/spirit/include/phoenix_stl.hpp> #include <algorithm> #include <iostream> #include <fstream> #include <vector> struct point { double _prob; double _x; }; int _tmain(int argc, _TCHAR* argv[]) { using namespace std; using namespace boost::phoenix; using namespace boost::phoenix::arg_names; vector< int > ints; // works std::transform( ints.begin() , ints.end() , ints.begin() , arg1 + 1 ); vector< point > points; // doesn't work std::transform( points.begin() , points.end() , points.begin() , bind( &point::_prob, arg1 ) * val( 2.0 ) ); return 0; } The error is: error C2679: binary '=' : no operator found which takes a right-hand operand of type 'double' (or there is no acceptable conversion) Regards, Christian

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receiver.cpp multicast example cannot receive messages on solaris 10
by jack240260＠hotmail.com 07 Nov '08

07 Nov '08

Hi: Just ask how you configure you receiver.cpp: listen_address? I used 0.0.0.0? As I even cannot receive message after sender.cpp add lines of outbount_interface option for socket. Thanks Jack

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Building Boost (python not found)
by Missing Rainbow 07 Nov '08

07 Nov '08

Hi All, While I try to build boost I got the following "python not found" error. Is this a problem? Or can I continue with the 'make' command? lotus 197 $ ./configure --with-toolset=sunpro --prefix=$b -n Building Boost.Jam with toolset sunpro... tools/jam/src/bin.solaris/bjam ./configure: python: not found -n Unicode/ICU support for Boost.Regex?... /usr Generating Boost.Build configuration in user-config.jam... Generating Makefile... lotus 198 $ python ksh: python: not found lotus 199 $ pwd /backup/dev_area/anna/boost/boost_1_37_0 lotus 200 $ Rgds, anna -- Two Party Fraud: Staged Presidential Debates http://missingrainbow.blogspot.com/2008/10/two-party-fraud-staged-president…

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Re: [Boost-users] question about threading library
by charles arthur 07 Nov '08

07 Nov '08

thank you for your quick reply. I now discover I need to build with'x64' and I've spent enough time in the documentation that I can figure that out. charles -----Original Message----- >From: Anthony Williams <anthony.ajw(a)gmail.com> >Sent: Nov 7, 2008 12:26 PM >To: boost-users(a)lists.boost.org >Subject: Re: [Boost-users] question about threading library > >"Robert Ramey" <ramey(a)rrsd.com> writes: > >> Thanks for this information. > >You're welcome. > >> I appreciate the effort you've put into this, and I have >> a lot of confidence in the library. But I feel it would be more >> useful to me and others if it were it to have a lot more tutorial type >> documentation and examples. > >You're not the only one who's mentioned that. I'll write some >tutorials when I get a chance. > >Anthony >-- >Anthony Williams >Author of C++ Concurrency in Action | http://www.manning.com/williams > >Custom Software Development | http://www.justsoftwaresolutions.co.uk >Just Software Solutions Ltd, Registered in England, Company Number 5478976. >Registered Office: 15 Carrallack Mews, St Just, Cornwall, TR19 7UL, UK > >_______________________________________________ >Boost-users mailing list >Boost-users(a)lists.boost.org >http://lists.boost.org/mailman/listinfo.cgi/boost-users

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