March 2011 - Boost-users - lists.preview.boost.org

[range] strange behaviour with range-based for loop and adaptors
by Nathan Ridge 12 Mar '11

12 Mar '11

Hello, I am experiencing some strange behaviour when using adaptors with a range-based for loop. Here's what I'm trying: #include <vector> #include <iostream> #include <boost/foreach.hpp> #include <boost/range/adaptor/transformed.hpp> std::vector<int> f() { return std::vector<int>{1, 2, 3, 4}; } int add1(int x) { return x + 1; } int main() { for (int i : f() | boost::adaptors::transformed(add1)) std::cout << i << ' '; std::cout << '\n'; } The output is 1 3 4 5, instead of the 2 3 4 5 that I would expect. Is there something funny going on with temporaries? Does the temporary returned by f() not stick around for the duration of the loop? Thanks, Nate.

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cyl_bessel_j performance
by Matwey V. Kornilov 12 Mar '11

12 Mar '11

Hi, cyl_bessel_j is several times slower than jn from glibc for me. What do I do wrong? Bessel function from boost.math seems to be pretty good coded and optimized but in a runtime it baffles me.

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[proto] Object got sliced when passed by reference
by Leon Sit 12 Mar '11

12 Mar '11

Hi all I have a class tree as the following template<typename T> struct base{ bool operator()(int i)const { return static_cast< const T&>(*this)(i); } }; struct F1:public base<F1>{ bool operator()(int i) const{ return true; } }; struct F2:public base<F2>{ bool operator()(int i) const{ return true; } }; struct F3 :public base<F3>{ std::string junk_; F3(std::string junk):junk_(junk){} bool operator()(int i) const{ std::cout << junk_ << std::endl; return false; } }; ================================================================== I am trying to use proto to derive the following systax Predicate<F1> f1; Predicate<F2> f2; Predicate<F3> f3("hodqhoqw"); cout << ((f1||f2)&&f3)(1) << endl; ================================================================== When proto get to the point of invoking the F3::operator(), the junk_ attribute got sliced away. I thought I am passing everything by constant reference but the exception tells me otherwise. The full sample code is attached, can someone tell me what I have missed? I am testing my code on vc9 and vc10, and I am not using virtual function for performance issue. Ultimately, I want to have the following syntax in the client code F1 f1; F2 f2; F3 f3("hodqhoqw"); cout << ((f1||f2)&&f3)(1) << endl; Thanks

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a question about boost::serialization
by 547880119 12 Mar '11

12 Mar '11

i am wondering how boost distinguish array and pointer serializatoin. although i have read the source code of boost. but i cannot understand it well. so, can anyone explain it to me ? thank you very much. Ps:I want to know how does is_pointer< T > work. ------------------ Hello, I'm HillBoREDy.

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Re: [Boost-users] [xint] a bug in operator>> (was: Boost.XInt formal review)
by Riccardo Murri 12 Mar '11

12 Mar '11

Hello, I wanted to do some testing of XInt for the review, so I thought I could try it with a gaussian elimination code that I'm working on. I only had a quick glance at the library; the documentation seems very clear and my code compiled fine with Boost.XInt at the first attempt, just by changing one typedef. I'd like to join Christofer Jefferson in his praise of the work done for making XInt easy to use. However, running it seemed to take forever. After a while I traced this down to the following bug: * a very simple I/O program that works with std integral types: $ cat a.cpp #include <iostream> int main(void) { int i; long x; while (not std::cin.eof()) { std::cin >> i >> x; std::cout << "Read i:" << i << ", x:" << x << std::endl; if (0 == i and 0 == x) break; }; return 0; } $ c++ a.cpp -I ~/sw/include/ $ ./a.out 1 2 Read i:1, x:2 0 0 Read i:0, x:0 * the same simple program fails and goes in a busy-loop cycle with XInt: $ cat a.cpp #include <iostream> #include <boost/xint/integer.hpp> int main(void) { int i; boost::xint::integer x; while (not std::cin.eof()) { std::cin >> i >> x; std::cout << "Read i:" << i << ", x:" << x << std::endl; if (0 == i and 0 == x) break; }; return 0; } $ c++ a.cpp -I ~/sw/include/ $ ./a.out 1 2 Read i:1, x:0 Read i:1, x:0 Read i:1, x:0 <repeats ad libitum in a busy loop> For the record, I've tried gcc 4.4.3 on Ubuntu 10.04, with Boost 1.45.0 plus XInt (from the .zip file). Unofrtunately, this prevented all my computational jobs from getting to do any number crunching (they have been stalled into the read cycle for hours before I noticed). I would like to see XInt accepted based on its simplicity of use, but in the event I really did not test anything in the library except compilation. Best regards, Riccardo

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How to print out the current machines time in extended ISO format
by Isaac Gerg 11 Mar '11

11 Mar '11

How do I do this using boost? The format I want is : %Y-%m-%d %H:%M:%S%F%Q I've messed around with this now for most of the afternoon and I can seem to get the %Q to be printed. The closest I've gotton is to use a hard coded time zone but I dont want this, I want the code to figure out the timezone for me. Thank you, Isaac

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Acsess boost::intrusive::list inside a map
by Dan Bloomquist 11 Mar '11

11 Mar '11

I would like to store lists inside a map value. I can: typedef /*boost::intrusive*/list< ClassBase > ClassList; typedef unordered_map< Unit*, ClassList> ClassMap; ClassList someList; And everything works fine, But: ClassMap someMap. And add to access the list: classMap[ pUnit ].push_back( aClass ); I get errors: Thanks, Dan. I get: 1>C:\cpp\boost_1_42_0\boost/intrusive/list.hpp(1478) : error C2248: 'boost::intrusive::list_impl<Config>::list_impl' : cannot access private member declared in class 'boost::intrusive::list_impl<Config>' 1> with 1> [ 1> Config=boost::intrusive::listopt<boost::intrusive::detail::base_hook_traits<CmdBase,boost::intrusive::list_node_traits<void *>,safe_link,boost::intrusive::default_tag,1>,unsigned int,true> 1> ] 1> C:\cpp\boost_1_42_0\boost/intrusive/list.hpp(117) : see declaration of 'boost::intrusive::list_impl<Config>::list_impl' 1> with 1> [ 1> Config=boost::intrusive::listopt<boost::intrusive::detail::base_hook_traits<CmdBase,boost::intrusive::list_node_traits<void *>,safe_link,boost::intrusive::default_tag,1>,unsigned int,true> 1> ] 1> This diagnostic occurred in the compiler generated function 'boost::intrusive::list<T>::list(const boost::intrusive::list<T> &)' 1> with 1> [ 1> T=CmdBase 1> ] 1>C:\cpp\boost_1_42_0\boost/intrusive/list.hpp(1478) : error C2248: 'boost::intrusive::list_impl<Config>::list_impl' : cannot access private member declared in class 'boost::intrusive::list_impl<Config>' 1> with 1> [ 1> Config=boost::intrusive::listopt<boost::intrusive::detail::base_hook_traits<CmdBase,boost::intrusive::list_node_traits<void *>,safe_link,boost::intrusive::default_tag,1>,unsigned int,true> 1> ] 1> C:\cpp\boost_1_42_0\boost/intrusive/list.hpp(117) : see declaration of 'boost::intrusive::list_impl<Config>::list_impl' 1> with 1> [ 1> Config=boost::intrusive::listopt<boost::intrusive::detail::base_hook_traits<CmdBase,boost::intrusive::list_node_traits<void *>,safe_link,boost::intrusive::default_tag,1>,unsigned int,true> 1> ] 1> This diagnostic occurred in the compiler generated function 'boost::intrusive::list<T>::list(const boost::intrusive::list<T> &)' 1> with 1> [ 1> T=CmdBase 1> ]

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Access violation when setting up a serial port
by Tangleman 11 Mar '11

11 Mar '11

This feels like it should be a very simple solution, but I'm very much a Boost newbie, and relearning C++. I'm trying to set up a serial port in a class constructor of a legacy program I am updating. The serial port and io_service definitions are in the header file. The class is MFC. Header file declarations: boost::asio::serial_port port; boost::asio::io_service io; Here is the class constructor: CCplusplus_TesterDlg::CCplusplus_TesterDlg(CWnd* pParent) : CDialog(CCplusplus_TesterDlg::IDD, pParent), port(io, "COM3") { m_hIcon=AfxGetApp()->LoadIcon(IDR_MAINFRAME); } If I comment out the port and io declaration and the port initialization from the constructor, I can pass the constructor fine in debug mode. However, if I leave them in, I get the following: First-chance exception at 0x771a6b90 in Cplusplus_Tester.exe: 0xC0000005: Access violation writing location 0xccccccd0. Unhandled exception at 0x771a6b90 in Cplusplus_Tester.exe: 0xC0000005: Access violation writing location 0xccccccd0. Debug mode breaks in win_mutex.hpp at line 56: ::EnterCriticalSection (&crit_section); Go ahead. Make me feel like an idiot. Any clues as to what I am doing wrong? Thanks! -- View this message in context: http://boost.2283326.n4.nabble.com/Access-violation-when-setting-up-a-seria… Sent from the Boost - Users mailing list archive at Nabble.com.

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fork() example asio 1_52_0
by Marco Piacentini 11 Mar '11

11 Mar '11

Hi...do you know what it means the parameters "_1" and "_2"? socket_.async_read_some(boost::asio::buffer(data_),boost::bind(&server::handle_read, this, _1, _2)); the complete example is: http://think-async.com/Asio/boost_asio_1_5_2/doc/html/boost_asio/example/fo…

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Re: [Boost-users] [ASIO] async_accept : Error m_val 1.
by Cyprien DIOT 11 Mar '11

11 Mar '11

Thank you for your help but it didn't change anything. After few hours working on this problem, i've fix it: In a new VS2010 project, with the same source code, this code works without any error in async_accept callback. Finally, i find out that it didn't work because i was using pragma lib in one of my file for managing windows services: #pragma comment (lib, "advapi32.lib") #pragma comment (lib, "user32.lib") When I removed this file, error disappears. Then, I put theses lib in project's configuration instead of using pragma and everything works! Although I don't understand the problem, it's now working. Thank you for your help Cyprien DIOT ----- Mail original ----- De: "Igor R" <boost.lists(a)gmail.com> À: boost-users(a)lists.boost.org Envoyé: Jeudi 10 Mars 2011 15:58:17 Objet: Re: [Boost-users] [ASIO] async_accept : Error m_val 1. > What is "already open" ? _client ? It has just been allocated before calling async_accept. > _io is properly initialized. > > If this error is about acceptor, how can I use it with async_accept ? I've seen http://www.boost.org/doc/libs/1_37_0/doc/html/boost_asio/reference/basic_so… but i don't see any line where the listen port is set to acceptor. Like Viatcheslav mentioned, set reuse_address option: http://think-async.com/Asio/boost_asio_1_5_2/doc/html/boost_asio/reference/… _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Re: [Boost-users] [Context] Mac OS X support?
by Julian Gonggrijp 10 Mar '11

10 Mar '11

Nat Linden wrote: > Anyway -- it seems likely to me that Boost.Context will support Mac OS > X 10.5+ "out of the box." I intend to check that. > > If it's important for Boost.Context to support Mac OS X <= 10.4, it > might be fairly straightforward to implement the Boost.Context API on > top of Pth. Reference [2] contains my macro-based attempt to establish > equivalences between the ucontext API and the Pth API. > > However, at this moment in history, one must ask how important it > still is to support Mac OS X <= 10.4? I'm completely ignorant about today's marketshare of Mac OS X 10.4, but I can tell you I'd rather like to see it supported for a while. Personally, I own an i686 machine with Mac OS X 10.6 and a PPC machine with Mac OS X 10.4. The latter is quite old and won't be able to pull anything more modern than 10.4. Therefore my only option for PPC testing is under Mac OS X 10.4. Since Apple's switch to x86 is historically close to the release of 10.5 this is probably true for more developers. Another, perhaps more general reason to support 10.4 is that, compared to both the older and the newer versions of Mac OS X it's still quite usable. I can't very well imagine anyone still using 10.3 but 10.4 doesn't seem strange. My (vague) impression is that some software suppliers still attempt to support 10.4 for this reason. Of course, both of these "arguments" could be easily overridden by some decent marketshare statistics. (Completely unrelated: hi, I'm Julian. This is my first post to the Boost users list.) (About equally related: what is the best way to reply to an existing thread? The instructions in the digest header don't seem to care much as long as you make sure that the subject field is correct. The Boost mailing lists website on the other hand suggests that one should rather not reply to digests at all and rather use per-message mailing or reply through the GMane web interface. Any opinions on this matter would be greatly appreciated.)

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Boost on MS Win 7 Mobile
by Hossein Haeri 10 Mar '11

10 Mar '11

Dear all, Is there any benchmarking regarding Boost material's performance on Win 7 Mobile? Which of the Boost libraries are known to be available basically on Win 7 Mobile and which aren't? What sort of porting effort do I need to undertake, if any? I would highly appreciate it if anyone on the list can provide advice/pointers regarding my above questions. TIA, --Hossein

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[Filesystem] v3 using wide url with boost::iostreams::mapped_file
by Bibbo, Joe 10 Mar '11

10 Mar '11

We recently flipped the switch from v2 to v3 of the boost file system. Now that boost:filesystem::wpath is no longer a valid type, how do you work with the wide url and boost:iostreams::mapped_file? With v2 we would void doSomethingWithMapfile(std::wstring& url) { boost::iostreams::basic_mapped_file_params<boost::filesystem::wpath> attribs; // initialize attribs, including attribs.path = url; // create our mapped file boost::iostreams::mapped_file mapFile(attribs); // An then do something with the map file. } Regards, Joe

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using bind with find_if
by Dennis Jones 10 Mar '11

10 Mar '11

Hello, I am currently using find_if with bind2nd to perform a search on a vector. My current code looks like this: struct OverrideMatches : public std::binary_function<const TItemOverride, const TItemOverride, bool> { bool operator()( const TItemOverride& OverrideSource, TItemOverride OverrideTarget ) const { return OverrideSource.ChildAssyItemRecNo == OverrideTarget.ChildAssyItemRecNo && OverrideSource.LinkItemRecNo == OverrideTarget.LinkItemRecNo; } }; TItemOverrideGateway::Container_t::iterator where = std::find_if( FOverridesContainer.begin(), FOverridesContainer.end(), std::bind2nd( OverrideMatches(), TItemOverride( "", 0, "", 0, ChildItemRecNo, LinkItemRecNo ) ) ); I would like to eliminate the need for that temporary object to hold the values I am searching for (and just specify the values instead), and to do that, I want to try using boost::bind instead of std::bind2nd, but I have not been able to determing exactly what that syntax would look like. I know I will need placeholders for the values to search on (ChildItemRecNo, LinkItemRecNo), but then how does the element from the vector get passed to the I think I want the functor to look something like this: struct OverrideMatches { bool operator()( const TItemOverride &OverrideSource, const RecNo_t ChildItemRecNo, const RecNo_t LinkItemRecNo ) { return OverrideSource.ChildAssyItemRecNo == ChildItemRecNo && OverrideSource.LinkItemRecNo == LinkItemRecNo; } }; If the above functor is correct (and maybe it's not, in which case, please correct me), how do I then rewrite std::find_if to use it with boost::bind? Thank you very much, Dennis Jones

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function_base.hpp type-punned pointer warnings
by KSpam 10 Mar '11

10 Mar '11

I get a ton of warnings (well over 5000 in the code base I am compiling) from function_base.hpp when compiling with gcc. boost-1.46.0/include/boost/function/function_base.hpp:321: warning: dereferencing type-punned pointer will break strict-aliasing rules boost-1.46.0/include/boost/function/function_base.hpp:325: warning: dereferencing type-punned pointer will break strict-aliasing rules This has been a known problem for a very long time, and the work around is quite simple. Replace reinterpret_cast<functor_type*>(&in_buffer.data)->~Functor(); with functor_type* p = reinterpret_cast<functor_type*>(&in_buffer.data); p->~Functor(); and replace reinterpret_cast<functor_type*>(&out_buffer.data)->~Functor(); with functor_type* p = reinterpret_cast<functor_type*>(&out_buffer.data); p->~Functor(); Would it be a reasonable request to have this simple patch applied to the boost source code? Respectfully, Justin

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min and max preferring NaN
by Rhys Ulerich 10 Mar '11

10 Mar '11

'Afternoon, The usual std::min and std::max prefer numbers over NaNs per http://en.wikipedia.org/wiki/IEEE_754_revision#min_and_max. POSIX's fmin(3) does as well. Can anyone suggest a better implementation (chained ternary complaints aside) for a NaN-preferring min or max than brute force things akin to template<class T> inline const T& minnan(const T& a, const T& b) { return UNLIKELY((boost::math::isnan)(a)) ? a : (a < b) ? a : b; } where UNLIKELY is a small macro telling the compiler to generate code expecting that the boost::math::isnan test fails? The need arises in a numerical simulation where I want to gradually accumulate a global minimum where throwing away NaNs ("windowing" in IEEE 754 revision-speak) is the unacceptable. Thanks, Rhys

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async_read_some/async_write_some
by Marco Piacentini 10 Mar '11

10 Mar '11

Hi...this is my question: are there the concatenation of these functions be considered like a multithread approach on a socket? I try to explain myself better... I need to have a behaviour like the following: inside a process, one thread read over a scoket, and one thread write over the same socket... is it possible to make the same beahviour simply create a chain of async_read and Async_write? or I have to handle the socket with lock-unlock mechanism? thank you...

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Re: [Boost-users] [ASIO] async_accept : Error m_val 1.
by Cyprien DIOT 10 Mar '11

10 Mar '11

Thank you for your answer. You're right, with message member function, I get the "Already open" error. I don't really understand it, my source code is: void Server::receiving() { boost::system::error_code error; tcp::endpoint endp(tcp::v4(), 14242); acceptor = new tcp::acceptor(_io); acceptor->open(endp.protocol()); acceptor->set_option(tcp::acceptor::reuse_address(true)); acceptor->bind(endp); acceptor->listen(); _client = new tcp::socket(_io); _client->close(); acceptor->async_accept(*_client, boost::bind(&ipc::handle_accept, this, boost::asio::placeholders::error)); } What is "already open" ? _client ? It has just been allocated before calling async_accept. _io is properly initialized. If this error is about acceptor, how can I use it with async_accept ? I've seen http://www.boost.org/doc/libs/1_37_0/doc/html/boost_asio/reference/basic_so… but i don't see any line where the listen port is set to acceptor. I'm sorry for my english which is not very good. Thank you ! ----- Mail original ----- De: "Igor R" <boost.lists(a)gmail.com> À: boost-users(a)lists.boost.org Envoyé: Jeudi 10 Mars 2011 00:42:24 Objet: Re: [Boost-users] [ASIO] async_accept : Error m_val 1. > m_val = 1; > m_cat = 0x00ab8d00 instance; > | [boost::asio::error::detail::misc_category] = {...} > | boost::noncopyable_::noncopyable = {...} > | __vfptr = 0x00a8bf18 const boost::asio::error::detail::misc_category::`vftable' Use message() member function of error_code to see the error description. IIUC, in your case it should be "Already open", i.e. you're trying to accept new connection to a socket which was already open. _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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[uBLAS] Predefined subrange or project
by Ryan 10 Mar '11

10 Mar '11

Is it possible to predefine a subrange or project with a specific range so that when called I only had to pass in the matrix? I'm currently dealing with several 9x9 matrices that I need to access the 3x3 submatrix (topleft, topmiddle, topright, etc.). Is there a way to typedef or templatize a subrange or project so that I just need to pass the 9x9 matrix and get the topleft matrix? Example: typedef subrange(input_matrix, 0, 3, 0, 3) topleft; //This is what I want to somehow define. matrix<double> A(9,9); topleft(A) = zero_matrix<double>(3,3); Ryan

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Re: [Boost-users] [ASIO] async_accept : Error m_val 1.
by Cyprien DIOT 10 Mar '11

10 Mar '11

I've made unit test for this problem. Server.h: #pragma once #include <boost/thread/thread.hpp> #include <boost/asio.hpp> #include <boost/array.hpp> #include <iostream> class Server { public: AssistGui(boost::asio::io_service &); ~AssistGui(void); void accept(const boost::system::error_code& e); void sendMsg(const char *msg, unsigned int size); private: boost::asio::io_service &io; boost::asio::ip::tcp::socket _client; boost::asio::ip::tcp::acceptor _acceptor; }; Server.cpp: #include "Server.h" using boost::asio::ip::tcp; Server::Server(boost::asio::io_service &ios) : io(ios), _client(ios), _acceptor(ios, tcp::endpoint(tcp::v4(), 14242)) { _acceptor.async_accept(_client, boost::bind(&Server::accept, this, boost::asio::placeholders::error)); } void Server::sendMsg(const char *msg, unsigned int size) { } Server::~Server(void) { } void Server::accept(const boost::system::error_code& e) { // same error :-( : "Already open" } int main() { boost::asio::io_service ios; Server s(ios); ios.run(); } The error is still the same "Already open". _WIN32_WINNT=0x0501 is defined. I tried to change port. No warnings at program compilation. Can you help me? Thank you Cyprien DIOT ----- Mail original ----- De: "Igor R" <boost.lists(a)gmail.com> À: boost-users(a)lists.boost.org Envoyé: Jeudi 10 Mars 2011 00:42:24 Objet: Re: [Boost-users] [ASIO] async_accept : Error m_val 1. > m_val = 1; > m_cat = 0x00ab8d00 instance; > | [boost::asio::error::detail::misc_category] = {...} > | boost::noncopyable_::noncopyable = {...} > | __vfptr = 0x00a8bf18 const boost::asio::error::detail::misc_category::`vftable' Use message() member function of error_code to see the error description. IIUC, in your case it should be "Already open", i.e. you're trying to accept new connection to a socket which was already open. _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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[Boost] [Interprocess] Use of Boost.Move in interprocess affecting causing compilation errors with 1.46
by Lars Hagstrom 10 Mar '11

10 Mar '11

Hi all, I'm having a problem compiling some code with boost 1.46 that was compiling fine with 1.36 to 1.43 (or thereabouts). It appears that this is somewhat related to the use of Boost.Move in the Boost.Interprocess library. I have tried to read up a bit on Boost.Move, but have failed to quite understand what of it applies to me. Here is a small piece of code that will cause the compilation error (explanations below): ---------------------- #include <boost/interprocess/ containers/vector.hpp> #include <boost/interprocess/containers/string.hpp> #include <boost/interprocess/managed_shared_memory.hpp> typedef boost::interprocess::basic_string < char, std::char_traits<char>, boost::interprocess::allocator < char, boost::interprocess::managed_shared_memory::segment_manager > > ShmString; class A { #if 0 public: A(const A&); A& operator=(const A&); #endif private: #if 1 ShmString m_name; #endif }; typedef boost::interprocess::vector < A, boost::interprocess::allocator < A, boost::interprocess::managed_shared_memory::segment_manager > > AVector; class B { public: void AddA(const A & a) {m_as.push_back(a);} private: AVector m_as; }; ---------------- g++ 4.4 compilation errors: ---------------- In file included from /usr/include/c++/4.4/memory:49, from /home/lars/boost_1_46_0/boost/interprocess/containers/container/vector.hpp:23, from /home/lars/boost_1_46_0/boost/interprocess/containers/vector.hpp:19, from mfp.cpp:1: /usr/include/c++/4.4/bits/stl_algobase.h: In static member function ‘static _OI std::__copy_move<false, false, std::random_access_iterator_tag>::__copy_m(_II, _II, _OI) [with _II = boost::container::constant_iterator<A, long int>, _OI = A*]’: /usr/include/c++/4.4/bits/stl_algobase.h:397: instantiated from ‘_OI std::__copy_move_a(_II, _II, _OI) [with bool _IsMove = false, _II = boost::container::constant_iterator<A, long int>, _OI = A*]’ /usr/include/c++/4.4/bits/stl_algobase.h:436: instantiated from ‘_OI std::__copy_move_a2(_II, _II, _OI) [with bool _IsMove = false, _II = boost::container::constant_iterator<A, long int>, _OI = A*]’ /usr/include/c++/4.4/bits/stl_algobase.h:468: instantiated from ‘_OI std::copy(_II, _II, _OI) [with _II = boost::container::constant_iterator<A, long int>, _OI = A*]’ /home/lars/boost_1_46_0/boost/interprocess/detail/move.hpp:1105: instantiated from ‘F boost::interprocess::copy_or_move(I, I, F, typename boost::disable_if<boost::interprocess::move_detail::is_move_iterator<I>, void>::type*) [with I = boost::container::constant_iterator<A, long int>, F = A*]’ /home/lars/boost_1_46_0/boost/interprocess/containers/container/detail/advanced_insert_int.hpp:53: instantiated from ‘void boost::container::containers_detail::advanced_insert_aux_proxy<T, FwdIt, Iterator>::copy_all_to(Iterator) [with T = A, FwdIt = boost::container::constant_iterator<A, long int>, Iterator = A*]’ mfp.cpp:46: instantiated from here /usr/include/c++/4.4/bits/stl_algobase.h:343: error: no match for ‘operator=’ in ‘* __result = __first.boost::container::constant_iterator<T, Difference>::operator* [with T = A, Difference = long int]()’ mfp.cpp:17: note: candidates are: A& A::operator=(A&) Which may not say too much, but if I change either the #if 0 to #if 1 or the #if 1 to #if 0 it suddenly compiles. So I'm thinking that the use of BOOST_MOVE_MACRO_COPYABLE_AND_MOVABLE(basic_string) in the interprocess string is somehow causing me to have to implement copy constructors and copy assignment operators in all classes that use them. Is this the way it is meant to be? I was fine with the compiler-generated ones before... Cheers Lars

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[lambda] How to write a lambda functor that returns a new functor
by Sebastian Theophil 10 Mar '11

10 Mar '11

Hi, How can I write a lambda expression with two placeholders, one for the callable object, and one for the function argument, such that supplying the callable object first returns a unary function? In the example below, generate should be a lambda expression with the first placeholder for the callable object itself, and the second placeholder for the argument. Calling generate(c) should return a unary function that is only missing the function call argument. In fact, it somehow returns type bool already, as proved by the static assert. #include <boost/lambda/bind.hpp> struct Arg { }; struct Callable : std::unary_function<Arg, bool> { bool operator()( Arg const& a ) const { return true; } }; int main( int argc, const char* argv[] ) { BOOST_AUTO(generate, boost::lambda::bind(boost::lambda::_1, boost::lambda::protect(boost::lambda::_1))); Callable c; BOOST_AUTO(fn, generate(c)); BOOST_STATIC_ASSERT((boost::is_same<BOOST_TYPEOF(fn), bool>::value)); Arg a; bool b = fn(a); _ASSERT(b==true); } Thanks, Sebastian -- Sebastian Theophil | stheophil(a)think-cell.com Senior Software Engineer think-cell Software GmbH | Chausseestr. 8/E | 10115 Berlin | Germany http://www.think-cell.com | phone +49 30 666473-10 | US phone +1 800 891 8091 Amtsgericht Berlin-Charlottenburg, HRB 85229 | European Union VAT Id DE813474306 Directors: Dr. Markus Hannebauer, Dr. Arno Schoedl

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boost::asio multiprocess
by Marco Piacentini 10 Mar '11

10 Mar '11

Hi guys...I would to make a simple multi process (not thread) server. I've seen the iterative example in which it handles one request at a time. Instead I need to handle more requests(more on less 10) at the same time. In the classic c and c++ examples, I've seen that the server is designed like the following: int listensd, connsd; // listening socket and conection socket pid_t pid; //process id listensd=socket(....); bind(listensd,...); listen(listensd,...); for(;;) { connsd=accept(listensd,...); if((pid=fork())==0) //child process { close(listensd); //close the listen socket do_it(connsd); //serve the request close(connsd); //close the connection socket exit(0); } close(connsd); //the parent closes the connection socket } Is it possible to do something like that with boost? I really don't know how obtain the two different socket, because in boost all the function (listen, bind, accept, etc.) return void. Thank you...

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program_options and BOOST_ALL_NO_LIB=1
by Gianni Ambrosio 10 Mar '11

10 Mar '11

Dear All, I have a simple test using program_options but even if I set BOOST_ALL_NO_LIB=1 the linker gives me errors. Any idea? Regards Gianni

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lambda::var( i )++
by er 10 Mar '11

10 Mar '11

Hello, Is there a variant of this int i = 0; lambda::var( i )++; in which I can do away with the external variable, i? In other words, a nullary functor that returns 0, 1, 2, successively? Thanks.

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