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

[type_traits] will the future has_operator_left_shift be able to test if a type is serializable to a stream ?
by Mathieu Champlon 06 Feb '11

06 Feb '11

Hello, I just tried the type_traits extension from the sandbox : http://svn.boost.org/svn/boost/sandbox/type_traits (by the way the source files are indented with tabs) Simply including for instance <boost/type_traits/has_operator_left_shift.hpp> on vc80 and vc100 yields : boost/type_traits/detail/has_binary_operator.hpp(80) : warning C4346: 'boost::is_class<boost::remove_reference<T>::type>::value' : dependent name is not a type prefix with 'typename' to indicate a type boost/type_traits/detail/has_binary_operator.hpp(142) : see reference to class template instantiation 'boost::has_operator_left_shift<LHS,RHS,RET>' being compiled boost/type_traits/detail/has_binary_operator.hpp(80) : error C2146: syntax error : missing ')' before identifier 'or' boost/type_traits/detail/has_binary_operator.hpp(142) : error C2039: 'value' : is not a member of '`global namespace'' boost/type_traits/detail/has_binary_operator.hpp(142) : error C2059: syntax error : ')' boost/type_traits/detail/has_binary_operator.hpp(142) : error C2143: syntax error : missing ';' before '{' boost/type_traits/detail/has_binary_operator.hpp(142) : fatal error C1004: unexpected end-of-file found It compiles fine on cygwin with gcc 3.4.4 though. I spent a few minutes trying to pinpoint the exact location of the error without much success (got lost in the macros). I'm using boost 1.42. Anyway, it seems that nothing in the documentation indicates the new traits are limited to numeric types. Moreover it sort of works for testing if a type is serializable to an std::ostream : BOOST_STATIC_ASSERT(( boost::has_operator_left_shift< std::ostream, int >::value )); And it also works for far more advanced cases (like a type convertible to another type which is serializable, or a class deriving from another class which is serializable, etc..) However it doesn't work with a pointer type, for instance this fails : BOOST_STATIC_ASSERT(( boost::has_operator_left_shift< std::ostream, void* >::value )); Will this use case be supported ? Thanks, MAT.

4 14

MPFR in Boost 1.45.0
by Novak Elliott 05 Feb '11

05 Feb '11

Hi, I searched the boost mailing list archives on MPFR and the last query was in Feb 2010 so I think this may be worth a new thread. I'm interested in using MPFR (C library for multiple-precision floating-point computations with *correct rounding - *http://www.mpfr.org/) with some of the boost math libraries (vectors, matrices). Support is available to do this via the bindings in boost/math/bindings/mpfr.hpp<http://www.boost.org/doc/libs/1_45_0/boost/math/bindings/mpfr.hpp>. As per the documentation ( http://www.boost.org/doc/libs/1_45_0/libs/math/doc/sf_and_dist/html/math_to… ): "In order to use these bindings you will need to have installed MPFR plus it's dependency the GMP library and the C++ wrapper for MPFR known as gmpfrxx (or mpfr_class)." However, when compiling the example listed in the documentation: #include <boost/math/bindings/mpfr.hpp> #include <boost/math/special_functions/gamma.hpp> int main() { mpfr_class::set_dprec(500); // 500 bit precision // // Note that the argument to tgamma is an expression template, // that's just fine here: // mpfr_class v = boost::math::tgamma(sqrt(mpfr_class(2))); std::cout << std::setprecision(50) << v << std::endl; } I get a large number of compile errors (attached). I do have GMP, MPFR and gmpfrxx installed, although to get the gmpfrxx example to work (source: example.cpp) I had to comment out the reference to GMP_RND_MAX as this enumerated type value, present in MPFR version 2.4.2, has been removed from mpfr.h from version 3.0.0. Does anyone have any experience is getting boost 1.45.0 running with MPFR 3.0.0? I'm wondering whether this an MPFR problem, a boost bindings problem, or both. cheers, Novak.

3 5

interprocess_condition::wait(scoped_lock<interprocess_upgradable_lock> &) missing
by John Ky 05 Feb '11

05 Feb '11

Hi boost users, I've discovered that the following doesn't compile. using namespace boost::interprocess; interprocess_upgradable_mutex mutex; interprocess_condition cv; boost::posix_time::ptime deadline; { scoped_lock<interprocess_upgradable_mutex> lock(mutex); sharable_lock<interprocess_upgradable_mutex> lock2(mutex); cv.wait(lock); // doesn't compile cv.timed_wait(lock, deadline); // doesn't compile. } It is failing because boost doesn't define the following methods: void interprocess_condition::do_wait(interprocess_upgradable_mutex &mut); bool interprocess_condition::do_timed_wait(const syssrv_boost::posix_time::ptime &abs_time, interprocess_upgradable_mutex &mut); I was thinking of making a basic implementation like so: Define a scoped_unlock class, which behaves just like scoped_lock except the constructor unlocks and the destructor locks. Then define the following: inline void interprocess_condition::do_wait(interprocess_upgradable_mutex &mut) { scoped_unlock<interprocess_upgradable_mutex> unlock(mut); interprocess_mutex &internal_mutex = mut.m_mut; scoped_lock<interprocess_mutex> internal_lock(internal_mutex); this->wait(internal_lock); } inline bool interprocess_condition::do_timed_wait (const syssrv_boost::posix_time::ptime &abs_time, interprocess_upgradable_mutex &mut) { scoped_unlock<interprocess_upgradable_mutex> unlock(mut); interprocess_mutex &internal_mutex = mut.m_mut; scoped_lock<interprocess_mutex> internal_lock(internal_mutex); return this->timed_wait(internal_lock, abs_time); } These functions simply do the following: - unlock the exclusive lock on the interprocess_upgradable_mutex (which is emulated with an internal interprocess_mutex) - then lock the internal interprocess_mutex - Call interprocess_condition::wait or interprocess_condition::time_ wait on the implementation lock which does all the work - unlock the internal interprocess_mutex - relock the exclusive lock on the interprocess_upgradable_mutex Intuitively, this should work. Is there anything I missed that would make this an incorrect implementation? Cheers, -John

3 10

Boost asio question
by Claude 04 Feb '11

04 Feb '11

Hi, it is possible obtain a Socket (boost::asio::ip::tcp::socket) from an acceptor object? This is my problem: I use the accept() method of acceptor for wait on a connection. But, in java, the method accept() of ServerSocket class return a socket object and I can pass this reference to a thread that handles it and I can continue to accept() in main program. It is possible obtain this behavior with asio? -- View this message in context: http://boost.2283326.n4.nabble.com/Boost-asio-question-tp3255518p3255518.ht… Sent from the Boost - Users mailing list archive at Nabble.com.

2 3

[BOOST::XPRESSIVE] Trouble with functor in regex
by Norbert Hauck 04 Feb '11

04 Feb '11

Hi, I'm tinkering around with xpressive but have run into a problem. Warning: I'm rather unprofessionnal as a programmer so I might have overlooked something very simple - please bear with me! ------Code-----Code------- #include "stdafx.h" #include <boost/xpressive/xpressive_static.hpp> #include <boost/xpressive/regex_actions.hpp> #include <boost/xpressive/regex_primitives.hpp> #include <string> #include <iostream> using namespace boost::xpressive; class DateVerify_Impl { public: typedef int result_type; int operator()(const std::string& cap,wchar_t* pdate)const //val references currdate { int yy = (cap[0]-'0')*1000 + (cap[1]-'0')*100 + (cap[2]-'0')*10 + (cap[3]-'0'); int mm = (cap[5]-'0')*10 + (cap[6]-'0'); int dd = (cap[8]-'0')*10 + (cap[9]-'0'); if ((yy > 2003 && yy < 2099) && (mm > 0 && mm < 13) && (dd > 0 && dd < 32)) { const int ddinmonth[] = {31,29,31,30,31,30,31,31,30,31,30,31}; if (ddinmonth[(mm-1)] >= dd) { if (!(mm == 2 && dd == 29) || ((yy%400 ? yy%100 ? yy%4 ? false : true : false :true) == 1)) { //stringcopy cap to val size_t convertedChars = 0; mbstowcs_s(&convertedChars,pdate,11,cap.c_str(),_TRUNCATE); return 1; } else return 0; } else return 0; } } }; int _tmain(int argc, _TCHAR* argv[]) { wchar_t currdate[11]; std::string date = "2011/02/02"; function<DateVerify_Impl>::type const dverify = {{}}; mark_tag datetag(1); smatch mtch; sregex tcrgx = bos >> (datetag= (repeat<4>(_d) >> '/' >> repeat<2>(_d) >> '/' >> repeat<2>(_d))) [check(dverify(datetag,&currdate) == 1)] >> eos; if (regex_match(date,mtch,tcrgx)) std::wcout << "YO BABY, YO !" << " ... and the winner is " << currdate << '\n'; return 0; } -- GMX DSL Doppel-Flat ab 19,99 Euro/mtl.! Jetzt mit gratis Handy-Flat! http://portal.gmx.net/de/go/dsl

1 0

[program_options] negative numbers in options value<vector<int> >()->multitoken()
by Andrzej Zielinski 04 Feb '11

04 Feb '11

Hi, I am using boost::program_options and found a problem with passing a series of positive/negative numbers. i.e myProgram.out --system 0 -2 2 -3 Similar problem like in: http://stackoverflow.com/questions/4107087/accepting-negative-doubles-with-… I do not want to disable short options. I want to make quotes working. So when I call myProgram.out --system '0 -2' error: in option 'system': invalid option value myProgram.out --system 0 -2 error: unknown option -2 What quotation do you mean ? I am using bash, on CYGWIN and in linux

1 1

compilation flag effect on boost::condition::timed_wait()
by Vishal Bayskar 04 Feb '11

04 Feb '11

Dear All, I am getting different behaviour of condition::timed_wait() function when I compile my code with NDEBUG flag and without NDEBUG flag. with using NDEBUG flag, timed_wait() wait for condition (mutext) as desired but whey I don't use NDEBUG flag while compiling my code it does wait for condition (mutex) but return at the same time when it is called. In both the cases return value is 1. Please note that it is not a race condition but it is happening every time. Also note that I am using other flags too for compiling my code like -Werror -pthread -fno-strict-aliasing -Wno-unused-variable -Wno-unused-parameter -Wno-unused-function -O3 -ggdb3 -m64 Please let me know what can be possible impact of NDEBUG flag on timed_wait() function. Thanking you Vishal DISCLAIMER: ----------------------------------------------------------------------------------------------------------------------- The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. It shall not attach any liability on the originator or NECHCL or its affiliates. Any views or opinions presented in this email are solely those of the author and may not necessarily reflect the opinions of NECHCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of the author of this e-mail is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. . -----------------------------------------------------------------------------------------------------------------------

2 2

[Interprocess] shared_ptr in a non-throwing mode
by Pietro Versari 04 Feb '11

04 Feb '11

Hi Ion (and everyone else), I'm a newbye and I have only one simple (stupid?) question: how can I construct a shared_ptr in a non-throwing mode? This example throw if there is enough space for MyType but isn't enough for my_shared_ptr: typedef managed_shared_ptr<MyType,managed_shared_memory>::type my_shared_ptr; my_shared_ptr sh_ptr = make_managed_shared_ptr( segment.construct<MyType>("object to share", std::nothrow)(), segment); Thanks Pietro Versari

1 0

Re: [Boost-users] Boost-wide concept docs
by Mathias Gaunard 03 Feb '11

03 Feb '11

On 03/02/2011 17:52, Edward Diener wrote: > I have seen concepts mentioned in documentation > for many Boost libraries but I never knew how to document a concept for > what I myself may be working on. Does Boost specify a preferred common > format for documenting a concept anywhere ? Yes, caramel (that's an XML format). It integrates with boostbook and quickbook. See libs/concept_check/doc/reference for examples.

3 2

[statechart]BitMachine with custom reactions. How to?
by vs＠spinke.de 03 Feb '11

03 Feb '11

Hello! I tried to add custom reactions to the statechart library example BitMachine. It shall not only change the state, but also perform some (self-defined) action on the transition. Could somebody tell me, where I have to add / change what in order to achieve the goal? Any hints are welcome. Thanks a lot. Volker

2 1