December 2012 - Boost - lists.preview.boost.org

Use of deprecated macros in Boost
by Marshall Clow 13 Dec '12

13 Dec '12

In Boost 1.50, we (Boost) marked a bunch of macros as "deprecated" In Boost 1.51, we deprecated a bunch more - replaced them with new, shiny macros. I've been working with many of you (library maintainers) to remove all the uses of deprecated macros in Boost, and we've been almost completely successful .. on the trunk. We're a week away from the freezing of the release branch for the 1.53 release, and I'd like to make sure that all those macro changes get merged over to the release branch. http://www.boost.org/development/ I will be happy to help - just let me know. Thanks in advance! -- Marshall

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Heads up - string_ref landing
by Marshall Clow 12 Dec '12

12 Dec '12

I'm about to check in some new functionality into the string_algo library; an implementation of string_ref. A string_ref is a non-owning reference to a string. It is implemented as a {pointer, length} pair, and is exceedingly useful when parsing, and manipulating strings in "read-only" ways. The header will be in boost/algorithm/string_ref.hpp, but I welcome discussion about where it should live. Ideally, I think it should be just "boost/string_ref.hpp". Basic sanity tests will be checked in with the header file - I have tested on clang, clang11, and gcc. One reason for checking this in now is to get the tests run on lots of different systems. Docs will be coming soon, but http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3442.html is the proposal for "a future version of C++" ;-) Please let me know what you think! -- Marshall Marshall Clow Idio Software <mailto:mclow.lists@gmail.com> A.D. 1517: Martin Luther nails his 95 Theses to the church door and is promptly moderated down to (-1, Flamebait). -- Yu Suzuki

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[smart_ptr][thread][test] breaking change on shared_ptr operator bool.
by Vicente J. Botet Escriba 12 Dec '12

12 Dec '12

Hi, https://svn.boost.org/trac/boost/changeset/81780 " Use explicit operator bool when available; ..." introduces a breaking change on shared_ptr in Boost.Thread and Boost.Test at least. I would preferred if this breaking change was announced and why not added conditionally so that the user could move smoothly to the new semantic. Anyway, I wanted to make this evident so that the Boost maintainer using this facility fixes their code as soon as possible. Best, Vicente

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[atomic] Header rearrangement
by Andrey Semashev 12 Dec '12

12 Dec '12

Hi, Before merging Boost.Atomic to release I would like to propose to rearrange library headers a bit: 1. The current boost/atomic/config.hpp and platform.hpp seem to be not intended for public use as they don't provide any public components. I propose to move them to boost/atomic/detail. 2. The boost/atomic.hpp header defines the atomic<> template. I propose to move its contents to boost/atomic/atomic.hpp. The boost/atomic.hpp will be left as the "include all" header and will only include boost/atomic/atomic.hpp for now. The motivation for the proposal is to cleanup the public library interface (header layout) and simplify extension later. For instance, function-style interface can be added as a new header in boost/atomic, it would fit naturally in the proposed layout. Also, with the upcoming transition to git it seems that all library headers should reside in the library's own subdirectory and not directly in boost/. AFAICT, the change will not affect any other libraries since only boost/atomic.hpp is included currently. If noone objects (Tim, I would very much like to hear from you on this), I can do the necessary changes.

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[thread 1.48] Multiple interrupt/timed_join leads to deadlock
by Gaetano Mendola 12 Dec '12

12 Dec '12

Hi all, I was investigating a rare deadlock when issuing an interrupt and a timed_join in parallel. I come out with the the following code showing the behavior. This is the backtrace of it: http://pastebin.com/xArHgHXf The deadlock is rare so sometime you need to wait a bit. I couldn't try it with boost 1.52 because the code is invalid due the precondition of "thread joinable" when issuing the timed_join. Is the code not valid or a real bug? Regards Gaetano Mendola ////////////////////// CODE ////////////////////// #include <iostream> #include <boost/thread.hpp> struct Runner { void operator()() { const boost::posix_time::time_duration mySeconds = boost::posix_time::seconds(100); boost::this_thread::sleep(mySeconds); } }; struct Interrupter { Interrupter(boost::thread& aThread, boost::barrier& aBarrier) : theThread(aThread), theSeconds(boost::posix_time::seconds(1)), theBarrier(aBarrier) { } void operator()() { theBarrier.wait(); for (int i=0; i<1000;++i) { theThread.interrupt(); theThread.timed_join(theSeconds); } } boost::thread& theThread; boost::posix_time::time_duration theSeconds; boost::barrier& theBarrier; }; int main() { for (size_t i = 0; i < 1000000; ++i) { Runner myRunner; boost::thread myRunnerThread(myRunner); boost::barrier myBarrier(2); Interrupter myInterrupter1(myRunnerThread, myBarrier); Interrupter myInterrupter2(myRunnerThread, myBarrier); boost::thread myInterrupterThread1(myInterrupter1); boost::thread myInterrupterThread2(myInterrupter2); myInterrupterThread1.join(); myInterrupterThread2.join(); myRunnerThread.join(); std::cout << "."; std::cout.flush(); } }

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[thread] [Boost-testing] Trunk regression failed on missing 'virtual_noexcept.cpp'
by Rene Rivera 11 Dec '12

11 Dec '12

Seems the thread lib has some missing test files? ---------- Forwarded message ---------- From: Jim Bell <Jim(a)jc-bell.com> Date: Tue, Dec 11, 2012 at 10:37 AM Subject: [Boost-testing] Trunk regression failed on missing 'virtual_noexcept.cpp' To: Running Boost regression tests <boost-testing(a)lists.boost.org> error: at G:/boost/GCC/trunk/tools_bb/**kernel\modules.jam:107 error: Unable to find file or target named error: 'virtual_noexcept.cpp' error: referred to from project at error: '../libs/thread/test' ______________________________**_________________ Boost-Testing mailing list Boost-Testing(a)lists.boost.org http://lists.boost.org/**mailman/listinfo.cgi/boost-**testing<http://lists.boost.org/mailman/listinfo.cgi/boost-testing> -- -- -- Grafik - Don't Assume Anything -- Redshift Software, Inc. - http://redshift-software.com -- rrivera/acm.org - grafik/redshift-software.com -- 102708583/icq - grafikrobot/aim - grafikrobot/yahoo

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Request for interest in a library to ease double dispatching
by Per Karlström 11 Dec '12

11 Dec '12

Hi, I have been tinkering on a template library to ease the use of double dispatching. Now I know there are other techniques such as visitor patterns that might solve this problem in a more general way. However I believe that there are occasions when using double dispatch is a good way forward. I have some excerpts of example code at the end of this mail. Of course if I somehow have missed a boost library that already handles this I would be happy to know about it. So if there is even any interest for this I would be happy if someone would like to cooperate with me to make this library better and in the end so good so that it can be part of boost. I feel I do not have the time to spare to finalize this on my own, plus I feel I still have things to learn and would be happy to cooperate with someone more experienced in template programming. What I in that case need help with is: *How (or is it) possible to make the library more transparent to the number of types that should be in the double dispatch hierarchy. Right now, as I have shown in the code at the end of this mail, you have to put a post-fix number telling how many types to use. *How (if possible) can a class be double dispatchable with different return types. The way I solved it was with a union. But would it somehow be possible to do like this struct Val : public DoubleDispatchable<bool,A,B>, public DoubleDispatchable<int,A,B> *What else would be needed to start the journey to make this a library fit for boost (is it even good enough to ever make into boost?) If anyone is interested in a cooperation I am happy to provide my working draft of this library and to have a more private talk about how we could move forward. Best Regards Per Karlström For now a union is used to hold the return value to make this simmilar for all types of returns. union ReturnVal { float float_type_m; bool bool_type_m; ReturnVal(const bool& bool_type_):bool_type_m(bool_type_){} ReturnVal(const float& float_type_):float_type_m(float_type_){} ReturnVal():bool_type_m(false){} }; In essence a library user can define handler classes akin to this: struct less : public DoubleDispatchHandler_3<ReturnVal,A,B,C> { return_type handle_alpha_alpha(const alpha_type& arg1, const alpha_type& arg2) const {return arg1 < arg2} return_type handle_alpha_beta (const alpha_type& arg1, const beta_type& arg2) const {return true;} return_type handle_alpha_gamma (const alpha_type& arg1, const gamma_type& arg2) const {return true;} //And all other combinations }; Or with a default function struct equal : public DoubleDispatchHandler_3<ReturnVal,A,B,C> { return_type handle_default() const {return false;} return_type handle_alpha_alpha(const alpha_type& arg1, const alpha_type& arg2) const; return_type handle_beta_beta (const beta_type& arg1, const beta_type& arg2) const; return_type handle_gamma_gamma (const gamma_type& arg1, const gamma_type& arg2) const; }; Then the base class is derived from DoubleDispatchable class Val : public DoubleDispatchable_3<ReturnVal,A,B,C> { public: virtual ~Val(){} virtual std::ostream& print(std::ostream& ost) const=0; virtual bool operator<(const Val& other) const =0; virtual bool operator==(const Val& other) const =0; virtual float combine(const Val& other) const =0; }; While Child classes had to define the member function dispatch_<type> struct A : public Val { int val_m; private: //Handles the first double dispatch call return_type dispatch_alpha(const alpha_type& alpha, const handler_type& handler) const { return double_dispatch(alpha,*this,handler); } return_type dispatch_beta(const beta_type& beta, const handler_type& handler) const { return double_dispatch(beta,*this,handler); } return_type dispatch_gamma(const gamma_type& gamma, const handler_type& handler) const { return double_dispatch(gamma,*this,handler); } public: A(const int& val_=0):val_m(val_){} //Normal calls to the operators via a template function bool operator<(const Val& other) const { return double_dispatch(*this,other,less()).bool_type_m; } bool operator==(const Val& other) const { return double_dispatch(*this,other,equal()).bool_type_m; } float combine(const Val& other) const { return double_dispatch(*this,other,add()).float_type_m; } std::ostream& print(std::ostream& ost) const { ost<<"A("<<val_m<<")"; return ost; } }; class B{...}; class C{...};

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Registration for C++Now 2013 is now open
by Boris Kolpackov 11 Dec '12

11 Dec '12

The seventh annual C++Now Conference (formerly BoostCon) will be held at the Aspen Center for Physics in Aspen, Colorado, May 12th to 17th, 2013. "We are thrilled to announce the second annual C++Now conference, the whole-language edition of BoostCon covering all the coolest topics in C++," said Dave Abrahams, Conference Co-Chair. "In 2012, we broadened the conference scope by adding a third track and offering more C++11 coverage than any other event, and the community responded with an unprecedented number of registrations. In 2013, we are going to build on that success with foundational sessions integrating what we've all learned about using C++11 during the past year, while continuing the exploration of cutting-edge topics that BoostCon attendees have come to expect." Early Bird Savings Deadlines! Early Bird conference registration, which ends April 14th, 2013, costs $599. After that date, the registration fee is $699. Register now at our registration page <http://www.eventbrite.com/event/2717332615>. Early Bird hotel registration ends December 31st, 2012 and saves $20 per night. Please reserve your room using the Aspen Meadows online reservation system <https://resweb.passkey.com/go/cplusplusnow2013> Speakers If you are interested in presenting, we are currently accepting proposals <http://cppnow.org/2013-call-for-submissions/>. Registration fee is waived for one speaker of every standard session presentation. Shorter sessions are prorated. Student/Volunteers Registration fees will be waived for a limited number of individuals that wish to attend as volunteers. Volunteer work consists of helping to run the conference and will not prevent volunteers from attending sessions. This is the first year this opportunity is being offered. If you are interested in applying to attend as a volunteer, contact us at <organizers(a)cppnow.org>. Sponsors For a copy of the conference Sponsorship Prospectus contact sponsorship(a)cppnow.org. C++Now is presented by Boost in-cooperation with ACM. Permanent link for this announcement is: http://cppnow.org/2013-registration-announcement/

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Using c++11 features in clang
by Marshall Clow 10 Dec '12

10 Dec '12

In response to a some questions on the boost-users list (and boost bug reports), I wrote up this: http://marshall.calepin.co/llvmclang-and-standard-libraries-on-mac-os-x.html I don't know if this should be a FAQ entry for Boost, or for clang. Suggestions/comments/edits welcome. -- Marshall Marshall Clow Idio Software <mailto:mclow.lists@gmail.com> A.D. 1517: Martin Luther nails his 95 Theses to the church door and is promptly moderated down to (-1, Flamebait). -- Yu Suzuki

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[hash] Tests fail on Intel compiler
by Andrey Semashev 10 Dec '12

10 Dec '12

Hi, I've been looking through Boost.Atomic and Boost.Thread tests on the "lazy piranha fedora 17 64" tester, intel-linux-13.0.1 compiler. The tests fail because Boost.Thread does not compile because of Boost.Hash. Here's an example of build log: http://www.boost.org/development/tests/trunk/developer/output/lazy%20piranh… The problem is that apparently BOOST_HASH_CONFORMANT_FLOATS is not defined on this compiler while there are both ::fpclassify and std::fpclassify functions. Are there valid reasons for not defining the macro on this compiler?

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