- Boost - lists.boost.org

Re: [boost] [c++11]
by Niall Douglas 19 Jun '13

19 Jun '13

> I wasn't suggesting making the library strictly C++03-compatible. My main > point was that the library has to be compatible with _todays_ and even better > - _yesterdays_ compilers to be actually useful. My choice of "reasonable" time > frame is 3-5 years, as I mentioned. That includes VS 2008 and VS 2010, which > already had some C++11 features, including rvalue references. Making VS 2013 > absolute minimum is a no-go, IMHO. I don't think anyone is making VS2013 an absolute minimum - rather they're making variadic templates an absolute minimum. Something which any other compiler than VS has had for years, and something which unlike many, if not most other C++11 language features is something which lets you write a ton of stuff you simply can't write without them. Now, nothing in proposed Boost.AFIO uses variadic templates in a way not replaceable with preprocessor programming. However it very /nearly/ did: I had this neato bit of evil variadic instantiation which let you convert an unknown set of trailing args into a std::tuple<> for storage, then /unpack/ said std::tuple<> back into an unknown set of trailing args, all with perfect forwarding. Effectively it was a compile-time std::function<> implementation. As proposed Boost.AFIO is also a closure execution engine where that closure can take arbitrary args and return arbitrary returns, that evil variadic template machinery was really useful because it lets you skip using std::function<> with its implied virtual function call. As proposed Boost.AFIO currently nests, in the worst case scenario, a fully bound std::function<> calling a partially bound std::function<> calling a partially bound std::function<>, that's three nested virtual indirect function calls. Recent Intel CPUs can prefetch and branch predict two nesting levels, but they can't cope with three, so performance takes a real nose dive and hence one of the reasons we currently see a peak 80k IOPS. That evil variadic template machinery gets rid of that problem. And its only replacement is std::function<> - you *cannot* implement that functionality (pure compile time std::function<>) without variadic templates because you can't properly unpack them without. None of this matters for proposed Boost.AFIO. But it certainly matters for the forthcoming C++11 only libraries coming soon to Boost, because they make /very/ heavy usage of functionality only possible with variadic templates. That means that they will require, as an absolute minimum for VS, VS2013 or Nov 2012 CTP. Other C++11 features one can make do without without too much cost, but losing variadic templates means a ton of extra source code complexity, much longer compile times and chopping out a lot of what C++11 enables which simply can't be done in C++03. I suspect that those libraries are probably going to force a new "variadic template support is mandatory" category of Boost libraries, probably sooner rather than later. I agree it's going to be frustrating for those stuck with older compilers: I pity those whose employers force MSVC6 on them to this very day. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

6 15

Can't compile code with BOOST_LOG_TRIVIAL
by ... ... 19 Jun '13

19 Jun '13

Hi, I am trying to compile this code : #include <boost/log/trivial.hpp> int main(void){ BOOST_LOG_TRIVIAL(trace) << "boost log is working"; return EXIT_SUCCESS;} And I get the following error message : g++ -o test Capture.o ffmpegTools.o FluxVideoModifie.o test.o vizILogger.o -lavformat -lavcodec -lavutil -lswscale -lopencv_core -lopencv_highgui -lboost_filesystem -lboost_log_setup -lboost_log -lz -lpthread -ldl -lm test.o: In function `main':/home/exploit/git/VIZIRD-CAPTURE/proj/capture//test.cpp:39: undefined reference to `boost::log::v2s_mt_posix::trivial::logger::get()'/home/exploit/git/VIZIRD-CAPTURE/proj/capture//test.cpp:39: undefined reference to `boost::log::v2s_mt_posix::trivial::logger::get()'test.o: In function `boost::log::v2s_mt_posix::record::reset()':/usr/local/include/boost/log/core/record.hpp:153: undefined reference to `boost::log::v2s_mt_posix::record_view::public_data::destroy(boost::log::v2s_mt_posix::record_view::public_data const*)'test.o: In function `boost::log::v2s_mt_posix::record boost::log::v2s_mt_posix::sources::basic_composite_logger<char, boost::log::v2s_mt_posix::sources::severity_logger_mt<boost::log::v2s_mt_posix::trivial::severity_level>, boost::log::v2s_mt_posix::sources::multi_thread_model<boost::log::v2s_mt_posix::aux::light_rw_mutex>, boost::log::v2s_mt_posix::sources::features<boost::log::v2s_mt_posix::sources::severity<boost::log::v2s_mt_posix::trivial::severity_level>, void, void, void, void, void, void, void, void, void> >::open_record<boost::parameter::aux::tagged_argument<boost::log::v2s_mt_posix::keywords::tag::severity, boost::log::v2s_mt_posix::trivial::severity_level const> >(boost::parameter::aux::tagged_argument<boost::log::v2s_mt_posix::keywords::tag::severity, boost::log::v2s_mt_posix::trivial::severity_level const> const&)':/usr/local/include/boost/log/sources/basic_logger.hpp:457: undefined reference to `boost::log::v2s_mt_posix::core::get_logging_enabled() const'test.o: In function `~record_pump':/usr/local/include/boost/log/sources/record_ostream.hpp:278: undefined reference to `boost::log::v2s_mt_posix::aux::unhandled_exception_count()'test.o: In function `record_pump':/usr/local/include/boost/log/sources/record_ostream.hpp:259: undefined reference to `boost::log::v2s_mt_posix::aux::stream_provider<char>::allocate_compound(boost::log::v2s_mt_posix::record&)'/usr/local/include/boost/log/sources/record_ostream.hpp:259: undefined reference to `boost::log::v2s_mt_posix::aux::unhandled_exception_count()'test.o: In function `~auto_release':/usr/local/include/boost/log/sources/record_ostream.hpp:243: undefined reference to `boost::log::v2s_mt_posix::aux::stream_provider<char>::release_compound(boost::log::v2s_mt_posix::aux::stream_provider<char>::stream_compound*)'test.o: In function `boost::log::v2s_mt_posix::sources::aux::severity_level<boost::log::v2s_mt_posix::trivial::severity_level>::set_value(boost::log::v2s_mt_posix::trivial::severity_level)':/usr/local/include/boost/log/sources/severity_feature.hpp:135: undefined reference to `boost::log::v2s_mt_posix::sources::aux::get_severity_level()'test.o: In function `boost::log::v2s_mt_posix::record boost::log::v2s_mt_posix::sources::basic_logger<char, boost::log::v2s_mt_posix::sources::severity_logger_mt<boost::log::v2s_mt_posix::trivial::severity_level>, boost::log::v2s_mt_posix::sources::multi_thread_model<boost::log::v2s_mt_posix::aux::light_rw_mutex> >::open_record_unlocked<boost::parameter::aux::tagged_argument<boost::log::v2s_mt_posix::keywords::tag::severity, boost::log::v2s_mt_posix::trivial::severity_level const> >(boost::parameter::aux::tagged_argument<boost::log::v2s_mt_posix::keywords::tag::severity, boost::log::v2s_mt_posix::trivial::severity_level const> const&)':/usr/local/include/boost/log/sources/basic_logger.hpp:260: undefined reference to `boost::log::v2s_mt_posix::core::open_record(boost::log::v2s_mt_posix::attribute_set const&)'test.o: In function `boost::log::v2s_mt_posix::core::push_record(boost::rv<boost::log::v2s_mt_posix::record>&)':/usr/local/include/boost/log/core/core.hpp:308: undefined reference to `boost::log::v2s_mt_posix::core::push_record_move(boost::log::v2s_mt_posix::record&)'collect2: ld returned 1 exit statusmake: *** [test] Error 1 In my makefile I added the links :LIBS_boost = -lboost_filesystem -lboost_log_setup -lboost_log And i have my libraries correctly installed because the command : $ sudo ldconfig -p | grep boost_l display :libboost_log_setup.so.1.53.0 (libc6,x86-64) => /usr/local/lib/libboost_log_setup.so.1.53.0libboost_log_setup.so (libc6,x86-64) => /usr/local/lib/libboost_log_setup.solibboost_log.so.1.53.0 (libc6,x86-64) => /usr/local/lib/libboost_log.so.1.53.0libboost_log.so (libc6,x86-64) => /usr/local/lib/libboost_log.solibboost_locale.so.1.53.0 (libc6,x86-64) => /usr/local/lib/libboost_locale.so.1.53.0libboost_locale.so (libc6,x86-64) => /usr/local/lib/libboost_loc Can you help me please ? Thanks,Guillaume Bersac237bis rue de Pessac33000 Bordeaux06.65.30.89.43

2 1

Weirdness in SVN
by Marshall Clow 19 Jun '13

19 Jun '13

Ok, this is quite worrisome to me. This morning, bug #6136 was reopened: https://svn.boost.org/trac/boost/ticket/6136 This is an "unused variable warning" in Boost.DateTime. I fixed this bug in the trunk: https://svn.boost.org/trac/boost/changeset/80699 I merged this bug fix (and several others) to the release branch: https://svn.boost.org/trac/boost/changeset/80797 But the files (both trunk and release) appear not to contain the change. If I do a "svn diff", the changes appear in the diff, but the file doesn't contain the change. I checked the other files referenced in change set 80797, and they appear to be fine - just this one. Any idea what could be happening here? My only explanation at the moment is that "Subversion is lying to me", and that's both (a) a huge potential problem, and (b) doesn't suggest a course of action. $ svn diff trunk/boost/date_time/format_date_parser.hpp -r 80698 Index: trunk/boost/date_time/format_date_parser.hpp =================================================================== --- trunk/boost/date_time/format_date_parser.hpp (revision 80698) +++ trunk/boost/date_time/format_date_parser.hpp (working copy) @@ -256,7 +256,6 @@ // skip leading whitespace while(std::isspace(*sitr) && sitr != stream_end) { ++sitr; } - charT current_char = *sitr; short year(0), month(0), day(0), day_of_year(0);// wkday(0); /* Initialized the following to their minimum values. These intermediate @@ -290,7 +289,6 @@ } wkday = mr.current_match; if (mr.has_remaining()) { - current_char = mr.last_char(); use_current_char = true; } break; @@ -310,7 +308,6 @@ } wkday = mr.current_match; if (mr.has_remaining()) { - current_char = mr.last_char(); use_current_char = true; } break; @@ -326,7 +323,6 @@ } t_month = month_type(mr.current_match); if (mr.has_remaining()) { - current_char = mr.last_char(); use_current_char = true; } break; @@ -342,7 +338,6 @@ } t_month = month_type(mr.current_match); if (mr.has_remaining()) { - current_char = mr.last_char(); use_current_char = true; } break; @@ -438,7 +433,6 @@ itr++; if (use_current_char) { use_current_char = false; - current_char = *sitr; } else { sitr++; $ svn diff trunk/boost/date_time/format_date_parser.hpp -r 80699 $ -- 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

2 3

[range] Best way to count the elements in a filtered range?
by Gonzalo Brito Gadeschi 19 Jun '13

19 Jun '13

I wonder what is the recommended way to count the elements in a filtered range. Let range be a random access range, and filter the result of filtered(predicate), auto filtered_range = range | filter; count_if( filtered_range, [](const&){ return true; }); // (& omitted in lambda) counts the elements in a filtered range. _If_ this is the best way to count the elements in a filtered range, what about defining Range boost::count(Range&& r); to count all element in the range? It could call size() if available and count_if otherwise. Bests, Gonzalo BG

4 7

[mailing list] Duplicated thread - Best way to proceed
by Gonzalo Brito Gadeschi 19 Jun '13

19 Jun '13

The thread: [boost] [range] Best way to count the elements in a filtered range? I sent an email with an unregistered email adress to the list. As expected, I did not receive a confirmation about the mail being accepted. I resent the mail with my registered email adress. As expected, the new mail was accepted. However, the unaccepted mail started getting replies. - What is the best way to proceed? - Why did the email sent with the unregistered email address get replies? - Shouldn't it have been rejected right away? Bests, Gonzalo BG

1 0

[range] Best way to count the elements in a filtered range?
by Gonzalo BG 19 Jun '13

19 Jun '13

I wonder what is the recommended way to count the elements in a filtered range. Let range be a random access range, and filter the result of filtered(predicate), auto filtered_range = range | filter; count_if( filtered_range, [](const&){ return true; }); // (& omitted in lambda) counts the elements in a filtered range. _If_ this is the best way to count the elements in a filtered range, what about defining Range boost::count(Range&& r); to count all element in the range? It could call size() if available and count_if otherwise. Bests, Gonzalo BG

3 2

Is anybody working on the Boost Windows installer?
by Antony Maria Sakkariaz 18 Jun '13

18 Jun '13

Hi, Good morning. I am new to Boost and this mailing list. When I visited BoostPro computing in order to download the Windows installer, I did not see any installer beyond version 1.51. Since BoostPro donated the installer source code to the community, I am checking to see if anybody is updating the installer for the newer Boost versions. In case nobody is working on this, then I thought I would try to do it. :-) Thanks, Antony

2 1

Re: [boost] [c++11]
by Niall Douglas 18 Jun '13

18 Jun '13

> > I should quickly explain why rvalue ref support is so important to proposed > > Boost.AFIO: it's a 100% batch API and therefore takes in batches of things > > to do and returns out batches of results. That implies lots of passing > > sequences of things around in STL containers, which without rvalue refs are > > not cheap to copy. Therefore while we could get the library working on > > Maybe BOOST_ASIO_MOVE_ARG (in boost/asio/detail/config.hpp) will work > for you. I don't understand how that makes std::vector<> or any other STL container suddenly magically start not copy constructing its contents on C++03 compilers. struct async_io_op has both rvalue and const lvalue copy and assignment constructors. It's left up to the compiler and STL container implementation to decide when and where to use them. I agree we should be using more std::move() to help the compiler where it needs it, but all performance tuning is being left till after the Boost import. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

2 1

Re: [boost] [c++11]
by Niall Douglas 18 Jun '13

18 Jun '13

> 2013/6/14 Sid Sacek <ssacek(a)securewatch24.com>: > <...> > > Sounds like it's not really worth the effort and simply just stick to the old style. > > Stick to the old style. Add #ifndef'ed C++11 specific features if they add > functionality or improve performance much. Boost libraries are tested using > C++11 and C++03 on different compilers and works good in all situations. Speaking of which, I was going to ask this list about the minimum compiler requirements for proposed GSoC Boost.AFIO, so now is as good a time as any. The existing code base being prepared for entry into Boost is pure C++11, or at least as much C++11 as is provided by the Nov 2012 CTP experimental MSVC compiler and therefore easily supported by GCC 4.6 and clang 3.x. The variadic templates used probably can be swapped out easily enough with Boost Preprocessor generators. The very extensive use of C++11 only library features could probably be replaced with Boost equivalents in most cases, though we really do need a fully C++11 functional std::exception_ptr rather than Boost's limited boost::exception_ptr. The thing we probably can't replace without major surgery is rvalue reference usage. It's used very extensively. Moreover, performance without rvalues would truly suck. So here's the question: is C++03 compiler and C++03 TR1 standard library support still an absolute, unnegotiable requirement for a library to become an official part of Boost? Or can we at least require rvalue reference support as a minimum? Or do we add a new category to Boost: some bits of C++11 requiring libraries? We're going to have to do this eventually anyway. Niall

12 20

[multiprecision] Are these types suitable as numeric types for unit tests?
by Daryle Walker 18 Jun '13

18 Jun '13

I'm writing new numeric types, and my unit tests use MPL lists of numeric types. I usually use stuff like int, unsigned, and double, but now I'm adding cpp_int and cpp_dec_float_50. Those types were OK when I was just doing type equalities and sizeof checks. Now I'm doing tests that use objects of those types and I'm getting problems. //==== typedef boost::mpl::list<int, unsigned, cpp_int> test_integer_types; typedef boost::mpl::list<double, cpp_dec_float_50> test_floating_types; //... BOOST_AUTO_TEST_CASE_TEMPLATE( test_complex_component_access1, T, test_integer_types ) { typedef complex_it<T, 0> real_type; typedef complex_it<T, 1> complex_type; real_type a; real_type const & aa = a; complex_type b; complex_type const & bb = b; a[ 0 ] = 6; BOOST_CHECK_EQUAL( a[0], T(6) ); BOOST_CHECK_EQUAL( T(6), aa[0] ); b[ 0 ] = 5; b[ 1 ] = 7; BOOST_CHECK_EQUAL( b[0], T(5) ); BOOST_CHECK_EQUAL( T(5), bb[0] ); BOOST_CHECK_EQUAL( b[1], T(7) ); BOOST_CHECK_EQUAL( T(7), bb[1] ); } //==== I'm getting warnings about integer overflow. The problem is at Line 59 of boost/test/tools/detail/print_helper.hpp. It sets an output stream's precision based on the digits given by std::numeric_limits. //==== BOOST_AUTO_TEST_CASE_TEMPLATE( test_complex_component_access2, T, test_floating_types ) { typedef complex_it<T, 0> real_type; typedef complex_it<T, 1> complex_type; real_type a; real_type const & aa = a; complex_type b; complex_type const & bb = b; a[ 0 ] = 6.0; BOOST_CHECK_CLOSE( a[0], T(6.0), 0.1 ); BOOST_CHECK_CLOSE( T(6.0), aa[0], 0.1 ); b[ 0 ] = 5.5; b[ 1 ] = -7.0; BOOST_CHECK_CLOSE( b[0], T(5.5), 0.1 ); BOOST_CHECK_CLOSE( T(5.5), bb[0], 0.1 ); BOOST_CHECK_CLOSE( b[1], T(-7.0), 0.1 ); BOOST_CHECK_CLOSE( T(-7.0), bb[1], 0.1 ); } //==== This time it's an error, at Line 59 of boost/test/tools/floating_point_comparison.hpp. There no (close enough) matching function for "fpt_abs" from some "boost::multiprecision::detail::expression<..." type. (It was truncated by the display. I don't know how to get a clean print-out of errors from Code::Blocks.) I'm guessing the expression template setup is screwing things up. Daryle W.

6 25