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

[msvc-14] Status of _HAS_AUTO_PTR_ETC=0 support
by Mateusz Loskot 03 Sep '15

03 Sep '15

Hi, VS2015 allows to disable the C++ library features deprecated in C++11: [1] "By default, we provide auto_ptr/etc. If you define _HAS_AUTO_PTR_ETC to 0 project-wide (which you should do via the command line or project file, not via #define), then we won't provide auto_ptr/etc." Attempt to compile the following test.cpp based on up-to-date Boost (master) fails: #include <boost/algorithm/string.hpp> int main() { return 0; } cl /EHsc /ID:\dev\boost.git /D_HAS_AUTO_PTR_ETC=0 test.cpp Below are two problems that can be solved with additional define of BOOST_NO_AUTO_PTR=1 D:\dev\boost.git\boost/get_pointer.hpp(48): error C2065: 'auto_ptr': undeclared identifier D:\dev\boost.git\boost/get_pointer.hpp(62): error C2923: 'std::unique_ptr': 'T' is not a valid template type argument for parameter '_Ty' I also expected _HAS_AUTO_PTR_ETC=0 should imply BOOST_NO_AUTO_PTR=1. Then, I hoped this would work: cl /EHsc /ID:\dev\boost.git /D_HAS_AUTO_PTR_ETC=0 /DBOOST_NO_AUTO_PTR=1 test.cpp Unfortunately, it fails due to uses of std::unary_function and std::binary_function in boost/algorithm/string/detail/case_conv.hpp. Those functions have been deprecated since C++11 and are disable by _HAS_AUTO_PTR_ETC=0. This basic evaluation made me wonder, does Boost support compilation with _HAS_AUTO_PTR_ETC=0 defined at all? [1] http://blogs.msdn.com/b/vcblog/archive/2015/04/29/c-11-14-17-features-in-vs… Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

2 2

Include line number in boost logs
by Florian Lindner 03 Sep '15

03 Sep '15

Hello, I try to implement that a log entry also logs its line number with boost::log. If any developer of it reads here, please also consider this a wishlist item... I think the best way to add an additional attribute for it core::get()->add_global_attribute( "Line", attributes::mutable_constant<size_t>(0) ); in my logger config that is called once at startup. #define logInfo(methodname, message) \ boost::log::core::get()->get_global_attributes()["Line"].set(__LINE__); \ BOOST_LOG_SEV(_log, boost::log::trivial::severity_level::trace) << message \ Is my idea, but boostlog.cpp:126:5: error: no member named 'set' in 'boost::log::v2_mt_posix::aux::attribute_set_reference_proxy' getting the attribute somehow seems to work, but how can I set the value of the attribute? Thanks! Florian

2 5

[Type Erasure] Ambiguous call with vs 2015 community
by Yuan Yao 02 Sep '15

02 Sep '15

Dear all, I try to use type erasure on the free function foo. However, VS 2015 failed to compile the following code, which is OK with GCC and CLang. ========================================================= #include <boost/type_erasure/any.hpp> #include <boost/type_erasure/free.hpp> #include <typeindex> std::type_index foo(int); BOOST_TYPE_ERASURE_FREE((HasGetField), foo, 1) using Type = boost::type_erasure::any< HasGetField<std::type_index(boost::type_erasure::_self const&)>, boost::type_erasure::_self const& >; std::type_index foo(int) { return typeid(int); } int main() { Type x{ 1 }; foo(x); return 0; } ========================================================= Source.cpp C:\Program Files\Microsoft Visual Studio 14.0\VC\INCLUDE\xlocale(341): warning C4530: C++ exception handler used, but unwind semantics are not enabled. Specify /EHsc Source.cpp(20): error C2668: 'boost::type_erasure::injectHasGetField<R (const boost::type_erasure::_self &),Base,boost::type_erasure::index_list<0>>::foo': ambiguous call to overloaded function with [ R=std::type_index, Base=boost::type_erasure::any_base<boost::type_erasure::any<HasGetField<std::type_index (const boost::type_erasure::_self &)>,boost::type_erasure::_self &&>> ] Source.cpp(7): note: could be 'std::type_index boost::type_erasure::injectHasGetField<R (const boost::type_erasure::_self &),Base,boost::type_erasure::index_list<0>>::foo(eval_if_c<0,boost::type_erasure::detail::maybe_const_this_param<const boost::type_erasure::_self &,Base>,boost::type_erasure::as_param<Base,const boost::type_erasure::_self &>>::type)' [found using argument-dependent lookup] with [ R=std::type_index, Base=boost::type_erasure::any_base<boost::type_erasure::any<HasGetField<std::type_index (const boost::type_erasure::_self &)>,boost::type_erasure::_self &&>> ] Source.cpp(7): note: or 'std::type_index boost::type_erasure::injectHasGetField<R (const boost::type_erasure::_self &),Base,boost::type_erasure::index_list<0>>::foo(eval_if_c<0,boost::type_erasure::detail::maybe_const_this_param<const boost::type_erasure::_self &,Base>,boost::type_erasure::as_param<Base,const boost::type_erasure::_self &>>::type)' [found using argument-dependent lookup] with [ R=std::type_index, Base=boost::type_erasure::any_base<boost::type_erasure::any<HasGetField<std::type_index (const boost::type_erasure::_self &)>,boost::type_erasure::_self &>> ] Source.cpp(7): note: or 'std::type_index boost::type_erasure::injectHasGetField<R (const boost::type_erasure::_self &),Base,boost::type_erasure::index_list<0>>::foo(eval_if_c<0,boost::type_erasure::detail::maybe_const_this_param<const boost::type_erasure::_self &,Base>,boost::type_erasure::as_param<Base,const boost::type_erasure::_self &>>::type)' [found using argument-dependent lookup] with [ R=std::type_index, Base=boost::type_erasure::any_base<boost::type_erasure::any<HasGetField<std::type_index (const boost::type_erasure::_self &)>,boost::type_erasure::_self>> ] Source.cpp(7): note: or 'std::type_index boost::type_erasure::injectHasGetField<R (const boost::type_erasure::_self &),Base,boost::type_erasure::index_list<0>>::foo(eval_if_c<0,boost::type_erasure::detail::maybe_const_this_param<const boost::type_erasure::_self &,Base>,boost::type_erasure::as_param<Base,const boost::type_erasure::_self &>>::type)' [found using argument-dependent lookup] with [ R=std::type_index, Base=boost::type_erasure::any_base<boost::type_erasure::any<HasGetField<std::type_index (const boost::type_erasure::_self &)>,const boost::type_erasure::_self &>> ] Source.cpp(14): note: or 'std::type_index foo(int)' Source.cpp(20): note: while trying to match the argument list '(Type)' ========================================================= Moreover, I wonder whether the declaration is a must? Thank you!

2 2

Re: [Boost-users] is it possible to group values with Boost's rtree?
by Andy Edwards 01 Sep '15

01 Sep '15

Noel wrote: > I had to do something similar packing 100k 3d objects into the smallest > number of groups, where each group contains only non-overlapping 3d > objects. I used the Boost Graph library with a smallest least ordering > graph coloring algorithm. Since this is a quasi-np hard problem, I know > the packing density is sub-optimal but still quite good for our > application. Perhaps that approach would work for you? Unfortunately > I?m not familiar with Boost rtree. > > ? Noel Belcourt Thanks for the tip Noel, but it sounds like I'll be able to accomplish it using Adam's suggestions (I don't need completely optimal packing density). Since I'll be using the rtree for spatial queries as well it's the best approach for me. Adam wrote: > It is possible though it isn't officially supported. Have a look at the > utilities in this directory: > > https://github.com/boostorg/geometry/tree/master/include/boost/geometry/ind… > > To traverse the rtree you must write a visitor similar to the > Boost.Variant visitor, defining operator() overloads taking nodes. There > is a boost::geometry::index::detail::rtree::utilities::view<> providing > read-only access to the rtree's internals, in particular to the > apply_visitor() method applying the visitor to the root node of the > rtree and depth() function returning the number of tree levels. To > access the node's elements container you may use > boost::geometry::index::detail::rtree::elements() function and to apply > the visitor to the child node you may call > boost::geometry::index::detail::rtree::apply_visitor() function. The > elements of an internal node are of type similar to std::pair<> where > the first member is a Box and the second member is a pointer to the > child node. The elements of a leaf node are of type value_type. This way > you may recursively traverse the rtree in depth-first order counting the > current level, create containers of values when some level is met and > then gather the values from leafs. See e.g. how the utilities in the > directory mentioned above are implemented. > > Regards, > Adam Thanks Adam! That sounds ideal. Glad I'll be able to use this! I wonder if a per-node predicate is planned for the public API in the future (rather than the value-only satisfies predicate)?

2 1

[boost] [afio] Formal review of Boost.AFIO
by Ahmed Charles 01 Sep '15

01 Sep '15

The formal review of the Boost.AFIO library starts, August 21st and ends on Monday August 31st. Boost.AFIO provides a portable API implementing synchronous and asynchronous race-free filesystem and scatter-gather file i/o. It requires a minimum of C++ 11. It has minimum dependencies on a Filesystem TS and a Networking TS implementation (e.g. Boost.Filesystem and Boost.ASIO). Backends are provided for the Windows NT kernel and POSIX. The utility of a portable library providing strong concurrent race guarantees about filesystem and file i/o can be seen in its tutorial where a transactional ACID key-value store is built from first principles. Boost.AFIO was brought to Boost as part of GSoC 2013 and Niall Douglas has continued to develop and improve the library since then, generating two internal implementation libraries Boost.APIBind and Boost.Monad which are expected to be separately brought for Boost review in 2016. The documentation can be found here: https://boostgsoc13.github.io/boost.afio/doc/html/afio.html The source code can be found here: https://github.com/BoostGSoC13/boost.afio/tree/boost-peer-review Online web compiler playpen can be found here: http://melpon.org/wandbox/permlink/DR8wCpu5Rl20GMdM? Please answer the following questions: 1. Should Boost.AFIO be accepted into Boost? Please state all conditions for acceptance explicity. 2. What is your evaluation of the design? 3. What is your evaluation of the implementation? 4. What is your evaluation of the documentation? 5. What is your evaluation of the potential usefulness of the library? 6. Did you try to use the library? With what compiler? Did you have any problems? 7. How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? 8. Are you knowledgeable about the problem domain?

9 17

[Interprocess] Problem with file_lock on Linux
by Jan Niklas Hasse 31 Aug '15

31 Aug '15

The following code #include <boost/interprocess/sync/file_lock.hpp> #include <iostream> #include <fstream> int main() { std::ofstream file("test.lock"); boost::interprocess::file_lock flock("test.lock"); std::cout << flock.try_lock(); std::cout << flock.try_lock() << std::endl; } outputs 10 on Windows and 11 on Linux. Shouldn't it also print 10 on Linux or am I missunderstanding file_lock? I've also tried locking from different threads, but no luck.

2 3

[SPAM] from: giridhar
by giridhar 30 Aug '15

30 Aug '15

Sup boost http://arheatingcooling.com/unlikely.php?rule=g94y8vfvqvgeu2 giridharms(a)gmail.com giridhar

1 0

[variant][mpl] silly mistake in make_variant_over usage?
by Nat Goodspeed 29 Aug '15

29 Aug '15

The following program fails to compile (148 lines of errors, will paste on request) with g++ (Ubuntu 4.9.2-0ubuntu1~14.04) 4.9.2 in -std=c++11 mode. This is using Boost 1.59.0. Command line: g++ -std=c++11 -I ~/boost_1_59_0 -o make_variant make_variant.cpp I assume I'm making a simple error. I would appreciate your pointing it out. Thank you! (Is there a simpler way to obtain a variant of the result types of passed functions? I was hoping I could just write: boost::variant< std::result_of<Fns>::type... >.) #include <boost/variant/variant.hpp> #include <boost/mpl/vector.hpp> #include <boost/mpl/transform.hpp> #include <type_traits> // std::result_of template < typename... Fns > typename boost::make_variant_over< boost::mpl::transform< boost::mpl::vector<Fns...>, std::result_of<boost::mpl::_1> > >::type multiplex(Fns && ... functions) { typedef typename boost::make_variant_over< boost::mpl::transform< boost::mpl::vector<Fns...>, std::result_of<boost::mpl::_1> > >::type return_t; // dummy for now return return_t(); } int main(int argc, char *argv[]) { boost::variant<int, char*> var = multiplex([argc](){ return argc; }, [argv](){ return argv[0]; }); return 0; }

2 2

is it possible to group values with Boost's rtree?
by Andy Edwards 27 Aug '15

27 Aug '15

Hi everyone, I need a way to take a collection of 3D objects and put them into disjoint minimally overlapping groups no bigger than some N. Can this be done with Boost's rtree or any other Boost libraries? I've done this by putting the objects in an R* tree and using the nodes at a certain level of the tree (for example, 2 levels up from the leaf level) to determine the groups. However, that was in my own Java R* tree implementation that provided read-only access to its internal nodes. I'd like to port this program to C++ using Boost's rtree, but it doesn't provide read-only access to its nodes, does it? Does anyone know if it would be possible to extend the rtree to provide this? Or would it be possible to write a custom predicate to get the groupings? Thanks! Andy

3 2

[filesystem] Relative Draft Proposal RFC
by Beman Dawes 27 Aug '15

27 Aug '15

There have been requests for a Filesystem library relative function for at least ten years. The requested functionality seems simple - given two paths with a common prefix, return the non-common suffix portion of one of the paths such that it is relative to the other path. In terms of the Filesystem library, path p("/a/b/c"); path base("/a/b"); path rel = relative(p, base); // the requested function cout << rel << endl; // outputs "c" assert(absolute(rel, base) == p); If that was all there was to it, the Filesystem library would have had a relative function years ago. Critical issues: Clashing requirements, symlinks, directory placeholders (dot, dot-dot), user-expectations, corner cases. A paper by Jamie Allsop, Additions to Filesystem supporting Relative Paths, is what broke my mental logjam. Much of [my proposal] is based directly on Jamie's analysis and proposal. The weakly_canonical function and aspects of the semantic specifications are my contributions. Mistakes, of course, are mine. The full proposal is at http://boostorg.github.io/filesystem/relative_proposal.html A preliminary implementation is available in the feature/relative2 branch of the Boost Filesystem Git repository. See github.com/boostorg/filesystem/tree/feature/relative2 The overall plan is to get feedback from boost developers, then merge to develop for boost 1.60, then propose to the C++ committee for addition to the Filesystem TS. Comments welcome. If you are one of the many people who have requested "relative" functionality, does this proposal meet your needs? If not, why? Thanks, --Beman

5 7