July 2014 - Boost - lists.preview.boost.org

Re: [boost] [geometry] Querying for Points nearest to a Segment.
by Adam Wulkiewicz 30 Jul '14

30 Jul '14

2014-07-29 3:07 GMT+02:00 Jeremy Murphy <jeremy.william.murphy(a)gmail.com>: > Veering slightly off topic but still related to Geometry development, I've > hit some hurdles with the rtree index. I could create an index of points > easily but then couldn't query for the nearest neighbour of a segment. (I > assume this is simply not supported at present; is it forthcoming?) So I > created a ring or polygon from the segment and tried to query for the > points that it covers/intersects, which is a feature listed in the > documentation, but I've hit this compilation error: > > > /usr/include/boost/geometry/algorithms/detail/overlay/get_turn_info.hpp:932:32: > error: no matching function for call to > ‘boost::geometry::model::referring_segment<const > boost::geometry::model::d2::point_xy<double> >::referring_segment(const > boost::geometry::model::point<double, 2ul, > boost::geometry::cs::cartesian>&, const > boost::geometry::model::point<double, 2ul, > boost::geometry::cs::cartesian>&)’ > > This constructor for referring_segment looks OK to me, except maybe for the > 'const' qualifier on the arguments? > Which version of Boost are you using? Indeed nearest(segment, ...) shouldn't work in 1.55. However intersects(ring_or_poly) should. Could you prepare some minimal failing example? E.g. this compiles for me, using develop branch (upcomming 1.56) or 1.55 without one, marked line: #include <boost/geometry.hpp> #include <boost/geometry/index/rtree.hpp> #include <boost/geometry/geometries/segment.hpp> #include <boost/geometry/geometries/ring.hpp> namespace bg = boost::geometry; namespace bgi = bg::index; typedef bg::model::point<double, 2, bg::cs::cartesian> P; typedef bg::model::segment<P> Seg; typedef bg::model::ring<P> Ring; typedef bg::model::polygon<P> Poly; typedef P V; int main() { typedef bgi::rtree<V, bgi::linear<16, 4> > RT; //typedef bgi::rtree<V, bgi::quadratic<16, 4> > RT; //typedef bgi::rtree<V, bgi::rstar<16, 4> > RT; RT rt; V v; rt.query(bgi::nearest(Seg(), 1), &v); // Using 1.55 without this line rt.query(bgi::intersects(Ring()), &v); rt.query(bgi::intersects(Poly()), &v); } Regards, Adam

3 3

[1.56.0 b1] Issue with mpl/is_convertable/asio
by Thomas Suckow 30 Jul '14

30 Jul '14

In testing '1.56.0 Beta 1' I have found that I am unable to compile https://github.com/splunk/pion on RHEL6_x64 Pion compiles fine with 1.55.0 I suspect the recurring "anonymous enum" is the kicker, though I am not sure where to even begin in diagnosing this. error: ‘const boost::asio::detail::buffer_sequence_adapter_base::<anonymous enum>&’ is/uses anonymous type error: no type named ‘type’ in ‘struct boost::is_convertible<const boost::asio::detail::buffer_sequence_adapter_base::<anonymous enum>&, const boost::iterator_range_detail::iterator_range_tag&>’ error: ‘value’ is not a member of ‘boost::mpl::aux::nested_type_wknd<boost::is_convertible<const boost::asio::detail::buffer_sequence_adapter_base::<anonymous enum>&, const boost::iterator_range_detail::iterator_range_tag&> >’ Full error log: http://pastebin.com/yeScQCpx If I get a chance I will see if I can reproduce this on a more modern compiler. Any assistance in correcting this before the 1.56.0 release would be appreciated. It also may or may not be related to http://thread.gmane.org/gmane.comp.lib.boost.devel/253259/focus=253261 Regards, Thomas

3 4

quince: queries in C++ expressions
by Michael Shepanski 29 Jul '14

29 Jul '14

Hello, boost! I've released a library called "quince", which lets you use a relational database in C++ rather than SQL. So it provides an EDSL to wrap the SQL syntax, it converts between C++ types (including user-defined class types) and SQL column types, and it enforces type safety at compile-time. I wanted to ask whether there would be an interest in this for boost, so I subscribed to this list today, and for the first time I discover Roland Bock's sqlpp11, which does all of those things too. First of all I'd like to say: nice work Roland! The truth is, if I had seen sqlcpp11 earlier, I would not have had felt the need to write quince. Nevertheless, I did write it, and so of course it has a different set of features. The full doco is at http://quince-lib.com, but let me quickly point out a few differences from sqlpp11. 1. If you want some class to be mapped into SQL data, quince lets you write this sort of thing: struct point { float x; float y; }; QUINCE_MAP_CLASS(point, (x)(y)) extern database db; table<point> points(db, "points"); The macro QUINCE_MAP_CLASS uses a bit of Boost.Preprocessor magic and a bit of template metaprogramming to produce all the statically typed metadata that quince needs, regarding the user's type. There is no code generation step. 2. Quince's EDSL looks somewhat different. This is my first day as a student of sqlpp11, so I'm not really qualified to define the distinctions, but I think part of it is that sqlpp11 exposes the concept of column aliases, where quince does not, and quince is preoccupied with the idea of compositionality, in a way that sqlpp11 is not (as far as I know). Anyway you can see an example of the quince EDSL here: http://quince-lib.com/getting_started.html . 3. Just as sqlpp11 uses /connectors/, quince uses /backend libraries/, or /backends/. Currently I provide backends for PostgreSQL and sqlite. Unlike sqlpp11, however, I have not yet published the interface between quince and the backends. It's no secret --the whole lot is open source-- but I'm not yet ready to declare that I know all the customization points I'm going to need. 4. Quince provides mappings for std::tuple<T, ...> and boost::optional<T>, whenever it provides mappings for the Ts. E.g. a boost::optional<int32_t> is mapped as an INTEGER column with its NOT NULL constraint turned off. If you have a query q1 that produces results of type T1, and a query q2 that produces results of type T2, then q1.left_join(q2, some_predicate) produces results of type std::tuple<T1, boost::optional<T2>>. 5. An application can customize the representation of data in a particular database, or a particular table. 6. Quince does not currently provide bulk insert. (It's on my to-do list.) I've barely scratched the surface, but right now I have the impression that both products have their distinctive pluses. Keen to know your thoughts. Regards, --- Michael

10 48

name of boost 1.56 tarball
by Menelaos Karavelas 29 Jul '14

29 Jul '14

Hello. Unlike previous versions which are named with underscores only, the boost 1.56 b1 tarball is named boost-1_56_0_b1.{zip, tar.gz, tar.bz, 7z}. Unpacking the tarball creates a boost-1_56_0_b1 directory instead of the expected one boost_1_56_0_b1 See also: http://sourceforge.net/projects/boost/files/boost/1.56.0.beta.1/ http://sourceforge.net/projects/boost/files/boost/1.55.0/ http://sourceforge.net/projects/boost/files/boost/1.54.0/ http://sourceforge.net/projects/boost/files/boost/1.53.0/ (older versions also follow the underscore filename pattern). Is there any particular reason for doing this? I suspect that it might cause problems to scripts looking for a specific pattern for the boost tar file and/or directory. All the best, - m.

2 1

[functional/hash] Interface-breaking changes to hash_combine
by Joaquin M Lopez Munoz 29 Jul '14

29 Jul '14

Hi, There's been a number of internal changes to the implementation of boost::hash_combine during this year, with the result that the documented procedure: http://www.boost.org/doc/html/hash/reference.html#boost.hash_combine namely, seed ^= hash_value(v) + 0x9e3779b9 + (seed << 6) + (seed >> 2), is no longer followed in all cases. This is a backwards compatibility breach --at the very least I think it should be documented. Best, Joaquín M López Muñoz Telefónica

3 2

News about proposed Boost.Application library
by Matus Chochlik 29 Jul '14

29 Jul '14

On Tue, Jul 29, 2014 at 9:39 AM, Klaim - Joël Lamotte <mjklaim(a)gmail.com> wrote: > > It would be nice if get_symbol returned a smart pointer that contained a > shared_ptr to the library. When all such references are released, the > library can be unloaded. > > > > I disagree. In my experience it would be more useful if it contained a > weak_ptr to the library, with a centralised system keeping all loaded > libraries alive and allowing the used to unload the library explicitely. > The get_symbol return type would then be testable. > That way it is easier to find issues related to plugins and its still > possible for the user to prevent these issues at runtime. > +1

1 0

[geometry] convex_hull: dispatch implementation details
by Jeremy Murphy 29 Jul '14

29 Jul '14

Hi, just wondering why boost::geometry::convex_hull is implemented with that dispatch-struct-apply business? Is it because of the two forms of convex_hull: output reference and output iterator? I'm writing a concave_hull implementation, so I'm wondering whether I should emulate the conventions in the convex_hull implementation. Thanks, cheers. Jeremy

2 3

Release branch will be closing Monday night.
by Marshall Clow 28 Jul '14

28 Jul '14

We will be “closing” the release branch late Monday night (Pacific Daylight time) in preparation for building a 1.56.0 release candidate on Tuesday morning. [ Actually, we’re just going to stop the automatic merging to the super-project, but … ] Please refrain from committing to the “master” branch of your libraries after 11:59 Monday night. (unless you have specific permission from the release managers) Thank you. — Marshall

4 5

Merging Pull Requests
by Axel Ismirlian 28 Jul '14

28 Jul '14

I have made some pull requests in several submodules of boost regarding compatibility changes for AIX several weeks ago. Is there any way to get them more attention? I have received no indication on most of them that they have been seen by their corresponding maintainers. Sincerely, -Axel

3 2

[wave] preprocess fails using b2
by Fletcher, John P 28 Jul '14

28 Jul '14

I have been using b2 to build the preprocessed files for boost phoenix. When I try to do this it now fails with a failure to build thread.cpp "g++-4.6" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -pedantic -pthread -Wextra -Wno-long-long -Wno-variadic-macros -Wunused-function -pedantic -DBOOST_ALL_NO_LIB=1 -DBOOST_SYSTEM_STATIC_LINK=1 -DBOOST_THREAD_BUILD_LIB=1 -DBOOST_THREAD_DONT_USE_CHRONO -DBOOST_THREAD_POSIX -DBOOST_WAVE_SUPPORT_THREADING=0 -DNDEBUG -I"../../.." -c -o "../../../bin.v2/libs/thread/build/gcc-4.6/release/link-static/threading-multi/wavetool-on/pthread/thread.o" "../../../libs/thread/src/pthread/thread.cpp" ../../../boost/ref.hpp:32:25: error: redefinition of â€˜class boost::reference_wrapper<T>â€™ ../../../boost/core/ref.hpp:59:25: error: previous definition of â€˜class boost::reference_wrapper<T>â€™ ../../../boost/ref.hpp:56:75: error: redefinition of â€˜template<class T> const boost::reference_wrapper<T> boost::ref(T&)â€™ ../../../boost/core/ref.hpp:131:74: error: â€˜template<class T> const boost::reference_wrapper<T> boost::ref(T&)â€™ previously declared here . It looks as though it is picking up two copies of the header file ref.hpp. This is the case with both gcc 4.6 and also gcc 4.9.0 It is not clear to me where the source file is coming from. At the moment all the libraries in my modular boost are checked out as develop. This is meaning that I cannot update my preprocessed files. Please advise me what to do. Thanks John

5 6