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

[1.51][thread] Compile errors when chrono is disabled
by Andrey Semashev 29 Jul '12

29 Jul '12

Hi, There is a problem with Boost.Thread on windows, when BOOST_THREAD_USES_CHRONO macro is defined. In win32/basic_timed_mutex.hpp there are references to Boost.Chrono not guarded with this macro, which results in compile errors. Could this be fixed before the 1.51 release? I can apply the change, if permission is granted.

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[offtopic] C++11 useful trick
by Eric Niebler 29 Jul '12

29 Jul '12

I recently ran into a limitation in recursive functions that make use of decltype in trailing return types. I've come up with a work-around that I think is a little non-obvious, so I thought I'd share. The problem came up while trying to implementing something like a variadic back() function. The "obvious" implementation doesn't work: template<typename T> T back(T && t) { return t; } template<typename T, typename ...U> auto back(T && t, U &&... u) -> decltype(::back(static_cast<U &&>(u)...)) // ERROR { return ::back(static_cast<U &&>(u)...); } int main() { int i = ::back(1,2,3); } The problem occurs on the line marked "HERE". Trouble is, the variadic "back" function is not yet in scope until after the return type. However, we'd like to use it when specifying the return type. The solution uses a default function template parameter to make the ::back symbol dependent, thereby deferring it's lookup until phase 2, when the symbol is visible. Check it: struct S { template<typename T> static T back(T && t) { return t; } template<typename T, typename ...U, typename Impl = S> static auto back(T && t, U &&... u) -> decltype(Impl::back(static_cast<U &&>(u)...)) { return Impl::back(static_cast<U &&>(u)...); } }; int main() { int i = S::back(1,2,3); } The trick is the "typename Impl = S" followed by a (now dependent) invocation of Impl::back. Voila. Apologies if this is a known technique, and I'm spamming the list with old news. It's news to me. -- Eric Niebler BoostPro Computing http://www.boostpro.com

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[type_erasure]broken link in any.html#any(const U&, const static_binding&)
by Larry Evans 29 Jul '12

29 Jul '12

The html page fragment: http://steven_watanabe.users.sourceforge.net/type_erasure/libs/type_erasure… contains a link, CopyConstructible, which sends my browser to: http://steven_watanabe.users.sourceforge.net/trunk/doc/html/CopyConstructib… which is not there. Maybe it should go to: http://www.boost.org/doc/libs/1_50_0/libs/utility/CopyConstructible.html or something similar? Also, why couldn't there be any number of arguments, something like: template<typename Map, class... U> explicit any(const static_binding< Map > & binding, U &&... arg); I think this would then allow any constructor to be used for the contained type. Of course then the requirement would have to be modified to be something like: The underlying type has a constructor accepting arguments, U&... arg. -regards, Larry

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[fusion] typo in documentation
by Steve Lorimer 28 Jul '12

28 Jul '12

In the fusion documents for algorithm pop-back, the example shows usage of pop_back as: assert(___pop_back__(make_vector <http://www.boost.org/doc/libs/1_50_0/libs/fusion/doc/html/fusion/container/…>(1,2,3)) == make_vector <http://www.boost.org/doc/libs/1_50_0/libs/fusion/doc/html/fusion/container/…>(1,2)); this should read: assert(pop_back(make_vector <http://www.boost.org/doc/libs/1_50_0/libs/fusion/doc/html/fusion/container/…>(1,2,3)) == make_vector <http://www.boost.org/doc/libs/1_50_0/libs/fusion/doc/html/fusion/container/…>(1,2)); link: http://www.boost.org/doc/libs/1_50_0/libs/fusion/doc/html/fusion/algorithm/…

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[type_erasure]any(const binding<Concept>&, ...) compile error
by Larry Evans 28 Jul '12

28 Jul '12

The attached, when compiled with with gcc4.8-20120624, produces compile error: ../../../boost/type_erasure/detail/construct.hpp: In instantiation of 'boost::type_erasure::any<Concept, T>::any(const boost::type_erasure::binding<Concept>&, U0&) [with U0 = value<boost::type_erasure::_a>; Concept = boost::mpl::vector<boost::type_erasure::copy_constructible<boost::type_erasure::_a>, boost::type_erasure::copy_constructible<boost::type_erasure::_b> >; T = boost::type_erasure::_a]': binding_of.cpp:71:32: required from here ../../../boost/type_erasure/detail/construct.hpp:99:9: error: invalid use of void expression ) ^ Am I doing something wrong? TIA. -Larry

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[1.51][ICL] Last minute commit
by Joachim Faulhaber 28 Jul '12

28 Jul '12

Hi, unaware of the fact that commits to the release branch need permission this week I did a commit today (Revision 79767). Sorry for that. So I'd like to ask for permission now. In other words, is it possible to not reverse this commit? Thanks, Joachim -- Interval Container Library [Boost.Icl] http://www.joachim-faulhaber.de

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Re: [boost] [type_erasure] Review
by Thomas Jordan 28 Jul '12

28 Jul '12

Hi, A couple of comments on the documentation (apologies my comments are not in the review template format): 1. The documentation should explain why the library is called 'TypeErasure' (as opposed to something like, e.g., 'Run Time Concepts' (RTC), for example). 2. The documentation needs a section placing the library in the context of 'Related Work', for example Adobe::Poly and related research papers. Some indication of the key differences and similarities would also be useful in this regard. 3. The description of the problem(s) the library addresses - i.e., the motivation for the library - in context of best-practice in 'modern C++', needs to be expanded in the documentation. This could be expedited by pointing to aforementioned outside papers/research on the subject, which already explain things like run-time concepts. 4. The documentation should give some brief glossary and/or include references to technical terms such as 'concept' 5. The documentation could do with some details regarding performance Vs classical OO. 6. The further work mentions support for C++11 rvalue references, what about move emulation for C++03? Cheers, Tom.

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Interest in a tweener library
by Julien Jorge 27 Jul '12

27 Jul '12

Hello, I wrote a C++ library to create tweeners and I'm thinking about porting it to Boost. The purpose of the tweeners is to interpolate the intermediate values between two given values during a time interval. Various easing functions can be applied to control the computation of the intermediate values. The library provides the following functionalities: - Interpolation is done on the value of a given variable or using an user-provided callback function, - The interpolated values are computed using a predefined easing function or any user-provided function respecting the contract, - Several tweeners can easily be executed simultaneously or in a row, The documentation of the library is available at http://libclaw.sourceforge.net/tweeners.html and the source code is available at http://sourceforge.net/projects/libclaw/files/libclaw/1.7.1/ as part of a larger library named Claw (check the claw/tween and claw/code/tween folders) Is there an interest to add this tweener library to Boost and what would be the adaptations to do? Regards, -- Julien Jorge

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Last minute commit
by Joachim Faulhaber 27 Jul '12

27 Jul '12

Hi, unaware of the fact that commits to the release branch need permission this week I did a commit today (Revision 79767). Sorry for that. So I'd like to ask for permission now. In other words, is it possible to not reverse this commit? Thanks, Joachim -- Interval Container Library [Boost.Icl] http://www.joachim-faulhaber.de

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[type_erasure] Review
by Karsten Ahnert 27 Jul '12

27 Jul '12

Hi, here is my review for Steven Watanabe's TypeErase library. First of all, I want to thank Steven for developing this library. My overall evaluation is that TypeErasue should be accepted as boost library. I did not looked very deeply into all details or the implementation but I tried to solve some problems with the library. So, I only looked at the library from the users perspective. = 1. What is your evaluation of the design? = The design looks clear and concise. I have only two small point: * Why do I need to specify relaxed_match to get a default constructable any? Maybe a empty() function would be nice to check if any holds a value (in case it is default constructable). I think a hint about a default constructable any should be in the tutorial. It is important for users. * Sometimes it is not clear, why some constructors work and others not, at least for me. Details are shown below. = 2. What is your evaluation of the implementation? = I did not looked into the implementation. = 3. What is your evaluation of the documentation? = * The documentation looks good. But I think more real-world examples would be very useful. I also encountered some problems where I could not find a hint how to solve it. For example, consider the case where you need an any (for example in a recursive data structure) to be a member of some other class: struct my_class { private: any_type a; }; What kind of constructor do I need to set up this any properly? I came up to define two constructors: struct my_class { template< class T > my_class( T t ) : a( std::move( t ) ) { } my_class( any_type a_ ) : a( a_ ) { } private: any_type a; }; = 4. What is your evaluation of the potential usefulness of the library? = The library is very useful and can be applied to a large number of problems. The library provides an alternative to classical OOP and can be used in many situations. = 5. Did you try to use the library? With what compiler? Did you have any problems? = I tried with gcc-4.7 and gcc-4.6 without problems. I wrote a test application with some kind of an expression system which can be build at runtime. (Maybe this example would be useful for the docs?) My main any definition is template< class Return , class Context > struct requirements : public mpl::vector< te::copy_constructible<> , te::typeid_<> , te::callable< Return( Context ) > , te::relaxed_match > { }; // ... template< class Return , class Context > using expr = te::any< requirements< Return , Context > > ; template< class Context > using boolean_expr = expr< bool , Context >; Then you can build base classes for unary and binary expressions which model the expr concept and contain the subexpression, for example: template< class Return , class Context > class unary_expr { public: typedef expr< Return , Context > expr_type; template< class T > unary_expr( T child ) : m_child( std::move( child ) ) { } unary_expr( expr_type child ) : m_child( child ) { } expr_type& child( void ) { return m_child; } const expr_type& child( void ) const { return m_child; } protected: expr_type m_child; }; At this point I needed some time to figure out that you need at least these two overloads of the constructor. Actually I am not sure if these two overloads are sufficient for all use cases. Some clarification in the docs or any hints would be very useful here. Having the base classes it is very easy to implement concrete expressions, for example: // Boolean expressions struct true_ { template< class Context > bool operator()( Context ) const { return true; } }; struct false_ { template< class Context > bool operator()( Context ) const { return false; } }; template< class Context > class not_ : struct unary_expr< bool , Context > { template< class T > not_( T child ) : unary_expr< bool , Context >( child ) { } bool operator()( Context c ) { return ! this->m_child( c ); } }; This works quite nice, but I always had problems to figure out how the any type are constructed, for example using expr_type = boolean_expr< void >; using not_ = not_< void >; using and_ = and_< void >; using or_ = or_< void >; true_ t; false_ f; // why does this not work? // expr_type e3( not_( f ) ); // cout << e3() << endl; // why does this work? expr_type e4( and_( t , or_( f , t ) ) ); cout << e4() << endl; The first example expr_type e3( not_( f ) ) does not compile. It fails because not_( f ) is interpreted as a function pointer: rule_engine.cpp:35:16: error: too few arguments to function ‘expr_type e3(not_)’ rule_engine.cpp:34:15: note: declared here I have no idea why the second one compiles. = 6. How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? = I spend about 10 hours with studying the library. = 7. Are you knowledgeable about the problem domain? = Some experience in boost.any, boost.function and a self written type erasure application. Not too much. Thank you again! Karsten

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[1.51.0] Release branch closed except by permission, beta next week
by Daniel James 27 Jul '12

27 Jul '12

Hello everyone, The release branch is now closed for all changes except by permission from one of the release managers. The beta release is planned for next Monday. Please can you write your entries for the release notes soon. As always you can edit them directly using subversion at: https://svn.boost.org/svn/boost/website/public_html/live/feed/history/ Or you can email them to me and I'll add them for you. The release notes are linked from the main page soon after the beta is released, so it would be complete by then. You can see the work in progress at: http://www.boost.org/users/history/version_1_51_0.html Finally, remember that the release notes are being compiled on the live site now, not the beta site. thanks, Daniel

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[graph] fails to complile on Cygwin
by Bernd Prager 27 Jul '12

27 Jul '12

Hi, I'm having trouble compiling Boost 1.51 on Cygwin 1.7.15, g++ (GCC) 4.5.3. It fails with: gcc.compile.c++ bin.v2/libs/graph/build/gcc-4.5.3/release/threading-multi/read_graphviz_new.o In file included from ./boost/proto/transform/when.hpp:25:0, from ./boost/proto/matches.hpp:43, from ./boost/proto/core.hpp:22, from ./boost/xpressive/regex_primitives.hpp:28, from ./boost/xpressive/xpressive_static.hpp:24, from ./boost/graph/graphviz.hpp:34, from libs\graph\src\read_graphviz_new.cpp:50: ./boost/proto/transform/env.hpp: In member function ‘boost::proto::functional::env_var<boost::proto::envns_::data_type>::impl<Env, true>::result_type boost::proto::functional::env_var<boost::proto::envns_::data_type>::impl<Env, true>::operator()(boost::proto::detail::arg<T>) const’: ./boost/proto/transform/env.hpp:330:36: error: ‘data’ is not a member of ‘boost::proto’ "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -mthreads -DBOOST_ALL_NO_LIB=1 -DBOOST_GRAPH_DYN_LINK=1 -DBOOST_HAS_ICU=1 -DNDEBUG -I"." -I"/usr/include" -I"libs/graph/src" -c -o "bin.v2\libs\graph\build\gcc-4.5.3\release\threading-multi\read_graphviz_new.o" "libs\graph\src\read_graphviz_new.cpp" ...failed gcc.compile.c++ bin.v2/libs/graph/build/gcc-4.5.3/release/threading-multi/read_graphviz_new.o... gcc.compile.c++ bin.v2/libs/graph/build/gcc-4.5.3/release/threading-multi/graphml.o In file included from ./boost/proto/transform/when.hpp:25:0, from ./boost/proto/matches.hpp:43, from ./boost/proto/core.hpp:22, from ./boost/xpressive/regex_primitives.hpp:28, from ./boost/xpressive/xpressive_static.hpp:24, from ./boost/graph/graphviz.hpp:34, from ./boost/graph/graphml.hpp:20, from libs\graph\src\graphml.cpp:17: ./boost/proto/transform/env.hpp: In member function ‘boost::proto::functional::env_var<boost::proto::envns_::data_type>::impl<Env, true>::result_type boost::proto::functional::env_var<boost::proto::envns_::data_type>::impl<Env, true>::operator()(boost::proto::detail::arg<T>) const’: ./boost/proto/transform/env.hpp:330:36: error: ‘data’ is not a member of ‘boost::proto’ "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -mthreads -DBOOST_ALL_NO_LIB=1 -DBOOST_GRAPH_DYN_LINK=1 -DBOOST_HAS_ICU=1 -DNDEBUG -I"." -I"/usr/include" -I"libs/graph/src" -c -o "bin.v2\libs\graph\build\gcc-4.5.3\release\threading-multi\graphml.o" "libs\graph\src\graphml.cpp" ...failed gcc.compile.c++ bin.v2/libs/graph/build/gcc-4.5.3/release/threading-multi/graphml.o... ...skipped <pbin.v2/libs/graph/build/gcc-4.5.3/release/threading-multi>cygboost_graph.dll for lack of <pbin.v2/libs/graph/build/gcc-4.5.3/release/threading-multi>read_graphviz_new.o... ...skipped <pbin.v2/libs/graph/build/gcc-4.5.3/release/threading-multi>libboost_graph.dll.a for lack of <pbin.v2/libs/graph/build/gcc-4.5.3/release/threading-multi>read_graphviz_new.o... ...skipped <p/usr/local/bin>cygboost_graph.dll for lack of <pbin.v2/libs/graph/build/gcc-4.5.3/release/threading-multi>cygboost_graph.dll... ...skipped <p/usr/local/lib>libboost_graph.dll.a for lack of <pbin.v2/libs/graph/build/gcc-4.5.3/release/threading-multi>libboost_graph.dll.a... gcc.compile.c++ bin.v2/libs/graph/build/gcc-4.5.3/release/link-static/threading-multi/read_graphviz_new.o In file included from ./boost/proto/transform/when.hpp:25:0, from ./boost/proto/matches.hpp:43, from ./boost/proto/core.hpp:22, from ./boost/xpressive/regex_primitives.hpp:28, from ./boost/xpressive/xpressive_static.hpp:24, from ./boost/graph/graphviz.hpp:34, from libs\graph\src\read_graphviz_new.cpp:50: ./boost/proto/transform/env.hpp: In member function ‘boost::proto::functional::env_var<boost::proto::envns_::data_type>::impl<Env, true>::result_type boost::proto::functional::env_var<boost::proto::envns_::data_type>::impl<Env, true>::operator()(boost::proto::detail::arg<T>) const’: ./boost/proto/transform/env.hpp:330:36: error: ‘data’ is not a member of ‘boost::proto’ "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -mthreads -DBOOST_ALL_NO_LIB=1 -DBOOST_HAS_ICU=1 -DNDEBUG -I"." -I"/usr/include" -I"libs/graph/src" -c -o "bin.v2\libs\graph\build\gcc-4.5.3\release\link-static\threading-multi\read_graphviz_new.o" "libs\graph\src\read_graphviz_new.cpp" ...failed gcc.compile.c++ bin.v2/libs/graph/build/gcc-4.5.3/release/link-static/threading-multi/read_graphviz_new.o... gcc.compile.c++ bin.v2/libs/graph/build/gcc-4.5.3/release/link-static/threading-multi/graphml.o In file included from ./boost/proto/transform/when.hpp:25:0, from ./boost/proto/matches.hpp:43, from ./boost/proto/core.hpp:22, from ./boost/xpressive/regex_primitives.hpp:28, from ./boost/xpressive/xpressive_static.hpp:24, from ./boost/graph/graphviz.hpp:34, from ./boost/graph/graphml.hpp:20, from libs\graph\src\graphml.cpp:17: ./boost/proto/transform/env.hpp: In member function ‘boost::proto::functional::env_var<boost::proto::envns_::data_type>::impl<Env, true>::result_type boost::proto::functional::env_var<boost::proto::envns_::data_type>::impl<Env, true>::operator()(boost::proto::detail::arg<T>) const’: ./boost/proto/transform/env.hpp:330:36: error: ‘data’ is not a member of ‘boost::proto’ "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -mthreads -DBOOST_ALL_NO_LIB=1 -DBOOST_HAS_ICU=1 -DNDEBUG -I"." -I"/usr/include" -I"libs/graph/src" -c -o "bin.v2\libs\graph\build\gcc-4.5.3\release\link-static\threading-multi\graphml.o" "libs\graph\src\graphml.cpp" ...failed gcc.compile.c++ bin.v2/libs/graph/build/gcc-4.5.3/release/link-static/threading-multi/graphml.o... ...skipped <pbin.v2/libs/graph/build/gcc-4.5.3/release/link-static/threading-multi>libboost_graph.a(clean) for lack of <pbin.v2/libs/graph/build/gcc-4.5.3/release/link-static/threading-multi>read_graphviz_new.o... ...skipped <pbin.v2/libs/graph/build/gcc-4.5.3/release/link-static/threading-multi>libboost_graph.a for lack of <pbin.v2/libs/graph/build/gcc-4.5.3/release/link-static/threading-multi>read_graphviz_new.o... ...skipped <p/usr/local/lib>libboost_graph.a for lack of <pbin.v2/libs/graph/build/gcc-4.5.3/release/link-static/threading-multi>libboost_graph.a...

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Building Boost 1.4.4 with mpi enabled.
by Mike Van Duzee 26 Jul '12

26 Jul '12

I am having issues building boost with mpi enabled. (Windows 7 64bit, Visual Studio 2008) - OpenMPI 1.6 was downloaded and compiled at C:\\openmpi - The following has been added to my user-config.jam: using mpi : mpicxx : <include>C:\\openmpi \\installed\\include <library-path>C:\\openmpi )\\installed\\lib : C:\\openmpi \\installed\\bin\\mpirun ; - The '--with-mpi' flag has been added to the call to bjam.exe. When I build I boost I get a number of unresolved external symbols: packed_skeleton_iarchive.obj : error LNK2001: unresolved external symbol ompi_mpi_byte packed_skeleton_oarchive.obj : error LNK2001: unresolved external symbol ompi_mpi_byte point_to_point.obj : error LNK2001: unresolved external symbol ompi_mpi_byte request.obj : error LNK2001: unresolved external symbol ompi_mpi_byte ... request.obj : error LNK2001: unresolved external symbol ompi_request_null mpi_datatype_cache.obj : error LNK2001: unresolved external symbol ompi_mpi_datatype_null bin.v2\libs\mpi\build\msvc-9.0\debug\address-model-64\threading-multi\boost_mpi-vc90-mt-gd-1_44.dll : fatal error LNK1120: 15 unresolved externals After looking at the call to link I can see that it is not linking to any of the Open MPI libs: link /NOLOGO /INCREMENTAL:NO /DLL /DEBUG /MACHINE:X64 /subsystem:console /out:"bin.v2\libs\mpi\build\msvc-9.0\debug\address-model-64\threading-multi\boost_mpi-vc90-mt-gd-1_44.dll" /IMPLIB:"bin.v2\libs\mpi\build\msvc-9.0\debug\address-model-64\threading-multi\boost_mpi-vc90-mt-gd-1_44.lib" /LIBPATH:"d:\thirdparty\msvc2008\x64\OPENMPI\1.6\installed\lib" @"bin.v2\libs\mpi\build\msvc-9.0\debug\address-model-64\threading-multi\boost_mpi-vc90-mt-gd-1_44.dll.rsp" Any help with this would be appreciated, Mike

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[1.51][program_options] Changesets not merged to release
by Andrey Semashev 26 Jul '12

26 Jul '12

Hi, I've noticed that changesets 79280 and 79283 have not been merged to the release branch. The first fixes compilation with STLPort and the second one removes warnings. Both look quite harmless and have been committed to trunk for quite a while. I don't see any regressions in tests caused by these changes. Can these be merged to trunk? I can do the merge, if permitted.

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BlueGo Beta 0.0.1
by Julian Amann 26 Jul '12

26 Jul '12

I build a small tool which builds boost libraries using Visual Studio 2010 x64. It can be downloaded from here: http://vertexwahn.de/ You just have to start the application and click the "Download and Build Boost 1.50.0 with Visual Studio 2010 x64" button - everything else should work automatically. The application downloads the current boost library and builds it. Julian

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[iterators]: collection_keys and collection_values
by Igor Lubashev 26 Jul '12

26 Jul '12

I'd like to propose adding collection_keys and collection_values to iterators library. ======== Motivation ======== I find myself very often having to iterate over all keys or values of a map (or multimap). The best I can do is to use BOOST_FOREACH to iterate over the collection value_type pairs and then work with .first or .second. That makes for awkward and unclear code. BOOST_FOREACH( const foo_bar_map_t::value_type &foo_bar_pair, my_map ) { baz(foo_bar_pair.second); } Instead, I'd like to do something like: BOOST_FOREACH( const bar_t &bar, collection_values(my_map) ) { baz(bar); } BOOST_FOREACH( const foo_t &foo, collection_keys(my_map) ) { baz(foo); } ======== Proposal ======== Add this to iterators library as collection_iterators.hpp Thanks, - Igor #ifndef .... #define .... #include <boost/iterator/transform_iterator.hpp> namespace boost { namespace detail { template<typename CollectionT> struct key_function : public std::unary_function<const typename CollectionT::value_type&, const typename CollectionT::key_type&> { typename key_function::result_type operator()(typename key_function::argument_type p) const { return p.first; } }; template<typename CollectionT> struct value_function : public std::unary_function<const typename CollectionT::value_type&, const typename CollectionT::mapped_type&> { typename value_function::result_type operator()(typename value_function::argument_type p) const { return p.second; } }; template<typename CollectionT, typename AdapterF> class collection_adapter { const CollectionT &c; public: typedef boost::transform_iterator<AdapterF, typename CollectionT::const_iterator> const_iterator; typedef const_iterator iterator; collection_adapter(const CollectionT &c) : c(c) {} const_iterator begin() const { return boost::make_transform_iterator(c.begin(), AdapterF()); } const_iterator end() const { return boost::make_transform_iterator(c.end(), AdapterF()); } }; } // Adapter for map-like collection -> iterable keys collection template<typename CollectionT> const detail::collection_adapter<CollectionT, detail::key_function<CollectionT> > collection_keys(const CollectionT &c) { return detail::collection_adapter<CollectionT, detail::key_function<CollectionT> >(c); } // Adapter for map-like collection -> iterable values collection template<typename CollectionT> const detail::collection_adapter<CollectionT, detail::value_function<CollectionT> > collection_values(const CollectionT &c) { return detail::collection_adapter<CollectionT, detail::value_function<CollectionT> >(c); } } // namespace boost #endif // ....

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website/docs: link broken
by Markus Werle 25 Jul '12

25 Jul '12

Hi! On http://www.boost.org/doc/libs/1_50_0/libs/scope_exit/doc/html/scope_exit/Ge… g_Started.html There is a link to http://www.boost.org/doc/libs/1_50_0/libs/scope_exit/doc/html/scope_exit/Tu… al.html which is broken. Error message is: 404 Not Found File "/home/grafik/www.boost.org/archives/live/boost_1_50_0/libs/scope_exit/doc /html/scope_exit/Tutorial.html" not found. Unable to find file. Markus

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Re: [boost] Macro for BOOST_NO_NUMERIC_LIMITS_MAX_DIGITS10 or use BOOST_NO_NUMERIC_LIMITS_LOWEST
by Stewart, Robert 24 Jul '12

24 Jul '12

John Maddock wrote: > > >> is there a way to don't include all the deprecated macros? > > Whoa - interesting question. > > I don't know of one. > > > > However, all the deprecated macros are defined (I > > _believe_) in one place, in boost/config/suffix.hpp > > Making it so none of them are defined _should_ be > > straightforward. > > > >Could I suggest to define all of them in a specific > >boost/config/deprecated.hpp file, so that we can add a > >deprecated warning when the file is included. +1 > I think it's too soon for that - as things stand you would > basically be injecting that warning into every Boost header > that includes boost/config.hpp. Aren't there some that have been deprecated for long enough to get that sort of treatment? IOW, create a mechanism for complaining about the use of old names and a policy for how long old names are defined without complaint, how long with complaint, and how long before they are removed. For example, newly renamed macros might be kept in config/suffix.hpp for four releases before moving them to config/deprecated.hpp. Then, names in deprecated.hpp might remain for two releases before removing them altogether. > Besides I don't see what harm defining the old names does? If you can't ever remove the old names, then the set of names that can appear in Boost code grows uncomfortably large. _____ Rob Stewart robert.stewart(a)sig.com Software Engineer using std::disclaimer; Dev Tools & Components Susquehanna International Group, LLP http://www.sig.com ________________________________ IMPORTANT: The information contained in this email and/or its attachments is confidential. If you are not the intended recipient, please notify the sender immediately by reply and immediately delete this message and all its attachments. Any review, use, reproduction, disclosure or dissemination of this message or any attachment by an unintended recipient is strictly prohibited. Neither this message nor any attachment is intended as or should be construed as an offer, solicitation or recommendation to buy or sell any security or other financial instrument. Neither the sender, his or her employer nor any of their respective affiliates makes any warranties as to the completeness or accuracy of any of the information contained herein or that this message or any of its attachments is free of viruses.

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[TypeErasure]
by Markus Werle 24 Jul '12

24 Jul '12

Hi Steven! I have one question: proto and spirit use _1, _2, etc. TypeErasure uses _a, _b, _c ... What was your reason to introduce yet another placeholder set? Markus

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[move] Implementing operator= in terms of pass-by-value and swap
by Krzysztof Czainski 24 Jul '12

24 Jul '12

Hello, Implementing the assignment operator (that is, the copy-, move- and other assignments) in terms of pass-by-value and swap is a common idiom [1]. {{{ T operator=( T b ) { swap(*this,b); return *this; } }}} If T is copy-constructible, the above works as a copy-assign. If T is movable, the above works as a move-assign. And for anything convertible to T the above assign will work (right?). Furthermore, this will also work for movable but not copyable classes (right?). It may not be the optimal version of assignment in some cases. In rare cases it might even be incorrect - for types like std::vector, which aren't expected to free reserved memory upon assignment. But assuming swap is a cheap operation, it should be close to optimal in many if not most cases. And in cases, where RVO kicks in, it may be even better than providing separate overloads of operator= for lvalues and rvalues [2]. Boost.Move docs [3] suggest writing the separate overloads of operator=, and in C++03 move emulation the macro BOOST_COPYABLE_AND_MOVABLE(classname) provides a third overload (necessary for the emulation to work in C++03). Should the user choose to write one overload of operator= in the pass-by-value version, he needs to use a different macro, that doesn't provide the additional overload of operator=. I found such a macro: BOOST_COPYABLE_AND_MOVABLE_ALT(classname), but no docs about it. I have the following suggestions, regarding Boost.Move: 1. Providing a macro, BOOST_MOVABLE(classname), that only provides the two needed conversion operators. Or if that is the purpose of BOOST_COPYABLE_AND_MOVABLE_ALT(classname), I couldn't find docs about it. And to avoid a macro entirely, maybe it is possible to provide a CRTP base class 'movable', that would provide these? 2. Now, that there's a separate macro, defining a movable class, it may make sense to add a separate macro for making a class noncopyable. And we already have a base class for that, if one wants to avoid a macro. 3. It would be nice if the docs [3] mentioned something about the alternative of providing only one operator= passing by value. [1] http://en.wikibooks.org/wiki/More_C%2B%2B_Idioms/Copy-and-swap [2] http://cpp-next.com/archive/2009/08/want-speed-pass-by-value/ [3] http://www.boost.org/doc/libs/1_50_0/doc/html/move/implementing_movable_cla… Regards, Kris

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Re: [boost] [type_erasure] [docs]contrast with boost::any
by Larry Evans 23 Jul '12

23 Jul '12

On 07/23/12 15:37, Larry Evans wrote: > On 07/18/12 00:13, Lorenzo Caminiti wrote: >> Hello all, >> >> *** The review of Steven Watanabe's proposed Boost.TypeErasure library >> begins on July 18, 2012 and ends on July 27, 2012. *** >> > The page: > > http://steven_watanabe.users.sourceforge.net/type_erasure/libs/type_erasure… > > says: > > x is approximately equivalent to a boost::any > > however, it doesn't say how te::any differs from boost::any. > > The attached shows that a boost::any can change it's > type, and, as such, is somewhat like boost::variant. > However, te::any, once it's created, cannot change > it's type, AFAICT. At least that's what the > attached code indicates when compiled with: > > #define SHOW_TE_FIXED_TYPE > A simplified version of that code (which doesn't require demangled_type_name), is attached. The attached also suggests that, when multiple placeholders are in the concept, the unary any *requires* a binding argument. This is shown by trying to compile the attachment with: #define SHOW_BINDINGS_MUST_BE_COMPLETE In contrast, the example here: http://steven_watanabe.users.sourceforge.net/type_erasure/libs/type_erasure… shows no binding is needed because the only placeholder in the concept is the default, _self. HTH. -regards, Larry

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[Review Request] array
by Brian Smith 23 Jul '12

23 Jul '12

Hi All, Based on the assumption that, almost no feedback is good feedback, I'd like to submit the array class for review. The requisite files are hosted at, https://github.com/BrianJSmith/Array Comment: The array class is a C++11 compatible implementation of static multidimensional arrays. Kind Regards Brian

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[TypeErasure] Forward constructors and binded types
by Vicente J. Botet Escriba 23 Jul '12

23 Jul '12

Hi,, In the example from the doc typedef mpl::vector< copy_constructible<_a>, copy_constructible<_b>, copy_constructible<_c>, constructible<_a(const _b&, const _c&)> > construct; std::vector<double> vec; int i = 10; double d = 2.5; tuple<construct, _a&, _b, _c> t(vec, i, d); any<construct, _a> v(get<1>(t), get<2>(t)); I don't see which type is constructed and stored in v and how this type is given. That is I don't see how _a is binded. Could you help me? Best, Vicente

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[TypeErasure] BOOST_TYPE_ERASURE_MEMBER
by Julien Nitard 23 Jul '12

23 Jul '12

Hi Steven, all BOOST_TYPE_ERASURE_MEMBER is only mentioned in the reference, it could be useful to add it to the tutorial: I guess that most user concepts will start from member functions of a given type. A sample on how to specialize it for types not having the said member function would be also welcome. Finally, why did you choose not to include the member's signature in the macro ? Isn't this giving the way for hard to find mistakes ? Regards, Julien

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[website] Server problems
by Daniel James 23 Jul '12

23 Jul '12

Hello, As you might have noticed, many of the php based pages were down this morning. The cause appears to be that the directory '/home/grafik/www.boost.org/' didn't have read and execute permissions for all, so php couldn't read a file within it. I fixed it by giving read permission - nothing in that directory is private so I don't think that will be a problem. Hopefully that's okay? I don't like messing round with these things too much, as I don't know the details about the setup. Does anyone have any idea what changed to cause this issue? Maybe an upgrade or configuration change? Could it use group permissions before but can't now for some reason? Or perhaps something accidentally changed the permission on the directory? It'd be useful to understand what happened. Daniel

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