November 2011 - Boost - lists.preview.boost.org

1.48 is another release without the logger
by Jeff Graham 14 Nov '11

14 Nov '11

Hello, Any progress on the logger?

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Re: [boost] Boost.Local Review (Nov 10, 2011 to Nov 19, 2011)
by Lorenzo Caminiti 14 Nov '11

14 Nov '11

Hello all, I have received a couple of questions on Boost.Local and I will answer them on the ML. On Mon, Nov 14, 2011 at 4:20 AM, Andrzej Krzemienski <akrzemi1(a)gmail.com> wrote: > 1. Can Boost.Local be used to create global functions? No, Boost.Local macros need to be used at local scope. If it were important to use the functionality of Boost.Local at global scope, it _might_ be possible to do so but another set of macros (BOOST_GLOBAL_?) will have to be defined for that. Does anyone see a need to use LOCAL_EXIT, LOCAL_BLOCK, or LOCAL_FUNCTION at global scope? If so, why? > 2. For Local Exits, is it possible not to bind any variable (because I will > only be calling global functions): > > int runCommand() { > ::DisplayWaitCursor(); > BOOST_LOCAL_EXIT( /*nothing*/ ) { > ::DisplayNormalCursor(); > } BOOST_LOCAL_EXIT_END; > > DoALongLastingOperation(); > } Yes, you can do this. However, the most portable syntax is to use void for the empty parameter list: https://svn.boost.org/svn/boost/sandbox/local/libs/local/doc/html/boost_loc… For example: #include <boost/local/exit.hpp> #include <iostream> void f() { std::cout << "f" << std::endl; } int main() { ::f(); BOOST_LOCAL_EXIT(void) { ::f(); } BOOST_LOCAL_EXIT_END return 0; }; This compiles and it prints "f" twice (at main entry and exit). HTH, --Lorenzo

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[1.48][flyweight] regression in release branch
by JOAQUIN M. LOPEZ MUÑOZ 13 Nov '11

13 Nov '11

Hi, Sorry for not having tracked this before. There's a trivial regression in Boost.Flyweight due to a change of namespace name in Boost.Interprocess: https://svn.boost.org/trac/boost/changeset/75464 OK to commit to branch? Joaquín M López Muñoz Telefónica Digital ________________________________ Este mensaje se dirige exclusivamente a su destinatario. Puede consultar nuestra política de envío y recepción de correo electrónico en el enlace situado más abajo. This message is intended exclusively for its addressee. We only send and receive email on the basis of the terms set out at. http://www.tid.es/ES/PAGINAS/disclaimer.aspx

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[iostreams][io_state_savers] Request for interest in some ios_base basic utilities
by Vicente J. Botet Escriba 12 Nov '11

12 Nov '11

Hi, I'm a beginner of the standard IOStream library. While restructuring Boost.Chrono I/O I have find some classes that could be of general use (if the design is correct, of course). The first one is quite simple, is used to define manipulators with parameters. Instead of defining a class and the correspondent stream inserters and extractors the manip template class do all this at once. It can be used as follows class mendl: public manip<mendl> { public: explicit mendl(size_t how_many) : count(how_many) {} template <typename out_stream> void operator()(out_stream &out) const { for (size_t line = 0; line < count; ++line) { out.put(out.widen('\n')); } out.flush(); } private: size_t count; }; Now mendl can be use to insert n new lines at once as follows cout << mendl(3); The second one is an ios specific smart pointer ios_base_state_ptr (based on the use of ios_base::pword and ios_base::xalloc). The class ios_base_state is a ios_base_state_ptr that can not be null. It can be used like struct MyData { std::string time_fmt; std::string duration_fmt; }; std::string get_time_fmt(std::ios_base & ios) { return ios_base_state<MyData>(ios)->time_fmt; } ios_base_state stores a new MyData in the ios if not already stored and provides an smart pointer interface to it. The 3rd one (ios_base_flags) uses the ios_base::iword and xalloc to provide access to specific ios flags. It can be used as follows: class fmt_masks : ios_base_flags<fmt_masks> { typedef ios_base_flags<fmt_masks> base_type; public: fmt_masks(std::ios_base& ios): base_type(ios) {} enum type { uses_symbol = 1 << 0, uses_local = 1 << 1 }; }; Usage of this class can be duration_style::type get_duration_style(std::ios_base& ios) { return (fmt_masks(ios).flags() & fmt_masks::uses_symbol) ? duration_style::symbol : duration_style::prefix; } The interface and the implementation of these classes is attached. Do you see a design flag on these classes? If not, do you think these kind of utilities could be added to boost? If yes, could these be merged with Boost.io_state_savers or Boost.IOStreams to form a larger io utilities libraries? Best, Vicente

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Are some of the trunk regression tests running in C++0x mode when they shouldn't be?
by Richard Webb 11 Nov '11

11 Nov '11

Looking at the Trunk regression tests, it appears that some of the GCC tests are running in C++0x mode when they shouldn't be. for example: Large numbers of the Sandia-gcc-3.4.6 tests are failing with the error: unrecognized command line option "-std=c++0x" If you look at the test results for assign, there are rvalue-reference related errors in toolsets which shouldn't have them. Looks like -std=c++0x is being specified when it shouldn't for some reason? Is something broken, or am i imagining it? Thanks, Richard Webb

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leak in win32 detail::basic_condition_variable
by Kenneth Porter 10 Nov '11

10 Nov '11

I'm finding that an element in the CV's generation_list is left orphaned sometimes when the CV is destroyed. I'm running Visual Leak Detector and it gives this stack dump of the allocation point of the leaked object: c:\devel\boost\boost_1_46_1\boost\thread\win32\condition_variable.hpp (172): boost::detail::basic_condition_variable::get_wait_entry c:\devel\boost\boost_1_46_1\boost\thread\win32\condition_variable.hpp (211): boost::detail::basic_condition_variable::do_wait<boost::unique_lock <boost::mutex> > + 0xC bytes c:\devel\boost\boost_1_46_1\boost\thread\win32\condition_variable.hpp (369): boost::condition_variable_any::wait<boost::unique_lock<boost::mutex> > c:\devel\boost\boost_1_46_1\boost\thread\win32\condition_variable.hpp (374): boost::condition_variable_any::wait<boost::unique_lock <boost::mutex>,boost::_bi::bind_t<bool,boost::_mfi::cmf0 <bool,bounded_buffer<Axis::Report> >,boost::_bi::list1<boost::_bi::value <bounded_buffer<Axis: + 0x1B bytes I compared the source file against trunk and it hasn't changed.

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asio ipv6 anycast
by Julian Faude 10 Nov '11

10 Nov '11

Hi, I am working on a project which depends on IPv6 anycast. In linux IPv6 anycast is available through a socket options called IPV6_JOIN_ANYCAST and IPV6_LEAVE_ANYCAST. Like the multicast option it's based on the ipv6_mreq struct. If I'm not mistaken there is no ipv6 anycast socket option in asio. Am I right? Is anybody working on it? Best, Julian

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[Test] Darwin Intel 11.1
by Belcourt, K. Noel 09 Nov '11

09 Nov '11

Hi, I've attached a patch that appears to fix problems with about 20 Boost libraries on trunk that depend on Boost.Test. This patch simply removes an argument to format_report(). The trunk tests (http://www.boost.org/development/tests/trunk/developer/summary.html ) currently reflect this patch. I've added this patch to the nightly trunk testing patch script until such time as we get this committed to trunk. -- Noel

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Fw: [atomic] review results
by Peter Dimov 08 Nov '11

08 Nov '11

-----Original Message----- From: Peter Dimov Sent: Monday, November 07, 2011 22:38 To: Helge Bahmann Subject: Re: [boost] [atomic] review results Helge Bahmann wrote: > yes makes sense -- there was a concern raised by Andrey Semashev that the > spinlock pool as implemented and used by shared_ptr presently may fail on > Windows due to the pool being non-unique (not had a chance to test this > yet), > and I have found a way to produce a similar failure using dlopen, atomics > private to shared libraries and RTLD_LOCAL -- currently I am therefore > leaning on creating a shared library just for the spinlock pool, but since > you wrote the initial implementation maybe you could comment as well? This is a problem in principle, but requiring all users of shared_ptr to link to a shared library is a non-starter. I wouldn't use such a shared_ptr, and I doubt many others will. And I wouldn't be surprised if this sentiment applies to Boost.Atomic as well.

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[parameter] type requirement compiler error
by lcaminiti 08 Nov '11

08 Nov '11

Hello all, The following parameter type requirement: (required (graph, *) ) (optional (root_vertex, (typename boost::graph_traits<graph_type>::vertex_descriptor), *boost::vertices(graph).first) ) Generates a GCC error: dfs.05.cpp:40: error: ‘graph_type’ was not declared in this scope Detailed code and error below. In fact, if I look at the code after pp, I can see that graph_type is define only after the type requirement is checked... why? What am I doing wrong? Thanks a lot! --Lorenzo #include <boost/graph/adjacency_list.hpp> #include <boost/graph/depth_first_search.hpp> #include <boost/range/irange.hpp> #include <boost/pending/indirect_cmp.hpp> #include <boost/parameter.hpp> #include <iostream> namespace graphs { BOOST_PARAMETER_NAME(graph) BOOST_PARAMETER_NAME(visitor) BOOST_PARAMETER_NAME(root_vertex) BOOST_PARAMETER_NAME(index_map) BOOST_PARAMETER_NAME(color_map) template< typename Size, typename IndexMap > boost::iterator_property_map<boost::default_color_type*, IndexMap, boost::default_color_type, boost::default_color_type&> default_color_map ( Size const& num_vertices, IndexMap const& index_map ) { std::vector<boost::default_color_type> colors(num_vertices); return &colors[0]; } BOOST_PARAMETER_FUNCTION( (void), depth_first_search, tag, (required (graph, *)) (optional (visitor, *, boost::dfs_visitor<>()) (root_vertex, (typename boost::graph_traits<graph_type>::vertex_descriptor), *boost::vertices(graph).first) (index_map, *, boost::get(boost::vertex_index, graph)) (in_out(color_map), *, default_color_map(boost::num_vertices(graph), index_map)) ) ) { std::cout << "here\n"; boost::depth_first_search(graph, boost::visitor(visitor). color_map(color_map).root_vertex(root_vertex). vertex_index_map(index_map)); } } // namespace graphs template< typename TimeMap > class dfs_time_visitor : public boost::default_dfs_visitor { typedef typename boost::property_traits< TimeMap >::value_type T; public: dfs_time_visitor(TimeMap dmap, TimeMap fmap, T& t) : dmap_(dmap), fmap_(fmap), time_(t) {} template< typename V, typename G > void discover_vertex ( V u, G const& g ) const { put(dmap_, u, time_++); } template< typename V, typename G > void finish_vertex ( V u, G const& g ) const { put(fmap_, u, time_++); } TimeMap dmap_; TimeMap fmap_; T& time_; }; using namespace boost; int main ( ) { typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS> G; typedef boost::graph_traits<G>::vertices_size_type size_type; enum {u, v, w, x, y, z, N}; char names[] = {'u', 'v', 'w', 'x', 'y', 'z'}; typedef std::pair<int, int> E; E edges[] = {E(u, v), E(u, x), E(x, v), E(y, x), E(v, y), E(w, y), E(w, z), E(z, z)}; G g(edges, edges + sizeof(edges) / sizeof(E), N); std::vector<size_type> dtime(boost::num_vertices(g)); std::vector<size_type> ftime(boost::num_vertices(g)); size_type t = 0; dfs_time_visitor<size_type*> vis(&dtime[0], &ftime[0], t); graphs::depth_first_search(g, vis); std::vector<size_type> dorder(N); boost::integer_range<size_type> r(0, N); std::copy(r.begin(), r.end(), dorder.begin()); std::sort(dorder.begin(), dorder.end(), boost::indirect_cmp<size_type*, std::less<size_type> >(&dtime[0])); std::cout << "order of discovery: "; for(int i = 0; i < N; ++i) std::cout << names[dorder[i]] << " "; std::cout << std::endl; std::vector<size_type> forder(N); std::copy(r.begin(), r.end(), forder.begin()); std::sort(forder.begin(), forder.end(), boost::indirect_cmp<size_type*, std::less<size_type> >(&ftime[0])); std::cout << "order of finish: "; for(int i = 0; i < N; ++i) std::cout << names[forder[i]] << " "; std::cout << std::endl; return 0; } $ g++ -Wall -I../../../../../boost-trunk.cygwin dfs.05.cpp dfs.05.cpp:40: error: ‘graph_type’ was not declared in this scope dfs.05.cpp:40: error: template argument 1 is invalid dfs.05.cpp:40: error: expected `::' before ‘,’ token dfs.05.cpp:40: error: expected identifier before ‘,’ token dfs.05.cpp:40: error: template argument 3 is invalid dfs.05.cpp:40: error: expected `::' before ‘{’ token dfs.05.cpp:40: error: expected class-name before ‘{’ token ../../../../../boost-trunk.cygwin/boost/parameter/preprocessor.hpp: In instantiation of ‘boost::parameter::aux::argument_pack<graphs::boost_param_params_40depth_first_search<int>, const boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, boost::no_property, boost::no_property, boost::no_property, boost::listS>, const dfs_time_visitor<main::size_type*>, boost::parameter::void_, boost::parameter::void_, boost::parameter::void_>’: dfs.05.cpp:88: instantiated from here ../../../../../boost-trunk.cygwin/boost/parameter/preprocessor.hpp:157: error: no type named ‘parameter_spec0’ in ‘struct graphs::boost_param_params_40depth_first_search<int>’ ../../../../../boost-trunk.cygwin/boost/parameter/preprocessor.hpp:158: error: no type named ‘parameter_spec0’ in ‘struct graphs::boost_param_params_40depth_first_search<int>’ ../../../../../boost-trunk.cygwin/boost/parameter/preprocessor.hpp: In instantiation of ‘boost::parameter::aux::argument_pack<graphs::boost_param_params_40depth_first_search<int>, const boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, boost::no_property, boost::no_property, boost::no_property, boost::listS>, boost::parameter::void_, boost::parameter::void_, boost::parameter::void_, boost::parameter::void_>’: dfs.05.cpp:88: instantiated from here ../../../../../boost-trunk.cygwin/boost/parameter/preprocessor.hpp:157: error: no type named ‘parameter_spec0’ in ‘struct graphs::boost_param_params_40depth_first_search<int>’ ../../../../../boost-trunk.cygwin/boost/parameter/preprocessor.hpp:158: error: no type named ‘parameter_spec0’ in ‘struct graphs::boost_param_params_40depth_first_search<int>’ dfs.05.cpp: In function ‘int main()’: dfs.05.cpp:88: error: no matching function for call to ‘depth_first_search(main()::G&, dfs_time_visitor<size_type*>&)’ -- View this message in context: http://boost.2283326.n4.nabble.com/boost-parameter-type-requirement-compile… Sent from the Boost - Dev mailing list archive at Nabble.com.

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[1.48 lexical_cast] Illegal Derefence
by Olaf van der Spek 08 Nov '11

08 Nov '11

Hi, This does an illegal dereference in boost\lexical_cast.hpp(1357): if ( Traits::eq(minus,*start) ) #include <boost/lexical_cast.hpp> #include <boost/range/iterator_range.hpp> int main() { boost::iterator_range<const char*> v; boost::lexical_cast<int>(v); } -- Olaf

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Boost interprocess: Segmentation fault
by thuannv 08 Nov '11

08 Nov '11

Hi everybody, I am beginner to develop with boost library. I am working with shared memory (boost.interprocess). So, I got error in executing and could anyone help me solve this problem? My problem is: - I wrote 2 process named SHMWriter and SHMReader. + SHMWwriter: write a map (int, int) into the SHM. + SHMReader: read the map value from SHM. - I executed the SHMWriter then SHMReader. - SHMWriter successfully executed. But, SHMWriter always executed failed (error: Segmentation fault). - The sources code are listed below: //SHMWriter: -------------------------------------------- typedef std::pair<int, int> MapValue; typedef allocator<MapValue, managed_shared_memory::segment_manager> MapAllocator; typedef map<int, int, std::less&lt;int>, MapAllocator> IntegerMap; const char* segName = "MAPSEGMENT"; const char* mapName = "MAPNAME"; int main() { shared_memory_object::remove(segName); managed_shared_memory segment(create_only, segName, 1000); MapAllocator allocator(segment.get_segment_manager()); IntegerMap* pOffsetMap = segment.construct<IntegerMap>(mapName)(std::less<int>(), allocator ); int key = 1; int ivalue = 10; MapValue value(key, ivalue); pOffsetMap->insert(value); return 0; } //SHMReader ----------------------------- typedef std::pair<int, int> MapValue; typedef allocator<MapValue, managed_shared_memory::segment_manager> MapAllocator; typedef map<int, int, std::less&lt;int>, MapAllocator> IntegerMap; const char* segName = "MAPSEGMENT"; const char* mapName = "MAPNAME"; int main() { try { managed_shared_memory segment(open_only, "MAPSEGMENT"); IntegerMap* pMap = segment.find_no_lock<IntegerMap>(mapName).first; int key = 1; int value = pMap->at(key); std::cout << value << std::endl; } catch(interprocess_exception& ie) { std::cout << ie.what() << std::endl; } catch(std::exception& stde) { std::cout << stde.what() << std::endl; } return 0; } -- View this message in context: http://boost.2283326.n4.nabble.com/Boost-interprocess-Segmentation-fault-tp… Sent from the Boost - Dev mailing list archive at Nabble.com.

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[Range] Confusing result of iterator_range::size()
by Sergey Voropaev 08 Nov '11

08 Nov '11

Hi, I try use boost::iterator_range as replacement for some standard container in my code. The function iterator_range::size() has non standart declaration: difference_type size() const; but not: size_type size() const When I compile code in VC++ 2010 I have a some warning and error. For example: #include <boost/range.hpp> #include <vector> #include <algorithm> int main() { int aaa[10] ={1,2,3,4,5,6,7,8,9,10}; std::vector<int> bbb(20); boost::iterator_range<int*> arr(aaa); if(bbb.size() > arr.size()) //warning C4018: '>' : signed/unsigned mismatch { } const size_t lng = std::min(bbb.size(), arr.size()); //error C2780: 'const _Ty &std::min(const _Ty &,const _Ty &,_Pr)' : expects 3 arguments - 2 provided //error C2782: 'const _Ty &std::min(const _Ty &,const _Ty &)' : template parameter '_Ty' is ambiguous // const size_t lng = std::min(bbb.size(), (size_t)arr.size()); //OK for(size_t i = 0; i < lng; ++i) { bbb[i] = arr[i]; } return 0; } I think declaration of boost::iterator_range must be fixed. Or there was some reason for this non standard declaration?

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Boost.Build is broken?
by Gennadiy Rozental 08 Nov '11

08 Nov '11

Hi, Frankly I do not know who supports Boost.Build, but how long it'll stay broken? I can't say when it started, but ever since I started working on Boost.Test changes I experience constant problems. I can't believe I am the only one. 1. When you take boost trunk and go into Boost.Test build or test directory and try building using any toolset it immediately fails with: ..\..\..\libs\test\build\Jamfile.v2:110: in modules.load rule boost-install unknown in module Jamfile</.../trunk/libs/test/build>. .../trunk/tools/build/v2/build\project.jam:314: in load-jamfile .../trunk/tools/build/v2/build\project.jam:62: in project.load .../trunk/tools/build/v2/build\project.jam:766: in project.use .../trunk/tools/build/v2/build\project.jam:89: in load-used-projects .../trunk/tools/build/v2/build\project.jam:73: in load .../trunk/tools/build/v2/build\project.jam:115: in load-parent .../trunk/tools/build/v2/build\project.jam:464: in initialize .../trunk/tools/build/v2/build\project.jam:309: in load-jamfile .../trunk/tools/build/v2/build\project.jam:62: in load .../trunk/tools/build/v2/build\project.jam:115: in load-parent .../trunk/tools/build/v2/build\project.jam:464: in initialize .../trunk/tools/build/v2/build\project.jam:309: in load-jamfile .../trunk/tools/build/v2/build\project.jam:62: in load .../trunk/tools/build/v2/build\project.jam:168: in project.find .../trunk/tools/build/v2\build-system.jam:570: in load .../trunk\tools\build\v2/kernel\modules.jam:283: in import .../trunk\tools\build\v2\kernel\bootstrap.jam:142: in boost-build .../trunk\boost-build.jam:17: in module scope 2. Once I remove boost-install from Boost.Test Jamfile, I get bun of errors like this: ..\..\..\libs\test\src\compiler_log_formatter.cpp(16) : fatal error C1083: Cannot open include file: 'boost/test/impl/compiler_log_formatter.ipp': No such file or directory Essentially boost home directory is missing from include path. How come? 3. Once I add "<include>../../.." into requirements section I can build with msvc toolsets. Now I am trying to use gcc toolset on Windows. I have latest cygwin installation and I am getting these errors (lots of them): gcc.compile.c++ ..\..\..\libs\test\build\bin\gcc\debug\link-static\compiler_log_formatter.o "g++" ... # compilation line here Access is denied. Apparently g++ is not an executable anymore with cygwin. I am able to workaround this by adding using gcc : 4.5.3 : g++-4.exe ; into user-config.jam, but why Boost.Build can't figure this out and do I need to support this file now myself? 4. After the fix I am able to build dll based tests, but when I attempt to use static library version of Boost.Test I am getting: gcc.archive ..\..\..\libs\test\build\bin\gcc-4.5.3\ debug\link-static\libboost_unit_test_framework.a "/usr/i686-pc-cygwin/bin/ar.exe" rc .... # list of object files here "/usr/i686-pc-cygwin/bin/ranlib.exe" ... # lib here The system cannot find the path specified. The system cannot find the path specified. This one I do not know how to fix. So the situation is that I cannot test any static library based unit tests (as a side note, this inability was the cause of crashes which interrupted trunk testing month ago). I addition whenever I want to check in my local changes to Jamfile (excluding hacks which I actually do not want to check in) it is rather annoying process. Any help would be appreciated, Gennadiy

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[atomic] review results
by Tim Blechmann 07 Nov '11

07 Nov '11

hi all, unfortunately only few reviews of boost.atomic arrived in time, however i count 3 YES and no NO, so i am happy to say: Helge Bahmann's boost.atomic library is ACCEPTED. since the library is an implementation of a c++11 feature for c++03, design, API and semantics are mostly fixed. many comments are going into details of the implementation, so i won't sum them all up ... iac, helge already said he wants to address the raised issues, the main points are summarized below. full implementation of the c++11 interface: the library currently only implements a subset of the c++11 library. it lacks the functional interface for integral atomic types and the ATOMIC_VAR_INIT / ATOMIC_FLAG_INIT macro. quickly consulting the latest draft that i currently have at hand the following two functions are missing as well: template <class T> T kill_dependency(T y); void atomic_signal_fence(memory_order); i encourage helge to provide a full implementation of the interface. documentation: the documentation is currently lacking a good API reference. i would therefore encourage helge to provide a doxygen-generated reference section. there were some concerns that it assumes that readers will have to be familiar with concurrency. maybe it is a good idea to point to some literature/tutorials about concurrent programming and/or to c++11 atomics. the section of real-world examples could probably include a link to shavit/herlihy's book `the art of multiprocessor programming'. it would also be helpful to have a detailed specification, if a platform/compiler combination supports a specific type natively (with run-time dispatching or specific compiler flags) ... maybe in form of a table. shared memory support/multi-module support: in multi-module applications and when using shared memory, the blocking emulation of atomics can cause troubles. for multi-module applications this can be resolved by placing the spinlock pool inside a shared library. shared- memory support could be realized by associating a (spin)lock with each blocking atomic<> instead of using a pool of spinlocks. boost should definitely provide atomics which support shared memory, either by default or by an additional implementation which is placed in the boost::interprocess namespace. i would like to thank helge for implementing boost.atomic and submitting it to boost and everyone who participated in the review. cheers, tim review manager

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[smart_ptr] Please merge 5327
by Steve M. Robbins 07 Nov '11

07 Nov '11

Peter Dimov, When you have a moment, could you merge the patch in ticket https://svn.boost.org/trac/boost/ticket/5327 It should be safe enough; Debian has been using this since August 2009. Thanks, -Steve

2 1

[parameter] named template parameters
by Lorenzo Caminiti 07 Nov '11

07 Nov '11

Hello all (and especially Boost.Parameter's authors), The Boost.Parameter docs suggest to implement parameter-enabled class templates using a series of typedes for the argument pack and the actual argument types. I think it is best to define extra template parameters with default values to old the argument pack Args and named template parameters ClassType, etc as shown below. This allows to use the named template parameters within the class declaration for example in a base class (boost::python::class_<ClassType, ...>) instead that just in the class definition. Do you see any problem in using extra template parameter to define the argument pack and named template parameters? #include <boost/parameter.hpp>#include <boost/python/class.hpp>#include <boost/type_traits/is_class.hpp>#include <boost/type_traits/is_base_and_derived.hpp>#include <boost/mpl/is_sequence.hpp>#include <boost/mpl/placeholders.hpp>#include <boost/mpl/not.hpp>#include <boost/mpl/and.hpp>#include <boost/noncopyable.hpp>#include <boost/shared_ptr.hpp> namespace py { namespace detail { struct bases_tag {}; } template< class B0 = void, class B1 = void, class B2 = void >struct bases : detail::bases_tag {}; BOOST_PARAMETER_TEMPLATE_KEYWORD(ClassType) BOOST_PARAMETER_TEMPLATE_KEYWORD(BaseList)BOOST_PARAMETER_TEMPLATE_KEYWORD(HeldType)BOOST_PARAMETER_TEMPLATE_KEYWORD(Copyable) template< typename Arg123X0 , typename Arg123X1 = boost::parameter::void_ , typename Arg123X2 = boost::parameter::void_ , typename Arg123X3 = boost::parameter::void_ , typename Args123 = typename boost::parameter::parameters< // IF(IS_EMPTY(DEFAULT(p)), required, optional) boost::parameter::required< tag::ClassType , boost::is_class<boost::mpl::_> > , boost::parameter::optional< // IF(IS_DEDUCED(p), deduced<tag::NAME(p)>, tag::NAME(p)) boost::parameter::deduced<tag::BaseList> // COMMA_IF(COMPL(IS_EMPTY(REQUIRES(p)))) REQUIRES(p) , boost::is_base_and_derived<detail::bases_tag, boost::mpl::_> > , boost::parameter::optional< boost::parameter::deduced<tag::HeldType> , boost::mpl::not_< boost::mpl::or_< boost::is_base_and_derived<detail::bases_tag, boost::mpl::_> , boost::is_same<boost::noncopyable, boost::mpl::_> > > > , boost::parameter::optional< boost::parameter::deduced<tag::Copyable> , boost::is_same<boost::noncopyable, boost::mpl::_> > >::bind<Arg123X0, Arg123X1, Arg123X2, Arg123X3>::type , typename ClassType = typename boost::parameter::value_type< Args123, tag::ClassType >::type , typename BaseList = typename boost::parameter::value_type< // ... COMMA_IF(COMPL(IS_EMPTY(DEFAULT(p)))) DEFAULT(p) >::type Args123, tag::BaseList, bases<> >::type , typename HeldType = typename boost::parameter::value_type< Args123, tag::HeldType, ClassType >::type , typename Copyable = typename boost::parameter::value_type< Args123, tag::Copyable, void >::type>struct class_ : boost::python::class_<ClassType, BaseList, HeldType, Copyable>{ typedef ClassType class_type; typedef BaseList base_list; typedef HeldType held_type; typedef Copyable copyable;}; } // namespace py struct b { virtual ~b() = 0; }; struct d : b { ~d() {} }; // Named parameters.typedef py::class_< py::ClassType<b>, py::Copyable<boost::noncopyable> > x1;typedef py::class_< d, py::HeldType< boost::shared_ptr<d> >, py::BaseList< py::bases<b> > > x2;// Deduced parameters.typedef py::class_< b, boost::noncopyable > y1;typedef py::class_< d, boost::shared_ptr<d>, py::bases<b> > y2; A couple more things: 1) I thing that BOOST_PARAMETER_TEMPLATE_KEYWORD(ClassType) macro should define a symbol _ClassType to be used for the named parameter so to be consistent with the BOOST_PARAMETER_NAME(x) which defined _x to be used for the named function parameter. However, ClassType is defined without the leading _. What is the reason for this asymmetry? 2) I'd expect a macro that allows to specify tag and passing argument name for template parameters BOOST_PARAMETER_TEMPLATE_KEYWORD((PassClassType, mytag) ClassType) as for BOOST_PARAMETER_NAME((pass_x, mytag) x) does for function parameters. Why is such a usage of BOOST_PARAMETER_TEMPLATE_KEYWORD not supported? Thanks a lot. --Lorenzo

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[smart_ptr] scoped_array / shared_array (size_t) constructor
by Olaf van der Spek 07 Nov '11

07 Nov '11

Hi, Currently, one has to manually allocate the array and pass the ptr to the constructor of scoped_array / shared_array. boost::scoped_array<unsigned char> A(new unsigned char[100]); boost::shared_array<unsigned char> B(new unsigned char[100]); This requires one to repeat the type and shared_array requires two allocations (one extra for the control block). std::vector has a constructor from size_t and one can write: std::vector<unsigned char> V(100); This avoids the type duplication and it'd allow shared_array to do only a single allocation. A few choices have to be made: 1. Should "new T[sz]" or "new T[sz]()" be used? 2. What should happen when size = 0? Should it call new T[0] or should it just use NULL? https://svn.boost.org/trac/boost/ticket/4637 -- Olaf

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[python] Please apply and merge 2208
by Steve M. Robbins 07 Nov '11

07 Nov '11

Hi, The patch has been used in Debian since August 2008 so it should be safe to apply. Thanks, -Steve

1 0

[units] spatial coordinates, vectors, x, y, z, something like that
by Janek Kozicki 06 Nov '11

06 Nov '11

Hi, I want to use boost::units to calculate diffraction & interference patterns and wave propagation in 3D. I need some way to represent points in spatial 3D space with 'length' dimension. What do you guys use for that? I need them to work with 'frequency' & 'speed' dimensions also. Don't tell me that I need to write my own 'vector' class ? best regards -- Janek Kozicki http://janek.kozicki.pl/ |

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Interest in bounded (Top-Bounded) Range adaptor.
by Fernando Pelliccioni 06 Nov '11

06 Nov '11

Is there interest in adding a Top-Bounded adaptor into Boost.Range ? Example: using namespace boost::adaptors; using namespace boost::assign; std::vector<int> input; input += 1,2,3,4,5,6,7,8,9; boost::copy( input | bounded(0), std::ostream_iterator<int>(std::cout, ",")); // prints nothing boost::copy( input | bounded(1), std::ostream_iterator<int>(std::cout, ",")); // prints 1, boost::copy( input | bounded(2), std::ostream_iterator<int>(std::cout, ",")); // prints 1,2, boost::copy( input | bounded(8), std::ostream_iterator<int>(std::cout, ",")); // prints 1,2,3,4,5,7,8, The above example is similar in behavior to ... boost::copy_n( input, 0, std::ostream_iterator<int>(std::cout, ",")); boost::copy_n( input, 1, std::ostream_iterator<int>(std::cout, ",")); boost::copy_n( input, 2, std::ostream_iterator<int>(std::cout, ",")); boost::copy_n( input, 8, std::ostream_iterator<int>(std::cout, ",")); The difference is that *copy_n* algorithm doesn't check for begin(range) != end(range) In the following line, an error occurs at runtime... boost::copy_n( input, 9, std::ostream_iterator<int>(std::cout, ",")); Unlike the following that runs ok... boost::copy( input | bounded(9), std::ostream_iterator<int>(std::cout, ",")); // prints 1,2,3,4,5,7,8,9, This behavior could be equated using *sliced(0, X)*, but sliced requires *RandomAccessRange*, unlike bounded that requires *SinglePassRange*. *bounded* code is based on *indexed* adaptor code, I think it is more efficient than *sliced* ( that uses *make_iterator_range* --> std::advance ). I don't know if this behavior can be achieved using other adapters, if so, please let me know. Is there interest in this for Boost? Regards, Fernando.

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[parameter] aux_/void.hpp: potential undefined behavior
by Krzysztof Czainski 05 Nov '11

05 Nov '11

Hello, Here's boost/aux_/void.hpp contents, without include quards and license note, where I marked a line with a comment to refer to it below. [code] namespace boost { namespace parameter { // A placemarker for "no argument passed." // MAINTAINER NOTE: Do not make this into a metafunction struct void_ {}; namespace aux { inline void_& void_reference() { static void_ instance; // (1) return instance; } } // namespace aux }} // namespace boost::parameter [/code] My question is: is it allowed to use an instance of an uninitialized empty struct? The struct void_ is empty. On line (1) a static uninitialized instance of struct void_ is defined, and it is then returned. Does the standard allow this? I can't imagine any real problems with this, but I'm curious if this has defined behavior according to the standard. A natural and simple solution to my concern is of course to change the line (1) to: static void_ instance = {}; I'd be happy to create a ticket with a patch, if my concern is valid. Regards, Kris

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[lockfree] review
by Gordon Woodhull 05 Nov '11

05 Nov '11

Hi Tim, Hopefully I'll have at least a partial review. I only know enough about the subject to be a little dangerous. (One course in concurrent data structures, one successfully implemented lockfree hash table - except for the memory reclamation. Unspecified barriers and ABA problems. :p ) Considering the difficulty of the subject, you seem to have carefully chosen a small set of algorithms where at least there is consensus that the sources you are using have solved the problem correctly. I apologize if this has already been covered, but I don't see anything in the documentation about which platforms and compilers this has been tested on. These algorithms are extremely susceptible to compiler and processor optimizations. Anyway, I thought I would try to run the tests, and maybe try changing the testing methodology a little, but I got a few compiler errors, below. Defining uint fixed most of these, but bench_1.cpp also appears to be out of date? Of course I also have my lack of understanding of boost build library linking to contend with. Hope to try again later. Cheers, Gordon ~/lib/boost_lockfree/libs/lockfree/test ~/src/boost-trunk grodo-mcwoohu:test gordon$ bjam ...found 141 targets... ...updating 21 targets... darwin.compile.c++ ../../../bin.v2/libs/lockfree/test/bench_1.test/darwin-4.5.3/debug/threading-multi/bench_1.o g++: unrecognized option '-no-cpp-precomp' bench_1.cpp: In function 'void test_fifo_pop()': bench_1.cpp:67:23: error: no matching function for call to 'boost::lockfree::fifo<long int>::dequeue(long int*)' ../../../boost/lockfree/fifo.hpp:214:10: note: candidate is: bool boost::lockfree::detail::fifo<T, freelist_t, Alloc>::dequeue(T&) [with T = long int, freelist_t = boost::lockfree::caching_freelist_t, Alloc = std::allocator<long int>] bench_1.cpp: In function 'void test_fifo_pop_unsafe()': bench_1.cpp:77:30: error: no matching function for call to 'boost::lockfree::fifo<long int>::dequeue_unsafe(long int*)' ../../../boost/lockfree/fifo.hpp:255:10: note: candidate is: bool boost::lockfree::detail::fifo<T, freelist_t, Alloc>::dequeue_unsafe(T&) [with T = long int, freelist_t = boost::lockfree::caching_freelist_t, Alloc = std::allocator<long int>] bench_1.cpp: In function 'void test_stack_pop()': bench_1.cpp:87:19: error: no matching function for call to 'boost::lockfree::stack<long int>::pop(long int*)' ../../../boost/lockfree/stack.hpp:179:10: note: candidate is: bool boost::lockfree::stack<T, freelist_t, Alloc>::pop(T&) [with T = long int, freelist_t = boost::lockfree::caching_freelist_t, Alloc = std::allocator<long int>] bench_1.cpp: In function 'void test_stack_pop_unsafe()': bench_1.cpp:97:26: error: no matching function for call to 'boost::lockfree::stack<long int>::pop_unsafe(long int*)' ../../../boost/lockfree/stack.hpp:207:10: note: candidate is: bool boost::lockfree::stack<T, freelist_t, Alloc>::pop_unsafe(T&) [with T = long int, freelist_t = boost::lockfree::caching_freelist_t, Alloc = std::allocator<long int>] "g++" -ftemplate-depth-128 -O0 -fno-inline -Wall -g -dynamic -no-cpp-precomp -gdwarf-2 -fexceptions -fPIC -I"../../.." -c -o "../../../bin.v2/libs/lockfree/test/bench_1.test/darwin-4.5.3/debug/threading-multi/bench_1.o" "bench_1.cpp" ...failed darwin.compile.c++ ../../../bin.v2/libs/lockfree/test/bench_1.test/darwin-4.5.3/debug/threading-multi/bench_1.o... ...skipped <p../../../bin.v2/libs/lockfree/test/bench_1.test/darwin-4.5.3/debug/threading-multi>bench_1 for lack of <p../../../bin.v2/libs/lockfree/test/bench_1.test/darwin-4.5.3/debug/threading-multi>bench_1.o... ...skipped <p../../../bin.v2/libs/lockfree/test/bench_1.test/darwin-4.5.3/debug/threading-multi>bench_1.run for lack of <p../../../bin.v2/libs/lockfree/test/bench_1.test/darwin-4.5.3/debug/threading-multi>bench_1... darwin.compile.c++ ../../../bin.v2/libs/lockfree/test/fifo_test.test/darwin-4.5.3/debug/threading-multi/fifo_test.o g++: unrecognized option '-no-cpp-precomp' fifo_test.cpp:103:18: error: 'uint' does not name a type fifo_test.cpp: In member function 'void fifo_tester<freelist_t>::add()': fifo_test.cpp:116:14: error: 'uint' was not declared in this scope fifo_test.cpp:116:19: error: expected ';' before 'i' fifo_test.cpp:116:26: error: 'i' was not declared in this scope fifo_test.cpp:116:31: error: 'nodes_per_thread' was not declared in this scope fifo_test.cpp: In member function 'void fifo_tester<freelist_t>::run()': fifo_test.cpp:187:1: error: 'nodes_per_thread' was not declared in this scope "g++" -ftemplate-depth-128 -O0 -fno-inline -Wall -g -dynamic -no-cpp-precomp -gdwarf-2 -fexceptions -fPIC -I"../../.." -c -o "../../../bin.v2/libs/lockfree/test/fifo_test.test/darwin-4.5.3/debug/threading-multi/fifo_test.o" "fifo_test.cpp" ...failed darwin.compile.c++ ../../../bin.v2/libs/lockfree/test/fifo_test.test/darwin-4.5.3/debug/threading-multi/fifo_test.o... ...skipped <p../../../bin.v2/libs/lockfree/test/fifo_test.test/darwin-4.5.3/debug/threading-multi>fifo_test for lack of <p../../../bin.v2/libs/lockfree/test/fifo_test.test/darwin-4.5.3/debug/threading-multi>fifo_test.o... ...skipped <p../../../bin.v2/libs/lockfree/test/fifo_test.test/darwin-4.5.3/debug/threading-multi>fifo_test.run for lack of <p../../../bin.v2/libs/lockfree/test/fifo_test.test/darwin-4.5.3/debug/threading-multi>fifo_test... darwin.link ../../../bin.v2/libs/lockfree/test/freelist_test.test/darwin-4.5.3/debug/threading-multi/freelist_test ld: library not found for -lboost_thread collect2: ld returned 1 exit status "g++" -o "../../../bin.v2/libs/lockfree/test/freelist_test.test/darwin-4.5.3/debug/threading-multi/freelist_test" "../../../bin.v2/libs/lockfree/test/freelist_test.test/darwin-4.5.3/debug/threading-multi/freelist_test.o" -lboost_thread -lboost_unit_test_framework -g ...failed darwin.link ../../../bin.v2/libs/lockfree/test/freelist_test.test/darwin-4.5.3/debug/threading-multi/freelist_test... ...skipped <p../../../bin.v2/libs/lockfree/test/freelist_test.test/darwin-4.5.3/debug/threading-multi>freelist_test.run for lack of <p../../../bin.v2/libs/lockfree/test/freelist_test.test/darwin-4.5.3/debug/threading-multi>freelist_test... darwin.compile.c++ ../../../bin.v2/libs/lockfree/test/ringbuffer_test.test/darwin-4.5.3/debug/threading-multi/ringbuffer_test.o g++: unrecognized option '-no-cpp-precomp' ringbuffer_test.cpp:209:14: error: 'uint' does not name a type ringbuffer_test.cpp: In member function 'void ringbuffer_tester::add()': ringbuffer_test.cpp:225:14: error: 'uint' was not declared in this scope ringbuffer_test.cpp:225:19: error: expected ';' before 'i' ringbuffer_test.cpp:225:26: error: 'i' was not declared in this scope ringbuffer_test.cpp:225:31: error: 'nodes_per_thread' was not declared in this scope ringbuffer_test.cpp: In member function 'void ringbuffer_tester::run()': ringbuffer_test.cpp:284:1: error: 'nodes_per_thread' was not declared in this scope ringbuffer_test.cpp: In member function 'void ringbuffer_tester_buffering::add()': ringbuffer_test.cpp:315:14: error: 'uint' was not declared in this scope ringbuffer_test.cpp:315:19: error: expected ';' before 'i' ringbuffer_test.cpp:315:26: error: 'i' was not declared in this scope ringbuffer_test.cpp:315:31: error: 'nodes_per_thread' was not declared in this scope ringbuffer_test.cpp: In member function 'void ringbuffer_tester_buffering::run()': ringbuffer_test.cpp:386:1: error: 'nodes_per_thread' was not declared in this scope

8 63

Re: [boost] [lockfree] review
by Boehm, Hans 05 Nov '11

05 Nov '11

[Dave Abrahams pointed me at this thread.] Alexander Terekhov <terekhov <at> web.de> writes: > > Dave Abrahams wrote: > > > > on Thu Aug 25 2011, Alexander Terekhov <terekhov-AT-web.de> wrote: > > > > > Ilya Sokolov wrote: > > >> > > >> > > >> AFAIK, in the example above another thread can't observe reordering > > >> without introducing UB. > > > > > > I meant "observed" as in "check the sequence of writes in the generated > > > code". > > > > Do we care about what the generated code looks like? IIUC what counts > > is the sequence of memory states that another another thread can see. > > > > > But int can be simply changed to relaxed atomic<int> so that another > > > thread can observe reordering without UB. > > > > Sure. > > I meant that for the example upthread, with an int instead of relaxed > atomic<int>, another thread's code triggering UB does not prevent us > from observing reordered writes in the writing thread's code (in > generated code), by looking at it. > > Changing int to relaxed atomic<int> simply removes UB but does not > change the relevant code in the writing thread. > > regards, > alexander. > I agree with Alexander and most of the recent postings. If I write mx.lock(); x = 1; mx.unlock(); my.lock(); y = 1; my.unlock(); There is nothing to prevent the stores to x and y from becoming visible out of order at the hardware level. Enforcing ordering here would add needless and substantial cost. But a data-race-free program cannot observe such reordering. (One reference for that is Sarita Adve's and my PLDI 08 paper. Unofficial TR version at http://www.hpl.hp.com/techreports/2008/HPL-2008- 56.html. I believe Mark Batty et al have a much more complete and formal proof.) If we change x and y to be atomic variables, and the stores to be memory_order_relaxed, then an observer can tell the difference. I.e. if x and y are initially zero, and another thread does r1 = y; r2 = x; (or the acquire versions), it can see r1 = 1 and r2 = 0, since there are no synchronizes-with relationships between threads, and thus nothing to enforce ordering. If you use memory_order_relaxed, or even the acquire/release forms, things do get MUCH more complicated. The equivalent rules for other languages are an interesting story. I believe Posix implentors assume the above rules. I have a PPoPP 2007 paper that explains why that's not exactly what Posix actually states. OpenMP 3.0 has stricter rules which are also not consistently obeyed, and are somewhat fixed in OpenMP 3.1. (See my MSPC 11 paper for some details.) Java has arguably the same rules as C++ in this respect. In my mind, the main way in which sequential consistency differs from the cheaper acquire/release semantics that Alexander wants is that a) Dekker's algorithm (which by itself isn't that practically interesting), plus a number of real lock-free algorithms (which do matter) don't work. b) In my mind, acquire/release is a far more difficult model to explain to non- experts than the model for C++ with only sequentially consistent atomics. You can no longer reason about interleaving thread actions, either for purposes of determining the existence of a data-race, nor when defining what data-race- free programs mean. This was extensively discussed in C++ meetings starting in about 2005. The current solution with default-sequentially-consistent atomics, but explicit support for weaker ordering, was the resulting committee compromise. Hans

6 19

Determining interest in Delegates submission
by Jared McKee 05 Nov '11

05 Nov '11

I would like to determine interest in a possible library submission. I have written some code which converts a member function and object pointer combination to a free function for use in C style callbacks. It has some limitations which I will describe shortly. The basic idea is to be able to convert: R (B::*)(T0,T1,…) and B* to R (*)(T0,T1,…) Here's an example usage: class foo { int x; int test(int v) {return x + v;} }; foo* a = new foo; a->x = 3; int (*f)(int) = delegate(a, &foo::inc); cout << f(4) << endl; // outputs "7" When I first attempted this I used a technique where I allocated some executable memory in the heap and dynamically created a free function to call the member function for the instance. It was fun attempting that but, as you can imagine, as soon as I used the optimizer flags on my compiler I would get segment faults :) My second approach was to use templates and the Boost Preprocessor library to create appropriate static arrays of pointers to free functions matching the required signatures and then hand those pointers out each time the delegate() function is called. The two downsides to this are: you can only call delegate() for a certain function signature a limited number of times, and it adds a lot of potentially unused code to your executable. Here's the code (I've stripped out error checking for the sake of illustration): #include <boost/preprocessor.hpp> #ifndef _delegate_h_ #define _delegate_h_ #define MAX_DELEGATES 256 #define DELEGATE_PARAMS 0 #include "delegate_template.hpp" #undef DELEGATE_PARAMS #define DELEGATE_PARAMS 1 #include "delegate_template.hpp" #undef DELEGATE_PARAMS // … #endif // delegate_template.hpp #define DELEGATE_STORE BOOST_PP_CAT(DELEGATE_STORE,**DELEGATE_PARAMS) template <class B, class R BOOST_PP_ENUM_TRAILING_PARAMS(**DELEGATE_PARAMS, class T) > struct DELEGATE_STORE { typedef B* objectPointer; typedef R (B::*memberFunction)( BOOST_PP_ENUM_PARAMS(DELEGATE_**PARAMS, T) ); typedef R (*freeFunction)( BOOST_PP_ENUM_PARAMS(DELEGATE_**PARAMS, T) ); static int delegateCount; static int delegateMax; static objectPointer delegateObjectPointer[MAX_**DELEGATES]; static memberFunction delegateMemberFunction[MAX_**DELEGATES]; template <int i> static R func( BOOST_PP_ENUM_BINARY_PARAMS(**DELEGATE_PARAMS, T, v) ) { return (delegateObjectPointer[i]->***delegateMemberFunction[i])( BOOST_PP_ENUM_PARAMS(DELEGATE_**PARAMS, v) ); } static const freeFunction delegateFreeFunction[MAX_**DELEGATES]; static freeFunction getDelegate(objectPointer o, memberFunction m) { int delegateIndex = delegateCount++; delegateObjectPointer[**delegateIndex] = o; delegateMemberFunction[**delegateIndex] = m; return delegateFreeFunction[**delegateIndex]; } }; template <class B, class R BOOST_PP_ENUM_TRAILING_PARAMS(**DELEGATE_PARAMS, class T) > int DELEGATE_STORE<B,R BOOST_PP_ENUM_TRAILING_PARAMS(**DELEGATE_PARAMS, T) >::delegateCount = 0; template <class B, class R BOOST_PP_ENUM_TRAILING_PARAMS(**DELEGATE_PARAMS, class T) > int DELEGATE_STORE<B,R BOOST_PP_ENUM_TRAILING_PARAMS(**DELEGATE_PARAMS, T) >::delegateMax = MAX_DELEGATES; template <class B, class R BOOST_PP_ENUM_TRAILING_PARAMS(**DELEGATE_PARAMS, class T) > typename DELEGATE_STORE<B,R BOOST_PP_ENUM_TRAILING_PARAMS(**DELEGATE_PARAMS, T) >::memberFunction DELEGATE_STORE<B,R BOOST_PP_ENUM_TRAILING_PARAMS(**DELEGATE_PARAMS, T) > ::delegateMemberFunction[MAX_**DELEGATES] = {0}; > template <class B, class R BOOST_PP_ENUM_TRAILING_PARAMS(**DELEGATE_PARAMS, class T) > typename DELEGATE_STORE<B,R BOOST_PP_ENUM_TRAILING_PARAMS(**DELEGATE_PARAMS, T) >::objectPointer DELEGATE_STORE<B,R BOOST_PP_ENUM_TRAILING_PARAMS(**DELEGATE_PARAMS, T) > ::delegateObjectPointer[MAX_**DELEGATES] = {0}; > #define FUNC_POINTER(z, n, params) &DELEGATE_STORE<B,R BOOST_PP_ENUM_TRAILING_PARAMS(**DELEGATE_PARAMS, T) >::template func< n >, template <class B, class R BOOST_PP_ENUM_TRAILING_PARAMS(**DELEGATE_PARAMS, class T) > const typename DELEGATE_STORE<B,R BOOST_PP_ENUM_TRAILING_PARAMS(**DELEGATE_PARAMS, T) >::freeFunction DELEGATE_STORE<B,R BOOST_PP_ENUM_TRAILING_PARAMS(**DELEGATE_PARAMS, T) > ::delegateFreeFunction[MAX_**DELEGATES] = { > BOOST_PP_REPEAT(MAX_DELEGATES, FUNC_POINTER,) }; template <class B, class R BOOST_PP_ENUM_TRAILING_PARAMS(**DELEGATE_PARAMS, class T) > R (*delegate( B* b, R (B::*f)( BOOST_PP_ENUM_PARAMS(DELEGATE_**PARAMS, T) ) ))( BOOST_PP_ENUM_PARAMS(DELEGATE_**PARAMS, T) ) { return DELEGATE_STORE<B,R BOOST_PP_ENUM_TRAILING_PARAMS(**DELEGATE_PARAMS, T) >::getDelegate(b, f); } // end Thankyou very much if you managed to read all the way to here! By the way, this is my first active participation in any open source project :) Jared

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