November 2007 - Boost - lists.preview.boost.org

Boost conventions and unnamed namespaces
by Maciej Sobczak 06 Nov '07

06 Nov '07

I have noticed that the Boost inspect program tries [*] to find unnamed namespaces and marks them as violations. [*] It does not find the one in its own sources, ironically. Does it mean that Boost conventions discourage the use of unnamed namespaces? Regards, -- Maciej Sobczak * www.msobczak.com * www.inspirel.com

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Dynamic Overload : some note
by Marco 06 Nov '07

06 Nov '07

Now the library tutorial is available in quickbook format on the Boost Sandbox Repository: http://svn.boost.org/svn/boost/sandbox/overload/trunk/ There is some more documentation available on-line: http://docs.google.com/View?docid=dfxvjncs_2c8cqsr At present it is more a supportive paper than real library documentation, however it can give some enlightenment on the overload tutorial terminology and some involving concept. Finally, I want to point out that even if the library seems enough stable you should be aware that it didn't still go through rigorous testing, and that refactoring and breaking changes are still possible. So if you're using Boost.Overload for your projects you'd keep in mind that at this stage of development I can't warrant backward compatibility of future library release. Regards, Marco Cecchetti -- Using Opera's revolutionary e-mail client: http://www.opera.com/mail/

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reference_wrapper() and operator()()
by Thorsten Ottosen 06 Nov '07

06 Nov '07

Dear reference wrapper authors, Is there any good reason that boost::reference_wrapper() does not provide a forwarding operator()(), so that we may use it to pass function objects by reference to algorithms? best regards -Thorsten

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Trac open bugs - by assignee
by Marshall Clow 06 Nov '07

06 Nov '07

[ 220 open bugs today, 220 yesterday ] If you are maintaining a library, and have not logged into the trac system at <http://svn.boost.org/trac/boost/>, please do so ASAP. Until you do that, no tickets can be assigned to you, and will remain under "None". Instructions on working with tickets can be found at: <http://svn.boost.org/trac/boost/wiki/TicketWorkflow> and a mapping of user names to "real names" can be found at: <http://svn.boost.org/trac/boost/report/16> 18 ramey 18 dgregor 16 djowel 16 az_sw_dude 16 None 15 grafik 12 doug_gregor 11 turkanis 8 dave 7 jsiek 7 anthonyw 7 agurtovoy 6 vladimir_prus 5 witt 5 samuel_krempp 4 shammah 4 johnmaddock 4 igaztanaga 4 bemandawes 3 pdimov 3 nesotto 3 jbandela 3 danielw 2 urzuga 2 t_schwinger 2 pavol_droba 2 nasonov 2 jmaurer 2 hubert_holin 2 ebf 1 speedsnail 1 samuel_k 1 rogeeff 1 matias 1 kaalus 1 hkaiser 1 guwi17 1 fcacciola 1 dlwalker 1 aaron_windsor 1 <Blank> <Blank> 1307 [lambda] invalid boostbook None 1048 Spirit returns full = false in 1.34 if there is trailing spaces in input None 1068 Mersenne twister disables streaming for Visual C++ None 1094 Finding the correct library to link (feature request for pkg-config support)h None 1187 bcp copy not needed files None 1222 lambda::ret<T> should declare result_type. None 1247 Typos in "boost/random/additive_combine.hpp"_ lines 68-69 None 1252 [pool] severe overhead with unaligned sizes. None 1270 uniform_smallint doesn't compile with lagged_fibonacci random number generators None 1291 config.hpp fails to compile with gcc -Wundef None 1311 Can't call base members on derived object in unit_test None 1342 dylib library names broken in Mac OS X None 1384 Linking problem with date_time library on Visual C++ 2008 Express None 1405 http://svn.boost.org/trac/boost/browser/trunk/libs/utility/test/Jamfile.v2 fails None 1407 Boost is doesn't install on MacPorts using Leopard None 960 [random] lognormal_distribution problem None 991 [pool] aaron_windsor 778 top-level configure is broken agurtovoy 1001 gcc 4.1.2 segfaults on mpl/test/apply.cpp agurtovoy 1051 MPL header ordering triggers bug agurtovoy 1099 unable to iterate through a "non-explicitly-declared" mpl::set agurtovoy 1215 Boost 1.34.1_ mpl: Wrong workaround detection using MinGW32 (or.hpp_ line #33) agurtovoy 1317 has_xxx randomly broken in msvc agurtovoy 588 mpl::remove compile error with gcc 4.1.0 agurtovoy 640 documentation mistake anthonyw 1154 tss destruction segfaults in conjunction with dlopen/dlclose anthonyw 1168 [thread] tss crashes randomly anthonyw 1226 macro TEXT() in GetProcAddress() anthonyw 1268 xtime_cmp changes to deal with overflow were reverted anthonyw 1323 Assertion Error during cleanup after running out of thread resources anthonyw 876 xtime documentation incomplete anthonyw 881 errors when build with Apache stdcxx az_sw_dude 1028 typo in boost header: date_time/time_defs.hpp az_sw_dude 1078 from_iso_string cannot read the output from to_iso_string az_sw_dude 1098 Urgent libboost-date-time1.33.1 : bugs on ia64 ? az_sw_dude 1147 date_time library contains global #define ERROR az_sw_dude 1160 warning: month_format shadows a member of this az_sw_dude 1162 warning: ticks shadows a member of this az_sw_dude 1289 posix_time::time_facet forgets to pass a_ref argument to base class az_sw_dude 1299 change in typedef stringstream_type in format_date_parser.hpp causing compilation error az_sw_dude 1306 invalid docbook in date_period.xml az_sw_dude 1386 date_time documentation Jamfile breaks building of boost docs az_sw_dude 287 wrong usage of ios_base::narrow az_sw_dude 316 date_time type conversion warning az_sw_dude 604 from_ftime incorrectly processes FILETIME filled with zeros az_sw_dude 642 operator<< for gregorian::date_duration not found az_sw_dude 889 Insane Dependencies az_sw_dude 890 date_time library supports only the current dst rule bemandawes 1230 mbstate uninitialized bemandawes 1378 filesystem path invalid name for hidden files (LINUX) bemandawes 1389 filesystem::ostream << boost::format generates operator ambigious error (in MSVC++) bemandawes 752 directory_iterator doesn't work with catch danielw 1044 Argument pack inaccessable in a functions return type danielw 1054 Parameter takes an "infinite" amount of time to compile with the Intel compiler. danielw 1097 keyword.hpp generates many warnings C4180: qualifier applied to function type has no meaning; ignored dave 1010 linking boost.python on freebsd dave 1019 iterator_facade::pointer should be the return type of operator-> (DR 445) dave 1085 Python rules for compiling in Mac OS X dave 1179 [boost.python] can not export a union in VC2005sp1 dave 1181 [boost.python] can modify enum value dave 1387 Review / update docs to reflect changes dave 865 Use of C++0x keyword as identifier dave 910 gcc strict-aliasing problems with python dgregor 1002 [iostreams] close_impl<closable_tag> does not comply with spec dgregor 1003 [iostreams] copy-paste error in typedefs for wchar multichar_filters dgregor 1139 [iostreams] Regex filter segfaults when zero matches found dgregor 1140 boost::iostreams linked_streambuf bug dgregor 1149 Minor doc error in basic_null_device dgregor 1164 Floyd Warshall broken with unsigned edge weights dgregor 1185 iostreams::direct_streambuf<T_Tr>::is_open always returns false if output iterator is not null dgregor 1192 [boostbook] problem when two files have the same name dgregor 1199 configure doesn't work with path containing whitespaces (MacOS X) dgregor 1232 mapped_file_source::is_open() is broken under windows dgregor 1310 [result_of] const-qualified function pointer doesn't work dgregor 1326 Unable to check graph isomorphism using LEDA adapter dgregor 1391 dominator_tree_test on Borland/CodeGear outputs overly long line dgregor 1394 Translate libs/graph/build/python/Jamfile to BBv2 dgregor 1395 Write Tests for Python Bindings dgregor 556 Bundled graph properties dgregor 732 Johnson All-Pairs needs better "no path" information dgregor 736 Const correctness violation djowel 1096 Tutorial needs updating for BBv2 djowel 1170 Emit Warnings instead of # symbols in the syntax highlighter djowel 1171 Quickbook title output djowel 1172 non-utf djowel 1176 Space after inline code djowel 1206 Escaping from within code? djowel 1273 CR+LF newlines in position_iterator djowel 1276 spirit problem with _GLIBCXX_DEBUG djowel 1277 Closing section like [pre with } causes Quickbok to crash djowel 1280 sections in imported source files get put inside <para> elements in docbook output djowel 1281 Quickbook produces invalid BoostBook/DocBook XML djowel 1324 tuple should have a swap() that operates element-by-element djowel 1396 wrong result_of invocation around transform_view djowel 241 Miss " = ParserT()" djowel 314 spirit insert_key_actor.hpp djowel 664 crash in boost::spirit::parse dlwalker 613 boost/crc.hpp uses non-standard conforming syntax doug_gregor 1021 [Graph][reverse_graph] Problem using reverse_graph adapter with an adapted user defined graph doug_gregor 1076 compile error: disconnecting struct with operator()() doesn't work in VS2005 SP1 doug_gregor 375 LEDA graph adaptors do not handle hidden nodes properly doug_gregor 402 random_vertex/random_edge are unnecessarily inefficient doug_gregor 403 Document copy_component doug_gregor 447 reverse_graph and constness of property maps doug_gregor 708 Dijkstra no_init version should not require VertexListGraph doug_gregor 733 Numbered headers don't work with "preferred" syntax doug_gregor 735 Fruchterman-Reingold grid performance can be improved doug_gregor 738 Memory leaks with signal::connect? doug_gregor 829 Implicit graph not implement doug_gregor 852 Problem with Boost and GCC 4.1 ebf 965 [doc] boost::variant tutorial - final example uses v1_v2 should be seq1_seq2 ebf 993 Variant should use least common multiple of alignments_ rather than maximum fcacciola 1301 copy-initialization from const-qualified object doesn't work grafik 1023 inspect grafik 1041 Cygwin requires PATH setting. grafik 1062 Cygwin install stage fails with combination of patches grafik 1146 KAI Referenced in compiler status acknowledgements grafik 1233 Boost website still refers to CVS grafik 1244 Broken links to unit test examples grafik 1318 http links have gone bad in boost.test documentation grafik 1322 trac rejects patch attachment as spam grafik 1400 broken link to threads-devel gmane archives grafik 546 boost.build needs fixes for HP/UX grafik 616 Boost Jam_ and non english directorys grafik 896 <native-wchar_t>off does not work when build with vc-8.0 grafik 959 linking fails when Boost is compiled with STLport 5.1.* on Linux (names mismatch) grafik 977 bjam crashes when compiled with gcc 4.2 grafik 986 Problem building Python modules on boost 1.34.0 guwi17 1237 Resizing symmetric matrices hkaiser 1079 boost-1.34.0 fails to compile. concept checks not satisfied. hubert_holin 162 Cannot compile octonion_test.cpp because of bug in sinc.hpp hubert_holin 647 octonion documentation bug igaztanaga 1080 boost::interprocess win32 global file mapping issue igaztanaga 1210 interprocess::barrier hangs during second use under linux (boost 1.33.1) igaztanaga 1231 interprocess_condition (emulated) hangs after notify_all(). igaztanaga 1390 Interpocess: managed shared memory failing completely under OS X jbandela 283 Compiler error for tokenizer on Solaris jbandela 501 token_iterator::at_end() result is inversed jbandela 665 bug in char_separator jmaurer 351 Diff in state of mersenne_twister gen between GCC3.41 & CW9 jmaurer 819 uniform_int<> with type's maximum availaible range error johnmaddock 1081 Empty string rejected as perl-style regex johnmaddock 1083 boost_regex 1.34.0 uses ICU library without linking to it johnmaddock 1314 Using SSE-intrinsics in VC8 causes static assert in type_with_alignment.hpp johnmaddock 1411 Fix BOOST_PARTIAL_SPECIALIZATION_EXPLICT_ARGS jsiek 416 Spelling of Edmonds-Karp-Algorithm jsiek 575 Calling subgraph::global_to_local on a root graph jsiek 636 strange compiling problem for transitive_closure jsiek 813 concept_check.hpp unused variable warning jsiek 815 remove_edge core dumps on self-circle jsiek 875 No iterator based constructor for adjacency_matrix jsiek 900 graphml reader namespace handling is broken kaalus 1184 property_tree assignment (operator) bug matias 1406 Understanding the Tables outdated nasonov 1220 lexical_cast requires RTTI nasonov 754 boost::any - typeid comparison across shared boundaries nesotto 1284 [range] sub_range assignment issue nesotto 1327 iterator value_type possibly cv-qualified nesotto 723 local_time_facet error in VS2005 Win2003 pavol_droba 1152 rle_example fails pavol_droba 1385 begin must be boost-qualified pdimov 1106 shared_ptr<T> should not convert to shared_ptr<U> when T* doesn't convert to U* pdimov 1108 shared_ptr does not compile under g++ with -fno-rtti pdimov 997 error in boost::bind doc ramey 1036 assert failure in oserializer.hpp:418 ramey 1038 "<" and ">" should be excaped in xml_oarchive ramey 1086 Serialization of weak_ptr produces invalid XML ramey 1089 missing boost::serialization::make_nvp in pointer container library ramey 1121 xml_archive_exception is missing seperate header file_ and documentation mismatch ramey 1137 Virtual destructor is missing ramey 1141 Dangerious operator<< for wostream ramey 1142 boost/serialization/optional doesn't include necessary header ramey 1223 boost::serialization chokes on correcly formatted empty XML element ramey 1267 Assertion `new_cid == cid' failed in basic_iarchive ramey 1285 [serialization] problem when including shared_ptr_132.hpp ramey 1286 Missing/Incorrect dllimport/dllexport directives prevent Windows DLLs from building ramey 1290 Serialization export.hpp (or type_info_implementation.hpp) is NOT self-contained and causes compile error ramey 1382 Missing #pragma warning(pop) in void_cast.hpp ramey 757 xml serialization fails when using namespace ramey 961 boost::basic_binary_oprimitive not instantiated correctly ramey 968 xml_grammar - incorrect define char ramey 969 basic_binary_iprimitive::load_binary bug rogeeff 1383 signal.h features not found on Mac OS samuel_k 585 64 bit compile warning/error for boost::format samuel_krempp 1195 patch: boost/format/parsing.hpp does not compile if BOOST_NO_LOCALE_ISDIGIT is defined samuel_krempp 1196 Patch: when BOOST_NO_STD_LOCALE is not defined_ boost/format/internals.hpp fails to compile. samuel_krempp 1278 declaration of 'str' shadows a member of 'this' samuel_krempp 704 format zero length string msvc-8 samuel_krempp 859 boost::format ignores a user defined locale shammah 284 pool::purge_memory() does not reset next_size shammah 290 perfomance: memory cleanup for pool takes too long shammah 386 boost::pool_allocator breaks with vector of vectors shammah 88 ct_gcd_lcm.hpp compilation error speedsnail 1138 Problems with TSS and static thread library t_schwinger 1100 Building boost.function_types fails cvs rev-1.1_ no chdir command in bash t_schwinger 1332 Inclusion of non existing file boost/fusion/sequence/utility/unpack_args.hpp in boost/fusion/sequence/utility.hpp turkanis 1033 iostreams::restrict doesn't work on an iostreams::file_source turkanis 1070 [iostreams]boost\iostreams\copy.hpp line80 copy_impl turkanis 525 problem with boost::iostreams when compiled with Visual C++ turkanis 699 Changing size of memory-mapped file on Windows turkanis 786 bug in iostreams/copy.hpp line 81 turkanis 791 iostreams::tee_filter is for output only turkanis 817 Performance problem in iostreams turkanis 822 Incorrect usage of bad_write()_ bad_seek() etc. turkanis 823 Seekable file_descriptor_source /sink? turkanis 824 BOOST_IOSTREAMS_HAS_LSEEK64 on Mac OS X turkanis 856 iostreams file_descriptor::write fails under Win32 urzuga 574 [boost::lambda] Compile error with libstdc++ debug mode urzuga 781 Lambda: (_1 + "y")(string("x")) Doesn't Compile vladimir_prus 1165 more quoting problems vladimir_prus 1274 Useless error message vladimir_prus 1275 boost::program_options::validation_error::what() is private vladimir_prus 1321 invalid docbook in tool documentation vladimir_prus 469 multitoken broken vladimir_prus 689 [program_options] Endless loop with long default arguments witt 1046 Boost.Python quickstart instructions mention nonexistent target witt 583 Fixes for build on IBM pSeries for AIX and Linux witt 834 Homepage regression links witt 957 The "Getting Started" page does not mention the stdlib option witt 973 zip_iterator has value_type == reference -- -- Marshall Marshall Clow Qualcomm, Inc. <mailto:mclow@qualcomm.com> The famous British scientist, Lord Kelvin, said: "When you measure what you are speaking about and express it in numbers, you know something about it, but when you cannot (or do not) measure it, when you cannot (or do not) express it in numbers, then your knowledge is of a meagre and unsatisfactory kind."

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[date_time] WinCE patch for microsec_time_clock.hpp
by David Deakins 06 Nov '07

06 Nov '07

Just a small patch for the date_time library. WinCE does not supply the GetSystemTimeAsFileTime Win32 method. It does however supply the individual GetSystemTime and SystemTimeToFileTime methods. The config headers already define BOOST_NO_GETSYSTEMTIMEASFILETIME to flag this situation and the patch uses this define to mark when the alternate function calls should be substituted. Thanks, -Dave Index: microsec_time_clock.hpp =================================================================== --- microsec_time_clock.hpp (revision 40672) +++ microsec_time_clock.hpp (working copy) @@ -120,6 +120,10 @@ FILETIME ft_utc; GetSystemTimeAsFileTime(&ft_utc); FileTimeToLocalFileTime(&ft_utc,&ft); + #elif defined(BOOST_NO_GETSYSTEMTIMEASFILETIME) + SYSTEMTIME st; + GetSystemTime( &st ); + SystemTimeToFileTime( &st, &ft ); #else GetSystemTimeAsFileTime(&ft); #endif @@ -134,6 +138,10 @@ FILETIME ft_utc; GetSystemTimeAsFileTime(&ft_utc); FileTimeToLocalFileTime(&ft_utc,&ft); + #elif defined(BOOST_NO_GETSYSTEMTIMEASFILETIME) + SYSTEMTIME st; + GetSystemTime( &st ); + SystemTimeToFileTime( &st, &ft ); #else GetSystemTimeAsFileTime(&ft); #endif

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[system][asio] Breaking changes procedure?
by Beman Dawes 06 Nov '07

06 Nov '07

At the suggestion of Emil Dotchevski, seconded by Chris Kohlhoff, on my trunk working copy I've moved the system-specific portions of the header <boost/system/error_code.hpp> into new headers. They are named: <boost/system/cygwin_error.hpp> <boost/system/linux_error.hpp> <boost/system/windows_error.hpp> This is a breaking change for asio, and any other boost code that depends on <boost/system/error_code.hpp> containing system-specific enums. New #includes are required for whichever headers apply. This isn't a disruptive change (because the effects are very localized), and normally I'd just coordinate it offline with Chris. But I'd like to shakedown the procedure that should be followed for disruptive breaking changes. Thus this posting to give others a chance to comment. I think the procedure for such breaking changes should be something like: * Create a branch, branches/system. The contents are the entire boost tree. * Apply the Boost.System changes to that branch. * Announce the branch on the list, and encourage any developers affected to update their libraries on the branch. * Once all affected libraries are changed on the branch and passing tests on developer's machines, merge the changes into a working copy of the trunk and do a single commit. * Watch regression tests closely to be sure nothing else broke. Does this sound right? --Beman

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[function_types] broken on gcc 3.3
by Eric Niebler 06 Nov '07

06 Nov '07

Function_types is causing the following xpressive failure on gcc 3.3: http://tinyurl.com/2uk9zq. ../boost/function_types/detail/components_impl/arity10_0.hpp:24: error: redefinition of `struct boost::function_types::detail::components_impl<R (*)(), L>' ../boost/function_types/detail/components_impl/arity10_0.hpp:24: error: previous definition of `struct boost::function_types::detail::components_impl<R (*)(), L>' -- Eric Niebler Boost Consulting www.boost-consulting.com

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[variant] Variants of references, when initialized from temporary objects, should own the temporary object.
by Joachim Kupke 06 Nov '07

06 Nov '07

The following code: #include <iostream> #include "boost/variant.hpp" struct Z { Z(int x) : x(x) { std::cout << "Created a Z with x == " << x << std::endl; } ~Z() { std::cout << "Destroyed a Z with x == " << x << std::endl; } int x; }; void f(boost::variant<const Z&> const& x) { std::cout << boost::get<const Z&>(&x)->x << std::endl; } int main() { int x = 17; std::cout << "A" << std::endl; f(x); std::cout << "B" << std::endl; } produces this output on gcc with boost 1.34.1: A Created a Z with x == 17 Destroyed a Z with x == 17 -11257 B Obviously, x holds a Z reference to a temporary Z, which is destroyed before f() returns. Needless to say, this is in stark contrast with what happens if f had been defined to take a const Z& instead of a boost::variant<const Z&> or a boost::variant<const Z&> const&. Is this a bug? --Joachim

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Looking for Thread Pool Library
by Dean Michael Berris 06 Nov '07

06 Nov '07

Hi Everyone, Has there been any development with regards to a working, portable Boost.Thread based Thread Pool library? Personally I've been using the following sample idiom for achieving what a thread pool is supposed to be accomplishing -- and I'm wondering (aloud) whether there are any existing implementations out there that rely solely on Boost.Thread. Currently, the following code snippet requires Boost.Asio, but I'm not sure if there's something that may be distilled from the recurring pattern below: { using namespace boost::asio; using namespace boost; io_service process_queue; shared_ptr<io_service::work> sentinel(new io_service::work(process_queue)); thread_group processor_threads; for(unsigned int spawn_counter = THREAD_COUNT; spawn_counter > 0; --spawn_counter) processor_threads.create_thread( bind(&io_service::work, &process_queue) ); // add all void nullary functors and post them here process_queue.post(function_object); // once all the work has been queued, remove the sentinel sentinel.reset(); processor_threads.join_all(); } Will something like this be useful as a utility library? Insights, pointers, and suggestions would be very much appreciated. Have a great day everyone! -- Dean Michael C. Berris Software Engineer, Friendster, Inc. [http://cplusplus-soup.blogspot.com/] [mikhailberis(a)gmail.com] [+63 928 7291459] [+1 408 4049523]

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Boost.TypeErasure
by Steven Watanabe 05 Nov '07

05 Nov '07

AMDG After 6+ months I've finally gotten back to this. I'd like to get some feedback on my ideas before I continue. The current version is in the vault. The basic interface is derived from Alexander Nasonov's dynamic_any struct increment : concept_<increment, void(_&)> { template<class T> static void execute(T& t) { ++t; } } any<increment> x(1); increment()(x); assert(type_erasure::any_cast<int>(x) == 1); Note that unlike Boost.Function references will not work. int i; any<increment> x(boost::ref(i)); // NO!! The reason is that if references were allowed it would be to easy to kill yourself. (I've been there. I allowed references at first and then implemented operator+ in terms of operator+=. When the left argument is a reference this means that I made a shallow copy of the reference, called operator += on that, thus violating the expectation that operator+ does not modify its arguments) A function can also return another polymorphic object whose dynamic type is different. template<class R, class P2> struct at : concept<at<R, P2>, R(const P2&, int)> { template<class T> static typename T::value_type execute(const T& t, int i) { return(t[i]); } }; any<at<_1, _> > any_container(std::vector<int>(1, 2)); any<> value(at<_1, _>()(any_container, 0)); assert(type_erasure::any_cast<int>(value) == 2); In this example _ is the placeholder that refers to the current object. The placeholder _1 is used to refer to the return type of at. Since there is a mechanism for handling multiple objects, we can capture multiple objects simultaneously using a tuple: template<class P1, class P2> struct add : concept_<add<P1, P2>, P1(const P1&, const P2&)> { template<class T1, class T2> static T1 execute(const T1& t1, const T2& t2) { return(t1 + t2); } }; int array[] = {...}; type_erasure::tuple<_1, _2, where_<add<_1, _2> > > tuple(&array[0], 0); any<> pointer_to_second_element(add<_1, _2>()(type_erasure::get<0>(tuple), type_erasure::get<1>(tuple)); assert(type_erasure::any_cast<int*>(pointer_to_second_element) == array + 1); The first two arguments to tuple<...> specify which placeholders correspond to those elements. The element 0 will be match _1 and element 1 will match _2. Note that add is not a true multimethod. It's arguments must ultimately come from the same place. i.e. you can apply it as many times as you want since its return type is known to always be the same as its first argument, but you cannot mix another type in e.g. long instead of int. Another thing to note is that it is always okay to discard functions. In the last example the result of calling add itself supports add since it is the same type. I don't care about that so I construct an any<> from it. I haven't shown it here, but any<...> takes up to 10 parameters or an MPL sequence. I can assign one any<> to another which has an arbitrary subset of its functions. One that has both increment and decrement can be assigned to one that supports only increment or to one that supports only decrement. Future Work: I intend to enable boost::ref iff there are no mutating operations for the type. There should be a class for references, so that you can throw away some operations without making a copy. I can implement multimethods if (a) The return type is fixed at compile time and (b) Every type specifies (through a traits template) a list of possible overloads involving it. Functions should be able to handle cases such as template<class P1, class P2> struct some_function : concept_<some_function<P1, P2>, void(const P1&, const P2&)> { //... }; any<some_function<_, std::string> > a1; tuple<_1, _2, where_<some_function<_1, _2> > > t(a1, std::string("The quick brown fox jumps over the lazy dog.")); where some of the arguments are any<>s and others are are of known type. In Christ, Steven Watanabe

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