December 2006 - Boost - lists.stage.boost.cppalliance.org

Proposed addition to the iterator library for iterating over all tuples.
by Alex Mendes da Costa 19 Jun '09

19 Jun '09

Hi folks: I quite often have to write code to do the following: Given N sequences, generate all the N-tuples s.t. the i'th element in each tuple is drawn from the i'th sequence. For example, if sequence S1 is { 1, 2, 3 } and sequence S2 is { 10, 20 }, I need to generate these tuples: (1, 10), (2, 10), (1, 20), (2, 20). I think this problem could be solved elegantly with a iterator similar to zip_iterator. I have some questions: (1) Is there already a way to do this in boost? (2) If not, would this be a worthwhile addition to the iterator library? (3) If so, could I contribute code for this, or must the existing library owners write it? (4) If so, how would I go about getting my code added? Most of the docs seem to be about submitting entire libraries, rather than extensions to existing libraries. Thanks, Alex

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[fusion] list/detail/at_impl.hpp, Suggest recrusive elem_at_c instead of recursive apply
by Larry Evans 24 Oct '07

24 Oct '07

In boost/fusion/.../list/detail/at_impl.hpp the apply is recursive; however, the only reason for the recursion is to "find the right element type". The other reason for apply is the same as that of the apply in.../vector/detail/at_impl.hpp. "find the right element type" in vector's at_impl is done with mpl::at. The similarity between list and vector at_impl would be more apparent if: template <typename Sequence, int N> struct elem_at_c { typedef typename mpl::eval_if< mpl::bool_<N == 0> , mpl::identity<typename Sequence::car_type> , elem_at_c<typename Sequence::cdr_type, N-1> >::type type; }; were used to find the right element type. Then the frist part of list::at_impl::apply would be: template <typename Sequence, typename N> struct apply { typedef elem_at_c<Sequence, N::value> element; typedef typename mpl::eval_if< is_const<Sequence> , detail::cref_result<element> , detail::ref_result<element> >::type type; which is very similar to the counterpart in vector: template <typename Sequence, typename N> struct apply { typedef mpl::at<typename Sequence::types, N> element; typedef typename mpl::eval_if< is_const<Sequence> , detail::cref_result<element> , detail::ref_result<element> >::type type;

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[Ann] Variadic Templates
by Doug Gregor 20 Aug '07

20 Aug '07

Hello Fellow Boosters, I have just completed implementing support for "Variadic Templates" in GCC. Variadic templates are C++ templates that can accept any number of "extra" template arguments, just like a function that uses C-style varargs (with "...") can accept any number of extra arguments. Unlike C varags, however, variadic templates work both for class templates and function templates, and are completely type-safe. Why do variadic templates matter for Boost? For one thing, they will allow us to eliminate the use of preprocessor metaprogramming in many, many places throughout the library. This can simplify our library implementations drastically, and eliminate those annoying "caps" on the number of arguments one can use (ever tried to use bind () with 11 arguments?). Beyond that, variadic templates are just plain fun, and there are undoubtedly a great number of metaprogramming applications. Here are a few teasers to illustrate what variadic templates can do: We can implement an MPL-like type vector with one line of code: template<typename... Types> struct vector { }; The "ellipsis" means that we can pack any number of arguments into the "template parameter pack" called Types. Of course, we can do the same for MPL's vector_c: template<typename T, T... Values> struct vector_c { }; Unimpressed? Here's an implementation of tuple that accepts any number of element types: template<typename... Values> class tuple; template<> class tuple<> { }; template<typename Head, typename... Tail> class tuple<Head, Tail...> : private tuple<Tail...> { protected: Head m_head; }; We're using recursion to build up the tuple. The ellipsis operator works with partial specializations, too, packing together "extra" arguments at the end. Of course, all of this would be useless if we couldn't write some of the other tuple operations, like operator==: inline bool operator==(const tuple<>&, const tuple<>&) { return true; } template<typename T, typename... TTail, typename U, typename... UTail> bool operator==(const tuple<T, TTail...>& t, const tuple<U, UTail...>& u) { return t.head() == u.head() && t.tail() == u.tail(); } Variadic function templates can accept any number of function arguments, so we can now (finally!) implement a type-safe printf() without mangling the tried-and-true printf() syntax or restricting ourselves to POD types: void printf(const char* s) { while (*s) { if (*s == '%' && *++s != '%') throw std::runtime_error("invalid format string: missing arguments"); std::cout << *s++; } } template<typename T, typename... Args> void printf(const char* s, const T& value, const Args&... args) { while (*s) { if (*s == '%' && *++s != '%') { std::cout << value; return printf(++s, args...); } std::cout << *s++; throw std::runtime_error("extra arguments provided to printf"); } I've also built prototypes of of Function and Bind, among other things. The Bind example is especially interesting, and worth a read (see below) Interested? There is more information and a complete implementation in GCC available at: http://www.generic-programming.org/~dgregor/cpp/variadic- templates.html I've written two documents describing variadic templates in more detail: http://www.generic-programming.org/~dgregor/cpp/brief-intro.pdf : A brief introduction to variadic templates, that walks through the printf() implementation. http://www.generic-programming.org/~dgregor/cpp/variadic- templates.pdf : A complete proposal to introduce variadic templates into C++0x. This contains annotated versions of the tuple, function, and bind prototypes along with a detailed description of the capabilities of variadic templates. The GCC implementation is complete, supporting all of the features described in the proposal. I've used it for proof-of-concept implementations of several libraries. In the (near) future, I hope to introduce variadic templates support into the "official" GCC, but I need your help! Are variadic templates worthwhile? Will they help us build better, cleaner Boost libraries in the future? Should we bring variadic templates to the C++ committee, to enable better implementations of TR1 components and eliminate the need for much of the preprocessor metaprogramming we do today? Feedback is greatly appreciated. Cheers Doug Gregor Open Systems Lab @ Indiana University

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Review Request: Boost Exception
by Emil Dotchevski 07 Jul '07

07 Jul '07

I believe the proposed Boost Exception library is now mature enough for formal review. Please read the documentation at: http://www.revergestudios.com/boost-exception/boost-exception.htm Here is a direct link to the source code, boost build jamfiles and tests. Tested with MSVC 7.1, MSVC 8.0, GCC 3.4.4, and Comeau C++ 4.3.8: http://www.revergestudios.com/boost-exception/boost-exception.zip Regards, Emil Dotchevski

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[BGL] Adapter from bidirectional to undirected graph
by Benoit 05 Jul '07

05 Jul '07

Hello everyone, I have been using the BGL for quite some time with both directed and bidirectional graphs (with adjacency_list). Sometimes i need to use these graphs in algorithms as if they were undirected... AFAICT, this is currently not possible because out_edges() exists in all cases, but don't do the same... The obvious solution consists in writing a dedicated adapter used for translating a bidirectional graph into a directed one at least for out_edges(), and optionally for other stuff (internal properties, vertex and edge descriptors?) to make this subtle change as transparent as possible. Can you think of another way ? Is there already such an adapter somewhere (i have unsuccessfully tried to find one...) ? In case it didn't exist, would anyone else be interested to have one ? Benoît PS : I'd like to thank the authors of the BGL, it's a pleasure to work with it everyday !

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[defer] - comments?
by simon meiklejohn 14 Mar '07

14 Mar '07

Anyone had a play with the defer library in the vault and want to comment on its usefulness? It clearly shares much in common with the asio Dispatcher concept but with the freedom to define more general Dispatchers. (e.g. 'Create thread per callback' and 'Dispatch Callback via Message Pump', both of which violate the specific guarantees of the asio Dispatcher concept, that the callback occur in a thread that has called asio::demuxer::run().) One potential application for defer would be in conjunction with asio, creating the thread(s) which call demuxer::run() in a succinct form. Cheers Simon

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[interprocess] problem in boost/interprocess/detail/atomic.hpp
by Glenn Schrader 09 Feb '07

09 Feb '07

I ran across this bug while running on a 2.6.9 Linux kernel. Since that kernel version doesn't have native interprocess mutexes and condition variables the interprocess library uses some emulation code. The x86 verion of the emulated semaphore uses atomic_dec32() from atomic.hpp but that function wasn't behaving properly. The following change in oost/interprocess/detail/atomic.hpp made things work properly: BEFORE: inline boost::uint32_t atomic_dec32(volatile boost::uint32_t *mem) { unsigned char prev; asm volatile ("lock; decl %1;\n\t" "setnz %%al" : "=a" (prev) : "m" (*(mem)) : "memory", "cc"); return prev; } AFTER: inline boost::uint32_t atomic_dec32(volatile boost::uint32_t *mem) { boost::uint32_t prev; // acts like an atomic 'return (*mem)--;' asm volatile ("movl $-1, %0;\n\t" "lock; xaddl %0, %1" : "=r" (prev) : "m" (*(mem)) : "memory", "cc" ); return prev; } -glenn

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Problem with MPL/GIL dynamic_image example on gcc-4.1.1
by Andreas Pokorny 08 Feb '07

08 Feb '07

Hi, GCC-4.1.1 gives me the attached error message while compiling dynamic_image. It boils down to: dynamic_image.cpp:14: instantiated from here boost/mpl/aux_/preprocessed/gcc/template_arity.hpp:85: error: call of overloaded 'arity_helper( aux::type_wrapper< .... >,aux::arity_tag<1>)' is ambiguous boost/mpl/aux_/preprocessed/gcc/template_arity.hpp:30: note: candidates are: char (&aux::arity_helper(...))[1] boost/mpl/aux_/preprocessed/gcc/template_arity.hpp:37: note: char (&aux::arity_helper(::aux::type_wrapper<F<T1> >,aux::arity_tag<1>))[2] boost/mpl/aux_/preprocessed/gcc/template_arity.hpp:37: note: char (&aux::arity_helper(::aux::type_wrapper<F<T1> >,aux::arity_tag<1>))[2] Is this a known mpl<->gcc-4.1.1 issue? Furthermore there are some odd warnings, and I am not sure what to think about these. The code there looks a bit fishy. I tried the example with gcc-3.4.4, gcc-4.2.0-alpha20060902 and gcc-4.3.0-alpha20061111. It compiled there, but the warning remained in the gcc-4 series. Regards Andreas Pokorny

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Re: [boost] Optimized portable isnan, isfinite, fpclassify etc
by Boris Gubenko 16 Jan '07

16 Jan '07

Boris Gubenko wrote: > I'm checking with the OS folks and will report back here, > for both HP-UX/ia64 and Tru64 Alpha. And the answer is: > You are correct that both platforms are capable of executing in > either endianness. However, the operating systems operate in only > one. > HP-UX is *always* big endian > Tru64 is *always* little endian > [...] > Summary: > A compile time check is adequate. > So, with current <endian.hpp>, I think, that we are all set for these platforms. Thanks, Boris ----- Original Message ----- From: "Boris Gubenko" <Boris.Gubenko(a)hp.com> To: <boost(a)lists.boost.org> Cc: "Boris Gubenko" <Boris.Gubenko(a)hp.com> Sent: Tuesday, October 17, 2006 9:12 AM Subject: Re: [boost] Optimized portable isnan, isfinite, fpclassify etc >> Now endian.hpp defines BOOST_BIG_ENDIAN on HP-UX. >> This was suggested by Boris Gubenko. >> >> If you are right John, then this seems to be incorrect. >> Shouldn't endian.hpp then define something like >> BOOST_UNKNOWN_ENDIAN on HP-UX? >> >> Boris, do you have any comments on this? > > I'm checking with the OS folks and will report back here, > for both HP-UX/ia64 and Tru64 Alpha. > > Thanks, > Boris > > ----- Original Message ----- > From: "Johan Råde" <rade(a)maths.lth.se> > To: <boost(a)lists.boost.org> > Sent: Tuesday, October 17, 2006 9:00 AM > Subject: Re: [boost] Optimized portable isnan, isfinite, fpclassify etc > > >> John Maddock wrote: >>> I'm not completely certain, but I believe HP-UX falls into this >>> category: >>> the idea is that you can pass binary data from one platform to another, >>> and >>> just switch the endianness bit to access it natively (think distributed >>> applications). >> >> Now endian.hpp defines BOOST_BIG_ENDIAN on HP-UX. >> This was suggested by Boris Gubenko. >> >> If you are right John, then this seems to be incorrect. >> Shouldn't endian.hpp then define something like BOOST_UNKNOWN_ENDIAN on >> HP-UX? >> >> Boris, do you have any comments on this? >> >> Then my fpclassify could use a fast implementation when BOOST_BIG_ENDIAN >> or BOOST_LITTLE_ENDIAN is defined and a slower implementation when >> BOOST_UNKNOWN_ENDIAN is defined. >> >> --Johan >> >> >> >> >> >> >> >> _______________________________________________ >> Unsubscribe & other changes: >> http://lists.boost.org/mailman/listinfo.cgi/boost >> >> >

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Support requests report
by Marshall Clow 11 Jan '07

11 Jan '07

[ Creeping up... ] Support count: 50 29 nobody 4 grafik 3 vladimir_prus 3 jsiek 2 turkanis 2 johnmaddock 2 az_sw_dude 1 urzuga 1 speedsnail 1 samuel_k 1 jbandela 1 fcacciola Assignee: az_sw_dude <http://sourceforge.net/users/az_sw_dude/> Summary: support new 2007 DST rules for timezone db Bug #: 1471723 <http://sourceforge.net/tracker/index.php?func=detail&aid=1471723&group_id=7…> Assignee: az_sw_dude <http://sourceforge.net/users/az_sw_dude/> Summary: new timezone db file for #1471723 - 2007 DST support Bug #: 1478619 <http://sourceforge.net/tracker/index.php?func=detail&aid=1478619&group_id=7…> Assignee: fcacciola <http://sourceforge.net/users/fcacciola/> Summary: boost::optional<enum> fails with /CLR Bug #: 973424 <http://sourceforge.net/tracker/index.php?func=detail&aid=973424&group_id=75…> Assignee: grafik <http://sourceforge.net/users/grafik/> Summary: Jam Fails to Build Bug #: 954048 <http://sourceforge.net/tracker/index.php?func=detail&aid=954048&group_id=75…> Assignee: grafik <http://sourceforge.net/users/grafik/> Summary: Compiling only needed version Bug #: 1377001 <http://sourceforge.net/tracker/index.php?func=detail&aid=1377001&group_id=7…> Assignee: grafik <http://sourceforge.net/users/grafik/> Summary: libraries won't build Bug #: 1524001 <http://sourceforge.net/tracker/index.php?func=detail&aid=1524001&group_id=7…> Assignee: grafik <http://sourceforge.net/users/grafik/> Summary: Having some trouble building boost Bug #: 1534701 <http://sourceforge.net/tracker/index.php?func=detail&aid=1534701&group_id=7…> Assignee: jbandela <http://sourceforge.net/users/jbandela/> Summary: Visual C++ 'Language Extensions' support Bug #: 1039338 <http://sourceforge.net/tracker/index.php?func=detail&aid=1039338&group_id=7…> Assignee: johnmaddock <http://sourceforge.net/users/johnmaddock/> Summary: Regex Bug #: 1156957 <http://sourceforge.net/tracker/index.php?func=detail&aid=1156957&group_id=7…> Assignee: johnmaddock <http://sourceforge.net/users/johnmaddock/> Summary: regex - perl syntax affects what gets matched Bug #: 1519824 <http://sourceforge.net/tracker/index.php?func=detail&aid=1519824&group_id=7…> Assignee: jsiek <http://sourceforge.net/users/jsiek/> Summary: Boost with Dinkumware C++ Library !? Bug #: 531963 <http://sourceforge.net/tracker/index.php?func=detail&aid=531963&group_id=75…> Assignee: jsiek <http://sourceforge.net/users/jsiek/> Summary: creating my own properties Bug #: 619615 <http://sourceforge.net/tracker/index.php?func=detail&aid=619615&group_id=75…> Assignee: jsiek <http://sourceforge.net/users/jsiek/> Summary: Max Flow Algorithm Bug #: 1445526 <http://sourceforge.net/tracker/index.php?func=detail&aid=1445526&group_id=7…> Assignee: nobody Summary: configure problem with aCC Bug #: 811040 <http://sourceforge.net/tracker/index.php?func=detail&aid=811040&group_id=75…> Assignee: nobody Summary: Problem compiling :/ Bug #: 942349 <http://sourceforge.net/tracker/index.php?func=detail&aid=942349&group_id=75…> Assignee: nobody Summary: boost for ARM platform? Bug #: 957850 <http://sourceforge.net/tracker/index.php?func=detail&aid=957850&group_id=75…> Assignee: nobody Summary: problem with debug builds on Solaris Bug #: 965747 <http://sourceforge.net/tracker/index.php?func=detail&aid=965747&group_id=75…> Assignee: nobody Summary: SLOOOWW tokenizer compilation on VC++6.0 Bug #: 969590 <http://sourceforge.net/tracker/index.php?func=detail&aid=969590&group_id=75…> Assignee: nobody Summary: BOOST ON WIN CE Bug #: 1101724 <http://sourceforge.net/tracker/index.php?func=detail&aid=1101724&group_id=7…> Assignee: nobody Summary: Error: Template with C linkage Bug #: 1109438 <http://sourceforge.net/tracker/index.php?func=detail&aid=1109438&group_id=7…> Assignee: nobody Summary: Link VC6 to Boost Bug #: 1118381 <http://sourceforge.net/tracker/index.php?func=detail&aid=1118381&group_id=7…> Assignee: nobody Summary: Boost on opteron AMD Bug #: 1200700 <http://sourceforge.net/tracker/index.php?func=detail&aid=1200700&group_id=7…> Assignee: nobody Summary: Linker Problems with VC .NET 2003 / STLPort / Boost Bug #: 1292345 <http://sourceforge.net/tracker/index.php?func=detail&aid=1292345&group_id=7…> Assignee: nobody Summary: Unable to build boost with Dinkumware STL version 4.02 Bug #: 1336312 <http://sourceforge.net/tracker/index.php?func=detail&aid=1336312&group_id=7…> Assignee: nobody Summary: Problem running configure for unsupported platform Bug #: 1339778 <http://sourceforge.net/tracker/index.php?func=detail&aid=1339778&group_id=7…> Assignee: nobody Summary: Configuration Bug #: 1380808 <http://sourceforge.net/tracker/index.php?func=detail&aid=1380808&group_id=7…> Assignee: nobody Summary: Embedded python won't compile Bug #: 1391956 <http://sourceforge.net/tracker/index.php?func=detail&aid=1391956&group_id=7…> Assignee: nobody Summary: Building universal binary on MacOSX Bug #: 1409774 <http://sourceforge.net/tracker/index.php?func=detail&aid=1409774&group_id=7…> Assignee: nobody Summary: symbian os Bug #: 1428189 <http://sourceforge.net/tracker/index.php?func=detail&aid=1428189&group_id=7…> Assignee: nobody Summary: Cross compiling boost for Windows CE (ARM) from VS2005 Bug #: 1457763 <http://sourceforge.net/tracker/index.php?func=detail&aid=1457763&group_id=7…> Assignee: nobody Summary: compiler is out of heap space in pass 2 Bug #: 1481122 <http://sourceforge.net/tracker/index.php?func=detail&aid=1481122&group_id=7…> Assignee: nobody Summary: Boost.Build v2 build script help for evc4 Bug #: 1498919 <http://sourceforge.net/tracker/index.php?func=detail&aid=1498919&group_id=7…> Assignee: nobody Summary: Compiling Shmem Bug #: 1504379 <http://sourceforge.net/tracker/index.php?func=detail&aid=1504379&group_id=7…> Assignee: nobody Summary: Bjam build should support attachment of individual build ids Bug #: 1530168 <http://sourceforge.net/tracker/index.php?func=detail&aid=1530168&group_id=7…> Assignee: nobody Summary: Having problems with building boost Bug #: 1545941 <http://sourceforge.net/tracker/index.php?func=detail&aid=1545941&group_id=7…> Assignee: nobody Summary: Building Boost with Open Watcom Compiler Bug #: 1547257 <http://sourceforge.net/tracker/index.php?func=detail&aid=1547257&group_id=7…> Assignee: nobody Summary: '-shared' not supported for linking under MacOS X Bug #: 1553825 <http://sourceforge.net/tracker/index.php?func=detail&aid=1553825&group_id=7…> Assignee: nobody Summary: failing on 6 targets in MacOS X Bug #: 1572712 <http://sourceforge.net/tracker/index.php?func=detail&aid=1572712&group_id=7…> Assignee: nobody Summary: bjam: command not found Bug #: 1586479 <http://sourceforge.net/tracker/index.php?func=detail&aid=1586479&group_id=7…> Assignee: nobody Summary: Problem building boost serialization library Bug #: 1610347 <http://sourceforge.net/tracker/index.php?func=detail&aid=1610347&group_id=7…> Assignee: nobody Summary: Boost on Mac w. CodeWarrior Bug #: 1610475 <http://sourceforge.net/tracker/index.php?func=detail&aid=1610475&group_id=7…> Assignee: nobody Summary: Building Boost with VS C++ 2005 express problem Bug #: 1616142 <http://sourceforge.net/tracker/index.php?func=detail&aid=1616142&group_id=7…> Assignee: samuel_k <http://sourceforge.net/users/samuel_k/> Summary: Boost.Format doesn't work on MSVC with /vd2 compiler option Bug #: 1545133 <http://sourceforge.net/tracker/index.php?func=detail&aid=1545133&group_id=7…> Assignee: speedsnail <http://sourceforge.net/users/speedsnail/> Summary: Multithreaded process pausing but not deadlocking or crashin Bug #: 1280829 <http://sourceforge.net/tracker/index.php?func=detail&aid=1280829&group_id=7…> Assignee: turkanis <http://sourceforge.net/users/turkanis/> Summary: Boost.Iostreams and newline translation Bug #: 1299123 <http://sourceforge.net/tracker/index.php?func=detail&aid=1299123&group_id=7…> Assignee: turkanis <http://sourceforge.net/users/turkanis/> Summary: boost.iostreams file_descriptor and sharing Bug #: 1445474 <http://sourceforge.net/tracker/index.php?func=detail&aid=1445474&group_id=7…> Assignee: urzuga <http://sourceforge.net/users/urzuga/> Summary: lambda vs pure virtual functions Bug #: 1231445 <http://sourceforge.net/tracker/index.php?func=detail&aid=1231445&group_id=7…> Assignee: vladimir_prus <http://sourceforge.net/users/vladimir_prus/> Summary: program_options Can one have options with optional values? Bug #: 1102652 <http://sourceforge.net/tracker/index.php?func=detail&aid=1102652&group_id=7…> Assignee: vladimir_prus <http://sourceforge.net/users/vladimir_prus/> Summary: program_options Can one have options with optional values? Bug #: 1102664 <http://sourceforge.net/tracker/index.php?func=detail&aid=1102664&group_id=7…> Assignee: vladimir_prus <http://sourceforge.net/users/vladimir_prus/> Summary: program_options bug? Bug #: 1114084 <http://sourceforge.net/tracker/index.php?func=detail&aid=1114084&group_id=7…> -- -- Marshall Marshall Clow Idio Software <mailto:marshall@idio.com> It is by caffeine alone I set my mind in motion. It is by the beans of Java that thoughts acquire speed, the hands acquire shaking, the shaking becomes a warning. It is by caffeine alone I set my mind in motion.

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