July 2007 - Boost-users - lists.preview.boost.org

[mpl] BOOST_MPL_AUX_LAMBDA_SUPPORT for classes without nested ::type
by Joaquín Mª López Muñoz 26 Jul '07

26 Jul '07

Hello, The following program does compile fine on a conformant compiler: #include <boost/mpl/apply.hpp> #include <boost/mpl/aux_/lambda_support.hpp> #include <boost/mpl/assert.hpp> #include <boost/type_traits/is_same.hpp> using namespace boost; using namespace boost::mpl; template<typename T> struct foo { BOOST_MPL_AUX_LAMBDA_SUPPORT(1,foo,(T)) }; template<typename T> struct bar { typedef T type; BOOST_MPL_AUX_LAMBDA_SUPPORT(1,bar,(T)) }; typedef apply1<foo<_1>,int>::type t1; typedef apply1<bar<_1>,int>::type t2; BOOST_MPL_ASSERT((is_same<t1,foo<int> >)); BOOST_MPL_ASSERT((is_same<t2,int>)); int main(){return 0;} Note that foo<_1> applied to int resolves to foo<int> whereas bar<_1> resolves to int, which is correct because the former class does not have a nested ::type while the latter does. This is documented in the MPL reference at: http://www.boost.org/libs/mpl/doc/refmanual/quote.html Now, if I compile the same program with a defective compiler (MSVC 6.0) not supporting PTS, I've got the following: ...\boost\boost\mpl\aux_\preprocessed\msvc60\apply_wrap.hpp(77) : error C2039: 'type' : is not a member of 'result_<int>' ...\boost\mpl\aux_\preprocessed\msvc60\bind.hpp(184) : see reference to class template instantiation 'boost::mpl::apply_wrap1<class foo_rebind,int>' being compiled whereas the code associated with bar<> works OK. So, it seems like BOOST_MPL_AUX_LAMBDA_SUPPORT does not provide lambda support for classes without nested ::type: 1. Is this so by design and/or documented somewhere? 2. If not, could it be fixed? Thank you, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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Compile probelms
by alex＠gorex.com.hk 26 Jul '07

26 Jul '07

Hi, I need help on compile Boost.Python. I keep having an error "cannot open file boost_python-vc80-mt-gd-1_34.lib" when I issue a commond bjam -sTOOLS=vc-8_0. I searched some notes from web and I added "import python" or "using python" already. However the problem still exists. anyone can advise?

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Re: [Boost-users] [thread] comparison with Intel Threading BuildingBlocks
by Ovanes Markarian 26 Jul '07

26 Jul '07

On Wed, July 25, 2007 15:54, Andrew Holden wrote: > Toon Knapen wrote: >> I just received (again) some doc on the Intel Threading >> Building Blocks >> (TBB) (http://www.threadingbuildingblocks.org/) >> >> I was wondering how the boost.thread developers/supporters >> would compare TBB with boost.thread (btw: the book of James >> Reinders on TBB mentions boost.thread) ? > > The two libraries are meant to solve different problems. Boost.thread > handles situations where the programmer wishes to explicitly manage > threads, often giving each thread a distinct task to perform. It would > be useful for situations like worker threads in a GUI program. It is > also useful I/O-bound threads, which would cause TBB to waste a > processor core. > > TBB, on the other hand, is useful for situations in which you have a > parallelizable task to perform, and you would rather not worry about > threading details, like a parallel for loop. Do you mean that TBB is more like a "future" which might be added to the upcoming tr2? >[...] With Kind Regards, Ovanes Markarian

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program_options error class
by ALiX 26 Jul '07

26 Jul '07

In the latest implementation of boost (1.34), the error class in boost::program_options is defined as a subclass of std::logic_error. This is, however, not stated in the documentation. In the documentation the class error is described as if it has no superclass from which it inherits. In my programs, can I safely rely on the fact that error inherits from std::logic_error, and so comfortably use the what() function to extract the error messages? Might this change in later implementations? Kind regards, /ALiX

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Fixed sized containers
by Dowie, Martin (SELEX) (UK) 26 Jul '07

26 Jul '07

All, I've noticed the addition of template class "array" to TR1. As I work in the embedded field this is going to be extrememly useful to me (thank you!). I was wondering if there were any plans to expand on this and standardize other statically fixed containers? Cheers -- Martin SELEX Sensors and Airborne Systems Limited Registered Office: Sigma House, Christopher Martin Road, Basildon, Essex SS14 3EL A company registered in England & Wales. Company no. 02426132 ******************************************************************** This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. ********************************************************************

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[statechart] asynchronous machine's post event question.
by Jiang Miao 26 Jul '07

26 Jul '07

Hi, According to the code struct Working:sc::state< Working, Active > { Working(my_context ctx):my_base(ctx) { cout<<__FUNCTION__<<endl; outermost_context_type& machine=outermost_context(); // machine is a asynchronous machine. A machine.post_event( EvtTerminate() ); B machine.my_scheduler().queue_event( machine.my_handle(),boost::intrusive_ptr<EvtTerminate>(new EvtTerminate() ) ); }; ~Working(void) { cout<<__FUNCTION__<<endl; } typedef sc::transition< EvtIdleWork,Idle > reactions; }; Is there any difference between A and B? Which is the better and recommended or Is there another better way to post event? Thank you.

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Re: [Boost-users] Support for sp_counted_base for HP Itanium aCC compiler
by Baruch Zilber 26 Jul '07

26 Jul '07

>Hi Baruch, > >thank you for doing this. > >Can you, please, post your code here (I guess, it is a header file like >sp_counted_base_gcc_ia64.hpp)?. It will be reviewed by the Boost community >and we'll review it at HP. And, then, it can be added to Boost, hopefully, >in Boost 1.35 time frame. > >Thanks again, > Boris I copy the file sp_counted_base_gcc_ia64.hpp to sp_counted_base_acc_ia64.hpp and change the following methods: atomic_increment(),atomic_decrement() and atomic_conditional_increment() The change was: #include <machine/sys/inline.h> inline void atomic_increment( int * pw ) { _Asm_mf(); static_cast<int>(_Asm_fetchadd(_FASZ_W, _SEM_REL, (void*)pw, +1, _LDHINT_NONE) + 1); } inline int atomic_decrement( int * pw ) { _Asm_mf(); return (static_cast<int>(_Asm_fetchadd(_FASZ_W, _SEM_REL, (void*)pw, -1, _LDHINT_NONE) - 1) - 1); } inline int atomic_conditional_increment( int * pw ) { return _Asm_mov_to_ar((_Asm_app_reg)_AREG_CCV, *pw, (_Asm_fence)(_UP_CALL_FENCE | _UP_SYS_FENCE | _DOWN_CALL_FENCE | _DOWN_SYS_FENCE)), _Asm_mf(), (_Asm_cmpxchg((_Asm_sz)4, (_Asm_sem)_SEM_REL, pw, *pw + 1, (_Asm_ldhint)_LDHINT_NONE)); } Thanks Baruch This message and the information contained herein is proprietary and confidential and subject to the Amdocs policy statement, you may review at http://www.amdocs.com/email_disclaimer.asp

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Re: [Boost-users] Tuple use/overuse?
by Roman Perepelitsa 26 Jul '07

26 Jul '07

> Joel de Guzman <joel(a)boost-consulting.com> on Thu, 26 Jul 2007 06:59:46 +0800 > > - bind expression with tuple becomes a nightmare > > Why? Ah access to the members? It's a nightmare indeed. I'd say boost::get is not bindable at all. typedef tuple<int, double> two; vector<two> src; vector<int> dst; // ouch const int & (*get_first)(const cons<two::head_type, two::tail_type> &) = get<0>; transform(src.begin(), src.end(), dst.begin(), get_first); Would not it be cool to write something like this instead? transform(src.begin(), src.end(), dst.begin(), get<0>()); And it's not hard to implement it. namespace boost { namespace tuples { template <int N> struct getter { template <class HT, class TT> typename access_traits< typename element<N, cons<HT, TT> >::type >::non_const_type operator()(cons<HT, TT> & c) const { return get<N>(c); } template <class HT, class TT> typename access_traits< typename element<N, cons<HT, TT> >::type >::const_type operator()(const cons<HT, TT> & c) const { return get<N>(c); } }; } template <int N> tuples::getter<N> get() { return tuples::getter<N>(); } } Does fusion have something like this? Regards, Roman Perepelitsa Deutsche Bank Moscow +7 (495) 660-74-08 --- This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and delete this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden. Please refer to http://www.db.com/en/content/eu_disclosures.htm for additional EU corporate and regulatory disclosures.

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Re: [Boost-users] [thread] comparison with Intel Threading BuildingBlocks
by Ovanes Markarian 26 Jul '07

26 Jul '07

On Wed, July 25, 2007 17:06, Andrew Holden wrote: > Ovanes Markarian wrote: >> Thanks for you link, a very interesting one ;) I ment this >> one in my previous post: >> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2276.html > > Another interesting technology. I'll need to examine it more closely. > It looks similar to TBB. Intel's implementation of TBB uses tasks and > thread pools. Instead of futures, it uses canned parallel algorithms > that WILL complete before returning, thus freeing the user from worrying > that values might not be ready. > > It looks like the futures run at a somewhat lower level than TBB, which > is certainly not a bad thing. I can already see the beginnings of some > ideas where it might do things that TBB can't, like any situation where > you wish to launch a separate thread (or task) and forget about it. I'm > also intrigued by the option of waiting an a specific return value from > the thread instead of joining the entire thread, like in boost.thread. > > I find myself wordering if this would be a worthy addition to > boost.thread. It looks like you could use a boost.thread condition > object in the implementation of a future. AFAIK Peter Dimov did some technology evaluation and implementation for futures. I also saw that Howard Hinnant was working on futures. May be there are already some implemenations which prove the concept. Boost Vault contains them at: http://boost-consulting.com/vault/index.php?&direction=0&order=&directory=C… With Kind Regards, Ovanes Markarian

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astar using namespace
by bringiton bringiton 26 Jul '07

26 Jul '07

I've removed the using namespace boost from the astar graph cities example. (I prefer to define namespaces explicitly). //using namespace boost; I've added boost:: to all the type names and it all compiles fine. However, some functions compile without the namespace. ie the following line: WeightMap weightmap = get(boost::edge_weight, g); Can someone please explain why I dont need a boost:: infront of the get?

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