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Re: [boost] [challenge!] find a common domain
by Krishna Achuthan 21 May '10

21 May '10

"Eric Niebler" <eric(a)boostpro.com> wrote in message news:< 4BF5CA3B.8090807(a)boostpro.com>... > On 5/20/2010 10:54 AM, John Bytheway wrote: > > On 19/05/10 07:02, Eric Niebler wrote: > > <snip> > >> Your job: implement the deduce_domain3 template that finds the > >> common domain of 3 domains. You're allowed to use decltype, but you > >> get bonus points for a solution that doesn't. Bonus also for > >> instantiating fewest templates. The challenge is for the ternary > >> case, but your solution should scale to N domains. If your solution > >> is better than mine, I'll use it in Proto and credit you! > > > > I attach my solution for completeness, though I think Daniel's is > > neater. I used a similar idea to him, but without the use of > > sizeof/decltype, and with the distance-to-not_a_domain implemented > > as a metafunction, rather than injected into the definition of domain. > > > > I think we use about the same number of instantiations, but Daniel's > > lends itself to unrolling much more than mine. I might argue that > > my implementation is a little easier to follow than his, but it > > would be a pretty feeble claim. > > Thanks, John. I'll need to investigate more closely. Everybody's code > is easy to follow when they wrote it! :-) Though I admit, Daniel's > solution is subtle and had me scratching my head for a while. > > And for completeness, here is my (decltype-based) solution. I tried to > make one giant expression that calculates the result in one shot. Like > Daniel, I use inheritance and overloading, but I build a parallel > hierarchy instead of reusing the domains. (For reasons that aren't > relevant, I don't want domains to actually inherit from other domains > in > Proto.) > > -- > Eric Niebler > BoostPro Computing > http://www.boostpro.com > Here's another try. No inheritance or function overloading. I have no idea how many template instantiations are there in this code and if it is acceptable. There is some influence from Daniel's solution in getting the default_domain resolutions right. - Krishna Achuthan

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Let's use stack exchange!
by Gennadiy Rozental 21 May '10

21 May '10

Hi, I've always envied a bit how stackoverflow site was operating. I like the interface much better than mailing lists. Search, filtering, thread tracking... Now that the engine behind it is free http://www.joelonsoftware.com/items/2010/04/13.html I think we can benefit a lot from using it for boost. In addition it should help us with review managers issues. We can use "reputation" based system to qualify potential managers. In practice: who should agree to this and who would do the work? Gennadiy

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[thread] Compiler eoorrs while running the tests
by vicente.botet 21 May '10

21 May '10

Hi, I get some compile errors with boost 1.43 gcc.compile.c++ ..\..\..\bin.v2\libs\thread\test\test_thread_return_local_lib.test\gcc-mingw-4.4.0\debug\threading-multi\test_thread_return_local.o ..\..\../boost/thread/detail/thread.hpp: In function 'boost::thread make_thread_return_local(boost::thread::id*)': ..\..\../boost/thread/detail/thread.hpp:111: error: 'boost::thread::thread(boost::thread&)' is private test_thread_return_local.cpp:16: error: within this context How can the following compile? boost::thread make_thread_return_local(boost::thread::id* the_id) { boost::thread t(do_nothing,the_id); return t; } Best, _____________________ Vicente Juan Botet Escribá http://viboes.blogspot.com/

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Re: [boost] [challenge!] find a common domain
by Krishna Achuthan 21 May '10

21 May '10

----- Original Message ----- From: <daniel(a)boostpro.com> Newsgroups: gmane.comp.lib.boost.devel To: <boost(a)lists.boost.org> Sent: Thursday, May 20, 2010 6:05 AM Subject: Re: [challenge!] find a common domain > On Wed, May 19, 2010 at 03:54:29PM -0700, Eric Niebler wrote: >> On 5/19/2010 3:29 PM, Daniel Wallin wrote: >> > On Tue, May 18, 2010 at 11:02:56PM -0700, Eric Niebler wrote: >> >> Your job: implement the deduce_domain3 template that finds the common >> >> domain of 3 domains. You're allowed to use decltype, but you get bonus >> >> points for a solution that doesn't. Bonus also for instantiating fewest >> >> templates. The challenge is for the ternary case, but your solution >> >> should scale to N domains. >> > >> > Here's mine. It's decltype based, but I guess it could be sizeof based >> > in C++03. >> >> Wow! SO much simpler than my solution. I'll need to study this in depth. >> I also specialized domain<default_domain> to insert an extra level in >> the inheritance tree like you did. That's a great simplification, but it >> took me a week to see that. Kudos. > > Thanks. :) > >> BTW, you're creating a zero-sized array in sized_type<0>. I just >> bumped all the integers by one and it works fine on msvc-10. > > Duh, good catch. > >> This looks more efficient at compile-time, too. I'll be embarrassed to >> post my solution. :-O But not yet. Anybody care to eliminate decltype so >> I can use this in Proto? Anybody think they can instantiate fewer templates? > > Here's one without decltype. The changes needed were pretty minor. It > might still be possible to reduce the number of instantiations. For > instance, you could specialize nth_domain<> on some more indicies (I'm > guessing the number of super domains should be fairly low), but I don't > know what the cost of specialization compared to instantiation is. > > -- > Daniel Wallin > BoostPro Computing > http://www.boostpro.com When I tried to compile the code using VC 2005, it failed with the following error: error C2064: term does not evaluate to a function taking 1 arguments deduce_domain.cpp 53 After I broke the struct into two pieces like below, it works fine. template <class D0, class D1> struct domain_depth { static const int value = domain<D0>::index - sizeof(domain<D0>::deduce((D1*)0)); }; template <class D0, class D1, int DefaultCase = sizeof(default_case((D0*)0, (D1*)0))> struct deduce_common : nth_domain<domain_depth<D0, D1>::value, D0> {}; - Krishna Achuthan

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[geometry][units] Vector Class
by Terry Golubiewski 21 May '10

21 May '10

I imagine that using geometry/unit together will be common. I just posted these files on boost-user too, but I wanted the geometry/units developers to see what I've done. I think it was too difficult to make a Vector<quantity<U,T>> class. However, it could be done, so that is very good! The problem is that the geometry library assumes that the types of T*T and sqrt(T) is the same as T. terry

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[Test] WinCE patch for floating point changes
by David Deakins 20 May '10

20 May '10

Hi Gennadiy, I noticed the recent floating point feature broke testing on Windows CE since it does not have the _controlfp_s function like full-blown Windows. Do you mind if I apply the attached patch to make testing work again (at least until a suitable real implementation is found for WinCE if possible). Thanks, -Dave

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boost thread slow with only one thread
by Natacha Fort 20 May '10

20 May '10

hi! here is my problem i am multithreading my program with boost but i don't get what i expect, and i can't understand why! i just run one thread and wait for it, and the fps are divide by 3. basically with no thread i have 30fps, and with 1 thread i have 10fps. here is the code: Code: boost::thread_group forces_threads; forces_threads.create_thread(boost::bind(&ElasticRods::computeBendingForces,this,edges,kb,edges_initial)); forces_threads.join_all(); i use thread_group because i want to run 7 thread but it is already too slow! do you have an idea of why this is so slow? thank you for your help!

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[config] Is there a macro to check if we are compiling in C++0x mode?
by vicente.botet 20 May '10

20 May '10

Hi, In Boost.Config I see "Macros that describe C++0x features not supported", but there is a macro to check if the compiler is working on C++0x mode? Best, _____________________ Vicente Juan Botet Escribá http://viboes.blogspot.com/

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Re: [boost] [MSM] move to trunk
by Christophe Henry 19 May '10

19 May '10

> On 5/18/2010 8:22 AM, Christophe Henry wrote: >> >> I'm a bit jetlagged but (luckily) had an uneventfull trip back. And >> the BoostCon was worth it! > > Indeed! It was great to meet you. It was great to meet you too! >> I plan to check in into the trunk in the next few weeks, I really want >> MSM to be in 1.44. >> I only need to write some unit tests so it should be pretty quick. >> I'll post a mail as soon as I'm done. > > If it's just a matter of unit tests and the interfaces are stable, I > suggest just merging it to trunk now and working on the tests there. > When it's ready, you can merge to release. > > -- > Eric Niebler > BoostPro Computing > http://www.boostpro.com Yes the interfaces and docs are stable, so it is just a matter of writing test cases and add a jam file. Then I will merge MSM to the trunk fast (probably tomorrow) and then start writing the tests. Thanks! Christophe

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sparse_vector class
by Neil Girdhar 19 May '10

19 May '10

boost/numeric/ublas/vector_sparse.hpp implements a "sparse vector" for arithmetic types. I generalized this for default constructible types, and was wondering if anything like this has been considered for inclusion as a separate boost library. Code available on request.

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