November 2008 - Boost - lists.preview.boost.org

[thread] sleep() with time_duration?
by Boris 15 Nov '08

15 Nov '08

If I want a thread to sleep for five seconds the shortest code I could come up with is: boost::system_time time = boost::get_system_time(); time += boost::posix_time::seconds(5); boost::thread::sleep(time); It would be nice if it was possible to pass a time_duration object to sleep() directly: boost::thread::sleep(boost::posix_time::seconds(5)); This would also be consistent with the deadline_timer in Boost.Asio whose constructor accepts both a time and a time_duration. Boris

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[Random] design of the random library
by Ares Lagae 15 Nov '08

15 Nov '08

I have some questions regarding the design of the C++/TR1 and Boost.Random library. What are the requirements on the UniformRandomNumberGenerator argument of operator() of random distribution class templates? It seems that the only requirement is uniform distribution, and both range and type (integer / floating point) are not specified. Does this mean that the random distribution class templates work with any kind of UniformRandomNumberGenerator? Does the normal_distribution work as expected with a linear congruential uniform random number generator? Or does the normal distribution assume a continuous distribution in [0,1[? Are these requirements documented? I could not immediately find them in the documentation. It seems operator() of most random distributions will first have to construct a uniform_01 random distribution from the UniformRandomNumberGenerator argument and then transform that distribution to the required distribution (e.g. the normal_distribution would construct a uniform_01 distribution from the UniformRandomNumberGenerator argument of operator() and then use the Box-Muller transformation). I would appreciate it if someone could clarify these issues. -- Ares Lagae, Ph.D. Computer Graphics Research Group, Katholieke Universiteit Leuven http://www.cs.kuleuven.be/~ares/

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default value for a variable using template argument
by Chris 15 Nov '08

15 Nov '08

Hi, did anyone ever suggest a template class which initializes a variable to a certain value? (see example) Is this too trivial? This is useful to prevent uninitialized values in objects. class A { defaulted<int, 1280> _width; defaulted<int, 1024 > _height; defaulted<int, 0> _depth; }; template <typename TYPE, TYPE value> class defaulted { public: defaulted() : _t(value) { } defaulted(const TYPE & value2) : _t(value2) { } operator TYPE & () { return _t; } TYPE * operator & () { return &_t; } const TYPE * operator & () const { return &_t; } operator const TYPE & () const { return _t; } TYPE & operator =(const TYPE & other) { _t = other; return _t; } private: TYPE _t; };

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[thread] other thread_group functions
by vicente.botet 14 Nov '08

14 Nov '08

Hi, I would like to know which of the following thread functions have a sens for thread_group? bool joinable() const; bool timed_join(const system_time& wait_until); template<typename TimeDuration> bool timed_join(TimeDuration const& rel_time); void detach(); I have another sugestion related to the _all suffix of the thread_group functions join_all and interrupt_all. Could you add the synonyms join and interrupt? In this way a thread_group can be seen as a compound object sharing the same interface as the element thread. ______________________ Vicente Juan Botet Escribá

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[thread] getting boost::thread* form boost::thread::id
by vicente.botet 14 Nov '08

14 Nov '08

Hi Anthony, I'm working with a keep_alive mechanism. I need to interrupt threads that are considered 'dead'. I have access to the thread specific context using a map : boost::thread::id -> context. This mapping is modified by self registration from the thread. On the other side I need a boost::thread pointer to interrupt the thread. With the current Boost.Thread interface, I don't see how I can get it either from the current thread or from the thread::id. Can I? Currently only the thread creator wrapper can add this information. I think that I could add a thread creator wrapper that add this as a thread specific pointer, but I will be able to get only the thread* for the threads created with this wrapper, which is not completly satisfactory. Do you think that at least one of these functions could be of general use: one for getting a boost::thread* form a boost::thread::id and one for getting the boost::thread* of the current thread? namespace boost { class thread { // ... static thread* get_thread_ptr(id); }; namespace this thread { thread* get_thread_ptr(); } } To implement this in Boost.Thread it will be need to store the thread* on the detail::thread_data_ptr. Do you think that this could be a possible addition on the Boost.Thread library? Thanks, Vicente

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[numeric_cast] request for boost::numeric_downcast
by Thorsten Ottosen 14 Nov '08

14 Nov '08

Hi Fernando, Amoung our utilities we have boost::polymorphic_cast boost::polymorphic_downcast The latter only performs a check in debug builds, and can then be used whenever the cast must succeed. boost::numeric_cast has no such alternative. Therefore I wuold like to see one. To keep in the naming convention from above, I think it could be reasonable to call this boost::numeric_downcast Furthermore, this should if possible be implemented in a seperate header (which is included in the main header) that can be compiled without exception-support. I think there are still platforms where they need this functionality, but don't want to sue exceptions. Any comments -Thorsten

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[thread] Conformance with N2497 move semantics
by vicente.botet 14 Nov '08

14 Nov '08

Hi Anthony, N2497 includes the following thread constructor overloadings template <class F> explicit thread(F f); template <class F, class ...Args> thread(F&& f, Args&&... args); void swap(thread&&); Boost.Threads try to conforms to N2497 as muh as possible. Boost.Threads defines already #ifdef BOOST_HAS_RVALUE_REFS template <class F> thread(F&& f); #else #ifdef BOOST_NO_SFINAE template <class F> explicit thread(F f); #else template <class F>explicit thread(F f, typename disable_if< boost::is_convertible<F&, detail::thread_move_t<F> >, dummy* >::type=0); #endif template <class F>explicit thread(detail::thread_move_t<F> f); template <class F,class ...Args> thread(F f, Args... args) I have some questions. Is there any deep raison for which template <class F> explicit thread(F f); should not always be defined? Is there any deep raison to emulate template <class F,class ...Args> thread(F f, Args... args) instead of template <class F,class ...Args> thread(F&& f, Args... args) Could template <class F, class ...Args> thread(F&& f, Args&&... args); rally be emulated? You provide 'void swap(thread&)'. Could 'void swap(thread&&)' be emulated? Do you know if the following overloadings are taken in account by the boost::swap utility? void swap(thread& x, thread& y); void swap(thread&& x, thread& y); void swap(thread& x, thread&& y); Thanks in advance, Vicente

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Re: [boost] Compiling 64bit regex 1.37.0 with VS2005
by Gary Mann 14 Nov '08

14 Nov '08

I also see the same problem compiling with 32 bit MSVC 7.1 SP1 (13.10.6030). I don't experience the issue when using STLport - only when using the native Dinkumware STL implementation (not surprising given the preprocessor directives in the file). src\usinstances.cpp(47) : error C2910: 'std::char_traits<wchar_t>::length' : cannot be explicitly specialized I tried grabbing the latest copy of the source file from SVN, but it appears identical to that included in the 1.37.0 distribution. I haven't tried updating all the source and headers for the entire regex component yet... Gary -- View this message in context: http://www.nabble.com/Compiling-64bit-regex-1.37.0-with-VS2005-tp20493076p2… Sent from the Boost - Dev mailing list archive at Nabble.com.

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Re: [boost] [utility/swap] Internal compiler error Siliconman borland-6.10.0 (CodeGear?)
by Niels Dekker - mail address until 2010-10-10 14 Nov '08

14 Nov '08

>> But unfortunately, the rather simple specialized_in_std.cpp test >> gets an internal compiler error (Fatal F1004) from borland-6.10.0. I >> guess this is a CodeGear issue, right? David (siliconman) wrote: > Yes, this looks like a compiler bug. I'll submit it to the bug > tracking system. Thanks! So did you report the bug to http://qc.codegear.com ? If so, can you please give me the report number? Kind regards, Niels

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[unordered] patch to remove warning on Visual C++
by Christopher Lux 14 Nov '08

14 Nov '08

Hi, appended is a small patch to fix some annoying warnings using Visual C++ 8.0 and 9.0. It would be nice if this could be looked at and applied to the trunk. The warnings were: 1>brick_pool.cpp 1>E:\devel\working_copies\schism_x64_vc90_sp1\externals\inc\boost\boost/unordered/unordered_map.hpp(388) : warning C4396: 'boost::operator ==' : the inline specifier cannot be used when a friend declaration refers to a specialization of a function template 1>E:\devel\working_copies\schism_x64_vc90_sp1\externals\inc\boost\boost/unordered/unordered_map.hpp(389) : warning C4396: 'boost::operator !=' : the inline specifier cannot be used when a friend declaration refers to a specialization of a function template Regards -chris -- Christopher Lux | | Bauhaus-Universität Weimar | faculty of media - virtual reality systems group Index: boost/unordered/unordered_map.hpp =================================================================== --- boost/unordered/unordered_map.hpp (revision 49734) +++ boost/unordered/unordered_map.hpp (working copy) @@ -385,8 +385,8 @@ friend bool operator==(unordered_map const&, unordered_map const&); friend bool operator!=(unordered_map const&, unordered_map const&); #else - friend bool operator==<>(unordered_map const&, unordered_map const&); - friend bool operator!=<>(unordered_map const&, unordered_map const&); + friend bool operator==<unordered_map>(unordered_map const&, unordered_map const&); + friend bool operator!=<unordered_map>(unordered_map const&, unordered_map const&); #endif }; // class template unordered_map

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