September 2008 - Boost-users - lists.preview.boost.org

How to test if a type is of some form?
by Peng Yu 24 Sep '08

24 Sep '08

Hi, I want to test if template argument is of some form like in the following code. I could define some helper class to do such test. But I'm wondering if there is any easy to do it with boost? The type_traits's is_same does not work in this case. I'm wondering if there could be some generalization of it. template <T> void f() { //For example, I want to test if T is of the // form of std::complex<S> } Thanks, Peng

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[Thread] Not able to compile a program with Thread library on ARM
by Rudi Dittrich 24 Sep '08

24 Sep '08

Dear all, I've got the following problem: I want to use the boost threading library provided in version 1.36 on an arm (imx31) based evaluation board with MontaVista linux and g++ version 4.2.0 on it. When I try to compile the following example with my arm-g++ compiler #include <vector> #include <boost/shared_ptr.hpp> #include <boost/thread.hpp> #include <boost/bind.hpp> class Worker { private: int _id; ///< The id of the worker. public: Worker( int id ) : _id( id ) {} // Is the function that is called when this worker is started. // Doesn't do anything usefull. void run() { for (unsigned int i=0; i<30000000; i++); } }; typedef boost::shared_ptr<Worker> worker_ptr; typedef std::vector<worker_ptr> worker_vec; // Starts worker threads. void run( int nr_workers ) { worker_vec workers( nr_workers ); boost::thread_group tg; for (int i = 0; i < nr_workers; i++) { worker_ptr w( new Worker(i) ); workers[i] = w; tg.create_thread( boost::bind( &Worker::run, w ) ); } tg.join_all(); } int main( int argc, char *argv[] ) { int worker_nr = 5; run( worker_nr ); return 0; } I get the following error message: /opt/montavista/mobilinux/devkit/arm/v6_vfp_le/lib/gcc/armv6fl-montavista-linux-gnueabi/4.2.0/../../../../armv6fl-montavista-linux-gnueabi/bin/ld: thread-test: hidden symbol `__sync_add_and_fetch_4' in /opt/montavista/mobilinux/devkit/arm/v6_vfp_le/lib/gcc/armv6fl-montavista-linux-gnueabi/4.2.0/libgcc.a(linux-atomic.o) is referenced by DSO /opt/montavista/mobilinux/devkit/arm/v6_vfp_le/lib/gcc/armv6fl-montavista-linux-gnueabi/4.2.0/../../../../armv6fl-montavista-linux-gnueabi/bin/ld: final link failed: Nonrepresentable section on output collect2: ld returned 1 exit status I do not get any linking errors while compiling it on my PC, so may be there is missing something? I've read in "http://lists.boost.org/Archives/boost/2007/09/127103.php " that this problems comes from the fact that __sync__fetch_and_add(&x,1) , which is needed by shared_pointers, is not implemented in gcc for ARM. So according to the problem stated above I've two questions: - Does there already exist a workaround which solves the problem mentioned above? - I have added a new header file (atomic_count_arm.hpp) to the boost/detail directory. It implements the atomic_count class with specific arm inline assemply instructions in the operator overloads functions. #ifndef BOOST_DETAIL_ATOMIC_COUNT_ARM_HPP_INCLUDED #define BOOST_DETAIL_ATOMIC_COUNT_ARM_HPP_INCLUDED namespace boost { namespace detail { class atomic_count { public: explicit atomic_count( long v ) : value_( v ) {} void operator++() { long tmp; int result; __asm__ __volatile__( "1: ldrex %0, [%2]\n" " add %0, %0, #1\n" " strex %1, %0, [%2]\n" " cmp %1, #0\n" " bne 1b" : "=&r"(tmp), "=&r"(result) // output parameters : "r"(&value_) // input parameters : "memory", "cc" // clobbers ); } long operator--() { long tmp; int result; __asm__ __volatile__( "1: ldrex %0, [%2]\n" " add %0, %0, #-1\n" " strex %1, %0, [%2]\n" " cmp %1, #0\n" " bne 1b" : "=&r"(tmp), "=&r"(result) // output parameters : "r"(&value_) // input parameters : "memory", "cc" // clobbers ); } operator long() const { long tmp; int result; __asm__ __volatile__( "1: ldrex %0, [%2]\n" " strex %1, %0, [%2]\n" " cmp %1, #0\n" " bne 1b" : "=&r"(tmp), "=&r"(result) // output parameters : "r"(&value_) // input parameters : "cc" // clobbers ); return tmp; } private: atomic_count(atomic_count const &); atomic_count & operator=(atomic_count const &); mutable long value_; }; } // namespace detail } // namespace boost #endif Further I've added the following lines into atomic_count.hpp: #elif defined( __GNUC__ ) && ( __GNUC__ * 100 + __GNUC_MINOR__ >= 401 ) && defined( __arm__ ) #include <boost/detail/atomic_count_arm.hpp> and before: #elif defined( __GNUC__ ) && ( __GNUC__ * 100 + __GNUC_MINOR__ >= 401 ) # include <boost/detail/atomic_count_sync.hpp> Then I recompiled boost and the threading example given above and suprise, it compiles. I'm also able to execute the test-program. So, do you think that this is feasable solution? Best regards, Rudi Dittrich -- GMX startet ShortView.de. Hier findest Du Leute mit Deinen Interessen! Jetzt dabei sein: http://www.shortview.de/wasistshortview.php?mc=sv_ext_mf@gmx

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no_std_locale_fail.test when compiling boost 1.36.0
by mess-mate 24 Sep '08

24 Sep '08

Hi folks, i'd like to compile the boost lib 1.36.0. But have over and over this error: **passed** bin.v2/libs/config/test/all/no_std_locale_fail.test/gcc-4.1.3/release/threading-multi/no_std_locale_fail.test How can i solve this ? Any help welcome best regards

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[Range] Adapt 2-iterator container constructors for Range?
by Nat Goodspeed 24 Sep '08

24 Sep '08

As I work with Boost.Range, I frequently want to call a method returning an iterator_range and, from that range, instantiate a standard container. I have a couple of helpers I'd like to propose for inclusion in the Boost.Range library. /** * From any range compatible with Boost.Range, return an instance of any * class with a constructor accepting a compatible iterator pair. */ template<class TYPE, typename RANGE> TYPE make_from_range(const RANGE& range) { return TYPE(boost::begin(range), boost::end(range)); } It would probably be appropriate to provide a non-const RANGE& overload as well. make_from_range<CONTAINER>(range) is helpful for, e.g., passing an argument to a function accepting const CONTAINER&. But what if you want to declare a local instance of such a container? /** * From any range compatible with Boost.Range, instantiate any class * with a constructor accepting a compatible iterator pair. */ template<class TYPE> struct instance_from_range: public TYPE { template<typename RANGE> instance_from_range(const RANGE& range): TYPE(boost::begin(range), boost::end(range)) {} // Again, a non-const RANGE& overload would probably be useful. }; Usage example: instance_from_range< std::vector<std::string> > my_vector(function_returning_range_of_string()); Perhaps instance_from_range might be more controversial because of the recommendation not to subclass standard containers. My thought is that once the (nearly trivial) constructor has executed, we can completely disregard the subclass. I've used it in a context where instance_from_range<CONTAINER> is "sliced" to the CONTAINER itself. Though these are small enough to recreate on demand, they're useful enough that I'd like to have them available everywhere. I hope others might find them helpful too.

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[Filesystem] has_root_path()
by Robert Jones 24 Sep '08

24 Sep '08

Boost 1.33.1 used to support has_root_path() on directory_iterators. 1.36 seems to use a slightly different mechanism for directory_iterators, based on instantiating basic_directory_iterator, and I'm struggling to see what has happened to has_root_path(). It's there somewhere, but not accessible in quite the same way as it was. How do I express directory_iterator -> has_root_path() in 1.36.0 ? Thanks - Rob.

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PDF Documentation
by Dustin Spicuzza 24 Sep '08

24 Sep '08

Hey, I've noticed that its mentioned in the docs that you can generate PDF documentation via boostbook, however it appears to fail violently when I try. I can build the HTML docs with little effort. Additionally, there are a number of links on the boost website to PDF versions of the docs that no longer exist and give 404 errors. Is PDF still a supported output format for the docs? Thanks. Dustin

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A compilation problem at function10.hpp in the function library
by Bob Lim 24 Sep '08

24 Sep '08

Hi guys, I cannot compile without error for function10.hpp in Visual Studio 2005 Pro. A simple source file to reproduce the problem is attached(Test.cpp). There is no such problem with other function0-9.hpp, except for function10.hpp. The error message encounter is as below, 1>d:\downloads\boost_1_36_0\boost_1_36_0\boost\mem_fn.hpp(318) : warning C4180: qualifier applied to function type has no meaning; ignored 1> d:\downloads\boost_1_36_0\boost_1_36_0\boost\function\function_template.hpp(381) : see reference to class template instantiation 'boost::_mfi::dm<R,T>' being compiled 1> with 1> [ 1> R=int (int,int,int,int,int,int,int,int,int), 1> T=MyClass 1> ] 1> d:\downloads\boost_1_36_0\boost_1_36_0\boost\function\function_template.hpp(277) : see reference to function template instantiation 'bool boost::detail::function::basic_vtable10<R,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9>::assign_to<F>(MemberPtr,boost::detail::function::function_buffer &,boost::detail::function::member_ptr_tag)' being compiled 1> with 1> [ 1> R=int, 1> T0=MyClass *, 1> T1=int, 1> T2=int, 1> T3=int, 1> T4=int, 1> T5=int, 1> T6=int, 1> T7=int, 1> T8=int, 1> T9=int, 1> F=int (__thiscall MyClass::* )(int,int,int,int,int,int,int,int,int), 1> MemberPtr=int (__thiscall MyClass::* )(int,int,int,int,int,int,int,int,int) 1> ] 1> d:\downloads\boost_1_36_0\boost_1_36_0\boost\function\function_template.hpp(779) : see reference to function template instantiation 'bool boost::detail::function::basic_vtable10<R,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9>::assign_to<Functor>(F,boost::detail::function::function_buffer &)' being compiled 1> with 1> [ 1> R=int, 1> T0=MyClass *, 1> T1=int, 1> T2=int, 1> T3=int, 1> T4=int, 1> T5=int, 1> T6=int, 1> T7=int, 1> T8=int, 1> T9=int, 1> Functor=int (__thiscall MyClass::* )(int,int,int,int,int,int,int,int,int), 1> F=int (__thiscall MyClass::* )(int,int,int,int,int,int,int,int,int) 1> ] 1> d:\downloads\boost_1_36_0\boost_1_36_0\boost\function\function_template.hpp(612) : see reference to function template instantiation 'void boost::function10<R,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9>::assign_to<Functor>(Functor)' being compiled 1> with 1> [ 1> R=int, 1> T0=MyClass *, 1> T1=int, 1> T2=int, 1> T3=int, 1> T4=int, 1> T5=int, 1> T6=int, 1> T7=int, 1> T8=int, 1> T9=int, 1> Functor=int (__thiscall MyClass::* )(int,int,int,int,int,int,int,int,int) 1> ] 1> d:\myprojects\testvaltype\testvaltype\testvaltype.cpp(45) : see reference to function template instantiation 'boost::function10<R,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9>::function10<int(__thiscall MyClass::* )(int,int,int,int,int,int,int,int,int)>(Functor,int)' being compiled 1> with 1> [ 1> R=int, 1> T0=MyClass *, 1> T1=int, 1> T2=int, 1> T3=int, 1> T4=int, 1> T5=int, 1> T6=int, 1> T7=int, 1> T8=int, 1> T9=int, 1> Functor=int (__thiscall MyClass::* )(int,int,int,int,int,int,int,int,int) 1> ] 1>d:\downloads\boost_1_36_0\boost_1_36_0\boost\mem_fn.hpp(326) : warning C4180: qualifier applied to function type has no meaning; ignored 1>d:\downloads\boost_1_36_0\boost_1_36_0\boost\mem_fn.hpp(331) : warning C4180: qualifier applied to function type has no meaning; ignored 1>d:\downloads\boost_1_36_0\boost_1_36_0\boost\mem_fn.hpp(345) : warning C4180: qualifier applied to function type has no meaning; ignored 1>d:\downloads\boost_1_36_0\boost_1_36_0\boost\mem_fn.hpp(350) : warning C4180: qualifier applied to function type has no meaning; ignored 1>d:\downloads\boost_1_36_0\boost_1_36_0\boost\mem_fn.hpp(362) : warning C4180: qualifier applied to function type has no meaning; ignored 1>d:\downloads\boost_1_36_0\boost_1_36_0\boost\function\function_template.hpp(123) : error C2064: term does not evaluate to a function taking 10 arguments 1> class does not define an 'operator()' or a user defined conversion operator to a pointer-to-function or reference-to-function that takes appropriate number of arguments 1> d:\downloads\boost_1_36_0\boost_1_36_0\boost\function\function_template.hpp(117) : while compiling class template member function 'int boost::detail::function::function_obj_invoker10<FunctionObj,R,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9>::invoke(boost::detail::function::function_buffer &,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9)' 1> with 1> [ 1> FunctionObj=boost::_mfi::dm<int (int,int,int,int,int,int,int,int,int),MyClass>, 1> R=int, 1> T0=MyClass *, 1> T1=int, 1> T2=int, 1> T3=int, 1> T4=int, 1> T5=int, 1> T6=int, 1> T7=int, 1> T8=int, 1> T9=int 1> ] 1> d:\downloads\boost_1_36_0\boost_1_36_0\boost\function\function_template.hpp(413) : see reference to class template instantiation 'boost::detail::function::function_obj_invoker10<FunctionObj,R,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9>' being compiled 1> with 1> [ 1> FunctionObj=boost::_mfi::dm<int (int,int,int,int,int,int,int,int,int),MyClass>, 1> R=int, 1> T0=MyClass *, 1> T1=int, 1> T2=int, 1> T3=int, 1> T4=int, 1> T5=int, 1> T6=int, 1> T7=int, 1> T8=int, 1> T9=int 1> ] 1> d:\downloads\boost_1_36_0\boost_1_36_0\boost\function\function_template.hpp(297) : see reference to function template instantiation 'void boost::detail::function::basic_vtable10<R,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9>::init<F>(FunctionObj,boost::detail::function::function_obj_tag)' being compiled 1> with 1> [ 1> R=int, 1> T0=MyClass *, 1> T1=int, 1> T2=int, 1> T3=int, 1> T4=int, 1> T5=int, 1> T6=int, 1> T7=int, 1> T8=int, 1> T9=int, 1> F=boost::_mfi::dm<int (int,int,int,int,int,int,int,int,int),MyClass>, 1> FunctionObj=boost::_mfi::dm<int (int,int,int,int,int,int,int,int,int),MyClass> 1> ] 1> d:\downloads\boost_1_36_0\boost_1_36_0\boost\function\function_template.hpp(363) : see reference to function template instantiation 'void boost::detail::function::basic_vtable10<R,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9>::init<boost::_mfi::dm<int (int,int,int,int,int,int,int,int,int),T>>(F)' being compiled 1> with 1> [ 1> R=int, 1> T0=MyClass *, 1> T1=int, 1> T2=int, 1> T3=int, 1> T4=int, 1> T5=int, 1> T6=int, 1> T7=int, 1> T8=int, 1> T9=int, 1> T=MyClass, 1> F=boost::_mfi::dm<int (int,int,int,int,int,int,int,int,int),MyClass> 1> ] 1> d:\downloads\boost_1_36_0\boost_1_36_0\boost\function\function_template.hpp(297) : see reference to function template instantiation 'void boost::detail::function::basic_vtable10<R,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9>::init<F>(MemberPtr,boost::detail::function::member_ptr_tag)' being compiled 1> with 1> [ 1> R=int, 1> T0=MyClass *, 1> T1=int, 1> T2=int, 1> T3=int, 1> T4=int, 1> T5=int, 1> T6=int, 1> T7=int, 1> T8=int, 1> T9=int, 1> F=int (__thiscall MyClass::* )(int,int,int,int,int,int,int,int,int), 1> MemberPtr=int (__thiscall MyClass::* )(int,int,int,int,int,int,int,int,int) 1> ] 1> d:\downloads\boost_1_36_0\boost_1_36_0\boost\function\function_template.hpp(265) : see reference to function template instantiation 'void boost::detail::function::basic_vtable10<R,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9>::init<F>(F)' being compiled 1> with 1> [ 1> R=int, 1> T0=MyClass *, 1> T1=int, 1> T2=int, 1> T3=int, 1> T4=int, 1> T5=int, 1> T6=int, 1> T7=int, 1> T8=int, 1> T9=int, 1> F=int (__thiscall MyClass::* )(int,int,int,int,int,int,int,int,int) 1> ] 1> d:\downloads\boost_1_36_0\boost_1_36_0\boost\function\function_template.hpp(778) : see reference to function template instantiation 'boost::detail::function::basic_vtable10<R,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9>::basic_vtable10<Functor>(F)' being compiled 1> with 1> [ 1> R=int, 1> T0=MyClass *, 1> T1=int, 1> T2=int, 1> T3=int, 1> T4=int, 1> T5=int, 1> T6=int, 1> T7=int, 1> T8=int, 1> T9=int, 1> Functor=int (__thiscall MyClass::* )(int,int,int,int,int,int,int,int,int), 1> F=int (__thiscall MyClass::* )(int,int,int,int,int,int,int,int,int) 1> ] ------ Thank you for looking into this. Best regards, Bob Lim Get your new Email address! Grab the Email name you've always wanted before someone else does! http://mail.promotions.yahoo.com/newdomains/sg/

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Re: [Boost-users] XML optional field
by Tan, Tom (Shanghai) 24 Sep '08

24 Sep '08

I am in the similar need and am trying RapidXml(http://rapidxml.sourceforge.net/) . I am still in the middle of modifying the code to support UTF-16 with wchar_t, as far as I can tell now, it's quite well designed and easy to use, esp. with the utilities wrapping around the core parser. If you are interested in my modifications to UTF-16, leave me a message at rockonedge at gmail. >Date: Tue, 23 Sep 2008 06:56:18 +0000 >From: Emanuele Rocci <rocciemanuele(a)hotmail.com> >Subject: [Boost-users] XML optional field >Hi AllI would like to build a configuration file for my application in XML.The Configuration files includes also optional sectionsi.e. there might be properties that are not required to be defined by the user. If I use BOOST serialization to load this file, the XML format seems to me that forces every field of the XML field to be REQUIRED. Do you know if with Boost serialization for XML there is some mechanismallowing or handling optional Xml field? Kind RegardsManu _________________________________________________________________

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[filesystem] has_branch_path()
by Robert Jones 24 Sep '08

24 Sep '08

I'm upgrading the Boost release in use at work from 1.33.1 to 1.36.0, with surprisingly few issues actually, but I am stuck on one thing. There's a function in 1.33.1, has_branch_path(), for which I cannot see the equivalent functionality in 1.36. Part of my difficulty is that the 1.33.1 header declares but does not define the function, and I cannot see where the body code is! Any suggestions would be appreciated at this point. Thanks. - Rob.

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Re: [Boost-users] [test] testing protected/private methods out of test suits
by trashing＠gmx.net 24 Sep '08

24 Sep '08

>Hi, > >>I'm not sure I understand the problem. This hack works regardless of >>the library decomposition. Visibility is purely a source-code >>concern, just include #defines and the header declaring the class and >>you can access anything even if it is in a different library. > >I don't believe this is true for all compilers or in all cases. For example, >changing the member visibility in a class I worked on broke binary >compatibility in a library I built with MSVC++ 8. Similar complications may >arise when using symbol hiding techniques, such as compiler-specific symbol >visibility support, link scripts, etc I've exactly that problem with MSVC++7.x. Compiling the class_to_test in the library with protected methods and trying to access this methods out from the test_case_class by including the header and #define protected public, gives me a "symbol not found compiler error". :-/

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