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question about BOOST_CONCEPT_REQUIRES
by Robert Ramey 18 Aug '13

18 Aug '13

#include "boost/concept/requires.hpp" #include "boost/concept_check.hpp" #include <iterator> template <typename T> BOOST_CONCEPT_REQUIRES(( ((boost::ForwardIterator<T>)) ((boost::LessThanComparable< typename std::iterator_traits<T>::value_type >)) ), (void) ) bubble_sort(T begin, T end); if I compile this with gcc 4.5.3 I get some error messages which I don't expect to see: z:\BoostRelease\libs\serialization\test\test_zmisc.cpp:13:1: error: * cannot appear in a constant-expression z:\BoostRelease\libs\serialization\test\test_zmisc.cpp:13:1: error: a call to a constructor cannot appear in a constant-expression z:\BoostRelease\libs\serialization\test\test_zmisc.cpp:13:1: error: template argument 1 is invalid z:\BoostRelease\libs\serialization\test\test_zmisc.cpp:13:1: error: template argument 1 is invalid z:\BoostRelease\libs\serialization\test\test_zmisc.cpp:14:28: error: invalid type in declaration before ; token Note this occurs even before the template declaration is invoked. Any insight would be appreciated. Robert Ramey

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[math] Solving quadratic, cubic & quartic functions
by Fredrik Orderud 18 Aug '13

18 Aug '13

I've run into an eigenvalue problem where I need to compute the roots of a cubic polynomial. This is a straight-forward problem to solve analytically, but I want to avoid reinventing the wheel if possible. The boost::math doc mentions some root-finding functions, but they all seem to be iterative - which should not be neccesary in my case. Can anyone tell me if boost includes any functions for analytically computing the roots of quadratic, cubic and possibly quartic polynomials? Thanks in advance, Fredrik Orderud

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framework for invoking func-ptrs with different argument numbers
by firespot 18 Aug '13

18 Aug '13

Hi, Consider the following task: Given a -) pointer to a function, and -) an iterator range with elements of type void *, the function-ptr shall be called with all the elements in the range as arguments. So conceptionally something like this: template <typename Func, typename Iter> void make_call(Func, Iter begin, Iter end) { int n = std::distance(begin, end); (*Func) (*(begin), *(begin + 1), *(begin + 2), ..., *(begin + n - 1)) } The interface (function declaration) here is +- what I want, the implementation shown of course is dummy-code not working. Does boost provide a more or less easy way to get this implementation smoothly done? C++ is 2003 version, so code must be compatible with e.g. VS 2008.. Note that I would know in principle a way how to do implement it myself, which involves the creation of a separate class for each number of arguments, but that's precisely what I want to avoid and I hope that wheel has already been invented in some boost-library :) thanks and regards, Thomas

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Boost::MPI Enum Bug
by Barker, Daniel 16 Aug '13

16 Aug '13

Hi All, I am writing some software which is using boost::mpi. I think I have run into a slight bug (or at least a limitation) with the library. It is very similar to this question on S/O: http://stackoverflow.com/questions/8127442/sending-complex-data-with-skelet… I am sending/receiving a class which has an enum member variable. Using normal send and receive was working fine but then I tried to use the skeleton/content mechanism and now my program failed with a segfault on calling `communicator::isend` with the content. While compiling, the compiler issued a warning about an uninitizialized variable: /home/dan/boost_1_54_0/boost/archive/detail/iserializer.hpp:539:9: warning: ‘i’ may be used uninitialized in this function [-Wuninitialized] I looked and noticed this was a function for handling enum values so I commented out the enum variable from my serialization member function and then the sending worked as expected. It looks like the same cause (using addresses of temporaries) as in the S/O question. If anyone is interested I have written a small example exhibiting this issue. I have a couple of questions regarding this: * Is it possible to get around this limitation/bug?^ * Is boost::mpi still being actively developed? I've found a few discussions about this but none really lead anywhere. Thanks, Dan ^ Perhaps it would be possible to write a custom serialize function for any enums but this would be a pain if one used many different enums.

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[container / move] return a container of non-movables from a function in C++03
by Adam Romanek 16 Aug '13

16 Aug '13

Hi, I'd like to return a container of non-movables from a function in C++03 with no success. here is a sample code that does not compile for me: #include <boost/container/vector.hpp> #include <boost/move/utility.hpp> class non_copyable { BOOST_MOVABLE_BUT_NOT_COPYABLE(non_copyable) public: non_copyable(){} non_copyable(BOOST_RV_REF(non_copyable)) {} non_copyable& operator=(BOOST_RV_REF(non_copyable)) { return *this; } }; typedef boost::container::vector<non_copyable> nc_vector; nc_vector create() { return nc_vector(); } int main () { nc_vector v(create()); return 0; } The compiler says: (...) /home/A.Romanek/tmp/boost/boost_1_54_0/boost/preprocessor/iteration/detail/local.hpp:37:1: error: passing ‘const non_copyable’ as ‘this’ argument of ‘non_copyable::operator boost::rv<non_copyable>&()’ discards qualifiers [-fpermissive] (...) See below for a full compiler output. I use Boost v1.54 and gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3. Is it a bug? Here is the full compiler output: In file included from /home/A.Romanek/tmp/boost/boost_1_54_0/boost/container/allocator_traits.hpp:388:0, from /home/A.Romanek/tmp/boost/boost_1_54_0/boost/container/detail/utilities.hpp:28, from /home/A.Romanek/tmp/boost/boost_1_54_0/boost/container/vector.hpp:37, from main.cpp:1: /home/A.Romanek/tmp/boost/boost_1_54_0/boost/preprocessor/iteration/detail/local.hpp: In static member function ‘static void boost::container::allocator_traits<Alloc>::priv_construct_dispatch2(boost::false_type, Alloc&, T*, const P0&) [with T = non_copyable, P0 = non_copyable, Alloc = std::allocator<non_copyable>, boost::false_type = boost::integral_constant<bool, false>]’: /home/A.Romanek/tmp/boost/boost_1_54_0/boost/preprocessor/iteration/detail/local.hpp:37:1: instantiated from ‘static void boost::container::allocator_traits<Alloc>::priv_construct(boost::true_type, Alloc&, T*, const P0&) [with T = non_copyable, P0 = non_copyable, Alloc = std::allocator<non_copyable>, boost::true_type = boost::integral_constant<bool, true>]’ /home/A.Romanek/tmp/boost/boost_1_54_0/boost/preprocessor/iteration/detail/local.hpp:37:1: instantiated from ‘static void boost::container::allocator_traits<Alloc>::construct(Alloc&, T*, const P0&) [with T = non_copyable, P0 = non_copyable, Alloc = std::allocator<non_copyable>]’ /home/A.Romanek/tmp/boost/boost_1_54_0/boost/container/detail/utilities.hpp:555:10: instantiated from ‘typename boost::container::container_detail::disable_if_memcpy_copy_constructible<I, F, F>::type boost::container::uninitialized_copy_alloc_n(A&, I, typename std::iterator_traits<_II>::difference_type, F) [with A = std::allocator<non_copyable>, I = non_copyable*, F = non_copyable*, typename boost::container::container_detail::disable_if_memcpy_copy_constructible<I, F, F>::type = non_copyable*, typename std::iterator_traits<_II>::difference_type = int]’ /home/A.Romanek/tmp/boost/boost_1_54_0/boost/container/vector.hpp:734:7: instantiated from ‘boost::container::vector<T, Allocator>::vector(const boost::container::vector<T, Allocator>&) [with T = non_copyable, Allocator = std::allocator<non_copyable>, boost::container::vector<T, Allocator> = boost::container::vector<non_copyable>]’ main.cpp:16:20: instantiated from here /home/A.Romanek/tmp/boost/boost_1_54_0/boost/preprocessor/iteration/detail/local.hpp:37:1: error: passing ‘const non_copyable’ as ‘this’ argument of ‘non_copyable::operator boost::rv<non_copyable>&()’ discards qualifiers [-fpermissive] WBR, Adam Romanek

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cross-compilation x86_64-w64-ming32: undefined reference to `InterlockedIncrement'
by Frédéric Bron 16 Aug '13

16 Aug '13

Hi, I am trying to cross-compile from linux 64 bits to windows 64 bits. I am using fedora 19 with -std=c++11 and boost 1.53.0 that comes with fedora. The compiler is x86_64-w64-mingw32-g++. The compile flags I use: -O3 -DNDEBUG -DWINDOWS -std=c++11 -Wall -Wextra -pipe -ffloat-store -DBOOST_DISABLE_ASSERTS -DBOOST_FILESYSTEM_VERSION=3 -DBOOST_FILESYSTEM_NO_DEPRECATED -DBOOST_THREAD_USE_LIB and a typical link command: $ x86_64-w64-mingw32-g++ -o foo.exe bar1.o bar2.o -Wl,--enable-auto-import -static -lboost_system-mt -lboost_filesystem-mt -lboost_thread-mt -lboost_chrono-mt -mthreads I then get the following errors (each line multiple times with different .text+0x###): /usr/x86_64-w64-mingw32/sys-root/mingw/lib/../lib/libboost_thread-mt.a(thread.o):(.text+0x286): undefined reference to `InterlockedIncrement' /usr/x86_64-w64-mingw32/sys-root/mingw/lib/../lib/libboost_thread-mt.a(thread.o):(.text+0x3e7): undefined reference to `InterlockedDecrement' /usr/lib64/gcc/x86_64-w64-mingw32/4.8.1/../../../../x86_64-w64-mingw32/bin/ld: /usr/x86_64-w64-mingw32/sys-root/mingw/lib/../lib/libboost_thread-mt.a(thread.o): bad reloc address 0x8 in section `.data' collect2: error: ld returned 1 exit status make: *** [mgw64-release/bin/transpose.exe] Erreur 1 I see that this may come from <boost/detail/interlocked.hpp> but I have no idea what this header is used for. This is what remains after the pre-processor phase (g++ -E): # 1 "/usr/x86_64-w64-mingw32/sys-root/mingw/include/boost/detail/interlocked.hpp" 1 3 4 # 137 "/usr/x86_64-w64-mingw32/sys-root/mingw/include/boost/detail/interlocked.hpp" 3 4 namespace boost { namespace detail { extern "C" long InterlockedIncrement( long volatile * ); extern "C" long InterlockedDecrement( long volatile * ); extern "C" long InterlockedCompareExchange( long volatile *, long, long ); extern "C" long InterlockedExchange( long volatile *, long ); extern "C" long InterlockedExchangeAdd( long volatile *, long ); extern "C" void* InterlockedCompareExchangePointer( void* volatile *, void*, void* ); extern "C" void* InterlockedExchangePointer( void* volatile *, void* ); } } Note that targeting windows 32 bits works allright but the result of the pre-processor phase is slightly different: # 1 "/usr/i686-w64-mingw32/sys-root/mingw/include/boost/detail/interlocked.hpp" 1 3 4 # 137 "/usr/i686-w64-mingw32/sys-root/mingw/include/boost/detail/interlocked.hpp" 3 4 namespace boost { namespace detail { extern "C" __attribute__((dllimport)) long __attribute__((__stdcall__)) InterlockedIncrement( long volatile * ); extern "C" __attribute__((dllimport)) long __attribute__((__stdcall__)) InterlockedDecrement( long volatile * ); extern "C" __attribute__((dllimport)) long __attribute__((__stdcall__)) InterlockedCompareExchange( long volatile *, long, long ); extern "C" __attribute__((dllimport)) long __attribute__((__stdcall__)) InterlockedExchange( long volatile *, long ); extern "C" __attribute__((dllimport)) long __attribute__((__stdcall__)) InterlockedExchangeAdd( long volatile *, long ); } } Frédéric

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Re: [Boost-users] Serialising templates with smart pointers....
by Marcus MacWilliam 16 Aug '13

16 Aug '13

I think my question is how do I add a serialize method to an interface class, which will invoke the serialize method on the derived sub-class. class Interface { public: virtual void aVirtual() = 0; private: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { call serialize on derived class } }; class Derived : Interface virtual void aVirtual() { // Do something } private: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & m_data; } }; -- Marcus A.T MacWilliam, Senior Software Engineer. 1Spatial Ltd. Tel: +44 (0)1223 420414, ext 2289, Mob: +44 (0)7803 706597. E-Mail: marcus.macwilliam(a)1spatial.com Skype:marcus.macwilliam Tennyson House, 7 Cambridge Business Park, Cambridge, CB4 0WZ. Registered in England No. 4785688, VAT Reg. No. 135539408. Website: http://www.1spatial.com/ E-mail: info(a)1spatial.com

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Re: [Boost-users] compiling error after upgrading from boost 1.33.1 to boost 1.36.0
by Henson Huang 16 Aug '13

16 Aug '13

Hi Igor, I'm using "new" to allocate the object. My code looks like, In hpp file, typedef Std::map<Std::string, int> MyMap; class MyClass { ........... private boost::shared_ptr< MyMap > m_myMap; } In cpp file MyClass::MyClass() { m_ myMap.reset(new MyMap); } MyClass::~MyClass() { m_ myMap.reset(); } Best regards, Hua

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compiling error after upgrading from boost 1.33.1 to boost 1.36.0
by Henson Huang 15 Aug '13

15 Aug '13

Hello, I upgraded the boost library in my workstation from boost 1.33.1 to boost 1.36.0. When I compiled my program, I got following errors, /usr/include/boost/detail/sp_counted_impl.hpp:192: error: template argument 3 is invalid /usr/include/boost/detail/sp_counted_impl.hpp:198: error: 'a' has not been declared /usr/include/boost/detail/sp_counted_impl.hpp: In constructor 'boost::detail::sp_counted_impl_pda<P, D, <template-parameter-1-3> >::sp_counted_impl_pda(P, D, int)': /usr/include/boost/detail/sp_counted_impl.hpp:198: error: 'a' was not declared in this scope /usr/include/boost/detail/sp_counted_impl.hpp: In member function 'virtual void boost::detail::sp_counted_impl_pda<P, D, <template-parameter-1-3> >::destroy()': /usr/include/boost/detail/sp_counted_impl.hpp:209: error: expected nested-name-specifier before 'template' /usr/include/boost/detail/sp_counted_impl.hpp:209: error: expected unqualified-id before 'template' /usr/include/boost/detail/sp_counted_impl.hpp:211: error: 'A2' was not declared in this scope /usr/include/boost/detail/sp_counted_impl.hpp:211: error: expected `;' before 'a2' /usr/include/boost/detail/sp_counted_impl.hpp:214: error: 'a2' was not declared in this scope I'm using gcc 4.1.2. Below is the file sp_counted_impl.hpp line 181 ~ 221, template<class P, class D, class A> class sp_counted_impl_pda: public sp_counted_base { private: P p_; // copy constructor must not throw D d_; // copy constructor must not throw A a_; // copy constructor must not throw sp_counted_impl_pda( sp_counted_impl_pda const & ); sp_counted_impl_pda & operator= ( sp_counted_impl_pda const & ); typedef sp_counted_impl_pda<P, D, A> this_type; //This is the line 192 public: // pre: d( p ) must not throw sp_counted_impl_pda( P p, D d, A a ): p_( p ), d_( d ), a_( a ) { } virtual void dispose() // nothrow { d_( p_ ); } virtual void destroy() // nothrow { typedef typename A::template rebind< this_type >::other A2; A2 a2( a_ ); this->~this_type(); a2.deallocate( this, 1 ); } virtual void * get_deleter( detail::sp_typeinfo const & ti ) { return ti == BOOST_SP_TYPEID( D )? &reinterpret_cast<char&>( d_ ): 0; } }; Please help to see how to resolve these errors. Best regards, Hua

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Re: [Boost-users] Boost-users Digest, Vol 3537, Issue 1
by Rick Aurbach 15 Aug '13

15 Aug '13

Michael, It sounds to me like you're making this altogether too complicated. Don't focus on the software; focus on the science. The size of the "degree" unit is the same for Kelvin and Celsius. (I.e., if the temperature changes by 1 degree K, it changes by exactly 1 degree C.) The only this that is different between Kelvin and Celsius is the zero point. For Kelvin, 0 degrees is absolute zero and there are no negative values of temperature. (Well, that's not quite right, but you'll never encounter the exceptions.) For Celsius, 0 degrees is the freezing point of water at sea level. To convert between Kelvin and Celcius, just add or subtract a constant. That constant has a value of 273.15. That is, you can make a dimensionally-safe conversion from Kelvin to Celcius by subtracting 273.15. Converting from Celsius to Kelvin by adding 273.15. Cheers, Rick Aurbach Aurbach & Associates, Inc. On Aug 15, 2013, at 9:24 AM, boost-users-request(a)lists.boost.org<mailto:boost-users-request@lists.boost.org> wrote: From: Michael Powell <mwpowellhtx(a)gmail.com<mailto:mwpowellhtx@gmail.com>> Subject: [Boost-users] [units] "Simple" conversion from Kelvin to Celsius Date: August 14, 2013 2:39:56 PM CDT To: "boost-users(a)lists.boost.org<mailto:boost-users@lists.boost.org>" <boost-users(a)lists.boost.org<mailto:boost-users@lists.boost.org>> Reply-To: "boost-users(a)lists.boost.org<mailto:boost-users@lists.boost.org>" <boost-users(a)lists.boost.org<mailto:boost-users@lists.boost.org>> Hello, It's been a couple of years since I've done any work with Boost.Units, and I am finding that I want to make a dimensionally-safe conversion from Kelvin to Celsius. I've got an I2C controller that reports in Kelvin, but I want to report it to the end-user in Celsius. The examples I am finding seem to "almost" fit the bill, but I am having a difficult time extrapolating a sane conversion. First, would help if I understood what the Boost.Units SI (my assumed base-system) base-temperature units were. I gather Fahrenheit? Or is it indeed Kelvin? I could be mistaken. Thank you... Regards, Michael Powell

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