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Re: [Boost-users] Some thoughts on Unary / BinaryFunctionConcept limitations
by Stephen Gross 12 Sep '05

12 Sep '05

> (1) The implementation of Unary and Binary (FunctionConcepts) > assume that > the return type is assignable ("r = f(arg)" tries to assign a value > to r). > But what if the return type is a reference? Won't the function > concept fail > to compile? Is this a bug? >That looks like a bug. >Here's a challenge for you: how would you fix this bug? In my own functor concept implementation, I used the function-pointer trick to make it work: ==== CODE ==== template<typename Func, typename Ret, typename Arg> struct special_UnaryFunctionConcept { void constraints() { Ret (Func::*x) (Arg) = Func::operator(); } }; ============== > (2) I'm implementing an NaryFunctionConcept for functors taking > more than 2 > arguments. The BOOST_CLASS_REQUIREx macro, however, appears to be > limited to > 4 types. This limits the NaryFunctionConcept to functors with up to > two > arguments. Is there a way to expand the BOOST_CLASS_REQUIREx macro > to handle > more than 4 types? >I'm sure there is a way. Can you think of a way to do it? Perhaps the >boost preprocessor library would help. Well, I was thinking that it BOOST_CLASS_REQUIREx for x > 4 could be added to the concept_check library in the same way that it is for x <= 4. Is this possible? > (3) I ran into a compiler problem when using BOOST_CLASS_REQUIREx; > when any > of the type macros have spaces or non-alphanumeric characters in > them, the > compiler reports an error. In the following example, I try to use > the macro > to require a UnaryFunctor taking a const std::string & and > returning an int. >Yes, you need to create a typedef for such types. This restriction >should be documented. I've checked in a fix to the docs. Ok, gotcha. Interesting... Thanks, --Steve

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Some thoughts on Unary / BinaryFunctionConcept limitations
by Stephen Gross 12 Sep '05

12 Sep '05

I'm just now learning about the concept_check library and how Unary and BinaryFunctionConcepts work in it. I have a few questions: (1) The implementation of Unary and Binary (FunctionConcepts) assume that the return type is assignable ("r = f(arg)" tries to assign a value to r). But what if the return type is a reference? Won't the function concept fail to compile? Is this a bug? (2) I'm implementing an NaryFunctionConcept for functors taking more than 2 arguments. The BOOST_CLASS_REQUIREx macro, however, appears to be limited to 4 types. This limits the NaryFunctionConcept to functors with up to two arguments. Is there a way to expand the BOOST_CLASS_REQUIREx macro to handle more than 4 types? (3) I ran into a compiler problem when using BOOST_CLASS_REQUIREx; when any of the type macros have spaces or non-alphanumeric characters in them, the compiler reports an error. In the following example, I try to use the macro to require a UnaryFunctor taking a const std::string & and returning an int. The code, however, fails to compile. Here's the code and error log: === CODE === template<typename T> class foo { BOOST_CLASS_REQUIRE3(T, int, const std::string &, boost, UnaryFunctionConcept); }; ============ Produces the following error (from g++): ==== ERROR LOG ==== test.cpp:42: error: parse error before `::' token test.cpp:42:80: pasting "&" and "UnaryFunctionConcept" does not give a valid preprocessing token test.cpp:42: error: parse error before `std' test.cpp:42:80: pasting "&" and "UnaryFunctionConcept" does not give a valid preprocessing token test.cpp:42:80: pasting "&" and "UnaryFunctionConcept" does not give a valid preprocessing token test.cpp:42: error: missing ';' before right brace test.cpp:42: confused by earlier errors, bailing out =================== Is this a bug? Thanks in advance for your thoughts, --Steve Stephen Gross Case Western School of Medicine Cleveland, OH "By Grabthar's hammer, by the sons of Worvan, you shall be avenged." - Dr. Lazarus

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Looking for example of BOOST_CLASS_REQUIREx
by Stephen Gross 12 Sep '05

12 Sep '05

I'm trying to find an example of how to invoke the BOOST_CLASS_REQUIREx macro (from the concept_check library). Can anyone point me in the right direction? Thanks, --Steve Stephen Gross Case Western School of Medicine Cleveland, OH "By Grabthar's hammer, by the sons of Worvan, you shall be avenged." - Dr. Lazarus

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Inheriting matrix_array
by Edward Grace 12 Sep '05

12 Sep '05

Dear all, I am evaluating aspects of the boost library. I wish to generate a simple implementation of ray transfer (ABCD) matricies, http://en.wikipedia.org/wiki/ABCD_matrix Since these matricies are 2x2 and will need multiplication, trace and other similar matrix like operations it makes sense to use: matrix_array<double,2> or boost::numeric::ublas::matrix_scalar<double> I wish to generate a ray transfer matrix class by overloading (say) matrix_array<double,2> and adding member functions such as: class rtm : boost::multi_array<double,2> { public: void setA(double val) { boost::multi_array<double,2>::operator()(0,0) = val; } }; Now, this is wrong... Essentially I just want to know something very simple.... When I inherit multi_array or any other class that I want to use the [] or (x,x) notation to access elements (subscript operators) how on earth do I do it? Your help will be greatly appreciated, this is driving me crazy! -ed

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scalar_matrix or containers and different contained types...
by Edward Grace 12 Sep '05

12 Sep '05

Dear All, Is there specifically a way I can do the following? boost::numeric::ublas::scalar_matrix<double> mD(3,3); boost::numeric::ublas::scalar_matrix<complex<double> > mC(3,3); mC = mD; Since I can do, complex<double> a; double b; a = b; without any problem why can the same thing be done with the container? Perhaps this is a more general point with C++ containers. If I can carry out a type conversion on the contained object (e.g. double -> complex<double> assuming the double is real) is there a way I can make sure the same carries through for casting of the contained objects? -ed -- Dr. Edward Grace Photonics Group, Physics Department Blackett Laboratory Imperial College SW7 2BW t: 020 759 47719 e: ej.grace(a)imperial.ac.uk w: http://ptweb.op.ph.ic.ac.uk/~graceej

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Serialization of template classes via base
by Bruno Martínez 12 Sep '05

12 Sep '05

Hi. This has been asked before here http://lists.boost.org/boost-users/2005/05/11706.php but I didn't understand the workaround. What I want is to serialize class B where class A { ... }; template<...> class B : public A { ... }; when I have an A*. The workarounds proposed were using RTTI non portably, or registering the classes each time. How would such solution look like? Regards, Bruno

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Boost post on codetools
by gast128 11 Sep '05

11 Sep '05

I have posted two articles ('File rename using boost regex and boost file system' and 'Building boost libraries for Visual Studio')on www.codetools.com on Boost issues. In this way I hope to promote Boost use in a community which is more geared towards MFC use. Wkr, me

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boost-1.33, [date_time]: missing std::localtime_r/gmtime_r
by Michael Haubenwallner 11 Sep '05

11 Sep '05

Hi, There's a problem on HP-UX (especially hppa2.0w-hp-hpux11.11) with gcc-3.3.6, where localtime_r and gmtime_r are not in namespace std. boost-1.33 itself is built with "<cxxflags>-pthread/<linkflags>-pthread" $ cat xx.cc #include <boost/date_time/posix_time/posix_time_system.hpp> $ g++ -pthread xx.cc In file included from /tools/snapshot/toolsbox-3.5.0.16rc.20050904/HP-UX/boost/include/boost/date_time/date_clock_device.hpp:12, from /tools/snapshot/toolsbox-3.5.0.16rc.20050904/HP-UX/boost/include/boost/date_time/gregorian/gregorian_types.hpp:26, from /tools/snapshot/toolsbox-3.5.0.16rc.20050904/HP-UX/boost/include/boost/date_time/posix_time/posix_time_config.hpp:14, from /tools/snapshot/toolsbox-3.5.0.16rc.20050904/HP-UX/boost/include/boost/date_time/posix_time/posix_time_system.hpp:13, from xx.cc:1: /tools/snapshot/toolsbox-3.5.0.16rc.20050904/HP-UX/boost/include/boost/date_time/c_time.hpp: In static member function `static tm* boost::date_time::c_time::localtime(const time_t*, tm*)': /tools/snapshot/toolsbox-3.5.0.16rc.20050904/HP-UX/boost/include/boost/date_time/c_time.hpp:56: error: ` localtime_r' undeclared in namespace `std' /tools/snapshot/toolsbox-3.5.0.16rc.20050904/HP-UX/boost/include/boost/date_time/c_time.hpp: In static member function `static tm* boost::date_time::c_time::gmtime(const time_t*, tm*)': /tools/snapshot/toolsbox-3.5.0.16rc.20050904/HP-UX/boost/include/boost/date_time/c_time.hpp:64: error: ` gmtime_r' undeclared in namespace `std' $ $ gcc -v Reading specs from /mnt/toolsjunk/snapshot/toolsbox-3.5.0.16rc.20050904/HP-UX/lib/gcc-lib/hppa2.0w-hp-hpux11.11/3.3.6/specs Configured with: /mnt/toolsjunk/snapshot/src/sasrvb/toolsbox-3.5.0.16rc.20050904/buildroot/gcc/gcc-3.3.6/configure --with-gnu-as --with-as=/tools/snapshot/toolsbox-3.5.0.16rc.20050904/HP-UX/hppa2.0w-hp-hpux11.11/bin/as --without-gnu-ld --with-ld=/usr/ccs/bin/ld --enable-threads=posix --with-local-prefix=/tools/snapshot/toolsbox-3.5.0.16rc.20050904/HP-UX --disable-nls --prefix=/tools/snapshot/toolsbox-3.5.0.16rc.20050904/HP-UX Thread model: posix gcc version 3.3.6 Two maybe interesting notes: 1) /usr/include/time.h only declares localtime_r/gmtime_r if '-pthread' compiler-flag is used (and therefore _REENTRANT is defined). 2) gcc-shipped <ctime> does not pull localtime_r/gmtime_r into namespace std Thanks! ~haubi -- Michael Haubenwallner SALOMON Automation GmbH Forschung & Entwicklung A-8114 Friesach bei Graz mailto:michael.haubenwallner@salomon.at http://www.salomon.at No HTML/MIME please, see http://expita.com/nomime.html

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Re: [Boost-users] [preprocessor] break "names"
by Mihalicza, Jozsef 10 Sep '05

10 Sep '05

Hi, Not a naive question, check this: http://lists.boost.org/Archives/boost/2005/03/83253.php Regards, József Mihalicza ________________________________ Feladó: boost-users-bounces(a)lists.boost.org meghatalmazó: Felipe Magno de Almeida Hi, Maybe it is a naive question, but I've been researching a little and couldnt find an answer to this(not an affirmative and nor negative): Is it possible to have such usages: SOME_MACRO(hello world) or SOME_MACRO("hello world") (or something that doesnt have much "characters overhead", like using space for every character) and have the expansion result in this: h e l l o w o r l d or even better: 'h','e','l','l','o', ' ', 'w', 'o', 'r', 'l', 'd' Well, what I'm trying to find is if it is possible to give something to a macro and the macro create an vector_c with all the characters inside it. Like: SOME_MACRO(Hello World) and expand to: boost::mpl::vector<char, 'H','e','l','l','o',' ','W','o','r','l','d'> Thanks in advance, -- Felipe Magno de Almeida Developer from synergy and Computer Science student from State University of Campinas(UNICAMP). Unicamp: http://www.ic.unicamp.br Synergy: http://www.synergy.com.br "There is no dark side of the moon really. Matter of fact it's all dark." _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Serialization segfaulting
by Dmitriy Morozov 10 Sep '05

10 Sep '05

Hi, I'm having problems with boost serialization library. There are two cases in which it is segfaulting on me. One is during a register_type() call, but we can discuss that one later. Another one which I am trying to debug right now is when I am trying to serialize a large binary tree (lots of pointers all over the place, sometimes pointing at themselves, sometimes at 0, sometimes jumping all over the tree). I am not quite sure how to approach the debugging of this issue since for some reason I am not able to step into the boost serialization routines themselves (but I'm not so good with the debugger). The actual segfault as given by DDD is: Program received signal SIGSEGV, Segmentation fault. 0x40075b75 in std::_Rb_tree<boost::archive::detail::basic_oarchive_impl::cobject_type, boost::archive::detail::basic_oarchive_impl::cobject_type, std::_Identity<boost::archive::detail::basic_oarchive_impl::cobject_type>, std::less<boost::archive::detail::basic_oarchive_impl::cobject_type>, std::allocator<boost::archive::detail::basic_oarchive_impl::cobject_type> >::insert_unique(boost::archive::detail::basic_oarchive_impl::cobject_type const&) () from /usr/lib/libboost_serialization.so.1.33.0 Any advice is appreciated. Best, Dmitriy P.S. On a completely unrelated note, when the abstract base class is a template, the BOOST_IS_ABSTRACT macro is not applicable. It would be helpful if the documentation listed the chunk of code that needs to be added in that case. It's pretty easy to find it in the header files (is_abstract.hpp), but it may be helpful to just list it.

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