June 2003 - Boost-users - lists.preview.boost.org

enable_if part of boost ?
by Anders Moe 22 Jun '03

22 Jun '03

Hi all. After reading about enable_if in CUJ I decided to see if this was present in boost, which it is, sort of, in function_base.hpp. However, it seems to exist in function::, and my impression is that its not really an official boost component. Is this correct ? Regards, Anders.

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boost::thread and .NET
by Bruno Martínez 22 Jun '03

22 Jun '03

Hello, I was wondering what outcome to expect from mixing .NET managed c++ and boost::thread. According to ms's docs a c++ application compiles for .net unchanged, but what kind of api can it expect? What may happen if I try to execute .net code in a thread created by boost::thread? Thanks in advance, Bruno Martinez ------------------------------------------------------ Internet en Uruguay es http://www.internet.com.uy

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boost::spirit and asts
by Dan Nuffer 21 Jun '03

21 Jun '03

Hi, I'm trying to write a grammar for a scripting language, and to do this I'm building an AST of each expression. I have this working fine, for the most part, but I've run into a problem -- I can't seem to figure out how to put right-to-left associative operators into the tree properly. I had this as a guess, but I'm really not sure: r = value | value >> root_node_d[ch_p('=')] >> r; _____________________________________________________________ <a href="http://www.gamedev.net">GameDev.net Email Service</a> - "Plenty of 1's and 0's" _____________________________________________________________ Select your own custom email address for FREE! Get you(a)yourchoice.com, No Ads, 6MB, IMAP, POP, SMTP & more! http://www.everyone.net/selectmail?campaign=tag

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Using Ublas for eigenvalue problems.
by Amit Bhatia 20 Jun '03

20 Jun '03

Hello everyone, I am working on trying to use ublas for finding the eigenvalues and eigenvectors of a positive definite matrix. I am not too sure whether this can be done in ublas. I have seen that there are calls for solving system of equations as well as doing rank updates, but still am not sure whether this could be done "safely" (eigenvalues getting close to zero) and efficiently ? I have read at a couple of places the advice' of using prewritten routines for this rather than trying to write one's own for this non trivial problem. I am a newbie! Any advice/suggestion/past experience with the same will be most welcome. regards, amit.

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BGL: Immutable vertex/edge descriptors?
by Tarjei Knapstad 19 Jun '03

19 Jun '03

If I use vecS for EdgeList and/or VertexList, whenever I remove a edge/vertex this also affects any vertex/edge with a higher numbered descriptor, i.e. removing vertex 0 results in subtracting 1 from every other vertex descriptor. I'm making a graphical editor for a structure that is represented as a graph, and to quickly determine which vertex/edge is selected and should be edited in any way I figure the best way is to keep a copy of the edge/vertex descriptor with the graphical object that is supposed to represent just that edge/vertex. If I use vecS this soon becomes a real pain if I have to update edge/vertex descriptors everywhere whenever I remove some part of the graph. I could of course add my own immutable descriptors as properties in the graph, but that just reverses the problem - I'll have to map these back to the 'real' descriptors when I want to modify/access the graph. I assume I can use listS to store both edges and vertices to solve this problem in that the descriptors become pointers which are not disturbed when I remove a vertex/edge? What about setS? If I go with listS I end up with another concern regarding the performance benchmarks on traversal in the BGL book. Is the code used to create those benchmarks available anywhere so that I can do a re-evaluation with later compiler versions? I hope someone can shed some light here. Thanks, -- Tarjei

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gcc3.2.3 regex STLPort-4.5.3
by david 19 Jun '03

19 Jun '03

Hi, I have some undefined references (see below). It looks like I have to use a compiler definition? Is it possible to use regex with gcc.3.2.3? In function `bool boost::re_detail::query_match_aux undefined reference to `boost::reg_expression<char, boost::regex_traits<char>, _STL::allocator<char> >::~reg_expression [in-charge]()' ( in function: In function `bool boost::re_detail::query_match_aux<char const*, _STL::allocator<char>, char, boost::regex_traits<char>, _STL::allocator<char> >(char const*, char const*, boost::match_results<char const*, _STL::allocator<char> >&, boost::reg_expression<char, boost::regex_traits<char>, _STL::allocator<char> > const&, unsigned, boost::re_detail::_priv_match_data<char const*, _STL::allocator<char> >&, char const**)': ) Bye

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_MSC_VER not defined on mingw32
by omnizionic 19 Jun '03

19 Jun '03

I downloaded and unzipped the latest boost (1.30.0) and tried using it in a simple file like this: #include <boost/smart_ptr.hpp> int main() { boost::shared_ptr<int> p(new int); return 0; } I compiled it, and got the following output: gcc -c -Wall -W -Werror -Wundef -Wfloat-equal -Wshadow -Wpointer-arith -Wcast-qual -Wwrite-strings -Wconversion -idirafter c: /programming/lib/kakefisk -Ic:/programming/boost_1_30_0 -O3 -fomit-frame-pointer -ffast-math btest.cpp -o btest.o In file included from c:/programming/boost_1_30_0/boost/scoped_ptr. hpp:16, from c:/programming/boost_1_30_0/boost/smart_ptr.hpp: 17, from btest.cpp:1: c:/programming/boost_1_30_0/boost/checked_delete.hpp:4:5: "_MSC_VER" is not defined In file included from c:/programming/boost_1_30_0/boost/shared_ptr. hpp:26, from c:/programming/boost_1_30_0/boost/smart_ptr.hpp: 19, from btest.cpp:1: c:/programming/boost_1_30_0/boost/throw_exception.hpp:4:5: "_MSC_VER" is not defined In file included from c:/programming/boost_1_30_0/boost/shared_ptr. hpp:27, from c:/programming/boost_1_30_0/boost/smart_ptr.hpp: 19, from btest.cpp:1: c:/programming/boost_1_30_0/boost/detail/shared_count.hpp:4:5: "_MSC_VER" is not defined In file included from c: /programming/boost_1_30_0/boost/detail/shared_count.hpp:27, from c:/programming/boost_1_30_0/boost/shared_ptr. hpp:27, from c:/programming/boost_1_30_0/boost/smart_ptr.hpp: 19, from btest.cpp:1: c:/programming/boost_1_30_0/boost/detail/lightweight_mutex.hpp:4:5: "_MSC_VER" is not defined In file included from c: /programming/boost_1_30_0/boost/detail/lightweight_mutex.hpp:68, from c: /programming/boost_1_30_0/boost/detail/shared_count.hpp:27, from c:/programming/boost_1_30_0/boost/shared_ptr. hpp:27, from c:/programming/boost_1_30_0/boost/smart_ptr.hpp: 19, from btest.cpp:1: c:/programming/boost_1_30_0/boost/detail/lwm_nop.hpp:4:5: "_MSC_VER" is not defined In file included from c:/programming/boost_1_30_0/boost/smart_ptr.hpp: 19, from btest.cpp:1: c:/programming/boost_1_30_0/boost/shared_ptr.hpp:390:60: "BOOST_MSVC" is not defined mingw32-make.exe: *** [btest.o] Error 1 I also tried compiling after setting the following in <boost/config/user.hpp> with no apparent effect: // define this to locate a compiler config file: #define BOOST_COMPILER_CONFIG <boost/config/compiler/gcc.hpp> // define this to locate a stdlib config file: #define BOOST_STDLIB_CONFIG <boost/config/stdlib/libstdcpp3.hpp> // define this to locate a platform config file: #define BOOST_PLATFORM_CONFIG <boost/config/platform/win32.hpp> Does anyone have any ideas as to where the problem might lie?

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Newbie: typle_basic.hpp gives compilation error.
by somlin71 19 Jun '03

19 Jun '03

(Trying to use the tuple function for the first time.) When adding #include "boost/tuple/tuple_comparison.hpp" a compilation gives the following errors: [C++ Error] tuple_basic.hpp(158): E2434 Template declaration missing template parameters ('template<...>') [C++ Error] tuple_basic.hpp(158): E2238 Multiple declaration for 'element<N,T>' [C++ Error] tuple_basic.hpp(143): E2344 Earlier declaration of 'element<N,T>'

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Re: Newbie COMPILATION PROBLEM
by louis.lebrun＠free.fr 19 Jun '03

19 Jun '03

Thanks for your reply. But in fact since I download BOOST 1.30, the problem didn't occure anymore. Louis -----Message d'origine----- De : gbiddison [mailto:gbiddison@velocity11.com] Envoyé : mercredi 18 juin 2003 18:49 À : Boost-Users(a)yahoogroups.com Objet : [Boost-Users] Re: Newbie COMPILATION PROBLEM Hi, I've seen this problem while trying to include boost\python.hpp in a recent project. The problem only seemed to occur for me if I included boost\python.hpp in the precompiled header file (stdafx.h). If I moved the #include so that it wasn't precompiled, the INTERNAL COMPILER ERROR (I have an english version of MSVC7) disappeared. Could this be the problem you are experiencing? Does anyone know of a better solution for this? It would be nice to be able to precompile boost headers ... Giles --- In Boost-Users(a)yahoogroups.com, "lebrun_l" <louis.lebrun@f...> wrote: > Hi All, > > I'am using > Microsoft Visual C++ .NET 7.0 > > I can't manage to compile a single example from the graph library. > > I get the following message : > > c:\BGL\boost_1_25_1\boost\type_traits\cv_traits.hpp(188): fatal > error C1001: ERREUR INTERNE DU COMPILATEUR > (fichier du compilateur 'msc1.cpp', ligne 2844) > Choisissez la commande Support technique du menu ? (Aide) > de Visual C++ > ou ouvrez le fichier d'aide du Support technique pour plus > d'informations > > Thank's in advance for your help. > > Louis

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RE: [Boost-Users] RE: A newbie question.
by Jim.Hyslop 18 Jun '03

18 Jun '03

Amit Bhatia wrote: > Thanks Jim, > I have another doubt which is due to my lack of any previous > experience > with things like templates(Well I am seeing the kind of > programming used in > BOOST for the first time :( ). I was looking at the random > number library, > and it mentions IntType a number of times. I can't figure out > where to look > for it? So is it a generic thing or is it part of some other > BOOST library. It's right under your nose, as they say ;=) The IntType is a parameter to the template, so it's whatever you tell the compiler you want it to be. Taking a snip at (ahem) random from one of the files: template<class IntType, IntType a, IntType c, IntType m> class linear_congruential { public: typedef IntType result_type; static const IntType multiplier = a; static const IntType increment = c; static const IntType modulus = m; static const bool has_fixed_range = true; static const result_type min_value; static const result_type max_value; explicit linear_congruential_fixed(IntType x0 = 1); // compiler-generated copy constructor and assignment operator are fine void seed(IntType x0); IntType operator()(); }; At this point, we don't know exactly what an "IntType" is. However, on the next lines: typedef random::linear_congruential<long, 16807L, 0, 2147483647L, 1043618065L> minstd_rand0; typedef random::linear_congruential<long, 48271L, 0, 2147483647L, 399268537L> minstd_rand; These typedefs provide typedefs that fix IntType as a long, with the various parameters converted to long. More detailed explanation about templates is beyond the scope of this list - it's really quite a basic topic. I'd suggest picking up a good C++ tutorial book. Koenig and Moo's "Accelerated C++" comes highly recommended (I haven't read it myself, but I have yet to hear a negative review of it). -- Jim

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