August 2002 - Boost-users - lists.preview.boost.org

Re: [Boost-Users] Re: Logical AND
by dan.ellis＠sophos.com 05 Aug '02

05 Aug '02

On 08/03/2002 05:04:26 PM news wrote: > > I need a match on "a AND is" when searching a sentence like "This is a > > test". >Regular expressions match sequences of characters. Your match says to match >a string when both of 2 different matching possibilities exist anywhere in >the string. To do this you must use 2 separate regular expression matches >separating them by the normal C++ "&&" operator. Maybe I'm misunderstanding what's wanted, but wouldn't is.*a do what he wants? Or if they need to be matched in either order: (is.*a)|(a.*is) It doesn't scale well, of course. -- Dan Ellis, Software Engineer, Sophos Anti-Virus Email: dan.ellis(a)sophos.com, DDI: 01235 540204 Real Business/CBI Growing Business Awards: Company of the Year Tel: 01235 559933, Web: http://www.sophos.com/

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uBLAS Observation: terrible execution speed for prod(matrix,prod(matrix,prod(matrix,matrix)))
by Walter Bowen 05 Aug '02

05 Aug '02

Hi, I am new to uBLAS. I am looking to see if it will be useful for my application (I develop 6-Degrees-of-freedom flight simulations used to analyze avionics systems.) I have benchmarked a few lines of code with RogueWave's Math.h++ (testing for execution speed) and made the following observation. Observation 1) For matrix products of two small (~3-by-3) matrices ( i.e., prod(smallMat1, smallMat2) ) uBLAS executes MUCH FASTER than Math.h++. Observation 2) For matrix produces of two large matrices (100 by 100) uBLAS and Math.h++ give similar execuation speed. Obervation 3) (This is the kicker...) for strung-together matrix products like "Mat1 * Mat2 * Mat3 * Mat4 * Mat5", which I am implementing as "prod(Mat1, prod(Mat2, prod( Mat3, prod(Mat4,Mat5) ) ) ) Math.h++ is MUCH MUCH FASTER than uBLAS. -- by ~2 orders OF MAGNITUDE! I believe that this is a characteristic of the scalability of template expressions. My question is this: Is there a way I an instruct uBLAS not to use template expressions when for strung-together matrix products? Regards, Walt

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Logical AND
by Mads M.P. 05 Aug '02

05 Aug '02

I've been looking for a parameter like "AND" when using regular expressions (from boost 1.28). I need a match on "a AND is" when searching a sentence like "This is a test". Is there a way to create such a search string by using regular expressions ? Regards Mads c(a)medit.dk

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Boost 1.28 Regex and VC6 link problem
by Edward Diener 04 Aug '02

04 Aug '02

Using Boost 1.28 and regex I get linker errors regarding raw_storage. I believe someone has brought this up before but I didn't save the previous answer. error LNK2001: unresolved external symbol "public: class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> __fastcall boost::re_detail::raw_storage<class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >::allocator(void)const " error LNK2001: unresolved external symbol "public: class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> __fastcall boost::re_detail::raw_storage<class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >::allocator(void)const " error LNK2001: unresolved external symbol "public: __thiscall boost::re_detail::raw_storage<class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >::raw_storage<class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >(class re_detail::detail::allocator_adapter<char,class boost::detail::simple_alloc> const &)" error LNK2001: unresolved external symbol "public: __thiscall boost::re_detail::raw_storage<class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >::raw_storage<class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >(class re_detail::detail::allocator_adapter<char,class boost::detail::simple_alloc> const &)" error LNK2001: unresolved external symbol "public: void * __fastcall boost::re_detail::raw_storage<class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >::insert(unsigned int,unsigned int)" error LNK2001: unresolved external symbol "public: void __fastcall boost::re_detail::raw_storage<class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >::resize(unsigned int)" It seems to be related to these lines in instances.hpp template class re_detail::raw_storage< BOOST_DEFAULT_ALLOCATOR BOOST_REGEX_CHAR_T) >; template class BOOST_REGEX_DECL re_detail::raw_storage<BOOST_DEFAULT_ALLOCATOR(BOOST_REGEX_CHAR_T) >; Are these lines in error ? Should one or both of them be removed ? My guess is that the line with BOOST_REGEX_DECL needs to be removed.

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Problems with mpl::find and std library
by Tanton Gibbs 03 Aug '02

03 Aug '02

I had a problem with using mpl::find and the std::find at the same time. Basically, my compiler, Compaq C++ V6.5-026, notes an ambiguity in find.hpp between the find_if that it uses and the find_if in the STL. I changed the line that reads struct find : find_if< Sequence, same_as<T> > {}; to be struct find : mpl::find_if< Sequence, same_as<T> > {}; and it works fine. I'm not sure if this is a compiler bug or if we need to find other occurences like this one and fix them. Any help is appreciated. Tanton

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boost.python - from_python for obj.__class__
by Nikolay Mladenov 02 Aug '02

02 Aug '02

Hi, I have exported some classes to python with boost.python, and now I am wondering: Does any body know how can I convert obj.__class__ (of an exported object from C++) to a class specific value( for example typeid(corespondong_cpp_class) )? Thanks in advance, Nikolay

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bjam issue related to boost::python
by Srivatsan Raghavan 02 Aug '02

02 Aug '02

hi all , i created a c++ extension module using python which worked fine.. then i wanted to embed a call to PyRun_SimpleFile in another app, and the script i was calling is attempting to use my extension module but i was getting telling me that the interpreter wasn't initialized after much searching, research, and work with msvc's Dependency Walker i narrowed it down to the fact that boost_python_debug.dll is trying to link to the release version of python22.dll , whereas it should be linking to python22_d.dll (which unfortunately does not come with the python installer , that has to be compiled manually ) at any rate, how can the boost::python Jamfile be modified to try this check when it comes boost::python ? --vat ==.sig== Evil requires nothing more to win than that good men do nothing

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[BGL] Vertex removal without iterator invalidation?
by Erik Arner 01 Aug '02

01 Aug '02

Yet another question from the BGL newbie... I understand that performing remove_vertex() on graphs with vertexList=vecS will result in invalidated itarors and descriptors for the graph. However, some toy examples i made suggest that if I remove a vertex in such a graph, the vertex descriptors and vertex iterators for vertices with *lower* ID than the removed vertex remain valid after removal, while those for higher ID vertices are invalidated. Is this a true feature of a graph with Vertexlist=vecS, or is my observation a mere coincidence? Is it safe to write code that exploits this "feature"? If it indeed is a feature, I can construct a sorted list of vertices to remove, and remove the vertices in descending order in an easy fashion. If it is not a feature, any suggestions on how to perform this task i.e. removing a list of vertices while keeping the VertexList type vecS? Thanks, Erik

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collection container
by Bohdan 01 Aug '02

01 Aug '02

Has boost any plans on creating container, that holds data by pointer, not by value? Rationale: It is impossible to use normally vector<...> for types that do not have copy constructor. Interface of vector< shared_ptr<...> > doesn't seems to be very convenient( for example with std::algorithms ). And most of all it is not good idea to show vector< shared_ptr<...> > interface to user of my lib, that wants to have container::iterator with normal behavior. AFAIK majority of existing libraries have/need such container ? As to me it is strange that neither stl nor boost have such class. I'm missing 'something' and there are important reasons for not doing this ?

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Creating groups of regular expressions
by cyndi_r2002 01 Aug '02

01 Aug '02

Hi, I have started using Regex++ and like it a lot but is there a way to use grouping constructs using Regex++ / any alternative that would provide the same functionality? Thanks, Cyndi

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