January 2005 - Boost-users - lists.preview.boost.org

uBLAS, Inverse of Matrices -- Urgent
by Hossein Haeri 26 Jan '05

26 Jan '05

Dear all, Am I missing anything? Isn't there any mechinary in uBLAS which can compute the inverse of a matrix? That being the case, isn't that hilarious? Or, if there is, what's that? All of the Best, --Hossein ___________________________________________________________ ALL-NEW Yahoo! Messenger - all new features - even more fun! http://uk.messenger.yahoo.com

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(?) MPL vs boost.lambda concerning lambda expressions
by Roman 26 Jan '05

26 Jan '05

Hi. Has anybody a suggestion about MPL vs boost.lambda concerning lambda expressions?

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VC7.1 Internal Compiler error compiling Graphviz 1-32
by Alessandro Cossetto 26 Jan '05

26 Jan '05

I tried to compile graphviz library but compiling graphviz_digraph_parser.cpp (and graphviz_graph_parser.cpp ) VC7.1 gave me an internal compiler error (compiler file 'msc1.cpp', line 2701). The error occours in boost\gaph\properties.hpp at line 203: template <class Graph, class Property> struct property_map { private: typedef typename property_kind<Property>::type Kind; typedef typename detail::property_map_kind_selector<Kind>::type Selector; ==> typedef typename Selector::template bind_<Graph, Property> Bind; typedef typename Bind::type Map; public: typedef typename Map::type type; typedef typename Map::const_type const_type; }; It happens when compiler tries to resolve the graph_traits instance (line 124 in graphviz_digraph_parser.cpp) namespace graphviz { ==> typedef boost::graph_traits<GRAPHVIZ_GRAPH>::vertex_descriptor Vertex; typedef boost::graph_traits<GRAPHVIZ_GRAPH>::edge_descriptor Edge; typedef GRAPHVIZ_GRAPH Subgraph; Using GCC I compiled the library wihtout problem. I was not able to find a workarount. Can anyone help me? Alessandro

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[ANN] Interfaces Library
by Jonathan Turkanis 26 Jan '05

26 Jan '05

I am pleased to announce the much anticipated (by me) release of a preliminary version of my interfaces library. The download page and online docs are here: http://www.kangaroologic.com/interfaces/ (For fun, click on "Online Documentation" and then on the Boost logo.) The library is an implementation of Christopher Diggins's proposal to add interfaces to C++, which was posted on comp.std.c++ early last year and later was described in the C/C++ User Journal. It provides a macro-based Interface Definition Language (IDL) which can be used to define C++ class types called interfaces. An interface is a lightweight value type associated with a set of named function signatures. An interface instance can be bound at runtime to any object which implements the interface, i.e., to any object of a type with accessible non-static member functions having the same name and signature as the set of functions associated with the interface. The functions of the bound object can then be invoked through the interface instance using the "dot" operator. Binding is completely non-intrusive: the object's type need not declare any virtual functions or derive from any particular base class. Current applications include: * Non-intrusive dynamic polymorphism - interfaces can often be used in place of abstract base classes, and are sometimes much faster. * Dynamic inheritance - allows function calls to be forwarded automatically to an object specified at runtime. * Smart Interface Pointers - smart pointers which can manage the lifetime of any object whose type implements a given interface. * Smart References - like smart interface pointers, but the managed object is accessed using the dot operator. * The Object Oriented Template Library, a project in the initial stages of development, by Christopher Diggins. Planned future applications include: * Runtime reflection - will allow an interface's functions to be enumerated and looked up by name at runtime * Aspect Oriented Programming as described in a August 2004 Dr. Dobb's Journal article by Christopher Diggins. Possible future applications include: * Integration with component architectures such as COM and CORBA. * Boost.Names - by abstracting the various uses of identifiers in C++ into preprocessor generated types called names, C++ classes and functions can be constructed in a straightforward manner using template metaprogramming. Best Regards, Jonathan

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what does BOOST_NO_ARGUMENT_DEPENDENT_LOOKUP
by Kevin Lee 25 Jan '05

25 Jan '05

I need some expert's opinion on this: When I try to use the boost 1.32.0 in my work env, if i don't define this flag BOOST_NO_ARGUMENT_DEPENDENT_LOOKUP, the lib/smart_ptr/test/intrusive_ptr_test.cpp fails to compile. if i do define it, my compiler would be happy (HP aCC) on intrusive_ptr_test. My questions are: 1) What is the BOOST_NO_ARGUMENT_DEPENDENT_LOOKUP? 2) What will be the other impacts if I do define it in my code globally besides the intrusive_ptr_test? Thanks in advance! Kevin Lee ----------------------------------------- This message and its attachments may contain privileged and confidential information. If you are not the intended recipient(s), you are prohibited from printing, forwarding, saving or copying this email. If you have received this e-mail in error, please immediately notify the sender and delete this e-mail and its attachments from your computer.

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Weak_ptr lost its operator==
by Brian McCandless 25 Jan '05

25 Jan '05

Hi, I just upgraded from boost 1.29 to boost 1.32, and found that operator== for weak_ptr has been dropped between these versions. My code uses std::find to find a weak_ptr in a container. This no longer compiles (g++-3.4.1) since find uses operator==. Has anyone else encountered this kind of problem? What are some good workarounds? Could operator== be put back? Thanks, Brian

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RE: [Boost-users] Serialization problem loading a vector of items
by Foster, Gareth 25 Jan '05

25 Jan '05

I seem to remember being told that std::string was not meant to be inherited from, could it be the same in your case? -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Bill Lear Sent: 24 January 2005 13:43 To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] Serialization problem loading a vector of items On Friday, January 21, 2005 at 12:29:37 (-0600) Bill Lear writes: >I am curious why loading a vector of items from an input stream fails >using one method but works using a slightly different method. >... I have not seen a response to this post. Along similar lines, I am having problems with sub-classing the std::vector class. I've tried multiple ways, but can't get it to load (de-serialize) properly. I've used private inheritance (my first choice), public inheritance. Neither work. Here is my attempt at public inheritance: template <class T> class RingBuffer: public std::vector<T> { public: RingBuffer() : _first_ind(0), _last_ind(0) { } double first() { return (*this)[_first_ind]; } double last() { return (*this)[_last_ind]; } void add(T v) { _last_ind = (_last_ind + 1) % size(); (*this)[_last_ind] = v; if (_last_ind == _first_ind) { _first_ind = (_first_ind + 1) % size(); } } private: int _first_ind; int _last_ind; friend class boost::serialization::access; template<class Archive> void serialize(Archive& ar, const unsigned int) { ar & BOOST_SERIALIZATION_BASE_OBJECT_NVP(std::vector<T>) & BOOST_SERIALIZATION_NVP(_first_ind) & BOOST_SERIALIZATION_NVP(_last_ind); } }; As before, I can save this to a stream, but cannot get it to load from a stream. I am using boost 1.32, with gcc 3.2. Bill _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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[string_algo] replace repeated char with single instance?
by Jeff Flinn 25 Jan '05

25 Jan '05

Am I required to use regex_finder to replace repeated chars with a single instance? I'm trying to cleanup a string for use with filesystem::path, for example: C:\\abc///def\\ghi => C:\abc\def\ghi There may be mixed forward and back-slashes. These are from environment variables that apparently are required by our use of NutCracker to support legacy apps under windows. If I need to use regex_finder what are the benefits of the string_algo versus just using the regex library? Thanks, Jeff

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C++ Template Metaprogramming - factorial example
by Brad Austin 25 Jan '05

25 Jan '05

Aleksey Gurtovoy wrote: > > Also, the first argument to eval_if is supposed to be an integral > > constant, and T4 is an expression of the form mpl::equal_to<T7,T8>, > > which again is just a nullary function, not an integral constant. > > Not if T7 and T8 are Integral Constants, see > http://www.boost.org/libs/mpl/doc/refmanual/equal-to.html. Okay, I see that now. Sorry, my mistake.

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Re: C++ Template Metaprogramming - factorial example
by Brad Austin 24 Jan '05

24 Jan '05

I wrote: > I recently purchased David Abrahams' and Aleksey Gurtovoy's new book > on the MPL, "C++ Template Metaprogramming" (obviously recently since > it's only been out a couple of weeks), and am working through some of > the examples. I'm having trouble with the factorial example in section > 8.3.1, page 160: > > #include <boost/mpl/int.hpp> > #include <boost/mpl/multiplies.hpp> > #include <boost/mpl/equal.hpp> > #include <boost/mpl/eval_if.hpp> > #include <boost/mpl/prior.hpp> > #include <boost/static_assert.hpp> > > namespace mpl = boost::mpl; > > template <class N> > struct factorial > : mpl::eval_if< > mpl::equal_to<N,mpl::int_<0> > // check N == 0 > , mpl::int_<1> // 0! == 1 > , mpl::multiplies< // N! == N * (N-1)! > N > , factorial<typename mpl::prior<N>::type> > > > > > { > BOOST_STATIC_ASSERT(N::value >= 0); // for nonnegative N > }; > > There's a minor issue in that equal.hpp is (apparently) mistakenly > included instead of equal_to.hpp, but even after fixing that, I can't > get this to compile in the form in which it's written. Should it, or > is it broken? After spending some more time on this I now believe the code is broken. There's some uncertainty because mpl::multiplies<> has apparently been either renamed or replaced with mpl::times<>, and only the latter is documented in the MPL Reference Manual, so I'm not certain whether or not the two behave identically. However changing "multiplies" to "times" didn't seem to make any difference in terms of the compilation errors, so in the analysis that follows I'm making the assumption that if there is any difference, it isn't doesn't change anything relevant to the problem at hand. According to the MPL Reference Manual, in an expression of the form mpl::times<T1,T2>, T1 and T2 must meet the requirements of an integral constant, not merely the weaker requirements of a nullary metafunction. In this case T2 is an expression of the form factorial<T3>, so for this to be vaild factorial<> must model an integral constant, not merely a metafunction *returning* an integral constant. However factorial<> derives from an expression of the form mpl::eval_if<T4,T5,T6>, and doesn't add any nested types or a value of its own. Therefore factorial<> only models an integral constant if mpl::eval_if<T4,T5,T6> does, which it doesn't. mpl::eval_if<T4,T5,T6>::type models an integral constant (provided T5:type and T6::type do), but mpl::eval_if<T4,T5,T6> is merely a metafunction returning that constant. Also, the first argument to eval_if is supposed to be an integral constant, and T4 is an expression of the form mpl::equal_to<T7,T8>, which again is just a nullary function, not an integral constant. So technically this would appear to be wrong, even though eval_if doesn't seem to mind in this case. FWIW, here's the final version of factorial<> I came up with. This version models an integral constant, and accepts for its argument either an integral constant or a nullary metafunction returning an integral constant: template <class N> struct factorial : mpl::if_< typename mpl::equal_to< typename N::type, mpl::int_<0> >::type, mpl::int_<1>, mpl::times< typename N::type , factorial< typename mpl::prior<typename N::type>::type > > >::type::type {}; Anyway, is this mailing list an appropriate place to bring up issues like this? I know David and Aleksey are members, but I'm not clear on whether their book qualifies as an official Boost product.

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